Sunday, February 24, 2013

Nikon D7100 vs D600

Now that we have the Nikon D600 and the D7100, we have one of the most level playing fields in comparing FX and DX. Both have 24mp, both with similar control layouts. In some ways, it's like the D3/D300 era, only with twice the megapixels, except that, the D600 and D7100 are essentially the same camera with different sensors stuff into them.

The question, of course, is not about choosing between the two cameras. When most people ask this question, what they are really asking is if they can find a way to justify the full frame camera that costs nearly double the price; this before the cost of lenses is added. As they say, bigger is always better... until it isn't.



Lenses, Diffraction Limitation and Moiré


Resolution loss due to diffraction will start creeping into D600 shots around f/11. However, with the D7100, the onset of diffraction begins at f/8. I want to emphasis "begin", as resolution doesn't drop off after the initial point of diffraction limitation... it's more a case that contrast begins to gradually decrease. What this means is that moiré is only a potential problem for the D7100 below f/8. Most people don't expect the moiré to be a a big issue in everyday shooting, but my guess is that fashion photographers might have to deal with it (textiles and clothing) more so than others. Note that if you are a landscape aficionado, the removal of the anti-aliasing filter isn't that great of an advantage at the smaller apertures. Truth be told, as the megapixel counts have increased, cameras like the Nikon D7000 and D800 were already using lighter filtration than cameras in the past.

Diffraction-wise, the advantage goes to the D600. Within it's aperture range, you have a slightly wider latitude in aperture before diffraction starts setting in. Whatever advantages that the D7100 has in removing the low-pass filter are mitigated by the high pixel density of the sensor and the demands this places on the quality of the lenses being used. Even though full frame lenses are cheaper than DX lenses, the larger pixels of the D600 place less of a burden on the quality of the glass.

Speaking of lenses, the kit lens for the D7100 is still the 18-105VR. This lens has been maligned a fair bit; it's really not a bad lens as it's actually quite sharp, but it suffers from pincushion distortion and high levels of lateral chromatic aberration. That said, the 24-85VR is a better kit lens for the D600 than the 18-105VR is for the D7100. You can use the D600 combo without really noticing the lens flaws; not so with the 18-105VR.
 
Another advantage of the FX over DX is that for the equivalent depth of field, the FX camera will be using a lens one stop down. Imagine going for a trendy super-shallow depth of field shot with the D7100 and a 50mm f/1.4 lens. Wide open, past primes have all sorts of optical flaws, though some would use the term "dreaminess" rather than "flawed". For the equivalent D600 image, an 85mm (because a 75mm doesn't exist) lens shot at f/2 would give the equivalent depth of field. The D600 image would be superior, because stopped down, the FX lens would be operating in a more optimal portion of it's aperture range, meaning that even though both lenses would give similar looking out of focus backgrounds, the D600 and FX lens would be more contrasty in the center of the image, presumably where the subject is.


Safe Hand Holding Ability


Assuming that the D7100 sensor is a variant of the D5100 sensor, my guess is that under non-professional usage ISO 3200 is about as high as you would want to take it. ISO 6400 would by my limit with the D600, which is in keeping with the 2.3x increase in sensor surface area. Under equivalent circumstances, you would get one additional stop in terms of safe hand holding speed. However, one additional stop is not the advantage that it used to be. In the D3/D300 generation, ISO 1600 was as high as you would want to take DX, and ISO 3200 for FX. As the ISO ranges of cameras increase, the additional stop of light gathering power becomes less significant.

With the current set of cameras, assuming a viewing angle the equivalent of 50mm FX/30mm DX, you can safely handhold the D7100 at maximum ISO and aperture in an indoor room. The extra stop that D600 gives you means that you can safely handhold if the room is dimly lit. Truth be told, I wouldn't push it this far. First, I'm excluding t-stop calculations for the efficiency of the lenses used, so the real world values would require more exposure compensation to achieve proper exposure. Secondly, under these circumstances, I would have long ago turned on the camera flash.

Outside of stationary objects, speed is speed, and the fact that D600 can go high up the ISO range means that it is more suited for capturing fast moving objects. However, what FX gives, it takes away, so if you've been using a lens like the 70-300VR, it now becomes "just" a 300mm max lens, whereas on the D7100 it would be the equivalent of 450mm... 600mm at 15mp in the D7100's high speed crop mode. Combine this with the D7100's 51-point autofocus module and you can make a case that the DX camera is actually the more versatile of the two.

