Checking out a Pentax SMC-A 35-105mm F3.5 - focus scale oddity


ChrisA

Link Posted 20/12/2020 - 10:38
Hello all, long time no see! Merry Christmas to all - impressed to see so many familiar names are still about. I haven't done much with my cameras for a long time, but I'd be grateful for a little advice.

A friend has bought a SMC-A 35-105mm F3.5 for her son, who has a K1000 and is getting into all-manual B&W photography.

I'm checking the lens over for her on my K-3 before she gives it to him, and I've found something rather odd about it.

Cosmetically it's excellent, verging on mint. The front and rear elements could do with a clean, but they're undamaged. The aperture control is smooth and the iris opens and closes perfectly.

The focus and zoom rings are tight and smooth, just as you'd expect for a good example of one of the old A series lenses. Exposure isn't bad, indicating that the lens is stopping down correctly.

However.... I've noticed two oddities - one minor, one potentially major.

The minor one is that the zoom ring doesn't go all the way to the 35mm marking at the wide end, as you can see here.

The major one is that at all distances, the focus distance scale is miles wrong. For instance, at the 105mm end of the zoom I can focus on chimneys half a mile away, and the focus scale says 3m (yes, three meters). At the 35mm end, the effect is even more pronounced - I have to shift into macro mode to get the same chimneys sharp with an indicated focus distance of under 1.5 m.

I've got the K-3's AF set to use the center spot only, and the visible sharpness in the viewfinder corresponds to the in-focus hexagon. I've also tried the lens on my K5-IIs and the issue is exactly the same.

I can't believe this can be right - it seems like there's something very wrong with the internals, but I'd be grateful for any thoughts or comments.

I've cross posted this at PentaxForums - hope that's ok but as my friend has only a very short time to decide whether to give the lens to her son or return it to the eBay seller, I was hoping for as wide an audience as possible. Thanks in advance.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Cayman

Link Posted 20/12/2020 - 11:31
i'd return it. Something is not right. It could have been dropped or taken apart and not reassembled properly. There are plenty of other good examples out there.

ChrisA

Link Posted 20/12/2020 - 11:33
Following on from the above, I've just compared the field of view at the short end, which should be 35mm, with that from a DA 35mm AL F2.4, on the same camera, on a tripod, without moving the camera between shots.

The short end of the 35-105 is noticeably longer than the 35mm prime, ie the magnification is significantly greater.

This is consistent with the zoom ring not moving all the way to the 35mm end of the scale, as shown in my earlier picture of the lens.

So I'm increasingly suspicious that there's something wrong with the lens.

Still grateful for any comments about whether this sort of thing is normal. I've never seen the focus scale issue on any lens before, however, so I'm highly suspicious.
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Pentax K-3, DA18-135, DA35 F2.4, DA17-70, DA55-300, FA28-200, A50 F1.7, A100 F4 Macro, A400 F5.6, Sigma 10-20 EXDC, 50-500 F4.5-6.3 APO DG OS Samsung flash SEF-54PZF(x2)
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Chrism8

Link Posted 20/12/2020 - 11:34
Cayman wrote:
i'd return it. Something is not right. It could have been dropped or taken apart and not reassembled properly. There are plenty of other good examples out there.

Yes, totally agree with the above.
Chris

www.chrismillsphotography.co.uk

" A Hangover is something that occupies the Head you neglected to use the night before".

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K1 - Sigma 85mm F1.4, Pentax DFA 150 -450 F4.5 / 5.6, Pentax DFA* 24 - 70 F2.8

Samyang 14mm F2.8, Pentax DFA* 70-200 F2.8

K3iii + K3ii + K5iis converted to IR, Sigma 17 - 70 F2.8, Pentax 55 - 300 F4.5 / F5.6 PLM

johnriley

Link Posted 20/12/2020 - 13:16
I would suspect it's been taken apart and not put together correctly. Another sample would be more cost effective than repairing this one, probably. I'd send it back as well.
Best regards, John

womble

Link Posted 20/12/2020 - 17:30
I'd send it back too. That isn't right (and isn't anything like my copy).

K.
Kris Lockyear
It is an illusion that photos are made with the camera… they are made with the eye, heart and head. Henri Cartier-Bresson
Lots of film bodies, a couple of digital ones, too many lenses (mainly older glass) and a Horseman LE 5x4.

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