Sensor Size Doesn't Matter. Unless It Does?

One of the things that has confused me quite a bit during my research of APS-C vs FF cameras has been the debate over whether FF cameras are needed. I literally cannot find a single page or blog post that doesn't say something to the effect of "maybe sensor sizes mattered in the past, they don't now though". On forums, the camps are well-divided: Fuji fans are convinced that their APS-C X-Trans sensor is God's work, and Sony fans scoff at the notion that anything can touch FF.
To make it even more confusing, using the DPreview studio tool, Sony FF cameras *as well as the Sony a6000* clearly outresolve the XT-1 at every ISO level. But the images I see out of Fuji cameras are very good, as good as any Sony. Maybe this doesn't matter too much.
Is there any way for me to know whether FF will make a difference for me, without just buying one and shooting it?

 

Pictures from my 6 MP Canon 10 D are very good. Why? Because I took them.

Apart from that: size matters. A larger sensor and/or larger photosytes are always better. Next question is if this matters
but that's to all of us to decide individually. In the end it largely depends on the use of the pictures. But in general full frame is better than a cropped sensor, Medium format is better than full frame. And to make it a bit more complicated every new generation sensors tend to be better than previous ones. Is today's full frame better than a 5 yr old cropped sensor? Depends largely on the person behind the camera.

 

OK, but the logical progression of "it's the person behind the camera" is that we're all shooting Instax. Clearly there's a quality line that cameras must cross - is it just a matter of getting the cheapest possible camera that will produce the minimum acceptable image quality?

 

Hi Evan. The first poster said it well. Basically, the larger the sensor (and individual pixels), the better the light-gathering capability, and
the larger one can enlarge the image before noise (digital "grain") appears in the output.
This is simply physics, and folks can debate this all they want, but I doubt the laws of physics will change as a result. That said however,
exactly how well an image or print addresses one's needs and purposes is rather subjective, and probably the underlying cause of this
debate. But in general, if you know you'll never shoot in extremely low light OR make poster-size prints (30x40 inches and up), then most
modern APS-C or M4/3 system should suffice. For example, the Olympus System with its micro 4/3 sensor (not to mention excellent
lenses), is quite satisfactory for many photographers' needs, Unless you regularly produce very large exhibition prints, or shoot in
exceedingly low "available" light. For those specific purposes, I think it's common knowledge that a FF System (such as Sony a7 Series,
or of course high-end Nikon/Canon) would be better suited to the task. Again, just my "educated" opinion.

 

The vast majority of people appear to be using DSLRs use a kit lens and shoot with flash when light is low and then post their photos on Facebook and send them around in email. So in those vast majority of cases, sensor size is irrelevant regardless of what one thinks of the technical arguments.
FWIW, I printed some architectural photos at 16x20. The prints all looked similar. When I went to find the original file on one of them, I discovered that it was shot with a crop camera. All the rest were full-frame. I looked carefully but there was no way to tell, even at unreasonable viewing distances. The complete process tends to reduce the effects of individual factors, in my experience.

 

My take on it doesn't differ from the previous posters in general. There may be other reasons to select one over the other though. If you want to use older lenses designed for FF bodies (film or digital), and utilize the available full angle of capture (sorry I couldn't think of the right word) rather than a crop, there's no choice but to use full frame bodies. I have a treasure chest of these lenses collected over the years, and, for the most part, I don't give a whit about the full wide capture, so I use them on an APS-C or Micro 4/3 body - they're less expensive usually as well. I no longer make poster sized enlargements, so while the larger pixel bodies don'tmean much...I use medium format if I need gigantic enlargements. Weight of gear is also an important consideration for some....especially those who tend to take the kitchen sink with them on vacations or hiking trips...every ounce counts, so APS-C or M4/3 becomes a real consideration. If I was professionally shooting these days, yes I'd probably go full frame...but most of my stuff is for personal enjoyment or to share on the web, so it is pretty irrelevant which I use...although I'd probably love a Leica M9.

 

This is a confusing conclusion. FF is better, apparently, but not better enough to make it worth recommending in nearly any non-professional situation. Would it be the correct conclusion to draw that the vast majority of FF purchasers are deluded, then?

 

The technique tends to overshadow the gear, IMO. These days just about all cameras have a great output. Anyway, whatever chest beating or $$$$'s one spends on the gear is meaningless....unless it's put to proper use....and the results will be relevant.
One has to tailor the camera to their particular needs. The info is out there.
Les

 

Evan, no, I think that for "non-professionals", it simply boils down to a balance between one's photographic "needs",
ergonomics, and wallet size . Personally, as a non-pro who occasionally sells work, I shoot Nikon APS-C, which
satisfies for most needs, however, I admittedly have G.A.S., and would love to dabble in the Sony a7 system. Bottom line:
Don't fret too much about gear, and just enjoy your photography! (Most modern systems, from m4/3 to FF and beyond,
are quite good. Only pixel peepers like me are on a constant quest for better image quality. Happy Shooting!

 

For portraits outdoors, although I have a MFT camera I pick up the 70-200 2,8 on full frame.
Matter of preference whether the better bokeh is worth the extra weight,Here a well known pro goes farthur still with a 300 2.8;
https://www.youtube.com/watch?v=U90BQUpISBs&list=TLKZEhpDdXk1Y

 

"Is there any way for me to know whether FF will make a difference for me, without just buying one and shooting it?"​

1. Do you prefer to shoot fast lenses wide open for shallow depth of field to isolate subjects from the surroundings? If yes, full frame may suit you better.
   
   Or do you prefer to have more of the photo in reasonably sharp focus? If so, APS or smaller sensors may suit you better. I usually prefer smaller sensor cameras for this reason - I usually want more in focus, not less. Smaller sensor cameras can accomplish this without stopping down as much, which is great for zone focused snapshots.
   
   
2. Do you shoot a lot of handheld low light candid photos or photos of non-stationary subjects/objects? If so, full frame would probably suit you better. If not, there are several APS and a few Micro 4:3 cameras with good low light performance for occasional or less critical use.
   
   
3. Do you shoot a lot of wide angle stuff where edge and corner sharpness without light falloff/vignetting is critical? If yes, full frame may suit you better. But improvements in ultra-wides for APS and Micro 4:3 have narrowed this gap. It's not as big an issue as it was a few years ago.

That's about all I can think of.
My main reason for considering full frame would be for the low light, high ISO advantage - I mean at or above ISO 6400, where even the best APS camera performance fades. I can't think of anything else that would matter much.
The nebulous IQ factor isn't much of an issue for me. I get excellent 11x14 prints from a teensy sensor Ricoh GRD4, even up to ISO 800, that rival my 35mm Tri-X prints in that squishy aesthetic we call apparent sharpness.

 

As others said, the larger the photosites, the better S/N ratio, and it's a matter of physics. Now, most of us don't need the best single piece of technology on the market. A Large Format sensor would definitely provide the best S/N quality for my photos, but 1) costs too much and 2) makes equipment too large and heavy. That's why APS-C is the good trade off for me, also because in the past few years APS-C sensors reached a very very good S/N ratio. I can say APS-C reached the sufficiency level for me, at the point that other factors - such as weight - are more relevant.
For what concerns Fuji. I'm a Sony owner, but I'm not a fanboy. I evaluated Fuji a couple of years ago, in the end I picked Sony for a number of subjective reasons - or, better, objective reasons weighted by subjective priorities. But I think Fuji stuff is excellent. I suspect DPreview ratings are biased because their software for demosaicing the files produced by the Fuji Trans sensor is not good enough. Probably even older versions of Lightroom were not good enough. There's clearly plenty of excellent photos around taken with Fuji, that would be ok for me.
There's anyway an issue that wasn't commented before (*): DoF and bokeh. The smaller the sensor, the deeper the DoF is, given the same ƒ number (and "equivalent" focal length). A 100mm µ43 ƒ/2.8 lens produces roughly the same DoF of a 200mm FF ƒ/5.6 lens (framing the same subject), thus the out-of-focus areas are less blurred. In fact, lens manufacturers for the µ43 systems make also lenses with very large apertures - e.g. ƒ/0.95, for people for which bokeh is fundamental. Unfortunately, they tend to be expensive and jeopardise the ligthweight factor. In general, the more you are interested in photos with large out-of-focus areas and isolated subjects (e.g. portraits or some kind of wildlife shots), the more chances FF fits better your needs ... _for this particular feature_; clearly also in this case there are other features to evaluate. I do also wildlife stuff where I like to isolate the subject, but - again - FF is too expensive and too heavy for me. So I live with APS-C. µ43 would probably be not good for me.
BTW, this bokeh thing is the most relevant limitation of photos taken with smartphones, since their sensors are even smaller. OTOH, for the typical casual photo made with smartphones (i.e. selfies), this is not a problem; it even makes focusing less critical and sharper.
You can find a fresh review of a long lens for µ43, also dealing with the bokeh topic, at PhotoZone:
http://www.photozone.de/m43/945_olympus40150f28pro
In particular there are some wildlife sample photos that explain the problem. As the review author shows, you can still render excellent bokeh with a µ43 system, but you need a stronger physical separation of the subject from the background.
(*) Well, at least at the moment I started to write my comment. I see that others in the meantime pointed out the bokeh thing.

 

If as myself you are not bothered about that dreadful 'B' word and simply put areas of my photos out of focus in editing as required I ignore comments earlier BUT seeing the work on another forum of somebody who recently changed from a 15Mp bridge camera to a 20Mp APS-C I would suggest that the difference is there and it is the size of the pixel which is making the difference that 'bigger is better' ... if assuming that is what you look for in a photos opposed to what the photo is saying.
I changed bridge to MFT a couple of years ago and immediately noted the improvement though some of that was 12<16Mp though now I believe without checking it is pixel size.

 

Lex, you've made some excellent points regarding the merits of FF v. APS-C/m4/3. I think that if we knew more about the
OP's subject and output media/size preferences, we could give more specific advice as well. Like you, I too, prefer more
in focus than less, particularly in my landscape and product shots.
If I may comment on your preference for smaller formats when "wanting more of the photo in reasonably sharp focus", I
might add that if one uses a FF system, and makes use of the hyperfocal distance when focusing, then one can maximize
depth of field for a given aperture, meaning that you wouldn't necessarily need to stop down to f/16 (thus minimizing
sharpness-robbing effects of diffraction) to achieve "reasonable sharpness" in your image. That technique, plus using
wider angle lenses or moving farther back from your subject, will serve to obtain greater overall image sharpness.

