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The effect of a DX sensor on your lens or... "The crop Factor"

Discussion in 'Lens Lust' started by Candidcameraman, Sep 7, 2008.

  1. I have been wanting to put this to the test for so long, cause I got tired of the 1.5 crop factor "you get more reach" argument... "A 50mm acts like a 75mm, it is longer on a DX body" comments...

    Essentially you are using a smaller sensor when using a DX camera, thus getting a smaller image. Granted you get more pixels per square inch but my point is that you are losing out in the end.

    This said DX isn't bad ... it just isn't what I thought it was... You do not get more reach with your lenses you just get a smaller sensor on which to capture the said image.

    This is an FX picture with a DX cropped added to it... See what I mean?

    Subscribe to see EXIF info for this image (if available)

    Maybe not... Okay here is the FX picture

    View attachment 248773

    Versus its DX counter part size for size compared to sensor size I call it the "real DX"

    View attachment 248774

    Of course the same resize as the FX shot above leads you to think it is closer to you but it is not. I was at the same distance with the D3 and D300...

    View attachment 248775

    You just lost all the shaded area

    View attachment 248776

    Now the DX crop on the FX camera and you have the same image

    View attachment 248777

    Well ... Same results... I used a 50/1.2 on a D300 and a D3 to show these and ... Well... That 50 did not turn into a 75mm on the DX... It stayed a 50, it did not give me more reach - it actually made me lose a whole big area that the lens covers...

    Why do I like FX... It just makes me use my lenses at 100% capacity as opposed to ... well you get the idea but for all of those who love the cropped sensor I saw this today and though of you :wink:

    View attachment 248778

    Kidding aside the real difference is in the sensor size, don't give me the "you get more reach because of the crop factor..." no... gime "I get less coverage and that's fine by me because when I crop I get more pixels left over" then we'll be speaking the same language.

    View attachment 248779

    So your 200mm lens is not a 300mm lens all of a sudden cause you shoot DX but still is a 200mm you just have less to work with, any questions?

    Again.. DX crop on the FX sensor and DX

    View attachment 248780

    View attachment 248781

    And FX

    View attachment 248782

    Which would you rather end up with... ? Mind you I had no tripod but not move from where I was sitting.
    Last edited by a moderator: Sep 7, 2008
  2. Only one comment.... Doesn't the amount of data stored impact this review? There is not the same amount of information stored within the DX space of the FX sensor.

    An FX image cropped has about 5 million pixels within 2,784 x 1,848. While the DX sensor stores 12.3 million pixels within an area of 4,288 x 2,848.

    While I totally agree with everything said, wouldn't the reduction in stored data give the DX a potential advantage when doing long zooms that can not be made up by moving closer to the subject?
  3. I have a question. Doesn't the DX crop give more reach if your lens cap is right side up?
  4. Dude,

    The real effects of the DX crop don't really show up until you start using telephoto lenses. On a 12mp DX sensor I was capable of using my 70-200 for most my jobs. With a 12mp FX sensor I've had to resort to switching out my 70-200 VR with longer lenses.

    You don't gain additional reach with DX, you get more pixel density which translates to more detail when shooting afar. With telephoto shooting, the results are more apparent. You can't judge a shot with a 50mm and say that you don't gain anything on DX, because you do.

    Honestly if someone could do a test with a D300 and 300 f/2.8 vs. a D3 with a 500 f/4 I'd love to see how they compare.

    If Nikon can mature FX with slightly more MP (I'd be happy at 16-18mp) and still retain high ISO, I'll be good! :smile:
  5. MikeG76


    Jun 11, 2008
    Middletown, NY
    It gives more reach when I use my red flash card vs my blue one.
  6. Wileec

    Wileec Guest

    Your rhetoric is circular . . .

    . . . It's great you have the resources to get a choice. Most of us don't.

    And while a DX sensor is smaller - it still has all the density it is supposed to, so based on field of view - the lens multiplier is valid. It is true we may not get the full field of view that the same lens (if FX compatible) on an FX body would capture, but it's not the same as using an FX camera in DX mode - which is a fraction of the field of view of the lens AND a fraction of the pixels the sensor is capable of using. With a DX sensor - we do get the limited field of view, but all the pixels the sensor has are used to capture that limited field of view, so it effectively provides a view that would require a far larger lens on an FX body to achieve.

    Another side of this is that a lens that tends to be questionable on the edges on an FX camera, will generally have no such issue on the DX body.

    There are pluses and caveats to both. And price is a factor that currently keeps FX out of the question for most DSLR shooters, so this discussion is moot since it is theoretical for most of us.

