FX vs DX Image Quality Comparison (yes.. this again) Your Thoughts?

JonMcGuffinJonMcGuffin Posts: 312Member
edited May 2015 in General Discussions
I know this is a kind of hotly debated topic and I certainly don't mean to open up the proverbial FX vs DX can of worms however I wanted to share some of my thoughts and pose some questions here to the forum members in regards specifically to image quality comparisons between cameras of the two different sensor types.

For what it's worth, I am a former D700 owner and shoot with a D7100 now while I await to buy a D750. I do shoot some product photographer so pixel peeping is, on occasion, a kind of job requirement for me.

With that said, it is a known "fact" that the following exists:
• FX Sensors have a typical 1-stop (+/-) advantage in low light sensitive range (ISO)
• FX Sensors have a typical 1-stop (+/-) advantage in dynamic range (this one is more dependent on generation of sensors being produced, but generally speaking FX has better DR than DX)
• FX Sensors, when making sure all other aspects are equalized, has a shallower depth of field. This could be a benefit or a downside depending on your perspective and what you're trying to accomplish.
Let's not argue those points as they are certainly "generally" true at the least.

What I want to inquire as to true image quality comparisons. By image quality I am referring to pixel clarity, micro-contrast, etc. It would seem to me that all things being very equal, that the larger sensor with the larger pixel photo sites should actually do a better job rendering and capturing an image. This would be better edge detail, better micro contrast, certainly less noise at even base ISO, etc.

I ask this question because I know of members here and around who have said repeatedly they can tell very easily when opening up a RAW image produced on a DX or smaller sensor versus one that was made on a FF sensor or larger.

Can you chime in if you believe this is true or false? Subjective opinion is fine, but has anybody made a real attempt to ascertain if this is in fact true or false? Again, forget the low light, DR, and shallow DOF benefits, I'm strictly looking at a IQ comparison between sensors. Also please bear in mind I am truly speaking to a pixel level of detail here. I realize 100000% that regardless when the output destination is a low rez .jpg on a website or a small print, etc whatever benefits there either are or aren't would be completely neutralized.
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Comments

  • tcole1983tcole1983 Posts: 981Member
    I will chime in even though I do not have an FX body. I have shot many times with my best friend who shoots a D800E. When we shoot similar venues I normally can't tell the difference in pictures at computer screen size. That is probably the size of a sheet of paper at largest. His photo editing skills are better so in that aspect I see a difference, but at an event we shot I honestly can't tell which pictures he took, and which ones I took with my D5000 and D5200....that is a smaller sizes. At larger sizes it becomes more apparent. I however am not a pixel peeper. In good light at lowest ISO I don't see much advantage at all. I don't see a large difference in any aspect really. I should pull some examples sometime as a comparison....strip the exif data and see what happens.
    D5200, D5000, S31, 18-55 VR, 17-55 F2.8, 35 F1.8G, 105 F2.8 VR, 300 F4 AF-S (Previously owned 18-200 VRI, Tokina 12-24 F4 II)
  • spraynprayspraynpray Posts: 6,290Moderator
    I have the D7100 and the D750. To be honest, the IQ boost is worth having, but I wouldn't say it will change your life for most of your shots. For sure the D7100 is stunning value for money right now. Just my humble etc...
    Always learning.
  • manhattanboymanhattanboy Posts: 1,000Member
    I ask this question because I know of members here and around who have said repeatedly they can tell very easily when opening up a RAW image produced on a DX or smaller sensor versus one that was made on a FF sensor or larger.

    Can you chime in if you believe this is true or false?
    If the shot was done at low ISO and done to approximate the same field of view and depth of field (to take out any dof and noise differences) and also assume I am blinded to the MP size for some reason, then the answer is still yes you can tell the difference IF there is a big difference in the pixel width between the two cameras. For example, a D4s/Df versus a 7100/7200 you can tell. Largely this is because you can "zoom" in on a larger pixel pitch photo from the FX way past 100% and still have things appear sharp. The higher res DX will blur past a 150% zoom. This really has nothing to do with FX versus DX per se and is really just a function of the fact that the pixels can be much larger to compensate for slight errors in the focusing of the light on the sensor. Is any of this worth caring about? Probably not ;)
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015
    I am not a pixel peeper I can't see why any one wants to

    In situations where you need to use High ISO values, you will see a noticeable difference

    When shooting into the sun and you need a high dynamic range, and want to pull up the details in the shadows in post, you will see a noticeable difference

    With good, well balanced light, and a mid range zoom, the difference will be less noticeable

    There are other things to consider, all have been discussed to death

    Here are a few of them

    There is no DX equivalent of the 24mm f1.4

    With a top end FX camera and a top end FX prime, the ability to crop is a definite plus


    Post edited by sevencrossing on
  • PB_PMPB_PM Posts: 4,221Member
    I have the D7100 and the D750. To be honest, the IQ boost is worth having, but I wouldn't say it will change your life for most of your shots. For sure the D7100 is stunning value for money right now. Just my humble etc...
    I think this just about sums up the discussion. We can talk all day about technical differences on microscopic levels, but really the difference depends on what you are shooting and how.

    Personally I prefer FX due to pixel clarity and quality. That just a sense that I have, but the D7000 is the newest DX body I've shot with personally. In my experience, FX Images just seem to have a smoother, more natural look. Maybe that's due to the physically larger pixels, or maybe it's just how the cameras process the images I don't know. That said, as the quoted post above states, the difference between the two in terms of final image quality at normal viewing sizes is minimal at best.
    If I take a good photo it's not my camera's fault.
  • JonMcGuffinJonMcGuffin Posts: 312Member
    So I intentionally left my own opinion on the subject out for two reasons and that is A) I haven't actually done a really good side-by-side test comparison and B) I wanted to keep as open as a mind here as possible. My findings subjectively are much the same of what you guys are saying.

    @Spraynpray: The D7100 is a phenomenal "value" buy and I've been saying for quite some time now this level of camera/sensor/price combination really represents a huge bang for your buck and certainly a photographic tool that can truly do just about anything asked of it.

    @Spraynpray: You say "to be honest, the IQ boos is worth having..." So in your mind there is unquestionably an IQ boost with FX over DX? Is it tangible in your eyes or do you just have subjective confidence in this?

    @PB_PM: I think you summed up my view and opinion on this better than I could have myself. I too feel and get a sense that the FX images just seem smoother and more natural and in my view it just seems to have something to do with the larger sensor (this is actually precisely why I asked). I also agree the differences are small, but if the are there; well, than that's what I want - you only live once.

    @sevencrossing: Yes, I know there are limitations of lenses with DX so I get that argument, but I wanted to steer clear of worrying about what is better based on those factors. I just want to know if all is in fact equal, does a larger sensor produce a "better" image than a smaller one. Or more directly does Full Frame produce better than APS-C/DX, etc.

    @tcole1983: I'd love to see some examples if you think you have some.
  • snakebunksnakebunk Posts: 921Member
    edited May 2015
    I think I could learn to tell the difference between two different camera models (maybe), but I don't think I can tell the exact size of the sensor just buy looking at a photograph. I actually think it is impossible because of all other differences between cameras and sensors, for example pixel density and sensitivity.
    Post edited by snakebunk on
  • spraynprayspraynpray Posts: 6,290Moderator
    @JonMcGuffin: I do a lot of 'difficult' low-light photography for recreational photography along with landscape and macro. In the area of low light photography, yes, there is a small IQ boost (I'll let you know about macro in a couple of months) but some of my best low light shots were done with the D7100. As I said, it will not change your life. You mention noise - be aware that all cameras are noisy when there are very few photons around but if you are talking about 'dim daylight' sort of levels, then the D7100 is no slouch but is beaten by the D750.

    If I had to choose between using the D750 with a crappy lens on it or the D7100 with an excellent lens on it, I would go with the better lens.

    Why don't you tell us what it is that you are looking to get out of buying the D750 that is lacking for you on the D7100? The AF point spread of the D750 irks me in comparison to that of the D7100 and so on - many small differences between the two. Some better on one body, some better on the other.

    Always learning.
  • JonMcGuffinJonMcGuffin Posts: 312Member
    So, another way to ask or look at this is this way...

