Why no 40mm pancake (or similar)?

Started Feb 9, 2018 | Questions thread
Astrotripper Veteran Member • Posts: 6,821
Forgot about Meike 28mm
1

uRebel Rob wrote:

Astrotripper wrote:

I don't know too much about optics design, but here's a little trend that might explain that.

Mount / Flange distance / Pancake lenses

MFT / 19.25 mm / 14, 17, 20 mm
EF-M / 18 mm / 22 mm
EF / 44 mm / 40 mm
EF-S / 44 mm / 24 mm
Sony E / 18 mm / 16, 20 mm
Leica M / 27.8 mm / 28, 35 mm

Pentax K / 45.4 mm / 21, 40, 43 mm

The 70mm/2.4 is pancake.

Yeah, missed that one. BTW, I really like their Limited primes. They are so cool

And add the discontinued samsung NX

Samsung NX / 25mm / 16mm, 20mm, 30mm

Do you see the trend? There are no pancake lenses that have significantly longer focal length than the flange distance of the mount they are designed for.

... (except for the pentax 70mm) ...

That's probably not a coincidence.

But yeah, the easiest pancake is around the flange distance, but Pentax has both the 21mm and the 70mm, both pretty far outside the normal range. Canon's EF-S pancake "cheats" a little, as it allows the lens to go into the camera body (and why you can't use canon EF-S lenses on FF bodies).

Pentax is known for it's pancakes, and it's going to be hard to match/beat the ~ 0.5x to 1.5x the flange distance range that they have.

A little bit of trivial, Pentax patented a trio of primes for Micro 4/3 just at the beginning of the system. 2.8/14, 2/17 and 2.8/17. But I think none were pancakes (around 60-70 mm in total length according to patent).

Obviously I omitted collapsible lenses that are only pancakes when collapsed.

So if you are hoping for a pancake short telephoto, I'm afraid you're out of luck.

Based on pentax's 70mm pancake FL being about 1.5x its flange distance, and applying it to m43's flange distance (and heavy rounding): 1.5 * 20 = 30mm. I think a m43 pancake 30mm lens is possible, but 40mm might be outside the flange distance's possibilities.

Another bit of trivia, Olympus has a bunch of pancakes patented, the longest being nearly 23mm (at 40mm total length).

I just remembered Meike makes some pretty slim primes. Their 28mm f/2.8 is definitely a pancake (and is pretty decent it seems). The 35mm is slim as well, but not slim enough to count as a pancake.

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