 

Awhile back dpreview listed a system of comparing sensor size to number of pixels and in it the DSLR came out tops and bridge cameras worst ... though some conservative bridge cameras were 'not too bad'. Funnilly I had a Canon P&S which rated with the DSLRs ... it was only 3.3Mp but given everything equal turned out excellent exhibition images [ A3 ] ... mind you back then DSLR's were only 5Mp anyway

 

Regarding my preference for greater DOF, I'm thinking mostly in terms of available light candids of people. I prefer a busy milieu. Some folks don't.
With a teensy sensor P&S digicam with 6mm lens (28mm equivalent) usually f/4 or even f/2.8 in a pinch is stopped down enough for adequate DOF. In tricky scenarios such as late day city candids -- bright periphery but lots of deep shade -- the light is usually around EV 11.
With my APS sensor cameras and 18mm lens, that usually works out to 1/500th @ f/8 for adequate DOF and minimizing motion blur (including my own camera shake) for quick snaps, which requires an ISO around 1600. Not bad with my Fuji X-A1, but ISO 1600 is getting into terrible territory with my ancient Nikon D2H which is very noisy above 800.
With a teensy sensor digicam like the Ricoh GRD4, the same hyperfocal setting is f/4 at ISO 400; maybe even f/2.8 at ISO 200 (shutter speed still at 1/500th). Very workable for most teensy sensor digicams, including many smartphone cams made during the past couple of years.
Just depends on the photographer's preferences for subjects, situations and shooting styles. For landscapes it'd be a whole nuther set of priorities. Ditto for street photographers who prefer shallow DOF to isolate subjects against a busy background - whole different situation, in which the full frame camera would shine.

 

My choice of Sony A7II was simple. With this new toy, my collection of Leica, Hasselblad and Contarex lenses becomes alive again. I used them with m43 cameras years ago but with a cropping factor to which I didn't prefer. I am comfortable with manual focus as I shoot 4x5 and 8x10 formats for 25 years.

 

Would it be the correct conclusion to draw that the vast majority of FF purchasers are deluded, then?​

A lot of them probably yes actually; I certainly hear a lot of people who tell me they want to "upgrade to FF because then I won't have this noise problem anymore" like FF can shoot a black cat in a dark room, and APS-C is only good in daylight. Yes, larger sensors have an advantage there, but let's not overdo it. Latest generations APS-C sensors are already spectacularly good in low light, it's not all that limiting anymore. Certainly for me personally, the reasons to shoot a full frame camera have nothing to do with high ISO.
DoF indeed. All of my lenses render nicer, smoother on the larger sensor. Being manual focus on a system with mirror they're easier to focus too - so, the point is: I chose the system to match my lenses best and get the best from those. And with a preference for wide-ish fast lenses, full frame offers a lot more choice than APS-C systems tend to do. In fact, only Fuji manages to cater for that (18mm f/2, 23mm f/1.4 etc.).
Studio scenes and test shots for resolution aren't all that relevant, even the (relatively) miniscule differences between the fuji X-Trans or the Sony Exmor sensor don't matter all that much. If you've got the really seriously good lenses that have their distinct rendering, and you know their tricks and manage to use them right (*): magic starts to happen. That's why most that replied in this thread probably have far more money tied up in lenses than they have in bodies.
So, given that all mirrorless systems can be adapted quite easily to use a wide array of lenses, including high quality magic stuff, I'd get the body that fits my hands, logic and budget best, and start investigating lenses instead.
___
(*) Yes, the photographer still matters most - even if gear has to match a certain quality level, it's still also about learning how to get the best out of it.

 

Size does matter in sensors. its just that there are trade-offs and that's where you have to choose. Technology closes some of the gaps in IQ amongst sensor sizes, but all things being equal, the larger the sensor/photosytes/ per resolution does matter. MF digital cameras even better.

 

I think sensor size will always matter. Just like cars, there is no replacement for displacement. Larger sensors produce better images. Go to Imaging Resource's Comparometer and compare two cameras with different sensor sizes but the same resolution: the 7D MKII vs the 6D. At all ISOs the image quality from the 6D is noticeably better than the 7D.

 

Sensor size matters only for the clearness and crispness of the image.
It does not matter at all for the message that's behind the picture and the story you want to bring across.
Just my humble opinion.

 

True Monika.

 

For many interesting opinions (facts?) on this question google "photosite size". Also Erwin Puts has an
article on Leica's take on this topic and the number of pixels on a ff sensor for maximum quality.

 

The eternal question: Does size matter? ;-)

 

Just like cars, there is no replacement for displacement.​

Sure there is. It's called Tesla.

Larger sensors produce better images.​

Better in what way? Is this "better" visible on Facebook where most photos end up?

 

If FF didn't matter the sales of MF digital cameras might be non-existant.

 

Is this "better" visible on Facebook where most photos end up?
Absolutely, for portraits the blurriness of the background, whatever you call it, is one of the few things where difference is visible on a computer screen.

 

Sensor size equates to lens size and to system size. I cannot speak to the laws of physics but images are almost all good enough for general purpose photography like landscape and portrait. The difference between APS-C and micro four thirds is overstated as well, since it is not like laying tiles in the garage where square footage is the thing. I looked at the overall thing and decided to go with micro four thirds. No legacy Canon EF lenses etc... So far so good. Each model year yields a little more of all the things discussed so far. To some ideal goal I cannot testify from experiece. All seem to have good points and a few tradeoffs. I like light weight and lens choices. Big items.. And good zooms. And nice quality JPEGs. Ergo no fuss over the sensor business at this point. Starting out again, I think I would still go with micro four thirds. And try to not confuse myself too much. Meaning whatever you choose may be just fine for you. No fatal errors possible. Or do you shoot sports or live concerts exclusively? I can handle the shallow DOF thing if I need to do that too...not so hard.

