scott_ferris

<p>Sheldon's two pictures are perfect examples of bad comparisons and not one of you has pointed out the glaring problems between the two images. </p>

<p>The 1.4 is clearly back-focused around two feet behind the lady as can be seen in the driveway, the 1.2 is perfectly focused on the groove the lady is standing on. For the 1.4 this dramatically decreases sharpness and contrast of the subject and also decreases the oof blur in the bush to picture right, and that is the most obvious difference in "bokeh", the focus inaccuracy in these two comparison shots is the main reason for the differences seen, just cover up two thirds of the right hand side of the image and you will see the real differences between these two lenses, practically nothing.</p>

<p>Now I don't care which you get, to me if you want a lens with a red ring on just because it matches your camera strap is just as good a reason as any, as is better build quality, weather-sealing etc etc, but don't kid yourself on the actual differences in image output, there are some differences, but they are tiny and if you do any kind of post processing these tiny differences are generally overwhelmed.</p>

<p>Kirsten,</p>

<p>I have the Acratech GP (since it came out several years ago), not the GPs, I use it upside down the vast majority of the time, I shoot a lot of real estate and architecture so need a level camera and it is great, there are no real disadvantages to using it that way all the time, well I haven't encountered any.</p>

<p>I can't recommend the Acratech heads enough, they are superbly made, innovative, light, durable, they just work! </p>

<p>If you don't want to zip the folder, then you can also just attach the folder itself, simple, fast, foolproof.</p>

<p>Barry Fisher,<em> "The screen's are quite good."</em><br>

<em> </em><br>

Scott Ferris,<em> "iMac's make little sense for serious photo orientated work."<br /></em></p>

<p>If the key feature for photo work, the screen, is only "<em>quite good</em>" we are talking about different kinds of tools. </p>

It sounds like misalignment of an element, lens don't like being dropped or having heir filter ringed hammered back into

shap! You can test for that yourself by mocking up a test target, but it will need to go to Nikon to be fixed properly.

Was IS on?

<p>I have about fifty rolls left in the freezer, but have had that same fifty rolls for the last five years, ever since getting a 21mp ff camera. I suppose that means I have very firmly moved on from Velvia!</p>

<p>That CNN gallery is way off in its colours, and colour is a major part of McCurrie's images. I have seen all those images in exhibition prints and they look nothing like that. But I have noticed that his more recent work is showing signs of heavy (dare I say clumsy?) post processing, maybe they were passed over to CNN like that.</p>

<p>Nowadays he predominantly uses a Nikon D3x with a 24-70 f2.8, and occasionally a Hasselblad H4D-40 but he is sponsored by them!</p>

<p>Craig,</p>

<p>I didn't write that to cause offense or to correct, I actually agreed with you <em>"if you use a shorter focal length from the same place then the same aperture will yield deeper dof, but as always that isn't the whole story"</em>.</p>

<p> I merely intended to head off the common misconception that people seem to extrapolate from that information, and assume without thinking, that wide angles always give more dof and longer lenses always give less dof for the same aperture, like I pointed out, there is a very common situation where people do think about this incorrectly. They assume if they take a portrait with a longer lens at the same aperture it will give them less dof. This is a very common real world situation, hardly a special case.</p>

<p> Rather than a technical exposé, for which there is plenty of room and useful links, I was adding a real world practical effect that is often overlooked and misunderstood.<br>

<br>

With regards what factors affect dof, in truth, focal length and subject distance are not needed to work it out. <a href="http://en.wikipedia.org/wiki/Depth_of_field">DOF is determined by subject magnification and aperture, </a>though coc plays a part too (and that bit covers your sensor size). The reason online dof calculators ask for focal length and subject distance is so they can work out the subject magnification for you as few people know how to do this themselves.<br /></p>

<p> </p>

<p>It is a bit too simplistic to say focal length affects dof, subject distance is far more important. Yes if you use a shorter focal length from the same place then the same aperture will yield deeper dof, but as always that isn't the whole story.</p>

