DPReview.com is closing April 10th - Find out more

RF800mm/f11 and size of AF-area on EOS R3/R5/R6/R7/R10

Started 9 months ago | Discussions thread
John Sheehy Forum Pro • Posts: 26,688
Re: RF800mm/f11 and size of AF-area on EOS R3/R5/R6/R7/R10
1

Stig Nygaard wrote:

The 600mm/11 and 800mm/11 both has an restricted AF area on the cameras we know.

Using these lenses on the R5 and R6 gives you an AF area covering 40% x 60% (width x height). I have always guessed that was caused by a combination of lens aperture (f11) and sensor size, and would expect that area to be scaled proportionally in both directions when used on a smaller APS-C sensor. I haven't done the exact math (and I think the Canon number are approximately anyway), but it seems to be somehow in line with that, when looking at AF area for EOS R7/R10 on https://cam.start.canon/en/H001/supplement_0110.html :

R5/R6: 40% x 60%
R7/R10: 60% x 80%

But to my surprise, the same table also show for EOS R3:

R3 : 80% x 80%

I'm confused. Apparently the size of AF area are not related to the size of sensor after all (or more factors than I thought are involved here) ?

PS. Notice that I have swapped width and height compared to the way Canon is showing it. Canon's way was confusing me (even more).

There is clearly no consistent correlation, better than body price. It can't be pixel density, because the R5 and R6 are the same. It can't be millimeters from the center of the frame, because the R3 goes way farther from the center than R7 and R10.

Therefore, and considering other decisions, I would guess that this is just a cripple to protect the sales of other lenses which have a higher markup.

-- hide signature --

Beware of correct answers to wrong questions.
John
http://www.pbase.com/image/55384958.jpg

Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow