35mm fx prime vs 50mm dx prime on dx camera question

Discussion in 'Photography Beginners' Forum' started by photo12345, Dec 19, 2015.

  1. photo12345

    photo12345 TPF Noob!

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    hey everyone, I'm in the market to pick up a 1.8 prime lense. I own a dx camera.

    At first I was going to go buy a 50mm dx lense.

    But if I buy a 35mm fx lense, will I get roughly the same effect on my dx camera as the 50mm dx lense?

    I'm trying to keep in mind that before 2016 is over I will be upgrading to a fx camera. Not that these lenses are very expensive but I figure it will save me a few bucks.

    Any insight would be greatly appreciated.

    Cheers


     
  2. tirediron

    tirediron Watch the Birdy! Staff Member Supporting Member

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    No, you will not. Whether a lens is crop or full frame only affects the image circle it projects onto the sensor. Focal length is focal length is focal length, and that doesn't change no matter WHAT sensor format is used. What does change is the field of view (and for practical purposes, that is ALL that changes). So, a 50mm lens, when used on a crop frame camera will always have a field of view of approximately that of a 75mm lens when used on a full frame camera, and a 35mm lens will have the field of view of a 52mm lens. In short, regardless of the format, when used on your crop body, these two lenses will still show a distinct difference in field of view.
     
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  3. KmH

    KmH In memoriam Supporting Member

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    No.
    A 35 mm FX lens on a DX camera still delivers a DX size image.

    DX is describing the smaller APS-C size camera image sensor. FX describes a 35 mm full frame image sensor
    A DX lens projects a smaller image circle than an FX lens does.
    It costs a bit less for Nikon to make a DX lens than to make the same lens as an FX lens because some of the glass elements in the lens are smaller and less costly to make.
     
  4. photo12345

    photo12345 TPF Noob!

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    Thank you for clearing that up for me. I was quite confused :)
     
  5. Ido

    Ido No longer a newbie, moving up!

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    Why? DX is perfectly suitable, usable, sufficient, … for pretty much anything nowadays. Moving from DX to FX is often just a slight improvement in technical image quality, that rarely is it actually worthwhile to do so. You should write down “Improve photographic skill & technique” on your New Year’s resolution, instead of “Purchasing an FX camera.”
     
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  6. john.margetts

    john.margetts No longer a newbie, moving up!

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    much the same can be said for lenses. Unless you are printing your pictures very large any improvement in image quality will be invisible. Printing at A4 or below, or viewing on a screen, you will be better off with DX sensor and mid-range lenses and spending the extra money on your better half.



    Sent from my A1-840 using Tapatalk
     
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  7. Ido

    Ido No longer a newbie, moving up!

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    I agree, though I suspect the reason behind buying one of these lenses is depth of field, not technical quality.
     
  8. astroNikon

    astroNikon 'ya all Bananas I tell 'ya Supporting Member

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    What camera do you have ?

    That would also help on your buying decision. For instance a Nikon 50/1.8 AF-D lens will NOT AutoFocus on a Nikon d3x00 or 5x00 series camera. Whereas a Nikon 50/1.8 AF-S lens WILL AutoFocus. Both are available NEW, with a $100 price difference, but as mentioned may or may not work with your camera.

    With Field of View I always reference people to pictures to better understand the difference of the image cirlces with a prospective lens ==> Camera Sensor Crop Factor and Equivalent Lens Focal Length
     
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  9. Solarflare

    Solarflare No longer a newbie, moving up!

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    ???

    I am not aware there is any 50mm DX lens in the first place ?

    There is an AF-S 35mm f1.8 DX and an AF-S 35mm f1.8. The later is a FX lens, since it has no "DX" in the name. Its twice as expensive, heavy, and big.

    And then there is a AF 50mm f1.8, AF-S 50mm f1.8, AF 50mm f1.4, AF-S 50mm f1.4. Those are ALL FX lenses, since none of them has a "DX" in the name.

    And 50mm would be a strange choice for a FX lens, anyway. If at all, Nikon would probably make a 56mm f1.4 DX lens. Well, I doubt they will do any such thing.


    As others have said, a 35mm is always a 35mm lens, and a 50mm is always a 50mm lens. The "DX" attribute simply means the image circle is smaller, i.e. the borders on a full frame sensor will often be dark (but some DX zooms actually have an area of their focal length in which they fully lighten the sensor).

    However, an APS-C [which NIkon calls DX] sensor is only ~24x16mm in size, while a full frame [which Nikon calls FX but its really the good old small format from film times] is ~36x24mm. So the APS-C sensor will only show the "middle" of the picture. Thus an APS-C sensor will have the same viewing angle on a 35mm lens as a ~53mm lens would have on a full frame sensor, and with a 50mm lens the viewing angle would be like ~76mm on full frame.


    So if you buy a 35mm f1.8 [FX, but thats not explicitly listed] instead of the 35mm f1.8 DX, you can use that lens on the FX cameras as well. It will have however have a different viewing angle on the FX camera, than on the DX camera.
     
  10. Braineack

    Braineack Been spending a lot of time on here!

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    lists (4) 50mm FX lenses; suggests that it would be strange.
     
  11. photo12345

    photo12345 TPF Noob!

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    I am using a D 5300

    Thank you for this read it made things much more clear for me.
     
  12. astroNikon

    astroNikon 'ya all Bananas I tell 'ya Supporting Member

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    with the D5300 you want lenses that have a built in focus motor.
    So look for the "AF-S" identifier on a lens

    for instance, this 50mm AF-D will NOT AutoFocus on your camera "AF Nikkor 50mm f/1.8D" ==> AF Nikkor 50mm f/1.8D from Nikon

    but this one will AutoFocus on your camera "AF-S NIKKOR 50mm f/1.8G" ==> Nikon AF-S NIKKOR 50mm f/1.8G Lens


    To use the "AF-D" type lenses you would have to upgrade to a body with a built-in focus motor. As they use a "screwdriver" type connection between the camera bodies' motor and the lens which is driven by the camera body itself. The AF-S there's an electrical connection (and it tells it what to do) which gives power to the lens' focusing motor. The in-body focus motor exists on D7x00 and higher cameras (and some older models such as D70/D90 etc)
     

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