FX lens on Dx camera

[Rickjs]

I bought a Nikon D7100 and have heard that putting a full frame lens on it would reduce the sharpness because of the size of the glass is optimized for the larger sensor. Is this true? one of the things I like about the 7100 is that it has an internal focusing motor, are there any DX lenses that don't have their own focusing motor that can use the 7100's focus motor?

 

[Peeb]

DX glass is typically cheaper and often lighter than FX counterparts so buying DX lenses for DX cameras is not a bad idea BUT...

if you even MIGHT get FX someday, then you'll be happy to already own FX glass when you do.

 

[fmw]

I bought a Nikon D7100 and have heard that putting a full frame lens on it would reduce the sharpness because of the size of the glass is optimized for the larger sensor. Is this true? one of the things I like about the 7100 is that it has an internal focusing motor, are there any DX lenses that don't have their own focusing motor that can use the 7100's focus motor?

In terms of sharpness the opposite of what you say is true. In general the challenging part of the lens in terms of sharpness is at the corners of the frame. The larger image circle of the FX lens crops out those corners on a DX camera. So what you heard was exactly wrong.

You can identify autofocus lenses that have focusing motors because the lens name will include the tag AF-S. The S stands for silent wave motor. An AF lens that does not have this tag will not have a motor. There are many older FX auto focus lenses without motors. They will make use of the motor in your 7100. Your 7100 will also work competently with pre AF AI lenses except that they will require manual focus.

 

[astroNikon]

AF and AF-D lenses require the inbody focus motor. You'll find those on FX lenses. For instance the 50mm f/1.8 AF-D. VErsus the 50mm f/1.8 AF-S. the afd lens is much smaller and more compact because , for one, it doesn't have a motor in the lens.

 

[Derrel]

The VAST majority of ALL Nikkor lenses ever made have been capable of filling the 24 x 36mm film or digitial image size. Typically, Nikon's very best lenses are **not ** what they call DX-Nikkor lenses. Many DX-Nikkor lenses are somewhat lower-tier; lenses like the 18-55 and 55-200 and 55-250, are examples of low-priced DX-Nikkor lenses. Most older and current Nikkor lenses that cover FX are pretty decent lenses, and will shoot good, crisp images on DX cameras.

 

[Javkin]

I agree with the advice and information you received above. I've been using a D7100 with both DX and FX lenses for years (and before that, a D50 and a D7000) . I can assure there is no lack of sharpness as as a result of shooting with FX lenses with these cameras. Some of my FX lenses, such as the the Nikon 70-200 f/4 AFS VR and the Nikon 300mm f/4 AFS, are amazingly sharp on the D7100.

Most current DX lenses have focusing motors. My older Tokina 11-16mm f/2.8 and Tamron 17-50mm f/2.8, both DX and both very good lenses, have no focusing motors.