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Greetings Pentaxians,

I have a few K-mount manual focus lenses that I used for a short while with my K1000. Unless I learn that any of these lenses are particularly good on modern Pentax dSLR's, then they'll likely stay in the camera bag with my K1000 for future amusement. I don't know much about Pentax optics and will be looking through the lens reviews and sample photos here over the next few days to gleam whatever information I can about them. Your insight is appreciated!

I only remember acquiring the lenses inexpensively since I was in college at the time. They're not particularly fast, either, so my intuition is telling me that I shouldn't expect much. The 50mm prime I remember purchasing new at a local camera store, but I can't recall how much I paid. There were more expensive options but this one was reasonable and they had it in stock.

I'm interested to know what kind of image quality and resolution I can realistically expect to get out of them today on a K-3 body. Also would be interested in knowing if the shake reduction (SR) built into the camera would afford me any additional stops of light with these lenses? Would I be able to use them in low light, or hand hold the telephoto without a tripod?

They are:
SMC Pentax-A ZOOM 1:3.5-4.5 35-70mm (Japan)
SMC Pentax-A ZOOM 1:4 70-210mm (Japan)
SMC Pentax-A 1:2 50mm (Taiwan)

The 70-210 and the 50mm both have a reddish-purple hue in the lens coatings when you hold them under a light.
The 35-70 is a bit different, with a more blueish hue. Not sure if different coatings were used.

... here's rolling the dice...

Thanks in advance!

[Adam]

Also would be interested in knowing if the shake reduction (SR) built into the camera would afford me any additional stops of light with these lenses?

The SR will work just fine, but you'll have to manually enter the focal length at startup for each lens. For the zooms, you can either enter the lowest focal length on the lens (most conservative, set it and forget it), the FL you plan to use the most, or somewhere in the middle.

The IQ from those lenses will be fairly good (the 70-210 and 50 are better than the 35-70 IMO) but I'd recommend looking in to modern lenses as a permanent solution, as even today's cheaper lenses can compete with older glass. Plus, having AF is convenient

[LensBeginner]

The SMC-A 70-210 (if it's the SMC version) it's a very good lens.
I was debating between that and the SMC Pentax-M 80-200mm, and chose the latter, but I believe they are close.
Resolving power is amazing once stopped down a bit.

[Na Horuk]

Hey, welcome!
Well, the lenses will be as good as they used to be (minus any quality degradation over time, like haze). Maybe the sensor will outresolve some of them, but probably not by much, at least no in the image centre. Bigger problems will be flare resistance, purple fringing, and chromatic aberration. The main suggestion here is to mount the corresponding hood, or even a tighter hood (for APSC equivalent FoV), as minimizing stray light will help with contrast, flare.
Since these are old manual lenses, you probably won't find and lens correction profiles for them.

With these lenses, just make sure the aperture ring is set to A mode (press the little button). On camera, you might still want to go to Menu and Enable aperture ring use (back of menu). Finally, you might want to read about Catch in Focus (aka focus trapping), a Pentax feature that gives DSLRs something similar to AF with manual lenses.
The A 50mm f2.0 will probably work really well, as all 50mm lenses are fairly sharp. The tele lens probably as well. The mid range zoom might be the least interesting, but give it a try. Beyond these, if you have no other lens, you might want to get one with full automation and AF. DA 35mm f2.4 is the affordable prime most people start with, and it should be about as sharp as that 50mm you have. Or maybe a WR zoom lens, since you have a WR camera (both need to be WR for the system to hold)

Lots of us use old lenses. The A series is well-respected, though people usually stick to primes, when it comes to older lenses.

Oh, just make sure the lenses don't have and fungus inside! You don't want to spread that infection. I think there are some blog posts out there that tell you how to check that.

[Spodeworld]

I remember asking Eric H. about this, and he said that the fungus does not spread from lens to lens, i.e., a lens with fungus doesn't threaten to contaminate one without.

Oh, just make sure the lenses don't have and fungus inside! You don't want to spread that infection. I think there are some blog posts out there that tell you how to check that.

[TER-OR]

The A50 f/2 is an underrated lens, very sharp with good contrast. Make sure to play around with Catch-in-Focus to make life a little easier.

Also consider buying some expandable rubber hoods to protect against sun flare or reflections.

[UncleVanya]

I remember asking Eric H. about this, and he said that the fungus does not spread from lens to lens, i.e., a lens with fungus doesn't threaten to contaminate one without.

Plus one to this. I have read that the spores are everywhere and it is the conditions inside the lens that let them get out of control not the presence or absence of them. Dry and cool is not going to go nasty... .

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Thanks for the replies so far! It's good to hear that there's still some life in those old lenses. I took some time to look through the lens reviews section as well and came away pretty impressed with the results some people have gotten with them, even though some were sharpened in post.

I didn't see any fungus but I will have to pay extra close attention next time, in case it's hard to notice.

Regarding the "Catch in Focus" feature... sounds nice!

[Piotrek K]

I would say 35 -70 is also very good - optically it is the same to the F 35 - 70 which has it's own "cult" lens club (https://www.pentaxforums.com/forums/122-lens-clubs/258498-smc-pentax-f-35-70-...cult-club.html)

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Thanks for sharing that, Piotrek... some very sharp shots.