 

I have digital from the year 2004, first small cameras with small sensors. with them, I made big posters (up to 60 x 120 cm), Made photographic books of high quality, also used with my hands, for more creativity, HD graduated filters or polarizer, or HD filters with these small cameras (no filter threads), between 6 to 10 Megapixels. As some say, the important is who is behind the camera. Later on, I bought full frame cameras (Nikon) with high quality lenses, yes, it helps for more creativity, Low light photography, wildlife, etc. but just lately I bought a mirrorless of Fujifilm and I am sure it will also help for some creativity for new books. You can make high qualith photos with any camera, with any sensor, small or big. It only depends on you behind the camera.

 

"blurriness of the background, whatever you call it, is one of the few things where difference is visible on a computer screen" Alan J.​

Alan and others are on point with this main "Bokeh" benefit in picking the FF format.
It's not just sharpness & clarity that photographers choose a 4x5 over 35mm.
It's also the unique "pop" or "3D effect" achieved; mainly due to less DOF in the higher mag "normal" lens.

2nd main point, if you're afflicted with G.A.S., then you definitely have many lenses that can be
fully resurrected by using the easier to deal with Sony FF cameras.

 

An important consideration for me was the depth of field to which I was accustomed. As I had spent decades with 35mm film cameras (not to mention 120 earlier), the depth of field I got from my Olympus digital SLRs was much too great some of the time (although at other times it was welcome). Therefore I used digital for some kinds of work and 35mm film for work where selective focus was necessary or desirable. By a happy coincidence, an affordable Sony A7 became available when I was forced to abandon film because having it processed had become too difficult.

 

What really matters, assuming the goal is to produce compelling photographs that speak strongly, is one's eye, imagination, understanding light and composition, etc. Most everything else is relatively and mostly mice-nuts (outside of certain edge conditions).

 

OMG. I would love a new 5Ds 50MP camera because I use a loupe and I love sharpness and I am a sharpness freak. I
have never, ever needed that kind of sharpness in actual practice. I have been photographing seriously since 1997.
Not so seriously for far longer. I have used medium format, full frame, 1.6 and 1.5 crop sensors for landscapes,
weddings, news, sports, portraits, etc. I have a number 18x24s hanging in my house that were taken with Bronica,
645s, Sony, 35mm film, 6.3 crop, 12.8 crop, 18.0 crop and 20-22 Megapixel sensors. I defy you to look at those pictures and tell which is which. I showed a lot with 6.3MP sensor pictures and won a few awards. I have taken one or two decent pictures with
my phone. Equipment is so good these days that I think this is hair splitting at the margins at its best. So if you are a
sharpness freak like me or you are fascinated with bokeh, or make really big pictures, or if a big camera serves your
ego, or have a real need or desire then by all means go for a full frame. All the rest is optional and becoming more so every year.

 

"Its the photographer, not the camera" must be true. Why else do we see all the best photographers using iPhones?

 

Why else do we see all the best photographers using iPhones?​

Plenty of them do.
Here's a great interview with one of them.

 

OP said: "Is there any way for me to know whether FF will make a difference for me, without just buying one and shooting it?"
Usually people who ask these questions don't need a full frame camera...why? because if they needed one they would know the reasons and the benefits of getting one. So maybe FF is not your best chance and you be better off with something less pricey, thus having the opportunity to get good glass which will make THE difference. Cheers!

 

late to the discussion, but i dont think sensor size impacts the ability to visualize an image, compose and frame it, and capture that image. that said, given a choice between a new Nikon d7200 and a refurbished d610 at roughly the same price, one has to decide whether 50% more reach with telephoto lenses and a better AF system are worth the tradeoff in high-ISO ability, shallower DoF, and no crop-sensor magnifier. it's all pretty subjective. But then, no one buys a sensor alone, you buy a camera with a sensor which is part of a system. So it's impossible to discuss the relative merits of sensors without also discussing how those sensors will be deployed, and with what lenses.
Personally, i own both full-frame and APS-C bodies and a variety of lenses. i see these as tools to help me achieve an objective: capturing the image i see in my mind before the shutter is pressed. When i see the results, what becomes clear is that a clean file is a clean file. if i pay attention to technique, it really doesn't matter what camera i use to obtain that result. That said, there are some technical limitations inherent in APS-C, as well as physical limitations inherent in FF. i dont really use my Fujis for shooting moving things or extreme low-light, but they're great for going light and casual photography. By the same token, i avoid lugging around a FF body and several heavy lenses in situations where that would be overkill. And i enjoy shooting @ 35mm, whether its on an X100 or a D3s. i think it helps me as a photographer to restrict myself to a single focal length at times, and to 'see' in 35mm. To be able to connect with the camera and feel like its an extension of my eye is much more important to me than which camera was used to get that shot. i want my photography to be intuitive and second-nature, and that only comes from shooting a lot.
But to answer the OP's question, i have to agree with Panayotis: if you dont already know why you need FF, you probably dont need FF at all.

