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03-28-2010, 04:23 PM   #16
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QuoteOriginally posted by RioRico Quote
One thing I'm fuzzy about: when using SR with a manual push-pull ~70-200 zoom (and maybe especially fixed-aperture glass like this) does one enter 200mm, or the value of the FL used prior to each specific shot?

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I would choose the focal length you think you may be using the most on the lens. if you spend more time near the 210mm end then 200 would be your best bet. if you spend more time near the 70mm end or somewhere in between, say below 135mm or so, would probably choose a medium focal length between them. this question has been asked before in regards to these types of zooms, and there really is no good answer since the body has no way of knowing what focal length you are at, in any given moment.

03-29-2010, 02:43 AM   #17
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QuoteOriginally posted by RioRico Quote
One thing I'm fuzzy about: when using SR with a manual push-pull ~70-200 zoom (and maybe especially fixed-aperture glass like this) does one enter 200mm, or the value of the FL used prior to each specific shot?

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Well, if you invest lots of time, you could adjust the SR for each focal length you use. I find that too tedious and would forget it anyway while shooting. So, I think choosing the shortest fl is the best bet. I know, some people use a medium fl. But generally in my experience the SR would ruin more shots when set at 200mm and you use 70mm as the other way round. An "overly enthusiastic" SR seems to be worse, than an "underperforming" SR.

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03-29-2010, 03:04 AM   #18
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QuoteOriginally posted by Ben_Edict Quote
Well, if you invest lots of time, you could adjust the SR for each focal length you use. I find that too tedious and would forget it anyway while shooting. So, I think choosing the shortest fl is the best bet. I know, some people use a medium fl. But generally in my experience the SR would ruin more shots when set at 200mm and you use 70mm as the other way round. An "overly enthusiastic" SR seems to be worse, than an "underperforming" SR.

Ben
That's what I did and it worked pretty good for me. I set the 70-210mm to 70, and my 35-70mm f4 to 35mm (or turned it off). I regret selling mine, but didn't use it much after getting the adaptall 80-200mm f2.8.
03-29-2010, 04:17 AM   #19
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QuoteOriginally posted by RioRico Quote
One thing I'm fuzzy about: when using SR with a manual push-pull ~70-200 zoom (and maybe especially fixed-aperture glass like this) does one enter 200mm, or the value of the FL used prior to each specific shot?

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I set mine to 120, my reasoning is similar to the poster above, but I've found that an SR setting of 120 is not too "over enthusiastic" for shots taken at 70mm. It probably "underperforms" a bit at the 210 end but it is a LOT easier than changing it for every different zoom length.

NaCl(there are enough adjustments to make anyway)H2O

03-30-2010, 10:10 PM   #20
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QuoteOriginally posted by NaClH2O Quote
I set mine to 120, my reasoning is similar to the poster above, but I've found that an SR setting of 120 is not too "over enthusiastic" for shots taken at 70mm. It probably "underperforms" a bit at the 210 end but it is a LOT easier than changing it for every different zoom length.
Wow, I'm glad somebody brought this issue up because I never thought of asking about it before! And I like this answer. Now if I forget to adjust my focal length setting, hopefully I'll no longer wonder why the SR didn't seem to work! There's nothing worse than having set it to 70mm and forgetting to change it when you zoom to 210mm. This 120mm seems like a nice middle ground; I'll have to try it out. Thanks again for the tip!
03-31-2010, 01:24 AM   #21
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Thanks for the answers, but what confuses me (because, duh, I haven't done any empirical tests, duh) is: the physical length of some lenses changes when you zoom in/out. I can understand that SR would need to accommodate a different physical length, like my Promaster-Tamron that stretches noticeably going from 60mm to 300mm. But the PA 70-210 under discussion doesn't change length. Front and rear elements remain in place; only interior elements move. I have a hard time grasping how SR handles such internal movement. Maybe there's a tech note somewhere (or maybe that's a trade secret).

And, an AHA! moment -- thinking about the above, I know now why some handheld macro shots have been disappointing, even with Catch-In-Focus. When my M42 90mm macro lens is fully extended to 1:1 magnification, it's now 180mm long. So I'd better reset the SR when it's stretched out. Bother...

