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08-07-2009, 06:38 AM   #1
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Lense question

I have a Pentax ME Super that I bought in Japan back in the early 1980's. I bought a few lenses for the camera and I was wondering if these lenses will fit a new Pentax Digital SLR body?

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BRJL

08-07-2009, 06:46 AM   #2
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They will. No AF of course, and make sure that the aperture ring sits in the A position if they have this position.

SR will require you to enter the focal length in order for the stabilization to work (Pentax advises the shortest focal length for zooms).

If the lenses don't have an A position on their aperture ring, you can still use stop down metering in Manual mode to meter the light. This envolves a one time adjustment in the custom settings menu (to allow the use of the aperture ring) and requires pressing the green button or AE-L button (depending on the model) to instruct the camera to mechanically stop down the aperture, meter the light and adjust the exposure settings.

Wim
08-07-2009, 07:01 AM   #3
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Actually, when setting the focal length for zooms, you input the LONGEST, or zoomed focal length, eg. 50 - 200 you would use the 200 length.
08-07-2009, 07:03 AM   #4
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...and, of course, if the lens is a K or M series lens, pressing the green button will set the correct shutter speed for the selected aperture, provided the camera is in M (for Manual exposure) mode.

That also goes for M42 mount lenses using the lens Auto setting - the lens Manual setting allows stop-down metering in other camera modes, without using the green button.

With A series lenses, automatic exposure works in the other camera modes, as with the current range of lenses.

Hope that's not too much information.

08-07-2009, 07:24 AM   #5
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QuoteOriginally posted by billtin59 Quote
Actually, when setting the focal length for zooms, you input the LONGEST, or zoomed focal length, eg. 50 - 200 you would use the 200 length.
Obviously you can do as you please when the camera asks for the focal length. But this is *not* what Pentax recommends.

Indeed, since most people use telezooms most frequently at their longest focal length, it would seem logical for these to select the longest focal length.

Not all zooms are telezooms of course, so the logic that the longest focal length is the most frequently used doesn't hold in all zooms. Wide angle zooms for instance are mostly used at their widest, and with standard zooms it's a matter of the photographer's preference and personal style entirely.

The reason why Pentax recommends the shortest focal length to be set has nothing to do with preferred focal length though, on the contrary it is purely scientific:
- Setting a focal length that is too long would lead to the sensor moving more than required to compensate and result in relative movement of the sensor in the opposite direction of the camera movement. This overcompensation is to be avoided because it may add more movement than it compensates.
- Setting a focal length that is too short would lead to undercompensation. This would still compensate some movement but not as many stops as setting correct focal length would.
Hence the shorter focal length in a zoom is to be preferred. Ideally you would switch off the camera every time you change the focal length on your zoom and set the closest value on the camera... If you have the time to do that of course...

Wim
08-07-2009, 07:28 AM   #6
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QuoteOriginally posted by Ishpuini Quote
Obviously you can do as you please when the camera asks for the focal length. But this is *not* what Pentax recommends.

Indeed, since most people use telezooms most frequently at their longest focal length, it would seem logical for these to select the longest focal length.

Not all zooms are telezooms of course, so the logic that the longest focal length is the most frequently used doesn't hold in all zooms. Wide angle zooms for instance are mostly used at their widest, and with standard zooms it's a matter of the photographer's preference and personal style entirely.

The reason why Pentax recommends the shortest focal length to be set has nothing to do with preferred focal length though, on the contrary it is purely scientific:
- Setting a focal length that is too long would lead to the sensor moving more than required to compensate and result in relative movement of the sensor in the opposite direction of the camera movement. This overcompensation is to be avoided because it may add more movement than it compensates.
- Setting a focal length that is too short would lead to undercompensation. This would still compensate some movement but not as many stops as setting correct focal length would.
Hence the shorter focal length in a zoom is to be preferred. Ideally you would switch off the camera every time you change the focal length on your zoom and set the closest value on the camera... If you have the time to do that of course...