Video 


The lack of an anti-aliasing filter shouldn't be a problem with the D7100. Many still cameras are prone to aliasing artifacts in video, but this is due to the fact that not all of the pixels are being used, and the ones that are being used are spread across the sensor, not adjacent to one another. One frame of 1080p is roughly the equivalent of a 2 megapixel image; in other words, a modern dSLR sensor has more pixels than what a high definition video stream needs. To get around this, only a certain number of pixels are used via sub-addressing. In other words, if aliasing artifacts are an issue with the D7100, they will be because of the reasons that plague all dSLR video functions, not because of the lack of the low-pass filter.

It looks like the D7100 has inherited the video functionality of the D600, so my guess is that for the most part, the D600 will have video that works in almost the same way. Naturally, the D600 has larger photosites, so you will have more exposure option and depth of field options. The D7100 has mercifully moved the microphone to the top of the camera, away from the autofocus motors. If you were to do serious videography, you would  use a proper external microphone, but for casual usage, I would prefer the D7100 over the D600.

Value for Money


This one's not a contest, the D7100 gives much more bang for the buck than the D600. Both cameras can do most things on a relatively equal footing. The D600 does what traditional full frame cameras do well: creating quality images that have a smooth tonal transitions. There is no question that the D600 will produce higher quality and more pleasing images, but you have to have the ability to bring it out of the camera if you want to produce images that stand out from the DX crowd. Think of all of those "what camera did this come from" threads that you see on DPReview... The D7100 is a more versatile camera, though, and its high speed crop mode and more advanced autofocus system alone make it a more intriguing choice. That said, both models represent Nikon well at their respective price brackets, and offer photographic capability that was undreamt of at these prices not just a few years ago.

17 comments:

  1. I have the D7000 and have been thinking about the 7100, Still not sure... to me its either the D800 or the D7100, But by the time I have the money for the D800 there will be the equivalent new version.. Help What Should I do??

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    1. Heh, heh, heh... the age old update question. I would wait, no need to be hasty. Considering that it was 3-ish years with the D700, the D800 will still have a fairly long shelf life if past trends hold. If you aren't printing big, the D7100 is on paper a more versatile camera, faster fps crop mode, etc. Another big factor is the cost of lenses to fully realize the D800's potential.

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  2. Regarding this comment. . "The D600 does what traditional full frame cameras do well: creating quality images that have a smooth tonal transitions". I would be interested in knowing to what degree crop cameras like the D7000/D7100 would be lacking in this quality compared to cameras like the D600? Is there any place on the web that I can see the difference in "smooth tonal transitions" between DX and FX? Mike

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  3. Unfortunately this is one of the things that's harder to quantify because it doesn't come across as well in the test targets that sites like DPR, Imaging-Resource, etc use. 'Smooth tonal transition' is really a combination of three things... more megapixels, greater dynamic range and the ability to use a lens deeper into it's resolution sweet spot at the same depth of field. I've shot the D600 back to back with the D7000... you notice the difference when you compare that way, but you might not if you only were given one image at a time. When you really pixel peep, even at low ISO, there's a bit of texture in the D7000 files that isn't there in the D600 files... but again, you might not notice it if you weren't shooting back to back.

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    1. Would you say that for web viewing or prints at 13"X19" or smaller, a camera like the D7100 or perhaps even the D7000 would not show any real loss in tonal quality(to be concerned about), when compared to the D600? I have an interest in doing more portrait work as well. My dilemma is that I read about the image quality being so much better with full frame cameras and it's easy to get sucked into the full frame idea and thinking that one is giving up too much with crop cameras as far as image quality is concerned.

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  4. You're really getting the benefit of more post-processing flexibility rather than outright quality. Every step along the way, you lose a bit of dynamic range, so once you print, the differences with modern cameras will star to even out. At the size that you are printing at, I think both cameras will do fine, it's just that you might have to be more mindful about post processing with the DX camera over the FX camera. In the summer, I do a lot of shooting at church weddings... even though I haven't gone full frame, I find that samples from my friend's 5DmII's and D700's are more pleasing... mostly because the shadows don't drop off quite as steeply when the lights get dim, and you can get a bit more differentiation in grey-shades. So except for extreme cases of dynamic range and darkness, I think that you're assessment is accurately, most people would be hard-pressed to tell the difference. Except, of course, until you try the 85 f/1.4 wide opn on a D600 or D700... it's just simply something that you can't replicate on DX.

