Formula for Calculating Focal Length when cropping in Post

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neverendinglight Contributing Member • Posts: 506
Formula for Calculating Focal Length when cropping in Post

Whenever I look for anything about cropping via google, I just get article after article about Crop Factor. I'm not interested in that.

I'm interested to know how people are calculating what the equivalent focal length is after they crop an image in post. And how many megapixels that file is. I know that if I take a picture with my A7Riv in APSC mode that it will output a 26MP file and that the focal length will be basically 1.5 times whatever stated focal length I'm using. But what if take a normal mode shot and I crop more than that in post? Or less than that? How do I determine what focal length I'm now seeing?

I'm curious because I'm trying to put together a hiking kit and wondering what I can get away with by using the 60 megapixel sensor or even the occasional 16 shot pixel shift. How much telephoto do I need if I can crop X amount type questions?

I've seen people say something along the lines of "I cropped this to a 200MM shot" and I'm wondering how they calculated that.

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Sony a7R IV Olympus E-M1 III Zeiss Batis 85mm F1.8 Zeiss Loxia 21mm F2.8 Olympus 12-100mm F4.0 +7 more
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