Wim
Where did you get that Pentax recommends inputting the shorter focal length? The manual states you use the LONGER, which since Pentax wrote the manual, I'm guessing that's also their recommendation.
08-07-2009, 07:30 AM   #7
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Asahi's oldest lens on the newest camera

I think there needs to be a sticky on every Pentax forum that says all Pentax lenses made since 1952 will fit the K-7 and other Pentax DSLRs.
Manual Focus Lenses :: View topic - Asahi's oldest SLR lens on the newest camera
08-07-2009, 07:47 AM   #8
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QuoteOriginally posted by billtin59 Quote
Where did you get that Pentax recommends inputting the shorter focal length? The manual states you use the LONGER, which since Pentax wrote the manual, I'm guessing that's also their recommendation.
Could you please refer me to the actual manual that says that, preferably with the page number?

I just checked both the K20D and K-7 manuals of which I have on-line copies and neither mention any recommendation other than setting the focal length closest to the actual focal length the zoom lens is set at.

My source is a SR white paper that was distributed by Pentax when SR was introduced. I don't have it on my PC here at work, but I have a copy at home. I will check it and post a quote here...
[EDIT]Just located the document on the Pentaxdslr.com site, and found that it doesn't mention any recommendation either. I will have to look closer where I got the information, but I know the source was a Pentax one. Anyway, it shouldn't be too hard to test... [/EDIT]

Wim


Last edited by Ishpuini; 08-07-2009 at 07:55 AM.
08-07-2009, 07:50 AM   #9
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QuoteOriginally posted by billtin59 Quote
Where did you get that Pentax recommends inputting the shorter focal length? The manual states you use the LONGER, which since Pentax wrote the manual, I'm guessing that's also their recommendation.
I knew there was a reason that I don't use zooms, they are all too technical for me.

Last edited by Kerrowdown; 08-07-2009 at 02:11 PM.
08-07-2009, 08:46 AM   #10
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I too remember nothing in any Pentax manual about entering the longest focal length. And I can absolutely verify from experience that inputting too long a focal length can produce images that are obviously much worse than not using SR at all. But not if you only overstate focal length by a little - you have to be off by a lot before it makes matters worse. Entering 200 when you are really shooting at 50 would probably count, but I've noticed it primarily when entering 200 if I am actually shooting at 28. Entering 200 if you are really at 150 would probably be fine - although not as good as actually entering 150.

Of course, as far as I know, there are no 50-200 manual lenses out there - the 50-200's from Pentax are all AF and communicate focal length automatically.

Also, the topic of using older lenses on a DSLR comes up maube 3-4 times a week. i recommend browsing the forums for other discussions of the topic, including references to how to make the aperture ring work with a DLSR, and the change in field of view you will see when using a lens on digital versus film (aka "crop factor").

Last edited by Marc Sabatella; 08-07-2009 at 07:58 PM.
08-07-2009, 05:23 PM   #11
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QuoteOriginally posted by Ishpuini Quote
Could you please refer me to the actual manual that says that, preferably with the page number?

I just checked both the K20D and K-7 manuals of which I have on-line copies and neither mention any recommendation other than setting the focal length closest to the actual focal length the zoom lens is set at.

My source is a SR white paper that was distributed by Pentax when SR was introduced. I don't have it on my PC here at work, but I have a copy at home. I will check it and post a quote here...
[EDIT]Just located the document on the Pentaxdslr.com site, and found that it doesn't mention any recommendation either. I will have to look closer where I got the information, but I know the source was a Pentax one. Anyway, it shouldn't be too hard to test... [/EDIT]

Wim
After actually looking this up in the K20 manual, pg 67, (as opposed to using my memory), it says "When using a zoom lens, select the actual focal length at the zoom setting in the same manner." It also goes on to explain that shooting distance influences SR as well. I suppose you could take this to mean when the lens is zoomed all the way (my initial interpretation), or you could take it as meaning whatever focal length you happen to be shooting at the moment, which seems impractical at best, and defeats the purpose of a zoom somewhat, don't ya think??

I have an old 80 - 200 zoom, and I input "200" and haven't had any problems at any focal length. to me, using the longer end covers you no matter where you are in the zoom range.
08-07-2009, 08:03 PM   #12
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It's not that setting to 200 "covers" yu if shooting at 80 - it's that it actually causes the sensor to *overcompensate*. I'm not sure if it would do so enough to to make the image worse than turning off SR, but it would probably come very close; if nothing else, it probably cancels out most if not all the advantage SR would otherwise have given you at 80. Try some tests with and withlout SR while shooting at 80 versus at 200. If you have the SR focal length set to 200, my guess is that you'll see SR giving a lot of improvement when actually shooting at 200, but not when shooting at 80.

