full frame dof advantage/disadvantage

Hi I needed to get my head around the dof issue.

As far as I'm aware a full frame sensor like the 5d mkii doesn't actually

give less DOF because l a lenses focal length doesn't change, whether

you use it on a FF or cropped camera. It's just that you have to

physically move closer to the subject with a FF so as to have the same

field of view as a cropped camera. And when you move closer you

naturally get less DOF.

So that being the case when you use a FF camera you have to increase

the the aperture, thus losing more light, and increasing the threat of

diffraction. I know that FF camera operate better at high iso but if more

DOF is required eg, macro or landscapes doesn't it make this a mute

point.

Please could you let me know if I'm right about this assumption or I'm

barking up the wrong tree.

Thanks.

<p>I wrote a long explanation of DOF issues related to format size and digital. You can read it at:</p>

<p><a href="http://www.bobatkins.com/photography/technical/digitaldof.html">http://www.bobatkins.com/photography/technical/digitaldof.html</a></p>

<p>Don't forget that you can stop down more with full frame than with APS-C before diffraction becomes a serious limiting factor on sharpness. You get around the same degree of diffaction blurring at f22 on full frame that you do at f16 on APS-C, so you can stop down an extra stop. This assumes both images will be displayed (printed) at the same physical size (so the APS-C image has to me enlarged more than the full frame image).</p>

<p>This calculator might also be of some use:</p>

<p><a href="http://www.bobatkins.com/photography/technical/bokeh_background_blur.html">http://www.bobatkins.com/photography/technical/bokeh_background_blur.html</a></p>

Thanks very much for responding so soon

I know that FF gives better iq and I'm 90%

sure this is the way to go for me. I'm just

trying to weigh up everything before I

part with my cash.

Thanks again.

<p>To me, this is a somewhat "technical feature" that may be of consideration, but not the primary one in the FF vs Crop decision process. I would consider what type of photography you plan to do and what range of lenses you will be using, to me that is more important overall than the potential "more/better" DOF.....<br>

What are your other criteria and/or reasoning towards this end?</p>

<p>IMHO it depends on what you're using. For example, I have a 50mm F1.4 lens that I use for portraits on my APS-C sensor and shoot 90% of the time at F3.2 as I've found the subject distance typically I have to be at for good portraits with a 50mm, along with the crop factor, the aperture ends up being perfect at F3.2 and that lens is incredibly sharp at that aperture. If I shoot faster the DOF is too narrow I start to get things like ears and/or nose blurry. So in that situation an FF would probably not make much difference. The situations F1.4 would be good, I find my subject is too far away.</p>

<p>When I put on my 70-200 F2.8 it's another story. I have step back too far with my APS-C that even at F2.8 I wish I could go faster... I'm shooting my 70-200 F2.8 at F2.8 about 85% of the time, and most often wishing I could zoom out even more... and it is because of this I want a FF.</p>

<p>Will the DOF make a difference on my wide angles and 50mm... probably not in my case. My 70-200 F2.8, absolutely. The 70-200 F2.8 is such a portraiture lens, and when it can work on my APS-C the results are stunning but most of the time I have the 50mm on my APS-C instead because currently with my shooting style and such it's more useful.</p>

<p>I think for the case you suggest, where you use the same lens and shoot from different distances to get the same framing, the crop sensor camera has the greater DOF if you shoot at the same aperture in both cases, but the FF camera has a slight advantage (slightly more DOF) if you shoot it at 1 stop smaller than in the crop sensor case. You can get often away with the smaller aperture because the larger format isn't as sensitive to diffraction blurring because the image need to be enlarged less to get it to the print.</p>

<p>Of course this doesn't take into account the resolution of the FF sensor vs. the APS-C sensor , noise issues etc. It gets a bit complex if you factor in everything! You'd have to anyalyze the actual case (what lens, what shooting distance, what aperture etc.) to get the hard numbers. I think the bottom line is that the difference isn't huge and if you want a crop sensor camera for other reasons, go with crop. If you want a full frame camera for other reasons, go with FF. </p>

<p>William said:</p>

<blockquote>

<p>Thanks very much for responding so soon I know that FF gives better iq and I'm 90% sure this is the way to go for me. I'm just trying to weigh up everything before I part with my cash. Thanks again.</p>

</blockquote>

<p>Well, I own the 5D2 and think it's an excellent camera, but your blanket statement that FF "gives better IQ" is not correct in all circumstances. If, for example, you use a crop-sensor body like the 7D to take a base image and then you crop it further, the 7D may actually yield higher Detail than a 5D2 with the same final crop. The finer pixel-pitch of the 7D can yield superior detail that noticeable, particularly when cropped. The 5D2 will generally be more resistant to noise than the 7D, but that's only one element of IQ. For macro and nature photography, you may or may not prefer the 7D's better detail. I use my 7D for nature and images that I plan to crop or where I need speedy handling and I use my 5D2 for everything else.</p>

<p>There is no absolute preferable camera. Your personal choice should be based on how you plan to use it, which you haven't really told us about in this thread.</p>

When I took photography seriously I about 8 years ago I bought into the canon system.