<p>For example if you use a 50mm at f2.8 and a 200mm at f2.8 but the subject remains the same size in the viewfinder, a common scenario for a portrait for example, (ie you moved back for the longer focal length) then the dof is the same. This is counter intuitive and seems to go against the "telephoto compression" meme, but it is true, your perspective is different but your dof is the same.</p>

<p>It is funny, people say the $5,000+ 200mm f2 gives incredibly narrow dof, well the 50 f1.8 at under $100 actually gives a narrower dof for the same subject size.</p>

<p>To get exactly the same image as a 1.5 crop camera setup with a 50mm lens @ f1.4 and 100 iso with a FF camera, all you need to do is stand in the same place and use these settings, 75mm lens f2.2 and 200 iso. These two images would be exactly the same when reproduced at the same size.</p><P>

With these settings there is less than one sixth stop difference in the depth of field and the noise would be comparable if the sensors were the same generation of technology, these figures also assume the end output is the same size for each camera.

<p>The term you are looking for Dylan, is equivalence.<a href="http://www.josephjamesphotography.com/equivalence/"> Here is a very good article</a> on all the technicalities involved. In short enlargement ratio, depth of field and noise have a crop factor too.</p>

<p>The vast majority of the time you can get exactly, and I mean exactly, the same image from different sensor sizes and lenses, but when you start going to very narrow depth of field, or ultimate low noise images, then the smaller sensors lose out.</p>

<p>These three images were shot with different cameras and sensor sizes but even under close scrutiny they are identical. However I couldn't do the same if the starting shot had been a FF shot with 50mm f1.2 @ 100iso because there is no crop camera equivalent 31mm f0.90 lens and crop sensors don't record honestly at iso 60.</p><div></div>

My Mini, last model, doesn't have a CD/DVD drive, my laptop, that had one when I bought it, had it's taken out and I put a

second HDD in its place, far more productive. I haven't used a CD/DVD for several years.

I got a Mac Mini, put a second drive in it, upgraded the RAM and am very happy. iMac's make little sense for serious

photo orientated work.

Just use a checksum generator and checker, the commonest formats are SFV and MD5. There are several free utilities

that do this with a GUI, much simpler than using Terminal commands in OS X.

 

Just search for checksum utility Mac. What these utilities do is calculate a long hexadecimal number that follows a formula, if two files are identical the hexadecimal number will be the same, if there is any pixel corruption within an image file the number will not match the number from the original.

I am currently doing a two month travel through India. I have one Fx body and a 24-70 f2.8, I don't need anything else.

Simple, comparatively light, always ready and it frees you to take the photos you can, not the imaginary images in your

head that you need to change lenses for.

 

It might be my lack of imagination but I can't imagine the need for a 70-200 on a Dx body, unless you are going to wildlife

reserves, street life is way too close to need that and the atmospheric conditions limit long range landscape opportunities.

 

The Old Delhi markets are the only place I would have used wider than 24 on Fx, and I have been to all the places you

list. A day trip to Agra from Dehli is not the way to see the Taj Mahal, spend the night before there and go at dawn, the

light is magical at that time of day. If you are there at dusk then the Hindu temple just to the North of the East gate is the

only place you can get to the river for atmospheric sunset shots. If you are still an Indian national take proof, you will save

a lot of money on entry fees, foreigner fees are typically ten to twenty times Indian rates ( at the Taj even more, 20Rs vs

750Rs) and this adds up.

 

Tripods are considered a security risk and actively banned from pretty much anywhere you would want to use one, armed

guards are everywhere and enforce this vigorously.

 

In your situation I would take one body and the 17-55, if you really need "backup" take the second body and the 11-16

and enjoy showing your family your homeland, either lens will give you infinite unforgettable photo opportunities.

Last time I was in Cambodia I took the 24-70 and a 1Ds MkIII and didn't want for anything else. So I would take your 5D

MkIII and 24-70. I'd also take a tripod as their use in Cambodia is virtually unrestricted.