And yes, you're right, it makes shooting manual zooms with SR a pain, which is why I don't bother buying manual zooms. But for those who do, better results would probably be obtained setting SR somewhere in the middle of the range - so that it doesn't overcompensate *too* badly at 80, and some compensation at 200 is better than none. Either that or set SR to 200 on the assumption that you'll most be using it at that end, but if you find yourself shooting at 80, you might be better off simply turning SR off.
08-07-2009, 08:29 PM   #13
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Hey brjl...wecome aboard! I bought a ME Super new in the early 80s....and still have the lenses that I aquired over the years for it.....and they work great! There are a few posts here on how to use them (there is a simple setting to allow your camera to use them) and there are a couple of hints to pass along for how to get the exposure right. It's fairly easy to do once you get the hang of it and it is very rewarding. Check out the posts "M club", "K club" or "Takumar club".

Cheers!
08-08-2009, 06:24 AM   #14
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QuoteOriginally posted by Marc Sabatella Quote
It's not that setting to 200 "covers" yu if shooting at 80 - it's that it actually causes the sensor to *overcompensate*. I'm not sure if it would do so enough to to make the image worse than turning off SR, but it would probably come very close; if nothing else, it probably cancels out most if not all the advantage SR would otherwise have given you at 80. Try some tests with and withlout SR while shooting at 80 versus at 200. If you have the SR focal length set to 200, my guess is that you'll see SR giving a lot of improvement when actually shooting at 200, but not when shooting at 80.

And yes, you're right, it makes shooting manual zooms with SR a pain, which is why I don't bother buying manual zooms. But for those who do, better results would probably be obtained setting SR somewhere in the middle of the range - so that it doesn't overcompensate *too* badly at 80, and some compensation at 200 is better than none. Either that or set SR to 200 on the assumption that you'll most be using it at that end, but if you find yourself shooting at 80, you might be better off simply turning SR off.
I understand your theory, but I don't see any evidence of it in practice. I also see no mention of over / under compensation in the manual, if it were a real concern I'm sure there would be a warning as there is for turning off SR when using a tripod.

I say toe-may-toe, you say toe-mah-toe Have a great weekend and Happy Shooting
08-08-2009, 07:09 AM   #15
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QuoteOriginally posted by billtin59 Quote
I understand your theory, but I don't see any evidence of it in practice.
Yes, but have you actually tested for this effect? It could well be SR has been reduced to zero effectiveness (or worse) and you've just never noticed. If in controlled testing you have demonstrated that while setting SR focal length to 200 reduces the effectiveness of SR compared to setting it correctly, but that it does not actually make SR counterproductive, then great. I'm honestly curious, and would love to see test shots to document just how much of a difference it makes in situations like this.

I *have* tested it, and know for a fact the effect is real, but I admit I don't know how far you have to be off in order for it to actually be detrimental as opposed to simply reducing effectiveness. Like I said, the effect is extreme and obvious if you have it set for 200 when the actual focal length is 28. The only question is at what point does the effectiveness of SR drop to zero and start to become counterproductive. Could be when you are off by 2X, 3X, 4X, or something else - would be interesting to find out. But my money is on 2X.

QuoteQuote:
I also see no mention of over / under compensation in the manual
They tell you to set the correct focal length; just because they don't spell out the consequences of not doing so doesn't mean anything. They don't spell out the consequences of doing a lot of things they tell you not to do.

QuoteQuote:
if it were a real concern I'm sure there would be a warning as there is for turning off SR when using a tripod.
As I said, they *do* tell you to set FL correctly; they just aren't explicit about the reasons. So even without giving a reason, they'll told you what you are supposed to do. Whereas, without this warning, how you would you know you were supposed to turn SR off when on a tripod?

Anyhow, we can theorized all we like; the proof is in actual tests. Mine have proved absolutely conclusively that the effect is real; the only question is how far you have to be off before it's makes SR counterproductive. Only testing would tell us for sure.
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