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    1. This comment has been removed by the author.

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  5. I just purchased a D7100 after much debate about the D600 and I dont regret it one bit. If you want to go FX then the D800 is the only camera above the d7100 worth looking at. The sample images I have seen from all three prove this. Go big or go home is the saying and if your not putting your images in an art gallery then no one would notice the difference. In this case forget the D600 even exists its D7100 or D800/E. Choose your weapon :)

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  6. Wonderful discussion -- my conundrum, like so many others:
    Supposing I use the same lens (Nikon 70-200 f/2.8 VR) , same subject (a gray seal at 100 feet), same ISO (800), same shutter speed, same f stop — one photo from D600 and from D7100 –
    Both cameras have the same megapixels (24) – but D600 is FX while D7100 is DX – so, the image on the FX sensor will be smaller than on the DX – we crop both so that the image will be 8×10 –
    The FX had to be downsized more than the DX to get to that size –
    therefore, since both cameras had the same megapixels, would not the DX have better IQ – because it didn’t have to be “downsized” as much??? “
    Also, even though the D600 image is downsized might it still be better IQ than the D7100 because the pixels on the D600 are larger??

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    1. You've pretty much hit on what the D300 birder crowd has been harping about. If you want to shoot at long distances, DX is a better format to do it. In your example, the downsized D600 pic won't have the same detail, and while it's true that as an FX image it won't been "stressing" the lens as much, the end result is a 16mp FX file versus a 24mp DX file. Per pixel, the D600 file will still look better, but the D7100 file will have more resolution. That said, 16mp is more than enough for an 8"*10", even 11"814" without much worries.

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  7. Whoops, got the math wrong. Meant to say that you would end up with an equivalent 10mp file if your cropped the D600 to the same field of view as the D7100. Print sizes still stand. You would still be able to get an acceptable 11by14 print.

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  8. I've tried many different cameras in my quest for finding the optimal balance between image quality and the size and weight of my photographic equipment. Everytime I try a smaller and lighter alternative to a full frame camera, I miss this: "creating quality images that have smooth tonal transitions". Also, full frame RAW files are more flexible.

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    1. I think that's really a function of the way Canon and Sony market. If the RX-1 can be so small, there's no reason why a FX camera couldn't be the size of the D7000 or smaller, but Nikon wants you to think that "FX" = "pro". The saving grace of the D600 is that even though it's a bigger camera, it doesn't feel big in your hands.

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  9. The difference in size and weight between the D7000 and D600 really isn't noticeable compared to the D7000 and D700 or D800. And I would still reach for a D600 over a D7100 it gives a much smoother tonal range and shallower depth of field. A pro camera has to be heavier/bigger to balance fast telephotos and fast zooms, try a 70-210 2.8 on a D7000, it feels lost! Also when you're making a living from taking photos you want the best tool for the job.

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  10. I risk sounding stupid. :) But here goes. I hope I can explain my question properly. With a Nikon DX camera of 24 mps using the same lens, then an FX camera of 36 mps why is it that the focal length of a lens would be more on the DX camera? I realize the size of the sensor is larger on the FX. But if the photo sensor is larger but the focal length is shorter on the FX is there a gain with an FX. I am really confused. Why is it that a FX camera takes a 'cropped' photo with a DX lens? Or am I trying to compare a pineapple to a tomato?

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    1. The effective field of view changes between DX and FX because the image circles cast by the different lenses are different sizes. The image circle cast by a 35mm FX lens is bigger than the one cast by the 35mm DX lens. In other words, if you mount the 35mm DX lens on an FX body, the image circle that it casts on the sensor won't be big enough to fill the whole sensor; the lens is only illuminating the center portion of the sensor.

      Conversely, when you mount the a 50mm FX lens on a DX body, the image circle that the lens casts is bigger than the DX sensor, so the DX sensor is only "looking through" the center part of the FX lens.

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  11. I appreciate your reply. I understand now. I suppose that explains the price difference with the FX and DX lens also. Thank you!

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