 

Plenty of them do.​

Naturally there are exceptions. Some of us go out with one lens and explore its potential. I've shot informal projects with nothing but a cell phone. However anything I can do with a cell phone, including uploading to the web, I can do with a real camera, plus a lot more. It would be foolish to go to a job without a Plan B, and I can't recall when I haven't been surprised by something in the field.
For me, a full frame camera meets current and future needs, Plan A and Plan B. I prefer it mostly because I can use a mixture of film and digital lenses I've accumulated over the years, in the same manner to which I'm accustomed. In particular, I can take wide angle shots without relying on ridiculously tiny or specialized lenses. A FF camera, like a Sony A7, is no larger than its APS-C competitors with similar capability. All else being equal, I can expect more resolution, lower noise, or a compromise thereof than with a smaller sensor. Hardly anything remains equal for long, and the A7Rii promises both more pixels and better ISO capability than most of its competitors.

 

>>> "Its the photographer, not the camera" must be true.
I think you're onto something, but imagine that could be confirmed experimentally.
Take a camera, any camera, and first give it to a beginning photographer that knows how to operate a camera, but has not yet learned to see or how to evaluate light. And then give it to an experienced photographer with a body of compelling/strong photographs. After a day's use in the hands of each, in a large city or national park, examine the results from each person.

 

I prefer it mostly because I can use a mixture of film and digital lenses I've accumulated over the years​

okay, but a beginner with no film-era experience moving up from an iPhone or P&S might have completely different criteria. and if we're getting technical, legacy lenses can be put to good use on many different sensor formats.

at the end of the day, what sensor format you're using isn't the deciding factor in whether your images are strong/compelling. it's whether you captured a strong/compelling image. i personally like to shoot with different cameras and different formats, depending on what im shooting. reason being, i dont ever want to be bored by photography or feel like it's become rote. if ive been shooting a lot of PJ stuff and fast-paced documentary/events, sometimes i'll force myself to take the opposite approach, and shoot slow, measured landscape pics on a tripod. in that case, methodology is far more important than what particular camera i used.

 

Naturally there are exceptions.​

There are plenty of exceptions. However, when you used the term "all" you denied that. Make up your mind.

I can do with a real camera​

Anything that can take a photo is a "real camera."

 

None of us can speak for all users. One approach is to organize and express our own reasons for making a choice, especially an expensive choice. My own experience is that we soon demand more of our equipment than we expected up front. If the OP has a reasonably clear notion of his needs and goals, then help his decision making process by suggesting parameters for consideration, and their relevance.
Legacy lenses may be a way to start, as well as extend your photographic journey. Used SLR lenses are plentiful and often inexpensive, and can work well enough to get by. For example, 21-24 mm lenses are a lot easier to find and cheaper than 14-16 mm lenses you need to get the same angle of view on an APS-C sensor. A used $250 Nikkor wide-angle may actually work better on a Sony A7 than a Leica lens costing three or four (or 20) times as much.

 

One of the top-rated (by critics) movies in theaters right now is Tangerine. It was shot on a phone.
There are people who think photography is about equipment and people who think it's about what it says. Nobody's equipment gets hung up on walls after they die, no matter how good it is. Photographs that say something, on the other hand, do.

 

Legacy lenses may be a way to start, as well as extend your photographic journey. Used SLR lenses are plentiful and often inexpensive, and can work well enough to get by. For example, 21-24 mm lenses are a lot easier to find and cheaper than 14-16 mm lenses you need to get the same angle of view on an APS-C sensor.​

i don't necessarily agree with this. One huge problem is that film era lenses work erratically and inconsistently on modern digital cameras and must be evaluated individually. this is especially true of today's high-MP sensors. as Thom Hogan wrote last week in an article about recommended Nikon lenses for FX,

"So what am I not recommending? 14mm f/2.8, 16mm f/2.8, 17-35mm f/2.8, 20mm f/2.8, 24-85mm f/2.8-4, 24mm f/2.8, 28-300mm f/3.5-5.6, 28mm f/2.8, 35mm f/2, 50mm f/1.2, 50mm f/1.4 or 1.8 (except for the 16mp cameras), 70-300mm f/4-5.6, 70-300mm f/4.5-5.6, 80-200mm f/2.8, 105mm f/2, 135mm f/2, 180mm f/2.8, 200-400mm f/4. Note that I would certainly recommend a few of these lenses for DX users (the 200-400mm f/4 comes to mind). Many of these lenses were designed before digital and are showing their age, some were designed in the digital age but just don’t resonate with the high megapixel count cameras, and a few have other liabilities "​

So it's hard to take such general and non-specific advice at face value when it doesnt reflect the actual user experience in most cases. granted, if you're using a D700 or Df and not a D610 or D800, lens flaws wont be as exposed, but the lack of modern coatings makes these lenses much more prone to flare. all things considered, the best lenses for modern digital cameras are the ones specifically designed for them.
the other point, about a scarcity of wide angle primes for APS-C, only really holds true for specific camera makers, like Nikon. Fuji, for instance, has a 14/2.8 and a 16/1.4. it's true an old Nikon 20 or 24mm will be cheaper, but also slower and not as sharp at open apertures. and even on a FF camera, a Nikon 20/1.8 G is going to be a better choice than any older Nikon 20mm. if we're including wide-angle zooms, the picture gets even better for APS-C shooters and even m4/3 users, with a variety of OEM and 3rd-party lenses which start at 14/15 or 18mm equivalents-- most of which can also be had for less $$ than their full-frame equivalents.

