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12-10-2008, 12:09 PM   #1
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Understanding Lenses

Good day,

I have recently acquired a Pentax Spotmatic and an assortment of lenses. I am currently considering upgrading to a DSLR and the possibility of using these lenses on a K200D would save me purchasing all new lenses for the new camera.

The lenses included with the kit are:
Soligor Wide Auto 1:28 f = 28mm
Bushnell Automatic Zoom 1:4.5 f=90~230mm
Hanimex Tele-Auto 1:2.8 f=135mm
SMC Takumar 1:1.8/55

I've tried Google, to no avail. While I make myself acquainted with the search button, has anybody any experience with any of these lenses?

I tend to shoot wildlife, macro and occasional landscapes. I've no interest in portraits.

With an adapter, would these screw mount lenses work effectively, if only in manual focus? I've a basic grasp of how to read the lens information, but not what they mean.

Thanks!

12-10-2008, 01:26 PM   #2
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The lenses will work just fine on any modern Pentax DSLR with a screw mount to K-mount adapter. You'll have to focus and set the exposure manually, but you'll be able to use the built-in light meter to determine what the exposure should be. And since the shake reduction on Pentax DSLRs is built into the body (and not into the lens as is done in Can*n and Nik*n cameras), these lenses will benefit from that.

The most important thing to understand is that the digital sensor is smaller than a piece of 35mm film, and this means that you'll only be using the central portion of the lens's image. The effect in terms of field of view is similar to using a focal length that's 1.5X longer than than that marked on the lens. So, for example, your 28mm wide angle lens will actually give you a field of view that's about the same as a 42mm lens on your Spotmatic.
12-10-2008, 02:05 PM   #3
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To add to Sean's comments...There may also be some metering issues with the screw mount lenses. This does not make sense on initial thought, but lenses lacking the electrical contacts on the mount apparently do not provide adequate information to the camera for the meter to give an accurate reading. Go figure.

This issue is pretty pronounced on the K10D and K20D and usually takes the form of severe underexposure at wide apertures. I don't have first-hand knowledge with the K200D except that the owner's manual makes note that exposure may not be accurate with m-42, Pentax-M, or Pentax-K lenses.

Steve
12-10-2008, 02:36 PM   #4
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QuoteOriginally posted by stevebrot Quote
To add to Sean's comments...There may also be some metering issues with the screw mount lenses. This does not make sense on initial thought, but lenses lacking the electrical contacts on the mount apparently do not provide adequate information to the camera for the meter to give an accurate reading. Go figure.

This issue is pretty pronounced on the K10D and K20D and usually takes the form of severe underexposure at wide apertures. I don't have first-hand knowledge with the K200D except that the owner's manual makes note that exposure may not be accurate with m-42, Pentax-M, or Pentax-K lenses.

Steve
And to add to Steve's comment - the good news is that you can "play" with your exposure settings after looking at the image on the rear LCD - you don't have to wait for the film to come back to check your exposure. Since you'll be in manual mode (most likely) it's easy to change the exposure settings. Also, become familiar with using the histogram to check exposure. Enjoy!!

12-10-2008, 02:38 PM   #5
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Thanks! It appears that it may be in my best interest to go with the K200D. Even with the metering issues, that is something I can play with as I go along. I can get the camera with the kit lens and a 50 - 200mm and still be within my budget. The weather sealing is a major plus as well.

Thanks!
Julie
12-10-2008, 02:47 PM   #6
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Julie, you might consider buying the K200D body only and going with the Tamron/Pentax 18-250mm lens. It might be a bit more expensive, but you might be able to get MS cash back if you do an eBay "buy it now" on the lens AND the K200d.

Enjoy - I really like my K200d!!
12-10-2008, 03:56 PM   #7
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QuoteOriginally posted by minikin Quote
Thanks! It appears that it may be in my best interest to go with the K200D. Even with the metering issues, that is something I can play with as I go along. I can get the camera with the kit lens and a 50 - 200mm and still be within my budget. The weather sealing is a major plus as well.

