seeking advice for lens upgrades

Discussion in 'Beyond the Basics' started by DScience, Oct 31, 2009.

  1. DScience

    DScience No longer a newbie, moving up!

    Joined:
    Apr 12, 2009
    Messages:
    1,513
    Likes Received:
    122
    Location:
    Denver, CO
    Can others edit my Photos:
    Photos NOT OK to edit
    Hi everyone,

    I want to start by asking a question that will probably make me look even more amateurish than I already am. But anyway, I am wondering the difference in view between a DX and FX lenses on a DX body; the D90 in particular. Let me get something straight, since DX have the crop factor (1.5 in my case) that means that a 50mm non-DX lens on my camera appears to be a 75mm lens; correct?

    Now let's take the new 35mm f1.8G DX lens that came out a while back. Even though this is a DX lens, doesn't it still appear as a roughly 52mm lens? I'll explain my question after this is taken care of because it's been confusing me since the beginning.
     
  2. Kegger

    Kegger TPF Noob!

    Joined:
    Dec 30, 2007
    Messages:
    569
    Likes Received:
    1
    Location:
    The warm, sunny, very polite South
    Can others edit my Photos:
    Photos OK to edit
    If it's an FX lens the crop factor comes into play. If it's a DX lens, it doesn't.

    Smaller rear lens only covers the DX sensor, so you actually have a 35mm representation.
     
  3. Derrel

    Derrel Mr. Rain Cloud

    Joined:
    Jul 23, 2009
    Messages:
    35,456
    Likes Received:
    12,795
    Location:
    USA
    Can others edit my Photos:
    Photos OK to edit
    A lens has only one focal length, no matter what device it is mounted to. You are correct in that a 50mm lens mounted on an APS-C Nikon body will have an angle of view similar to the angle of view a 75mm lens on a full-frame 35mm or FX digital produces.

    Using a DX prime like the 35mm 1.8 from Nikon, the angle of view on a DX Nikon body like a D90 will be roughly equivalent to the angle of view of a 52mm lens used on a full-frame film body or an FX format Nikon like a D700.

    An older 35mm f/2 AF-D Nikkor will also have the same angle of view on a DX body as the newer 35mm 1.8 AF-S model has on a DX body. The angle of view factor or FOV factor on DX bodies applied to both full-field lenses and to reduced-field or "DX" lenses.

    When a DX lens is mounted on a Nikon FX camera, the default behavior of the camera is to switch the capture size to the DX mode; the 35/1.8 AF-S G can cover almost the whole frame of a D3, but not quite: when used in the 5:4 proportion capture mode on the D3, the 35/1.8 F-S G covers that format pretty well, but with vignetted corners. What kegger wrote about the FOV factor *not* being applicable to DX lenses used on APS-C cameras is not quite stated correctly. It does not matter what type of lens is put on a D1-D2-D100-D200-D40-D50-D70-D80-D60-D3000-D5000-D90-D300 body; the focal length of any lens used on an those APS-C camera bodies will be a narrower angle of view than if the same focal length were to be mounted onto a full-frame camera.
     
    Last edited: Oct 31, 2009
  4. DScience

    DScience No longer a newbie, moving up!

    Joined:
    Apr 12, 2009
    Messages:
    1,513
    Likes Received:
    122
    Location:
    Denver, CO
    Can others edit my Photos:
    Photos NOT OK to edit

    That's what I thought...Kegger.


    Anyway, the reason why is because I don't see the point in getting DX lenses, unless you have a reason why NOT to ever get a FX camera. I say this because after really looking into Nikon's glass, it seems obvious that they spend the most time and and effort in the they're 'real' lenses; non-DX. All their great glass that I want is for FX cameras. I eventually would like to have a full frame, and so I just feel it's a better decision to invest in non-DX glass, especially if BOTH will give you the crop factor.
     
  5. DScience

    DScience No longer a newbie, moving up!

    Joined:
    Apr 12, 2009
    Messages:
    1,513
    Likes Received:
    122
    Location:
    Denver, CO
    Can others edit my Photos:
    Photos NOT OK to edit
    It's weird to think you've probably been using your D300 for years thinking you're getting the 'true' focal range for your DX lenses.
     
  6. musicaleCA

    musicaleCA TPF Noob!

    Joined:
    May 23, 2009
    Messages:
    2,303
    Likes Received:
    0
    Location:
    Vancouver, BC
    Can others edit my Photos:
    Photos OK to edit
    They're cheaper to produce because less glass is used. They're lighter in weight for the same reason. They're simply more compact. And all that together can be very useful in some situations. If I'm going to take candids from a telephoto range, would I be best served shooting with my EF 70-200/f2.8L USM IS, which is gigantic, heavy, and off-white, or my much smaller, lighter, black, and less imposing EF-S 55-250/4-5.6 IS? On top of that, the only way to get true wide and ultra wide angle lenses for crop cameras is to buy DX or EF-S glass, since you won't find FX or EF glass at 10mm.
     
  7. DScience

    DScience No longer a newbie, moving up!

    Joined:
    Apr 12, 2009
    Messages:
    1,513
    Likes Received:
    122
    Location:
    Denver, CO
    Can others edit my Photos:
    Photos NOT OK to edit
    Good point. Yea I suppose that would be one situation where I would get a DX lens, if I needed a ultra wide angle.
     

Share This Page