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Lens questions on a DX camera body

lens dx fx crop factor d5000 nikon photography

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4 replies to this topic

#1 PiNoYz



  • Joined: 30-August 06
  • Location: Chicago, USA
  • OS: Windows 8.1,Windows 7, Android OS 4.4.4

Posted 28 May 2012 - 04:07

I'm really confused about the lens details, so my question is to all of you photography experts.. Are DX lenses really that focal length that they are or do you have to factor in the crop factor? (I have the Nikon D5000)
For instance, is a 35mm DX lens really a 35mm lens or is it 52.5mm (1.5x crop factor)?

The same question goes for the FX format lenses. What would the focal length of an FX lens be on a DX camera body?
An example is, 24-85mm, it is an FX lens. So on a DX body, will that focal length be 24-85mm or be 36-127.5mm?

I hope you can understand what my question is asking!
Thanks for your help guys!

#2 Andre



  • Joined: 04-November 02
  • Location: pastryville

Posted 28 May 2012 - 09:51

A 35mm DX or any other DX (crop) lens for that matter lens has similar optical properties (ie field of view) to that of an eqeuvalent FX lens. The only difference (besides build quality of the glass) however is that the DX lenses don't cover the whole 35mm film frame hence you get very heavy vignetting if you put it on an FX body. One important thing to note, while for example a 35mm lens on DX gives you an eqeuvalent focal length of around 50mm on FX, it can not be compared to a true 50mm lens on an FX body.

All in all, your assumptions are correct. Any lens (given its focal length is represented in full frame terms) put on a crop body should be multiplied by the crop factor of the camera sensor.

#3 shan



  • Joined: 03-January 06

Posted 28 May 2012 - 10:23

Dont be confused with mm , to be simple DX= small sensor = captures small area , FX= bigger sensor so bigger area which is 1.6 times more than DX . with the same FX lens, DX body will capture 1.6x less area. hope following pic helps.Posted Image

#4 OP PiNoYz



  • Joined: 30-August 06
  • Location: Chicago, USA
  • OS: Windows 8.1,Windows 7, Android OS 4.4.4

Posted 28 May 2012 - 19:37

Thanks for your reply guys! It was really helpful!
I'm only asking this question cause I want to buy another lens for my gear and was looking at an FX lens and wasn't sure if the FX lens would be the same focal length when put into a DX body.
The field of view of an FX lens will be smaller (more zoomed in/smaller area) in a DX body when compared to an FX body, correct?

I hope I am understanding this right.. ;)

#5 Argote


    Formerly known as ArtOf_War

  • Joined: 24-June 04
  • Location: SF Bay Area, USA
  • Phone: Galaxy Nexus

Posted 30 May 2012 - 11:01

An FX and DX lens of the same focal length should work the same on a DX body (given they have the same optical quality, this will usually not be the case) and both will give you the angle of vision a lens of that length times the crop factor would on an FX body.