Thanks!
Julie
The K200D is a great camera. For an example of what can be done with thread-mount and older k-mount glass, check out these threads on this forum:

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31601-takumar-club.html

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/27739-m-club.html

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31353-off-brand-club.html

There are also threads devoted to Russian/Soviet lenses, M-42 Carl Zeiss, and anything found dirt cheap!

Steve
12-10-2008, 04:10 PM   #8
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QuoteOriginally posted by minikin Quote
Hanimex Tele-Auto 1:2.8 f=135mm
SMC Takumar 1:1.8/55
I have these two. With a M42 to K mount they can be used on a digital body with stop down metering. If you want to do macro, then you will want to use manual focusing anyway.

However, the Hanimex is quite a cheap lens, so don't expect too much from it. It looks well built, but I have always found the results disappointing - there is not the colour or contrast that I get with my CZJ 135/3.5 or (more recently purchased) S-M-C Takumar 135/3.5. The Hanimex 135/2.8 I have has a "macro" setting. Basically, there is an extra focus ring at the front, so when you have it at close focus - 1.5m - you turn the extra ring so that you can, umm, get to about 80cm and get a whopping 1:4.5 "macro" feature (according to the lens markings)! That is not particularly good at all.

The SMC Takumar 55/1.8 is a good lens, fast for a near 50, and sharp even open. It will focus down to 45cm, which gets you quite close and IMO it is a much better option for the sort of "macro" that the Hanimex is designed for. And I have had some excellent portraits with it on digital, it renders skin colours very well.

I have just done a quick test for both lenses at close focus - the Hanimex set at 1:4.5. I get 40% greater magnification with the Hanimex, but the image was horribly soft at f/2.8, ordinary at f5.6 and acceptable at f/8. The Takumar is very sharp at f/1.8, and at f/1.8 it is sharper than the Hanimex at f/8.

Since I do not have enough M42 body caps, I use my Hanimex as a "body cap" to keep the dust out of the Yashica 35mm body that I rarely use.

Richard

12-10-2008, 05:45 PM   #9
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You can also shoot the Takumars ( and M42 lenses in general ) in AV mode, no need for the green button. More than likely you'll have to dial in some exposure compensation, but once you dial it in, you can shoot away !!
12-11-2008, 08:38 AM   #10
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Thanks for all the info! The possibilities are looking better and better. I had half committed to the new body, even if the old lenses wouldn't work. Now the question is K20D or K200D...

It appears I have much reading to do, and if it warms up at all, I hope to take the film body out and see what I can come up with.

Thanks again!
Julie
12-11-2008, 12:07 PM   #11
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The replies have been very good for this thread. To me, the metering issue is the biggest pitfall to overcome when using manual aperture lenses, and it's certainly not a showstopper. By what I have read, the K10D (my camera, of course ) is the most susceptible to this issue, while all the others handle it better to some degree or another.

I have mostly experienced overexposure at smaller apertures rather than underexposure at wide apertures (this is probably because I don't have any manual lenses faster than f/2.8 yet), but you learn to compensate with a little practice. Just chimp a couple of shots and adjust your settings accordingly.
12-11-2008, 01:51 PM   #12
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QuoteOriginally posted by minikin Quote
Thanks for all the info! The possibilities are looking better and better. I had half committed to the new body, even if the old lenses wouldn't work. Now the question is K20D or K200D...

It appears I have much reading to do, and if it warms up at all, I hope to take the film body out and see what I can come up with.

Thanks again!
Julie
Try both bodies and see which one you like best. The pricing is getting pretty close There is a distinct advantage to the K20D as far as image quality, but they are both great cameras.

Steve
12-11-2008, 01:52 PM   #13
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QuoteOriginally posted by CFWhitman Quote
...I have mostly experienced overexposure at smaller apertures rather than underexposure at wide apertures ...
The behavior varies from lens to lens. Very strange.

Steve
12-11-2008, 02:07 PM   #14
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QuoteOriginally posted by stevebrot Quote
The behavior varies from lens to lens. Very strange.

Steve
That is quite possible, but it could also partly be a different point on the same curve. Going by the progression, a lens that underexposes at f/1.4, but exposes correctly at f/2.8, will probably overexpose at f/8, if you see what I mean. The curves may be in different places for different lenses (that is, the point of correct exposure may vary), but the general trends seem to be similar.
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