    D750 FX 24Mp - 85mm 1.4 Lens @ F 8
    D7200 DX 24Mp - 56mm 1.4 Lens @ 5.6
    The goal here is to frame both images identically and also have same DOF. Middle road aperture to remove lens differences such as CA's, vignetting, LoCa, and corner sharpness, etc. This should get the lens out of the equation.

    Both cameras are current generation "best of best" sensors with their respective size.

    Snap a picture at same exposure, using base ISO 100 for each. Shoot on a tripod with remote release, etc. And shoot a scene that has pretty considerable amount of contrast and dynamic range in the image.

    Strip out all the EXIF data.

    Do you think you could tell which was which even if allowed to:

    A) Zoom in 100%, 200%, or whatever magnification you wanted.
    B) Push and pull highlights/shadows all you wanted.

    If you think you could tell, would you always be able to tell? If this was done with 10 different scenes, would you pick it right each time?
  • JonMcGuffinJonMcGuffin Posts: 312Member
    @Spraynpray. Thank you for asking. I'm not really convincing myself out of the D750. I'm gonna go for it regardless because:

    a) Better low light performance
    b) Ability to use a shallower DOF
    c) Better buffer than my wimpy d7100
    d) Better high ISO performance regardless of light

    I was spoiled with my D700 and so considering I have plenty of FX glass, it's well worth it.

    I ask because we've all read the arguments countless times but what always comes into play are the ISO, dof, etc and I can't seem to get or find a straight answer to the question strictly based on pixel quality. Does a FX sensor give I higher quality image than a DX when all the limitations of DX are addressed.

    It feels/sounds like the answer is either it doesn't, or its exceptionally minimal, and that the real reason to choose FX over DX isn't IQ, it's simply a more capable tool in terms of flexaviltity, etc.
  • heartyfisherheartyfisher Posts: 3,181Member
    edited May 2015
    Hi @JonMcGuffin Interesting thoughts ..

    I am of the other persuasion regarding the D750 vs D7200 .. I have looked at them both in a lot of detail and have decided to go with the D7200 .. However, I have not got either so my opinion may be totally wrong. but for what its worth. These are my thoughts on the subject.

    Firstly, there is an IQ difference generally between FX and DX and the advantage does go to FX. why is this? for me the reason is not what’s been mentioned in this thread. ie its not the higher ISO and dynamic range of 1 stop (which I dispute since we have the D7200, DR is equal/better and high ISO is about 1/2 to 2/3 stop behind). The IQ from the D7000, 2 generations behind the latest DX and FX and with AA filter of course does not represent current DX IQ. Your scenario comparing DX and FX using 2 different lenses I think wont be revealing any info especially with the use of the 56 F1.4 which has a very unique image rendering. IE the lense attributes would play a much bigger part in identifying the different images.

    So what makes the difference ? Its because the FX pixels are generally bigger and its because the lenses we use on our cameras are almost always less sharp than what the sensor can resolve and its because of diffraction. ie unless you have an OTUS you will be better off with an FX sensor.

    The reason is that the larger pixels will make a less sharp lense seem sharper. So why have I decided to go D7200 vs FX ? its because the difference is so small (< 1%?) compared to the flexibility of options (upto 200%-300%) available to a DX system for any given price point. However, if you are comparing between the D7200 and the D750, the lack of AA in the D7200 vs the AA in the D750 would again at the very least equalise this criterion. (The photographylife review seems to show that the D7200 performs better, but then they have sharp lenses..)
    Post edited by heartyfisher on
    Moments of Light - D610 D7K S5pro 70-200f4 18-200 150f2.8 12-24 18-70 35-70f2.8 : C&C very welcome!
    Being a photographer is a lot like being a Christian: Some people look at you funny but do not see the amazing beauty all around them - heartyfisher.

  • snakebunksnakebunk Posts: 921Member
    @JonMcGuffin: Given your example my guess is the D7200 will be a little bit sharper because of the lack of filter and because the corners are cropped away. If you shoot at higher ISO I think the D750 will get better because the larger sensor collects more light, hence less noise.