 

I am currently in India with that same 1Ds MkIiI and 24-70 and want for nothing.

 

But all these choices are personal to the kinds of images you make.

The AFmodule is in the bottom of the camera, manual focus by eye through the viewfinder relies on exact placement of the

focusing screen in the top of the camera so the two systems are totally unconnected, it could be that your focusing screen needs shimming to get it to the correct

place. Most camera repair shops can do this though most people would only trust this kind of job to an authorized Canon

repair facility.

 

It is also worth noting that focusing screens actually have an effective aperture, modern DSLR screens are around f 2.8,

this makes it impossible to manually focus more accurately than that unless you can change screens, so people claiming

to get 100% accuracy manuually focusing super fast primes wide open with standard screens are talking bull.

Tudor,

 

If you are panning anything in any direction Mode 2 will help, it can be a combination of horizontal and vertical and it will

work fine.

 

Indeed Mode 2 works vey well for aircraft as they have a steady and smooth path they follow, even when pulling hard

turns and manoeuvers.

Tudor,

 

Why would you say Mode 2 IS does not cover vertical panning? You clearly don't understand how Mode2 works. It allows

you to pan in any direction, it works out what direction that is and then cancels any shake/vibration not in that one specific

direction.

 

Again, Mode 2 allows you to pan in any direction.

First off, sorry for your bad luck Steve.

 

Second, for those saying insurance will cover it, my experience is it 100% will not, an open car window means you are not

considered, by the insurance company, to have taken enough care to prevent the theft, second with no forced entry there

is no "proof" as required by most insurance companies to consider a claim.

You need to light your print viewing area with the same luminance value as your screen is outputing and those bulbs must

be high a CRI type to get accurate colours.

 

Think about it, your screen is projecting its own light, your print is reflecting the light that falls onto it, unless you control

the colour, power, and range of that light your prints cannot be a consistent match to your screen.

You can't hope to get a monitor to print match without one, calibrating your screen with a puck and software, and two,

optimizing your print viewing condition to your screen profile. Most people have their screens far too bright and their print

viewing space far too dark, if your screen is brighter than a sheet of photo paper your prints will always look dark.

All lens designs are a compromise of many different factors, ultimately the market sets the value and manufacturers

produce the best product they can to be competitive.

 

L lenses consistently have exotic glass elements to radically improve iq, and are usually of more robust construction with

many being genuinely weather sealed, this, along with the key element of faster apertures and in the case of zooms often

constant apertures, means the price is not set so low in the design compromise equation.

 

But don't forget, sharpness is only one of many of those compromises, look at the 200 mm f2.8 a superb little lens

possibly only lacking IS, but what a bargain. Compare that to the 200 mm f2.0, a mere one f stop faster and the inclusion

of IS, but at that price you know there are zero compromises with regards the image quality.

 

The differences between the two 100 mm macro lenses are the best direct comparison of what being an L gets you. The

L gives you Hybrid IS, weather sealing, much more robust construction, better coatings, one UD element, etc etc, but the

image quality of the two is identical, that additional cost went into making the lens "better" but with no improvements in IQ.

 

Generally the market has decided most L lenses are worth the money, in comparison to the green ringed DO lenses that

don't appear to have been good sellers, but only you can say if the design and manufactureing compromises work for

your situation. For instance if you were shooting stamps all day in a studio from a stand then the L macro would offer you

nothing of value over the non L.

Howard wether the particular shot is possible due to environmental reasons or not is not the point. The point has always

been that this is a perspective 101 problem and perspective is not altered by focal length, the shot, as I demonstrated

with he Hyatt link, is 100% possible (given the room) but only by standing much further back.

 

His 200 will only change the shot if he moves, otherwise it will be just like your two, a crop. Harry wanted the market to

look bigger in relation to the dorms, he can only do that by changing perspective, ie moving.