Michael Reichmann's take on smaller full frame Sony FE mount lenses

Started Dec 18, 2013 | Discussions thread
EarthQuake Senior Member • Posts: 2,584
Re: False

rhlpetrus wrote:

Lab D wrote:

FrankS009 wrote:

"A lens has to be of a certain size to cover full frame. That size is now smaller than it used to be, because FE mount lenses don't have to have the large rear register distance that ones designed for DSLRs did. "

This is not true for lenses over 40mm. A 200mm needs some way to be 200mm. (There are a couple exceptions like lenses with reflectors and the Canon DO lenses, but they cause other issues). So a FF 200mm lens will need to be 200mm and have a much larger diameter than say an M43 150mm lens which will have more reach.

This may be why Sony so far only has lenses up to 70mm. To compare, my 90mm EFL M43 lens is not only longer than anything that FF has, but is tiny in comparison to even those much shorter lenses (especially diameter which is 2 out of the 3 dimensions).

btw, the longer registration distance allows you to make longer pancake lenses. This is why the Canon FF pancake lens is so small.

I have a Nikkor 70-300mm zoom and it's not even close to 30cm long. Actually, it's about 150mm long zoomed in and about 200mm zoomed out.

That distance, plus the flange distance is the total distance of the optical design. So add 46mm for the Nikon F flange. So your lens at 300mm is about 250mm, not far off of what was stated above.

This is important, because with telephotos, when you shrink the flange distance to make the camera smaller, you need to make the lens longer. There is no free lunch here.

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