A used $250 Nikkor wide-angle may actually work better on a Sony A7 than a Leica lens costing three or four (or 20) times as much.​

Actually, if you look at this thread, Nikkor wide-angles don't have a stellar reputation on the A7. And really, this comment is so general and vague as to be utterly meaningless, since there's no analysis to support that speculative claim.
So i think there's a bit of disingenuousness in projecting one's personal tastes as a truism for every shooter out there which isn't acknowledged by contradicting yourself ("My own experience is that we..."). legacy lenses can work well with mirrorless cameras, or not so well. it depends on a number of factors, including implementation of focus peaking (since AF will often be unavailable), and the optical design of the lens itself. also, anytime you are using an adapter, you are introducing another variable into the equation. you might be delighted, or you may be disappointed with the results; there's simply no one size fits all rule here.

 

just getting back to the OP's original question--XT1 or A7 series--it's not that simple. with the XT1, you have a solid 16mp APS-C body which punches above its weight. But more importantly, you have a more complete lens lineup of both primes and zooms for everything except maybe extreme low-light work (above ISO 5000) and sports.
with the Sonys, you have four full-frame sensor sizes--12mp, 24mp, 36mp, and 42mp--which will impact your lens choices. And those lens choices: a so-so kit lens which is unremarkable for a full frame sensor, a better but pricey Zeiss-branded standard zoom which only goes to f/4, a 70-200 which only goes to f/4, and an incomplete series of primes. if you're doing low-light work, you give back much of the sensor's advantage with the slower lenses, although the Sony 55/1.8 and just-released 28/2 and 35/1.4 mitigate this somewhat. the bottom line is that a complete Sony system is probably gonna be considerably more expensive -- you're paying a bigger premium for that full frame glass. for example, the Sony 35/1.4 is $1600; the Fuji 23/1.4 is $900. the Sony 16-35 is $1350; the Fuji 10-24 is $1000. Also, the best Sony camera for low-light, the A7s, is "only" 12mp, so if you were planning on cropping and/or huge enlargements, that might not be the best choice. also have to consider that only the 24mp A7II and 42mp A7RII have in-body stabilization. Overall, the Fuji XT1 offers a slightly better price to performance ratio and a more complete lens selection than Sony, but the Sony's are better for video and offer mega-resolution, which you may or may not need. if you're just posting images on Flickr and social media, it might be overkill. if you're making prints for gallery exhibition and have deep pockets, the Sony offers medium format-quality in a smaller package. of course, you could save money and just shoot medium format film.

 

I have a Nikon 20/2.8, 24/2, and 24/2.8 wide angle primes, which perform reasonably well on a Sony A7ii. In particular they are sharper in the corners than my Leica Summaron 35/2.8, Summicron 50/2, Zeiss Biogon 28/2.8 and Biogon 35/2.8. The long back focus length (~ 50 mm) of Nikon lenses produces a telecentric effect, so that the angle of incidence at the sensor is much less than with a Biogon 28 or 35, which approaches within about 6 mm.
The Leica and Zeiss ZM lenses perform much better in the center than any Nikon SLR lens, but the overall performance is not as good. I published a comparison of 50 mm lenses on pnet a short time ago (http://www.photo.net/digital-camera-forum/00dMNG). The photos are in my portfolio in a folder by that name.
The Sony A7ii and Zeiss lenses is very close to medium format performance, but perhaps not quite there yet. The 42 MP A7Rii will probably tip the scales. The in-body image stabilization of the m2 version is good enough I am nearly divorced from my tripod.
For the best corner to corner performance, you would want a Sony/Zeiss or Zeiss lens designed for the A7 with the 2 mm cover glass in mind.

 

The discussion of legacy lenses reminds me of the film-era Nikkor Series E 75-150mm f/3.5 lenses I tested a few years ago. This lens had been highly rated and recommended by some in the past despite being a Series E lens.
I have two copies and I decided to see how well they did on my D7000 with 16MP. Both lenses were carefully focused in live view on a fence about 2400 feet (~730m) away in a neighborhood of trees and houses viewed from a higher vantage point.
Both copies were wonderfully sharp and clear in the center, but their sharpness severely deteriorated out towards the edges even though they were being used on a crop-sensor camera. I searched in vain for evidence of field curvature, but could not find any distance where the lenses were sharp at a pixel level towards the edges. They just were not sharp away from the center at that degree of magnification. The lenses would probably have done fine on 35mm film enlarged to 8" x 12" (~20cm x 30cm), but could not hack it on a sensor that's low resolution by today's standards.

 

using Leicas on Sony cameras is a known issue, sometimes resulting in color shift. but their uneven performance doesnt mean older Nikons are any better on those bodies. legacy lenses dont have modern flare coatings and werent designed for digital cameras, so weird things can happen.

 

One of the top-rated (by critics) movies in theaters right now is Tangerine. It was shot on a phone.
There are people who think photography is about equipment and people who think it's about what it says. Nobody's equipment gets hung up on walls after they die, no matter how good it is. Photographs that say something, on the other hand, do.​

While I'm perfectly aware than a smartphone is a very good photographic tool for _certain_ kind of photos, the citation is totally inappropriate. I don't know about Tangerine, but I'm talking in general: given that most of the media stuff around is just crap (sure, including mega-productions with big bucks in equipment), the ultimate marketing tools for moviemakers is "hey, I just made this with an iPhone". Which totally contradicts the second paragraph, that people and ideas should be more important than equipment.
The relationship between technology and creativity is well known: visual arts need technology for make their products. Sometimes they need a very broad range of possibilities, sometimes they need only very simple things. The fact that there are indeed masterpieces made with a black pencil and white paper doesn't mean that Raffaello and Michelangelo didn't need a very sophisticated palette of colours for their masterpieces. Another example in painting is that the French Impressionists couldn't have created a new visual style without a new array of technologies (most notably, thin brushes, portable canvas facilities - no en plein air otherwise - and new colours).
Bringing it back to our topic: the OP asked whether FF is needed. The answer has been given: there are certain kinds of shots that are harder, or even impossible to do, with smaller sensor. Maybe one wants them, so he needs FF. Maybe one doesn't want, so he doesn't need FF. It's clear that every photo or movie done with an iPhone can't make use of shallow DoF. There is a number of movies, ranging from Ingmar Bergman's to Sergio Leone's (just to make two very different, random citations), that couldn't have been made - and couldn't be made today - with an iPhone.

 

Unless you need to shoot in near darkness or need extremely shallow depth of field, crop sensor cameras can do very, very well these days.
I have two big Nikons, but I just got back from shooting a Nikon D5200 ($309 new on eBay) with a used Sigma 17-50 f/2.8 OS lens, and I have to say that I am in love.
--Lannie

 

I don't know about Tangerine, but I'm talking in general: given that most of the media stuff around is just crap (sure, including mega-productions with big bucks in equipment), the ultimate marketing tools for moviemakers is "hey, I just made this with an iPhone".​

Since you don't know it, it might be better not to comment on it. It's not being marketed as a movie made on a phone. And it is getting tremendous reviews for its content, which is far more important, like any still photograph, on what is inside, not what is used to create it.

There is a number of movies, ranging from Ingmar Bergman's to Sergio Leone's (just to make two very different, random citations), that couldn't have been made - and couldn't be made today - with an iPhone.​

Since they are both people who figured out how to say what they wanted with the mediums available, I'm sure they would figure out what to do with a phone too, if they were working now.

 

There is a number of movies, ranging from Ingmar Bergman's to Sergio Leone's (just to make two very different, random citations), that couldn't have been made - and couldn't be made today - with an iPhone.​

Paging Captain Obvious! i dont think the point was that any movie ever made could have been made with an iPhone.

Unless you need to shoot in near darkness or need extremely shallow depth of field, crop sensor cameras can do very, very well these days.​

one could add, 'unless you need massive resolution' to that list, but Lannie has a good point. we've reached a point in camera development where even entry-level offerings are better than anything available 10 years ago.

 

Marshall McLuhan used to say the "media is the message". I never did actually figure out what he meant. The media I
have used, including crop, full frame, and medium format, all has been useful to me. I once was a professional and I
think the difference in these three formata lay in very thin margins between them in actual practice. I think you all are
arguing about how many angels can dance on the head of a pin. As Raylan Givens (my new serialized hero would
say," it don't really amount to much in the long run what y'all use".

 

actually, mcluhan said, "the medium is the message."

 

You are absolutely right Mr. Arnold. I stand corrected. I still don't know what he meant. Have a nice day.

 

I think people who even get involved in these discussions about sensor size are sometimes missing the point that images are made by a system, not a sensor. The system has five components: Image formation (the lens), Image capture (the sensor), Image processing (in camera and out of camera tools), Image rendering (printing, display) and Image visualization (i.e. you, the photographer).
Rather than asking whether this sensor is better than that sensor, perhaps we should be asking what the weakest link in our respective systems is and how best to improve it. Would moving from a m4/3 or a APS-C sensor to a full frame sensor improve *your* photography? That is a question only you can answer.
For my part, while the Sony A7R II (which I covet) would be objectively superior in any way measurable to my A6000. I have to admit it probably would not significantly improve my images... even if I paired it with a Zeiss Batis or Leica WATE lens. At this stage in my development as a photographer, my images are my are more often limited by my abilities than by my gear. Of course, if I happen to win the lottery or cash in big on stock options, I won't let my lack of ability hold me back - I admit, I am a weak minded consumer

The biggest, newest sensor in the world still produces crap images with lenses that don't perform well.
The hot full frame Nikon/Canon/Leica/Sony body with a top of the line lens produces crap images in the hands of a photographer with no vision or imagination.
The default settings of image processing engines in even the best cameras produce results which are often dull.
Some of the world's greatest images were made were made by visionary photographers using systems that by today's standards rate barely better than a pinhole camera made from a shoebox.

 

You are absolutely right Mr. Arnold. I stand corrected. I still don't know what he meant. Have a nice day.​

You might try reading his book Understanding Media: The Extensions of Man, From Wikipedia:
"McLuhan proposed that media themselves, not the content they carry, should be the focus of study—popularly quoted as "the medium is the message". McLuhan's insight was that a medium affects the society in which it plays a role not by the content delivered over the medium, but by the characteristics of the medium itself."

