Why no 40mm pancake (or similar)?

Started Feb 9, 2018 | Questions thread
peppermonkey Veteran Member • Posts: 4,908
Hmm...

Guy Parsons wrote:

peppermonkey wrote:

...of camera and lens would give you a 1/10 AF success rate? Asking because I don't ever recall such poor AF rate... Well okay my GF1 was't the greatest in AF but my GX8 has been stellar with all my primes...

It was at an Olympus night shoot in Sydney and they had a table covered with lenses and bodies to try.

I was using my E-PL5 then with my 12-40/2.8 lens. The light where the group was gathered was so low it was hard to make out which lens was which on the table.

I spent some time with night shots of the city and Bridge etc and of the group itself in the low light and the 12-40/2.8 worked like a lens should, even though i was at ISO 25600 for a lot of the candid people shots.

Picked up the 75/1.8 with drooling anticipation of wonderful things to happen and to my dismay it just could not AF at all (well, about 1 in 10 try success) on the same subjects despite my constant use of small centre focus spot on vertical contrast and reframe to shoot. Gave up on it thinking it was a faulty lens and tried the 45/1.8 and got the same tragic AF results. So went back to 12-40/2.8 and AF OK again.

My theory at the time was that in such low light the live view image is so noisy and the depth of field so shallow that the AF was consistently being missed. Some others at the time in this forum agreed with my findings as they had seen the same behaviour.

Years later a cheap 45/1.8 came available from a shop going out of business so bought it on a whim and sure it works fine in good to low light, but no way will I bother with it in extremely low light.

Regards..... Guy

Well, the newer Panasonic are supposed to be much better with AF in very low light conditions and I certainly haven't noticed any problems with AF.

Then again, I don't think I have ever tried taking many photos at such low light where I would need ISO 25600, so who knows, maybe the modern Panasonic's would also have problems.

Or it could be the age of the lens, i.e. older lenses have a more difficult time...but then again, I never had real problems with my Panasonic 20mm. Well, with my GX8 anyhow. GF1 definitely had problems with hunting and such in very low light with my 20mm.

I think I'll have to try it out. And even if it did work, see if the results are even worth bothering with.

Interesting anyhow, thanks for the info.

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Hubert
My non-digital gear: Agfa Isolette, Ricohflex VII, Bessa R, Bessa L, Zorky 4, Fed 2, Konica Big Mini, Konica Auto S2, K1000, Yashica Electro 35 GX, Recesky
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