Anyway, does anyone here have knowledge of how SR works, and whether the distinction between stretching and non-stretching zooms is significant? Or should that be asked in a new thread?
03-31-2010, 03:32 AM   #22
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QuoteOriginally posted by RioRico Quote
Thanks for the answers, but what confuses me (because, duh, I haven't done any empirical tests, duh) is: the physical length of some lenses changes when you zoom in/out. I can understand that SR would need to accommodate a different physical length, like my Promaster-Tamron that stretches noticeably going from 60mm to 300mm. But the PA 70-210 under discussion doesn't change length. Front and rear elements remain in place; only interior elements move. I have a hard time grasping how SR handles such internal movement. Maybe there's a tech note somewhere (or maybe that's a trade secret).

And, an AHA! moment -- thinking about the above, I know now why some handheld macro shots have been disappointing, even with Catch-In-Focus. When my M42 90mm macro lens is fully extended to 1:1 magnification, it's now 180mm long. So I'd better reset the SR when it's stretched out. Bother...

Anyway, does anyone here have knowledge of how SR works, and whether the distinction between stretching and non-stretching zooms is significant? Or should that be asked in a new thread?
The physical length of the lens has not really anything to do with the SR setting. The Shake Reduction is dependent on the focal length. Thus, with a manual zoom lens, where the camera cannot read out the actual focal length of the lens and use that info for SR, you need to set an adequate fl manually.

On the other hand, it is clear, that the mechanical built of the lens (i.e. its length, weight and generally balance) will affect camera shake. For instance, you can still use the Bigma handheld at 500mm, but you can't really use the Pentax 500/4.5 handheld, because it is just too big. Such a difference between lenses will influence the effectiveness of SR, but cannot be set in the camera.

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04-18-2011, 08:21 PM   #23
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This focal length range (70-210) is probably the most popular...

There are dozens of lenses in this range and only few are really good, for example the Tamron Adaptall SP 70-210mm f3.5 (19AH model) is one of the best. If you can find one for less than $300, buy it immediately. Then you have to buy the Adaptall PKA (another $120). This lens provides the same quality that the 19AH and comes with the PKA mount already. I really like it. Someone recently asked me if I would sell it and I offered but he has not decided. In the meantime, I placed it on the FOR SALE section of the Marketplace in this forum. Here are some samples, mostly taken at 200mm and f4.
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At 200mm f4


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At 200 mm f


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At 200mm f


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At 200mm f



04-18-2011, 08:59 PM   #24
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^^ The SMC Pentax-A 70-210 f4 is regarded as on the best lenses available in this focal range. I wouldn't even bother with a tamron and adaptal mounts, unless you absolutely need the 3,5 over the 4. I have taken some of my best shots with the A 70-210mm and can recommend it without hesitation to anyone. the built in hood is also really nice. its only real flaw (discounting any hatred toward push pull zooms in general) is 'zoom creep'. optically it is a stellar performer even wide open.
04-18-2011, 11:50 PM   #25
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I see this is a resurrected thread, but I can see that it might be helpful to point newcomers to the subject of SR/FL to this page:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/132496-shake-reduc...ll-time-2.html

Apologies in advance for those who are already familiar with this!

And just a footnote: it's not necessary to remember the formula or even the "best" focal length - most vintage zooms fall into one of 2 categories, "wide/normal" and telephoto. So, if the zoom in question is similar to 28-90, just input 40mm to the camera; if it's similar to 70-210, just input 100mm.

Just by restricting yourself to either 40mm or 100mm, you'll be getting most (or all) the benefits of SR, and will be assured of avoiding any negative effects.

(Of course, you'll always get the best results if you take the trouble of changing FL to match the lens's zoom setting.)
04-19-2011, 12:23 AM   #26
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It's a very good lens

1) Sharp enough wide open - especially at the shorter end. Performance drops off a bit after about 180mm. It's decent but certainly at f/4 noticeable. For best results stop down when you can.

2) The macro setting at 70 can create very sharp shots when stopped down. Maximum magnifcation is only slightly better at 70-macro than the full 210mm - the difference being at 70-macro the minimum focus distance is shrunk dramatically. This in itself can be handy

3) Abberations are fairly well controlled most of the time once stopped down. Like most lenses of this era you do get CA and PF wide open in high contrast situations

4) Bokeh is lovely for a zoom lens. Easily one of the lenses strengths.

5) General colour rendering and image quality is attractive and appealing. Contrast is good.
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