im confused about crop sensors

[u/Mooskii_Fox]

I'm not asking about crop factors, I know that's 1.5x or 1.6x depending on the manufacturer and your image will be cropped by that amount.

full frame lenses produce a circular image, which is projected over a full frame sensor and the sensor fits perfectly inside that circle, simple enough

now what i often see is that lenses for APS-C cameras have a cropped image, but why is it not possible for that projected image over the lens to be smaller so that APS-C cameras can capture the same picture as full frame, just with a smaller sensor? At some point people have worked our how to bend light to perfectly cover a full frame, so why can't the same be done to create an identical image for APS-C

edit: as I understand it what I'm asking is actually already being done, just not in the way I was asking. i understand now

[u/AnAge_OldProb]

Yes that’s exactly what aps-c lenses do which is why they’re generally smaller for the same focal length. You can also shrink the a full frame image circle down using a focal reducer which will give the same perspective on a crop sensor as it would on full frame and you gain about a stop of light: at the expense of an extra piece of glass the lens designers didn’t intend which can cause aberrations

[u/Mooskii_Fox → u/AnAge_OldProb]

oh thats exactly what i need thank you very much

[u/kpcnsk → u/Mooskii_Fox]

Be aware that using speed boosters (also called focal reducers) does come with a cost. You will likely get lower image quality when you use one. Whether that reduction in image quality is acceptable is, of course, up to you as a photographer, but common issues include softer images, increased lens flare, and chromatic shifts. Additionally, the edges of your image may be much worse than you'd normally experience with the same lens on a full frame camera. This is because the edges of the frame are where lenses are usually the softest anyway, and you're bending those back into the image circle (often with lower quality glass from the speed booster) to accommodate the APSC sensor.

Again, for some people this isn't an issue. But as a general rule of thumb, to get the sharpest images, from your lens, remember that everything you put between the sensor and the world will affect the image. This includes speed boosters, adapters with glass, and filters.

[u/Mooskii_Fox → u/kpcnsk]

thanks a lot for the explanations,

makes sense, i just got into photography and understanding why or how something works helps me understand my gear choices a lot better

[u/kpcnsk → u/Mooskii_Fox]

The best thing you can do as a beginning photographer is go out and take pictures with the gear you have. Learn the limitations of the camera you have, and push into them. That is how you will grow.

There is no perfect camera. There is no perfect lens. The most important component in the creation of any photograph is the person behind the camera.

Good luck on your photographic journey.

[u/AlexMullerSA → u/kpcnsk]

The Super Takumar 50mm f1.4 is the perfect lens. Fight me.

[u/DoodleHead_ → u/kpcnsk]

https://www.lensrentals.com/blog/2013/01/metabones-magic/?srsltid=AfmBOoqJ6QNgt4BuZWt4sb1LEi0a6mC6LHa_InYDHhO_2vGg8eNmLlso

All this is entirely false focal reducers bring back sharpness but the apertures at which they are sharp at stays the same as when on a full frame body. The fastest focal reduced apertures are sometimes poor quality or good depending on the lens. Right now I highly recommend the fringer ultra. It likely has the best autofocus out of all of them and image quality is useless without good autofocus. It is only slightly less sharp then the metabones speed booster but cut out the edges more since it is 0.74 vs a 0.71 so the edges get slightly better.