Understanding full frame lenses with aps-c

[aabee]

Currently shooting with a T7 mostly nature. I want to upgrade my lens collection with a bigger telephoto lens but am not clearly understanding the cropping with a full frame lens on an aps-c. Will photos be of lesser quality? Should I just bite the bullet and upgrade my body too?

[kvbarkley]

Don’t worry about it. If anything the quality of an EF lens on an EF-s body will be better. 

[rs-eos]

As mentioned, no issues. When using EF lenses (or RF lenses) with APS-C sensor cameras, the portion of the lens that is used (what covers the sensor) will be the central part. i.e. the edges of the lens won't contribute to the image. This has advantages on APS-C cameras since things like decreased corner sharpness/contrast or vingetting effects will be greatly reduced or not present.

If you later to move to a full frame camera, do know that the entirety of the EF (or RF) lens will now be used. So you could then start to see some quality decreases in image corners. But really nothing of major concern. Sometimes, depending upon the quality of the lens, it's very minor.

[March411]

Like kvbarkley mentions the quality will not be a concern, you will simply have a little added reach. The only reasons to upgrade is if you are not happy with you current gear or you are looking to upgrade for the purpose of benefiting from the improved sensors and AF systems. If you happy with the results why spend the money?

Deleted and re-posted due to errors

Marc
Windy City

[johnrmoyer]

Usually, the best part of a lens is the center and not the edges. The APS-C camera only uses the center of the lens and so the photos will be of better quality than the same lens on a full frame camera.

For example, the MTF chart for "EF100-400mm f/4.5-5.6L IS II USM" shows better resolution and contrast 15mm from the center of the sensor than 22mm from the center of the sensor. The sensor on an APS-C camera is  22.8mm wide, so half would be less than 12mm. The full frame sensor is 35mm wide, so half would be 17mm. The distance to the corners is a little more.

A less expensive but very good on APS-C lens is the "EF 70-300mm f/4-5.6 IS II USM".

Either lens is sometimes available refurbished from Canon, https://www.usa.canon.com/shop/camera-lenses/refurbished-camera-lenses 

When I have purchased refurbished from Canon, it seems to me at least as good as new and maybe better.

[kvbarkley]

As JohnRMoyer says, the EF 70-300mm II is a very good telephoto for your T7.

If you want a bit more reach, the Tamron/Sigma 150-600's for Canon EF mount work well.

I have the 70-300 and the Tamron 150-600 for my T6S.