 

Probably from the same Wikipedia reference as Barry cites:
"The medium is the message" is a phrase coined by Marshall McLuhan meaning that the form of a medium embeds itself in the message, creating a symbiotic relationship by which the medium influences how the message is perceived.
Although Dick may not have introduced McLuhan's quote in reference to sensor size as medium related, photography itself and its varied equipment forms are available with different media, like photoelectric sensor or silver halide emulsion based media, or small format versus large format, or iphones versus larger format cameras.
Each of these media also can form a symbiotic relationship with the user. An iphone facilitates the human desire for autoportraiture or selfies, larger format works for the more methodical type of photography, classical 35mm photography allows portability and the physically active photographer or the sports photographer needing long lenses, and so on.
Perhaps the FF sensor is best for limiting the depth of field for those photographers seeking subjects that can pop from the background or artists seeking to obscure certain elements for various reasons. Limited DOF is more difficult to do with smaller format sensors. Medium format digital or film goes that one better than 35mm FF of course.

 

To pick up obliquely on the McLuhan references, it seems clear that at least the question of sensor size does matter, if the number of responses in this thread is anything to go by.

 

Of course size does matter; most other things do too. For example, the guy behind the camera does matter. The focal length of the lenses matters too. Even among the same size, we also have many sensors very different from each other.
But personal preference matters too; i.e we cant say which size is the best. Personally, for my own uses, I prefer a size about APS-C sensor. However, I also believe that manufacturers are not (currently) trying hard to make great cameras and lenses for APS-C size. Well, and this fact does matter too.

 

I know the OP question was about sensor size, but how about the size of the 'box' getting the sensor to where you want it to be to snap the picture? I've had Canon FF, Canon APSC, Fuji APSC and Ricoh APSC. Pixel Peeping on a computer screen the Canon FF was better resolution-wise and noise-wise, but when comparing all of them something struck me: for my needs, when I made prints in the real world, the differences were simply non-existent. So, I joyfully dumped the Canon FF (and FF lenses!) and consolidated to the Fuji system. Now, I carry a camera with me far more often then before, which means I take pictures in places now that i wouldn't have with FF. So, in that sense, for me, clearly the APS-C Fuji is better--because the Canon FF wouldn't have even been there.
Of course, others needs vary, so what I'm willing to haul around for what purpose will be different from what others are willing to haul around.

 

Good point about camera and lens size.
And one reason why small mirrorless full frame cameras and optics (especially small and relatively fast primes) have a lot going for them.

 

I've got four cameras, a Nikon D3, a Leica M9, a Panasonic GX7 and aan Olympus OMD EM5 mk. II. First off, megapixels don't seem to make a big difference between, 12, 16 and 18. I've taken shots with the D3 up to 17x25 and they looked just as good as the others. If you're not shooting in extremely low light, I don't think there will be a noticeable difference unless you're looking at individual pixels on your computer. If you're doing that, get a life.

 

One valuable benefit when I started using a FF Sony a7ii, which I didn't really think about, was greater flexibility in cropping the image and still retaining a pixel/resolution needed for printing. Just a thought.

 

There is a common misconception that sensor size matters because a bigger sensor gathers more light. It is utterly false, and a misleading simplification. Every sensor gathers just the amount of light its lens forwards onto it. If you take a given lens and put an FF sensor behind it, it will gather the exact same amount of light and produce the exact same quality as if you put a tiny sensor behind it (assuming that you put the sensors in the focal distance in both cases). In the latter case, light will be just condensed to a smaller area, thus the image screened to the sensor will be brighter - again, just in a smaller area. The net amount of light will be the same.
But size still matters. How? First, it might matter because the net pixel area ratio on a bigger sensor might be bigger. In other words, technical separation of photodiodes on the sensor takes less space relative to the base area. But this is almost negligable.
The real difference which a bigger sensor results in is that it's more capable of bokeh - because of the greater focal length. Nothing else really matters.

 

I'm replying to a really old thread here, but for posterity, I don't want to let that last one sit unanswered. That comment is
completely wrong. If you put a lens in front of a sensor with an area of one square inch, it will gather four times the light of
the same lens in front of a sensor with an area of 1/4 inch. No lens I can think of has the function of changing its optics to
concentrate light onto a small sensor. The total "amount" of light hitting the sensor is a function of the brightness of the
image coming through the lens times the surface area of the sensor.

 

Lens DO concentrate light. That's their primary function. That's why you can burn ants with magnifiers. Given that you screen the _same_ image (not a bigger or smaller one) to a bigger and a smaller area, that area will receive the same amount of light. That's why you see the image coming from a projector lighter when you put the screen closer.

Now, obviously, this is a bit of a hypothetical statement, as for the same lens you can't simply change the focal length keeping the view angle, so you can't screen the same image to a different sensor (maybe with an adapter). But for the sake of the main question, namely that how much sensor size matters in light gathering capacity in general - well, not too much. Apart from the fact that the sensor logic has a more-or-less fixed cost in space, and apart from another factor, namely that you can use wider apertures for bigger sensors, it doesn't matter at all.
Sensors receive what comes from the lens (and the aperture), so the only thing what matters is how much light comes through them - which is a function of the size of the lens' outer area, the view angle (how much of the rays are relevant) and the aperture of course.
This is the reason why you see tests on youtube claiming that the Sony a7r ii in crop mode has roughly the same low light capability as the Sony a7s ii.
"The total "amount" of light hitting the sensor is a function of the brightness of the image coming through the lens times the surface area of the sensor."
This is just not true.