FX/35mm lens on a DX body?

Started Sep 27, 2012 | Discussions thread
Guidenet Forum Pro • Posts: 15,748
A few mistakes. Maybe typos.

pavi1 wrote:

It will work perfectly and the one who recomended not to use DX lens on FX is not someone you should be taking advice from.

Lena Hale wrote:

Is it impossible to use an FX lens on a DX body, or will it just cause image abnormalities? I know that it's possible, just not recommended, to use a DX lens on a 35mm body and I want to know if it works the other way too.

Lena several answers seem to be not correct. Here's how it works. Slimandy has it correct and maybe some others.

Using a FX lens on a DX camera. No problem whatso ever and in fact is what many of us do when using a DX camera. There are just too many areas where there is no good choice amoung DX lenses to choose what you need. Besides, there are several FX lenses that are of better quality than what is available in DX. There are no strange abnormalities one might have doing this. It's normal.

Using a DX lens on an FX body. The DX lens is not designed to project a large enough image circle to cover the FX sensor, but sometimes you can get away with it in certain situations. I'd not recommend it though. For example, the DX 35 f/1.8 will mount on an FX camera and you can tell the camera to stay in FX mode. At f/1.8 there will be a very slight vignetting, but stopping down to f/8 will show a sharp delination in the vignetting emphasizing the image circle.

Some other DX lenses like Nikon's excellent pro-grade 12-24 f/4 DX are usable through part of their zoom range. In this case the lens is usable in FX mode from 18mm to 24mm. This lens is too expensive to be messing around, buying it only for part of it's zoom range. Most DX buyers buy the consumer Nikon 10-24 f/3.5-4.5 DX variable aperture.

DX on an FX body in DX mode. All DX lenses can be used on all FX bodies if you tell the camera to automatically change to DX mode when a DX lens is attached. The only problem is that you're only using less than half of the sensor. You're wasting much of the reason for buying an FX camera. However, it might give you some use from your DX lenses while you're slowly upgrading to FX lenses.

That all said, remember that a 100mm lens is a 100mm lens regardless on whether it's DX or FX. You apply the same crop factor on a DX body to determine the field of view. It's only field of view that changes, not reach or magnification. It's not the equivalent of a longer lens. It just crops a smaller rectangle from the same image circle. No magic happened. There's a lot of people who agree the focal length doesn't change, then they immediately want to change it by claiming a longer focal lenth. It's not easy sometimes to get your head around it.

  • So, FX lens fits on either FX or DX camera without issue but a DX lens only is recommended on a DX camera.

One more thing to think about. Many of us love to shoot super-wide angles. We love our 14-24, 16-35, 17-35 and 17-40 lenses on FX cameras. They are all pretty wide on the wide side. My favorite is my Nikon 16-35 f/4. Put that on DX though and the field of view becomes like a 24-50, not that wide. Even Nikon's 14-24 works out to be a 21-36 which is wide, but not that wide either. Sigma makes a fairly good FX 12-24 and it works out to be 18-36 which is also not quite enough for my blood. They just don't make an FX lens that is wide enough to translate into a good superwide on DX. So, if you're like many of us and love that super wide side, you'll have to consider a DX lens for your DX camera. Otherwise you'll always be fighting that "not wide enough" concern.

Most of all, have fun and welcome to our world of photography.
Cheers, Craig

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