One of the biggest reasons for this is that I always wanted a FF camera and NIKON at

the time weren't making FF cameras. So I decided to by into a company that were

already designing lenses to be used on FF digital cameras. So over the years I only

bought EF lenses.

I have a 28-135, sigma 105 macro, canon 24-70 , canon 70-200 2.8 is, even my wide

angle lens a Tokina 12-24 one of the reasons I bought it was that its a EF fitting so I

could use the long end of it on a FF camera.

I want the iq benefits of a FF , but mainly so I can use my lenses the way they were

ment to be.

I'm always having to change between my 24-70 and my 12-24, my 70-200 doesn't get

as much use as I would like because I'm too close to use it, the time I use it the most is

for concerts, and the zoo, I don't do a lot of that but when I do I think how would I

survive with a FF because I'll be losing the magnification.

As I said when I started I wanted a FF camera, I thought crop cameras would fade out,

but after years of using one I don't think they ever will because there a lot of benifits,

except the build quality of the EFS lenses when you can be paying the same for a L lens

( another reason I stuck with EF lenses ) .

But after years of using a crop camera I feel it's time for a change.

Because I love all photography in a few years I'll properly buy a better crop camera.

At the moment I'm trying to hold off from buying a 5d mkii and wait for the 5dmk iii, if

its a lot better I'll get that or I'll get a mkii because the prices will drop.

Thanks for all of your responses It's nice to hear from balanced people who appreciate

the benefits of both FF and cropped cameras.

<p>william,</p>

<p>For a very lengthy and detailed article on the issue, <a href="http://www.josephjamesphotography.com/equivalence/#exposure">read this.</a> Like Bob Atkins says, one, you can't take dof in isolation when making comparisons across sensor sizes, and two, both 1.6 and "FF" sensor sizes are capable of very good results, and bad ones. As an aside there are far more lens options that you can get for "FF" that you cannot get true equivalents for on crop cameras, if that is important to you then it might make a difference.</p>

<p>But yes, you are barking up the wrong tree assessing the situation as you are. :-) </p>

<p>Well, you answered my question when you said you didn't use your 70-200mm much because you're usually too close. Clearly you're not cropping your crop-sensor images, so I think that you're likely to enjoy an IQ increase by going to a FF camear and using your excellent lenses.</p>

<p>I love my 5D2. To anyone buying one, I'd encourage you to explore its high-ISO capacities to the fullest extent possible. for example, I'm pleased and amazed with my results at ISO 6400 shooting night street scenes. Good luck and enjoy. (Keep your crop-body for macros and the occasional sports shooting). </p>

I don't want to start a thread within a thread but I would like to ask

David this as he owns a 7d and a 5d mkii. While I have been testing

these two cameras I seemed to notice that the 7d produced slightly

darker images about half a stop, I was using manual and exactly the

same settings. At the time I was testing the 7d against my old 20d.

Hope you don't mind me asking.

<p>No problem William.</p>

<p>I shoot only in RAW and tend to "expose right" (to the right of the histogram) so I don't notice this. I have read others saying something similar to what you're saying, but only when they compared in-camera jpegs. Also, you should know that I do my RAW conversion with DxO's Optics Pro, which automatically compensates for differences in camera bodies.</p>

<p>Full frame is a state of mind: <br /> <a href="http://www.photographyblog.com/news/canon_develops_ultra-large-scale_ultra-high-sensitivity_cmos_sensor/">http://www.photographyblog.com/news/canon_develops_ultra-large-scale_ultra-high-sensitivity_cmos_sensor/</a></p>

<p>:) </p>

Now you mention it, the images were jpeg.

Thanks

<p>Different explanations work for different people. Here's what I've written on the subject:</p>

<p><a href="http://www.graphic-fusion.com/fullframe.htm#dof">http://www.graphic-fusion.com/fullframe.htm#dof</a></p>

<p>Sections following this one might also be of interest. It might be clear, and it might not. YMMV. ;-)</p>

<p><em>So that being the case when you use a FF camera you have to increase the the aperture, thus losing more light, and increasing the threat of diffraction. </em></p>

<p>Diffraction does not impact any format more than another for a given FoV / DoF.</p>

<p>Yes, you will have to stop down more on FF to match the FoV / DoF of a crop body. Yes, this will cost you light and mitigate the high ISO noise advantage of the FF sensor assuming, of course, that you are confined to said FoV / DoF. But most real life situations don't work out quite like this because people do not target a specific, measured DoF. They just want a generic "blurred" or "in focus" background, and there's some play there for most scenes.</p>

