Tamron Still Believes in APS-C

Started 10 months ago | Discussions thread
nnowak Veteran Member • Posts: 7,728
Re: Tamron is leaving $ MONEY $ on the table not making EF-M, Fuji-X lens

ihgold2 wrote:

nnowak wrote:

ihgold2 wrote:

dwfrommonterey wrote:

Not everyone care to upgrade to Fullframe, majority of "consumer" don't want to spend $2000 when an $500~$1000 APS-C DSLR or Mirrorless will do.

Canon RP with decent kit lens $999. Right now.

That's a really tempting offer. Do you think f/7.1 is limiting though, in that kit lens? IQ notwithstanding, seems like f/7.1 being the largest possible aperture would be frustrating. What does everyone think?

f/7.1 on full frame is equivalent to f/4.5 on Canon APS-C crop. Yes, f/7.1 sounds slow, but when you consider that an equivalent EF-M lens would need to be 15-66mm f/2.5-4.5, f/7.1 suddenly looks pretty good. Going the other way, the EF-M 15-45mm f/3.5-6.3 is equivalent to a full frame 24-72mm f/5.6-10. After converting for equivalence, the EF-M 15-45mm ends up a full stop slower than the RF 24-105mm f/4-7.1.

No, f/7.1 is not ideal for low light use, but it is still better than any of the existing EF-M zooms.

Thanks, yeah, I guess that does put it in perspective.

Naive question then: hypothetical exposure, f/7.1, ISO 400 ... will those result in different shutter speeds one FF vs crop bodies?

No, the shutter speeds will be the same.

I think I understand that the DOF, and maybe some other qualities of the image, will be different. But is the exposure itself fundamentally calculated differently?

No, exposure is not calculated differently.  What does change is the image sensor noise with different sensor sizes.  ISO 12800 on the RP will have roughly the same noise levels as ISO 5000 on your M5.

Here is a hypothetical with the same shutter speed (same motion blur), same angle of view, same depth of field, and the same noise levels.  Basically, the same final image...

EOS RP + 24-105mm f/4-7.1 at 105mm, f/7.1, ISO 6400, and 1/100 shutter speed

EOS M5 with a lens at 66mm, f/4.5, ISO 2500, and 1/100 shutter speed

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