topic Re: Why Use an APS-C Lens With Full Frame Camera in EF & RF Lenses

Why Use an APS-C Lens With Full Frame Camera

jejapa3131 — Tue, 01 Jul 2025 12:14:16 GMT

All,

I was in a camera store last week and the rep that I was talking to mentioned using a APS-C lens with a full frame camera. With a Canon you are losing 60% of your pixels or only using 40 % of your pixels. Why would you want to use that combination?

Re: Why Use A APS-C Lens With Full Frame Camera

p4pictures — Tue, 01 Jul 2025 04:42:50 GMT

It's a case of just because you can do something, doesn't mean you should do that.

If the only lens you have is one designed for APS-C and you have a full-frame mirrorless it might be a short term solution until you get a full-frame lens.

Re: Why Use an APS-C Lens With Full Frame Camera

deebatman316 — Tue, 01 Jul 2025 13:29:33 GMT

Also some cameras such as the EOS RP shoots with a crop in video mode anyway. So you’re not using the entire sensor area while recording video. I believe the EOS RP has a large crop. I think it’s a 2x crop in video mode. So you’ll never use the entire FF sensor in video mode regardless of if you use a FF or APS-C lens.

Re: Why Use an APS-C Lens With Full Frame Camera

ebiggs1 — Tue, 01 Jul 2025 14:03:36 GMT

"It's a case of just because you can do something, doesn't mean you should do that."

Everybody should heed that. Reread if necessary.

Re: Why Use an APS-C Lens With Full Frame Camera

March411 — Tue, 01 Jul 2025 15:23:51 GMT

My EF-S 35mm f/2.8 Macro IS STM gets used frequently on both my R5 and R6 MkII, chances are I will hold onto this lens as long as it keeps working. It produces some beautiful images. I get 18 MP on the R5 which is more than enough, that said it has it's application but isn't an every day lens. On the R6 MkII, if my composition isn't **bleep** near perfect, a crop really hurts IQ with only 9 MP.

Outside of this single lens unless there is a specific application I don't really see the rational of purchasing an APS-C for a full frame sensor.

Re: Why Use an APS-C Lens With Full Frame Camera

johnrmoyer — Tue, 01 Jul 2025 19:14:43 GMT

@jejapa3131 wrote:

All,

I was in a camera store last week and the rep that I was talking to mentioned using a APS-C lens with a full frame camera. With a Canon you are losing 60% of your pixels or only using 40 % of your pixels. Why would you want to use that combination?

I would advise against buying a new RF-S lens for a full frame camera, but I have used EF-S lenses on my EOS R5.

I already had the EF-S18-135mm f/3.5-5.6 IS USM lens which I had been using with my EOS 80D. This lens is one of those Canon recommends for focus stacking. On my EOS R5, there are only a few less pixels in 1.6x crop mode than on my EOS 80D.

https://www.rsok.com/~jrm/2023Oct15_birds_and_cats/2023oct04_wildflower_IMG_6673-6676c.html

A wild orchid Spiranthes lacera var. gracilis commonly called Slender Ladies' Tresses blooming in Norman, Oklahoma, United States, on October 4, 2023 (focus stack of 4 images)

Camera Model Name	EOS R5
F Number	11.0
ISO	100
Focal Length	29.0 mm
Camera Temperature	37 C
Focus Distance Upper	0.62 m
Focus Distance Lower	0.44 m
Lens Model	EF-S18-135mm f/3.5-5.6 IS USM
Focus Stack	Depth Composite of 4 Images