<p><em>I know that FF camera operate better at high iso but if more DOF is required eg, macro or landscapes doesn't it make this a mute point.</em></p>

<p>It's a moot point for the most part any way given said subject matter. Landscape and macro are generally shot from tripods at low to mid ISO.</p>

<p><em>I know that FF gives better iq and I'm 90% sure this is the way to go for me. I'm just trying to weigh up everything before I part with my cash.</em></p>

<p>FF only gives better IQ at higher ISOs against an APS-C sensor of comparable resolution / technology level, with the exception of dynamic range which is roughly 1 stop greater for FF in the current Canon lineup.</p>

<p>All that said, your lens collection is arranged around FF. But I would honestly wait to see what Canon releases over the next 6 months. There has to be a 5D mkIII some where in their pipeline.</p>

<p>Unfortunately for someone who wants to understand all this prior to making a buying decision, you likely need to do some real shooting with different size formats, up to medium format and beyond, in order to see for yourself how DOF considerations <strong><em>in practice </em></strong>are going to be affected by the "size of the box." All of the theory in the world is not likely to emblazon itself on your memory quite like the simple practical difficulty of getting the proper DOF in actual photography. There is no universal solution, but in my opinion full-frame is more versatile--but there are important exceptions.</p>

<p>After you see what actually tends to happen, you can go back and re-examine your theories to see if they explain the difficulties. (You will get empirical feedback that will challenge your present assumptions, but that is alright. You will likely be pleasantly surprised at what happens with full frame cameras. If not, picking up a refurbished crop sensor camera is not going to set you back very much. Having both will turn out to be advantageous over the long haul, even if it seems outrageously expensive at the outset--fortunately, not everything has to be bought at the outset, if ever.)</p>

<p>I realize that the above does not really address the question in your case, since you want to be able to understand the physics of it before you make the purchase. Rest assured that there are good theoretical reasons why larger formats tend to give shallower depth of field, whether it currently makes sense or not.</p>

<p>I personally like the ease of getting shallow DOF with full frame, and, for my purposes, having to stop down to get a longer DOF (when I do need it) does not typically cause diffraction problems.</p>

<p>--Lannie</p>

<p>In my experience, full-frame cameras have the advantage that for a given level of image quality, if you do not require the highest resolution and print at more modest sizes (i.e. A4/letter) you have the option of choosing almost any aperture and get a good result (with the exception of f/22 and smaller). You will still get better quality at or near the optimum aperture of the lens but for acceptable quality the range of apertures is broad. With small-sensor cameras you really have to hit the best aperture of the lens to get adequate detail in the smaller frame (assuming your final print is of the same size). You also have to limit your ISO down, and finally any focusing errors will be magnified.<br>

For your application though, tripod based, base ISO macro and landscape photography, it is easier to achieve these optimal settings (ISO 100, f/5.6, live view manual focus) and get a good result. However, on the other hand many people like to use wide angle for landscape photography and in my experience, wide angles perform better on full frame cameras (my experience is with Nikon). On the other hand while a crop camera allows you to record finer details at a given working distance, again you need to stop down many macro lenses to get good results with crop cameras whereas a decent quality can be achieved wide open with many lenses on full frame.</p>

<p>Still regarding the depth of field thing ... if you <em>always </em>want the most depth of field you can get, then crop cameras work well. But if you <em>want</em> the option of blowing out your background (sometimes to get a really clean background e.g. at 1:2 you may need to use a wide aperture) and I find the quality is retained better if you use a full-frame camera at wide aperture. I think for macro a crop camera is a very useful asset to have in your bag, but it would never be my primary camera.</p>

<p>Ilkka, pixel-pitch is more important the sensor size in determining the limit of detail. Because of this, some crop-sensor cameras with more dense pixels can actually resolve more detail than their FF brothers, particularly if a crop-sensor image is further cropped in PP. The 7D vs. the 5D2 is such a case. Remember, detail and noise are just two measures of IQ, but you need to understand where one might be an advantage for your intended uses.</p>

<p>I suspect that the next generation of FF cameras will have even denser pixels and will match the detail of the best crop-sensor bodies, but then the crop-sensors will get denser and then the FF sensors will get denser and... you get the idea.</p>

<blockquote>

<p>Still regarding the depth of field thing ... if you <em>always </em>want the most depth of field you can get, then crop cameras work well.</p>

</blockquote>

<p>... except that you can use an extra stop smaller an aperture on a FF camera without diffraction being a problem, so really the upper usable limit of depth of field is about the same, regardless of formats. FF does give you an extra stop on the shallow DoF end.</p>

