Aperture knowledge required on APSC camera: If I put a 300mm 2.8 lens froma Nikon D610 camera onto a Nikon D7100 camera, I understand that I would get the field of view equivalent to...

35B Loc: Australia

If I put a 300mm 2.8 lens froma Nikon D610 camera onto a Nikon D7100 camera, I understand that I would get the field of view equivalent to 450mm. My question is does the 2.8 aperture change?
My current thinking is it would give me a 450mm 2.8, but uncertain.

Thanks in advance for your help.
35B

JPL

What really happens is that nothing changes with the lens, it will still be 300mm and f2.8 no matter what camera you put behind it. The only change is the sensor size. D7100 has smaller sensor and often referred to as crop sensor because it will crop the image the lens is projecting when compared to a full frame sensor. Then change in field of view is only related to the crop sensor being smaller than full fram sensor. That is it.

jerryc41 Loc: Catskill Mts of NY

35B wrote:

If I put a 300mm 2.8 lens froma Nikon D610 camera onto a Nikon D7100 camera, I understand that I would get the field of view equivalent to 450mm. My question is does the 2.8 aperture change?
My current thinking is it would give me a 450mm 2.8, but uncertain.

Thanks in advance for your help.
35B

Right - 450mm equivalent. That's why many people like to use an FX lens on a DX body. The aperture is determined by a mathematical formula based on measurements of the lens, so that never changes - real or equivalent.

Longshadow Loc: Audubon, PA, United States

JPL wrote:

What really happens is that nothing changes with the lens, it will still be 300mm and f2.8 no matter what camera you put behind it. The only change is the sensor size. D7100 has smaller sensor and often referred to as crop sensor because it will crop the image the lens is projecting when compared to a full frame sensor. Then change in field of view is only related to the crop sensor being smaller than full fram sensor. That is it.

cdayton

JPL wrote:

What really happens is that nothing changes with the lens, it will still be 300mm and f2.8 no matter what camera you put behind it. The only change is the sensor size. D7100 has smaller sensor and often referred to as crop sensor because it will crop the image the lens is projecting when compared to a full frame sensor. Then change in field of view is only related to the crop sensor being smaller than full fram sensor. That is it.

👍👍👍

cdayton

PS it's more or less the same way a cell phone does telephoto - crops off the edges and enlarges to cover its tiny sensor.

Tracy B. Loc: Indiana

Watch this:
https://youtu.be/DtDotqLx6nA

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

The simple answer, no, 2.8 is 2.8.

Bobspez Loc: Southern NJ, USA

Interesting. The video says the opposite of the posters here. It says, the crop factor is also multiplied by the aperture in regard to equivalent depth of field. And iso is multiplied by crop factor squared in terms of equivalent noise.

Tracy B. wrote:

Watch this:
https://youtu.be/DtDotqLx6nA

cameraf4 Loc: Delaware

And the video is much more objective as well. We should all thank Tracy for bringing this to us. I know I learned stuff.

dandi Loc: near Seattle, WA

I think it’s a great article that answers many questions we have here. Especially I like what he said at the end (part 11, the Summary). Enjoy.

https://photographylife.com/sensor-crop-factors-and-equivalence

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Tracy B. wrote:

Watch this:
https://youtu.be/DtDotqLx6nA

This is nonsense Tracy. Not your fault, but his explanation is a bit convoluted and ill-informed.

While it is true that depth of field changes, he does not take into consideration the greater enlargement required to get to the same print size which diminishes DoF. If you read any and all DoF tables, they will show that for the same lens at the same distance and aperture, changing just the sensor size will result in less, not greater depth of field. The increase in depth of field occurs as you move back with the crop sensor to get the same framing due to the narrower angle of view when the lens is used on the crop sensor.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

35B wrote:

If I put a 300mm 2.8 lens froma Nikon D610 camera onto a Nikon D7100 camera, I understand that I would get the field of view equivalent to 450mm. My question is does the 2.8 aperture change?
My current thinking is it would give me a 450mm 2.8, but uncertain.

Thanks in advance for your help.
35B

No, the aperture does not change. F2.8 on crop is the same as F2.8 on full frame. There are depth of field considerations, which you should study using the many DoF table and calculators.

tdekany Loc: Oregon

Gene51 wrote:

This is nonsense Tracy. Not your fault, but his ex... (show quote)

Tracy B. Loc: Indiana

Gene51 wrote:

This is nonsense Tracy. Not your fault, but his ex... (show quote)

Yes well, watch this: (not your fault)
https://youtu.be/0OtIiwbAZi8
Gene: especially look at 34:20 in video.