    It would be fun to do the test, but it is impossible because there are no equal lenses with different focal length.
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015
    but it is impossible because there are no equal lenses with different focal length.
    I think the

    For DX
    AF-S DX NIKKOR 35mm f/1.8G

    and the FX
    AF-S NIKKOR 50mm f/1.8G

    are compatible

    Post edited by sevencrossing on
  • spraynprayspraynpray Posts: 6,290Moderator
    Yes I agree. 35/1.8 & 50/1.8
    Always learning.
  • Vipmediastar_JZVipmediastar_JZ Posts: 1,708Member
    edited May 2015
    Use the Nikon 24-70mm
    FX 70mm
    DX 46mm x 1.5=69mm

    or
    70-200mm
    105mm DX
    158mm FX

    therefore you use the same lens to do the test.
    Post edited by Vipmediastar_JZ on
  • JonMcGuffinJonMcGuffin Posts: 312Member
    Use the Nikon 24-70mm
    FX 70mm
    DX 46mm x 1.5=69mm

    or
    70-200mm
    105mm DX
    158mm FX

    therefore you use the same lens to do the test.
    Ok, that would seem to take care of the lens and focal length. Now what about the aperture?
  • Vipmediastar_JZVipmediastar_JZ Posts: 1,708Member
    I didn't consider that but your example seems practical 5.6 and f8 or f8 and f11 depending on the lens 2.8 or f4 version.
  • MsmotoMsmoto Posts: 5,396Moderator
    I am of the opinion that in a practical sense, one can see differences only at huge magnifications and that while pixel peeping is interesting, for a commercial photographer it probably makes little difference. What determines what I would use for a photo assignment is entirely dependent on the nature of the end result desired by a client.

    So, if it is high speed action, pick the body which can shoot high FPS, D4/D4s. And, heavily cropping from full frame still results in stunningly sharp images at 20" x 30" enlargements.

    Products...I would use a full frame with high pixel count, i.e., D800/810. Also, for products I would use a PC lens as correction in the original image is always best IMO.

    The only reason I might use a crop sensor is .....mmm....really cannot think of any.

    I have shot billboards which are razor sharp from 2 1/4" format. There are examples of billboards from full frame 35mm. All of this discussion is rather like the issue of whether Nikon will have a pro DX body. Well, it is probably not here because the vast majority of pros shoot full frame for reasons that this is what works best for a high level professional.

    The above is only my opinion, has no more validity than anyone else on the forum. Maybe I need to grab a D7200....but, as the used D800E I purchased blows my mind with its ability to create images...I just do not see a need. And, I do not even have the 14-24, nor the 24-70 f/2.8 Nikkor lenses.
    Msmoto, mod
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015
    but, as the used D800E I purchased blows my mind with its ability to create images...I just do not see a need.
    That sums things up pretty well

    No one has ever suggested the IQ of a D7100 or D7200 is better than a D800, D800E or D810
    nearly as good? may be but not better

    Post edited by sevencrossing on
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015


    @sevencrossing: Yes, I know there are limitations of lenses with DX so I get that argument, but I wanted to steer clear of worrying about what is better based on those factors. I just want to know if all is in fact equal, does a larger sensor produce a "better" image than a smaller one. Or more directly does Full Frame produce better than APS-C/DX, etc.

    Good luck with your pixel peeping

    but when choosing between DX and FX. The glass you would like to use ( and can afford) must be taken into account

    You are more likely to see the difference with a rage of primes, than with a convenience of zooms
    Post edited by sevencrossing on
  • IronheartIronheart Posts: 3,017Moderator
    but, as the used D800E I purchased blows my mind with its ability to create images...I just do not see a need.
    That sums things up pretty well

    No one has ever suggested the IQ of a D7100 or D7200 is better than a D800, D800E or D810
    nearly as good? may be but not better
    Actually, they have, and it is. If you have to crop the D810 image to get the same framing as the D7200:
    https://photographylife.com/reviews/nikon-d7200/2
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015

    Actually, they have,
    Dx does have the advantage of reach

    BUT one swallow doesn't make a summer
    Post edited by sevencrossing on
  • sevencrossingsevencrossing Posts: 2,800Member
    edited May 2015
    I certainly don't mean to open up the proverbial FX vs DX can of worms .
    But this is nrf :)

    and needless to say, the argument of reach is appearing
    Post edited by sevencrossing on
  • JonMcGuffinJonMcGuffin Posts: 312Member
    Yeah, let's not go to the "reach" part here. I'm just strictly interested in IQ and I'm not talking about cropping am image taken from a FF sensor. But it sounds as though the tech is essentially so good now that in reality that's all a crop sensor is.