<p><em>"Because of this, some crop-sensor cameras with more dense pixels can actually resolve more detail than their FF brothers, particularly if a crop-sensor image is further cropped in PP. The 7D vs. the 5D2 is such a case."</em></p>

<p>I keep seeing this written and it makes no real world image sense, as a technical exercise it does, but in actual use it doesn't. If you use the correct lens to frame your subject, ie a 70-200, at 100 on the crop camera and at 160 on the ff camera, how does 5,184 pixels along the long side (7D) translate to better resolution than 5,616 pixels along the long side (5D MkII)? It doesn't.</p>

<p>This is just yet another example of people reading tests that just don't translate to real world use. Yes the 7D has more outright lpmm resolution than the 5D MkII, but it needs to it captures images considerably smaller, its system resolution is still lower than the 5D MkII. In correctly framed real world images where neither is cropped the 5D MkII system resolution, what you actually get on paper, is higher. </p>

<p>So frame your landscape image with a 10mm lens on the 7D, and a 16mm lens on the 5D MkII, the 7D puts 18 million pixels on the subject, the 5D MkII puts 21 million pixels on the subject.</p>

<p>If you do not have a lens long enough then a crop camera with higher pixel density might, with good technique, realise a higher resolution than a cropped ff image, all the rest of the time it will not.</p>

<p>It is like asking how far a car can go on a tankful of gas and being told it does 30mpg, without knowing how big the fuel tank is that figure is irrelevant, the 7D does 35mpg but has a 10 gallon tank (350 miles per tank), the 5D MkII does 30mpg but has a 15 gallon tank (450 miles per tank). </p>

<p> </p>

<p>Scott, re-read what you quoted from me. I'm speaking of cropping a crop-sensor image. So, in your example, I'd be shooting out at 200mm on the 70-200mm and then doing a 20% to 50% crop to get the composition that I want. <strong>This is quite common with birds and wildlife photography</strong>. I use my 500mm with a 1.4x TC on my crop-sensor 7D and still end up cropping many of those images further. I'm not talking about landscape vs. landscape, where you use the whole image.</p>

<p>Anyway, if you take the same image on FF and crop it all the way down to about 30% to try to get the subject the same size on a print as the 7D image, the 7D will exhibit more detail. It'll also be more subject to noise, which is an issue to consider when deciding on the best compromise for your subjects.</p>

<p>Here's a 209% crop of a 7D image taken with a 500mm lens, with no extra sharpening:<br>

<a title="200% crop using Velvia 50 emulation by dcstep, on Flickr" href=" src="http://farm7.static.flickr.com/6196/6149068830_6d612180f8_z.jpg" alt="200% crop using Velvia 50 emulation" width="636" height="424" /></a></p>

<p>David,</p>

<p>I did read your quote, the key word is<strong> "particularly"</strong>, my point is that cropping to match is the <strong>only </strong>situation where a crop camera puts more pixels on the subject.</p>

<p><em>" pixel-pitch is more important [than] the sensor size in determining the limit of detail"</em></p>

<p>Taken in isolation pixel pitch is meaningless. That is the main issue I was debunking. It is not true. The number of pixels on the subject and the quality of those pixels and your technique all contribute to, or destroy, your resolution.</p>

<p>If you agree with me, why are you arguing about pixel-pitch? Pixel-pitch DOES matter when you crop a crop-sensor and then try to get same size subject from a FF camera with the same reach-limited lens. The number of pixels AND the size of the pixels both matter. Finer pixels can render finer detail, assuming competent technique.</p>

<p>I think we agree, but you seem threatened that I think there's a circumstance where a crop-sensor might be superior to a FF sensor for a particular task. There's a reason that I own and use both a 7D and a 5D MkII.</p>

I'm sure I'll get a FF, for wildlife I find 200mm to short on a crop

camera, and as David said he uses a 500mm lens and a 1.4 converter,

I can't see me getting a 500mm lens.

A few things crossed my mind about FF and cropped.

1, if I got a 1.4 converter this would make up for what I'll be missing

from losing the reach of a cropped, I know I could use it on the crop

camera and get even more reach but it should help.

2, FF cameras are better at high iso and there's a lot of talk that you

won't see the different between cropped and FF at low iso . But

wouldn't you have more shadow detail at low iso on a FF then a crop

camera.

3, Even if you crop a 5d mkii to match a 7d, you will get less pixels but

the remaining pixels will be physical larger then the ones on the 7d

and thus be able to gather more information. This must count for

something.

4, after reading, I think it was Sarah's article, am I right in assuming

that the best EFS lenses are optical made better then EF lenses so they

can cope with the extra magnification a cropped camera would put on

it and any imperfections would be more obvious.

What is pixel pitch I've never heard that term before.