I know it depends on brand to brand and model to model, but in general terms, what is the shortest focal length I can have before the black zone (A) starts to form, or it is barely noticeable? (B)

For full-frame 35mm and a cropped sensor?

I don't mind distortions or aberrations, just the black zone.

I know it depends on brand to brand and model to model, but in general terms, what is the shortest focal length I can have before the black zone (A) starts to form, or it is barely noticeable? (B)

For full-frame 35mm and a cropped sensor?

I don't mind distortions or aberrations, just the black zone.

Edited.

Here are 2 fish eye lens shoots.

The first one has the totaly circular surrounding.

On the second one the exif info reads 8mm on a croped Canon Rebel sensor and the circle is more to the edges.

https://www.flickr.com/photos/zbowling/2746925285

I´m just wondering if there is a generic parameter where you should expect this disc fo form.

(I'm not refering on lens hoods, filters or lenses designed for a diferent sensor format)

I know it depends on brand to brand and model to model, but in general terms, what is the shortest focal length I can have before the black zone (A) starts to form, or it is barely noticable? (B)

For Full frame 35mm and a Croped sensor?

I don't mind distortions or aberrations, just the black zone.

I know it depends on brand to brand and model to model, but in general terms, what is the shortest focal length I can have before the black zone (A) starts to form, or it is barely noticeable? (B)

For full-frame 35mm and a cropped sensor?

I don't mind distortions or aberrations, just the black zone.