    I'm getting the strong perception here that, overall, when it comes to strict IQ given all other things remaining the same, there is virtually or possibly even no difference between the IQ of a FX or DX sensor. That the benefit from an FX sensor come by way of other benefits (which effect IQ of course).

  • PB_PMPB_PM Posts: 4,221Member
    edited May 2015
    I think it's easy to forget that this isn't 2006-2008 period when the first full frame cameras/sensors came out. The larger pixels in the early models had a huge advantage over the previous generation CCD equipped, and early CMOS equipped, crop cameras. It was 2 and half to 3 stops better back then. Today the primary reason to choose full frame over a crop sensor is not low ISO IQ (ISO 50-1600), it's a combination of factors. To me the advantage is as such:

    1. Large pixels do lead to cleaner images, throughout the upper ISO range (3200+), even if only by 1 stop. Every professional review I've look at backs up this belief without question (Nikon cameras).

    2. Better range of high quality lenses at a wider range of price points. You do not need to buy $1500+ lenses to get good images with an FX camera. If you believe that you need $1500 glass to get to shots with FX, then you also believe the same of any 24MP DX body too. If anything you need better glass with DX, since the pixels are more tightly packed. So much for FX cameras needing more expensive glass...

    The reality is that previous generation pro glass is still very good, especially for the dollars pay for them. You can get superior images, at the pixel level, with expensive modern glass, but unless you are selling your stuff or printing at large sizes, what difference does it really make?

    Did camera makers create this FX/full frame advantage? Yup, when they stopped releasing crop sensor glass at a meaningful rate. Actually it started back in the film days, but who's counting?

    3. Viewfinder Experience. The larger viewfinder is much nicer, brighter and causes less eye strain in extended use.

    4. Reach is not the be all and end all of photography. Yes DX shooters, reach is not the most important aspect of wildlife photography, as hard as that may seem to believe. I've been shooting wildlife for the better part of 7 years now, and out of those 7 years the last 4 have been with FX and I don't miss DX "reach" for a second. Chances are that if the subject looks small in an FX viewfinder at 400mm (300mm DX), it's too far away for just about any lens to get a clean shot of (meaning either heat distortion or other atmospheric conditions start to play a big roll in image quality). That's just my experience, which includes renting super telephoto lenses. Sorry to burst your bubble. Big glass (400mm+) still works best with subjects that are 10-50m away, in all but the most ideal conditions. I haven't spent bucket loads of cash on telephoto lenses, but rather found some older glass that is reasonably priced instead. Is it the very best? Nope. Is it more than good enough? Yup. Kind of getting back to part of point 2 here though.

    Final thoughts:
    I'd take an FX body, even a D700, as a starter camera over a D7200, any day of the week. Why? Now days it's cheaper, has a better buffer, more photography centric features, better build, and control layout. Yes I have a D750 with similar controls to a D7200. I still like the controls of the D700 better. Moving on, the available range of glass; you can buy the entire range of F2.8D prime lenses (used, 24mm, 35mm, 50mm, 85mm) for less than $1k. Slap those on a $850-900 D700 and you are good to go. To get matching focal length primes like that for a D7200, which is difficult, would likely cost far more. With zooms, advantage does go to the D7200, since most DX glass available is an excellent range super zooms, but you will pay more.

    The only reasons not to at least consider a used FX body over a new DX body (as a starter hobby kit with a price cap of $2k) in my mind would be, a) An innate desire to have the latest and greatest, (It's not a crime, it's okay!) b) Heavy cropping. Everyone crops sometimes, if not most of the time. c) you need to be able to shoot video, d) you print big (like 18x24 and larger) on a regular basis, or view images primarily on a 4k+ monitor.

    Am I crazy and not completely logical here? Maybe. Do I expect many people to agree? Nope. Does it matter? Nope. Just throwing ideas out there, since not every subject has, or deserves, cookie cutter answers.
    Post edited by PB_PM on
    If I take a good photo it's not my camera's fault.
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