    I think a truer test of this kind of thing would be to setup a tripod and shoot a scene with a 200mm lens on a DX and a 300mm lens on the FX, then compare those shots. That seems the more realistic comparison. Bottom line for a given shooter is what a camera captures. We all can bemoan what we can't capture, be it with a higher density sensor, a larger sensor, a higher ISO performing sensor, etc. More will come from making the most of what we have would be my thought.
  7. Actually that's a point Jonathan made in a thread today and I quote:

    "my only gripe is that I need the MP density I get with daylight telephoto shooting" so yes, DX has a big potential but once a 24 megapix Nikon FX camera is out... that will be negated until then in the Nikon camp the DX density is pretty great when one need to crop a shot, still doesn't give you more reach though...
    Last edited by a moderator: Mar 15, 2017
  8. Errrr I don't get that one, sorry - a bigger lens to achieve what? No, that was a 50mm lens capturing images using a D300 with a DX sensor and a D3 with an FX sensor... The DX sensor did not give me more reach - just a limited field of view, the camera I was using as a prop for this did not appear closer in the viewfinder of the D300.

    Lenses do not tend to be questionable at the edge of an FX sensor in my own experience, quite the contrary.

    My only point is that no... you do not have more reach, that 200mm does not magically extend to 300mm on a DX sensor, you'll get the same reach on an FX sensor and that's my only point.

    I used a DX sensor for quite some time but honestly did not see a loss of reach in any of my lenses when I made the switch to FX so I put it to the test and ... well that 200mm stays a 200mm you just lose all the edges... and that can be crucial when using a zoom lens lie a 70-200 when you need all you can at 70mm - that's when an FX sensor rules but when you are at 200mm and you need to crop a picture by 50% to get the image you want then a DX sensor in this case rules the day as Jonathan said earlier today (psssst that 200mm on a DX sensor is still a 200mm but don't tell anyone :wink: a DX sensor does not give you more reach, that's just plain silly nonsense and that's my point.)
  9. That's the wording..... And it makes sense.
  10. But more pixels per square inch is exactly the point. It gives a lot more cropping ability for smaller (or distant) subjects. The D300 and D700 are both 12 Mp cameras but the D700 is only has 5.1 Mp DX size images. Cropping an image that's 25% of a DX frame on a D300 results in a 3 Mp image whereas with the D700 the image would only have 1.25 Mp.

    DX has its place and so does FX. It just so happens that Dx costs a lot less as well.
  11. You can't just resize a DX image and then say it's the same distance. Post up the D300's original image resized the same as the FX and pixel for pixel the DX image will be closer. Based on your methods of comparison that'd be like taking a picture with an 85mm and another one with a 50mm, cropping the 50mm and saying they're the same.
  12. Wileec

    Wileec Guest

    I understand and agree - yet effectively, because of the pixel density, you are getting what it would take a much larger lens to capture on an FX body - which is why we call it the lens multiplier. That's why I suggest the only real test of this is to set up two cameras with two lenses and compare what they capture. Frame to frame.

    It doesn't give more reach - but because it's not a digital zoom, which in fact is a subset of the pixels resampled to fill the full area (video and still cameras often use this) - it IS effectively a greater zoom.
  13. I coined it! Don't be stealing it now!

    MP Density™

    Copyright 2008-2009 Jonathan F/2

    Hahahahaha! :tongue::biggrin::wink::tongue:
  14. You know what's funny, I think it's even more important to shoot with high quality glass on DX. I like using the 80-400 VR again on FX because it doesn't show it's weaknesses! :wink:
    Last edited by a moderator: Mar 15, 2017
  15. Wileec

    Wileec Guest

    Test anyone?

    So, how about one of you guys with a 12mp DX body and a 12mp FX body do a test with 200mm on the DX and a 300mm on the FX and let us see how each of those frames compare. A picture is worth a thousand words and two pictures, . . . well . . . .

    Just a thought.
  16. Wait... Didn't I re-use your words BEFORE you applied the copyright? What's the rules on that? :confused:  :smile: :biggrin:
  17. Darn it, I'll just release it to public domain! :smile:
  18. Wileec

    Wileec Guest

    I don't have a choice, but I sure prefer shooting with the Nikon 80-200mm f/2.8 on my D300 compared to shooting with the Tamron 200-500mm I have. I have to work harder to get sharp images with that Tam.
  19. JeffKohn


    Apr 21, 2005
    Houston, TX
    But you're arguing semantics that don't really matter for real-world shooting. What matters in the real world is whether you can get the framing you want with the resolution you want. If using a D3 means you have to crop down to 5mp, the D300 is going to produce better results.

    Personally I find the argument of using "all" of the lens as a reason for favoring FX pretty strange, especially since that part of the image circle you're now using beyond DX tends to be where the image quality of the lens degrades.
  20. How can it possibly be closer, taking into account the size of the sensors, you'd have to test it yourself, I assure you it is not closer.

    That 50mm on a DX sensor does not act like a 75mm it just is a smaller sensor, you are using but a portion of the image going through that lens, the part ending up on your sensor is smaller than on a 35mm film or FX sensor.

    I used to think that a DX sensor gave me more reach but let me assure you it does not.

    Do the test and you'll be surprise and even become a believer :smile:

    DX does not give you more reach, it gives you the same exact reach just that ... you have a smaller area capturing the image that's all, so yes all the corners and all that are not in the picture, that's for sure.
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