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01-11-2010, 03:00 PM   #1
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Image stabilization and manual SMC A series lenses

Whenever I connect my old A series lenses to one of my DSLRs and turn the camera on, it faithfully prompts me to select the focal length of the lens so that it can accommodate the lens to the image stabilization. Yet, when I review the handheld, available light results, the images aren't as sharp as when I use their D or D* autofocus cousins. However, when I use my studio flash with these lenses, everything is pin sharp as we'd expect from such excellent glass. SMC A lens + tripod + available light also produces excellent results.

is there a story here about image stabilization with MF lenses that I'm missing?

01-11-2010, 03:38 PM   #2
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'A' lenses shouldn't require you to enter focal length for starters. Have you checked the electrical contacts on the lens mount?
Secondly, do you allow the SR system to engage before firing the shutter? It requires a momentary pause after locking focus before the SR is engaged, noticed by the SR hand sign lighting up in the viewfinder.
01-11-2010, 03:42 PM   #3
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QuoteOriginally posted by Ash Quote
'A' lenses shouldn't require you to enter focal length for starters. Have you checked the electrical contacts on the lens mount?
Secondly, do you allow the SR system to engage before firing the shutter? It requires a momentary pause after locking focus before the SR is engaged, noticed by the SR hand sign lighting up in the viewfinder.
All three bodies with any one of my SMC A lenses requires the focal length selection. I'll keep an eye on the SR hand, but I don't see this issue with the new D lenses.
01-11-2010, 04:02 PM   #4
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QuoteOriginally posted by Ash Quote
'A' lenses shouldn't require you to enter focal length for starters.
Can someone else confirm this? I have a Pentax-A 50mm f/1.7 and it also asks for the focal length every time I turn the camera on.

I sometime have trouble with slightly blurry/fuzzy pictures as well. But I attribute it to my poor manual focusing skills and the shallow DOF since I like to shoot it wide open or close to it.

01-11-2010, 04:06 PM   #5
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QuoteOriginally posted by Rusty Rat Quote
All three bodies with any one of my SMC A lenses requires the focal length selection. I'll keep an eye on the SR hand, but I don't see this issue with the new D lenses.
Are you Auto focusing with the D lenses? ? If so, have you checked your diopter adjustment?
01-11-2010, 04:07 PM   #6
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QuoteOriginally posted by Ash Quote
'A' lenses shouldn't require you to enter focal length for starters. Have you checked the electrical contacts on the lens mount?
Secondly, do you allow the SR system to engage before firing the shutter? It requires a momentary pause after locking focus before the SR is engaged, noticed by the SR hand sign lighting up in the viewfinder.
This is incorrrect, A lenses only have 6 pins (pin locations ) the 7th pin, which carries focal length and focus distance information appeared on SMC-F lenses (the first AF lenses).

A lenses only carry encoding for maximum and minimum aperture.

As for sharpness with A lenses, the other question is how are you focusing and what shutter speeds. ALso how long do you hold the SR confirmation

I have no issues with hand held shots on my K7, and have posted in the past a shot at 1/40 with a 500mm lens (SMC 300mm F4 with 1.7x AF TC) hand held. I think SR works just fine thank you

01-11-2010, 04:22 PM   #7
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QuoteOriginally posted by Ash Quote
'A' lenses shouldn't require you to enter focal length for starters. Have you checked the electrical contacts on the lens mount?
Secondly, do you allow the SR system to engage before firing the shutter? It requires a momentary pause after locking focus before the SR is engaged, noticed by the SR hand sign lighting up in the viewfinder.
Sorry Ash...Lowell is correct.

"A" series lenses don't communicate focal length data to the camera. That is a characteristic of Pentax AF lenses.

Steve
01-11-2010, 04:44 PM   #8
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If it was diopter or any other focusing issue, why is the tripod and flash work pin sharp? Only the handheld stuff is soft. D lenses, even when manually focused, are fine.

01-11-2010, 04:48 PM   #9
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QuoteOriginally posted by Rusty Rat Quote
If it was diopter or any other focusing issue, why is the tripod and flash work pin sharp? Only the handheld stuff is soft. D lenses, even when manually focused, are fine.
Can you post something along with the exif data.

Also, what mode are you shooting in. I just had a thought, DA lenses will carry information on ideal settings, If you are in green mode the camera will follow these, but not with A lenses.

We really need to see a DA lens shot and an A lens shot with data to help, but if the A lenses are good on tripod and flash, then it is something either you are doing or letting the camera do for you incorrectly.

PHOTOS PLEASE
01-11-2010, 04:52 PM   #10
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A couple of things about SR:
  • It has to be engaged in order to work. If the little shaky hand is not visible in the viewfinder, SR is not engaged.
  • SR doesn't work for moving subjects
  • You can't pan and use SR. The SR uses an inertial sensor. Both your camera and subject have to be stationary.
  • SR should not be used when the camera is on a tripod. The SR system will introduce motion if none is present. Turn SR off when on a tripod -or- use the 2 second mirror-up delay (automatically disengages SR).
  • SR is has limitations. You are not going to be able to hand-hold your FA 200 at 1/30s.

Are we sure its the SR:
  • In focus?
  • Adequate DOF?
  • Lens sharp at that aperture?
Comparison with flash shots don't tell the whole story unless the shooting aperture is the same. Most of your "A" lenses are pretty fast glass with narrow DOF. If focus is even a little off, your results may not be up to your standard.

Now before you scoff at the focus issue, you might want ask about how you do your manual focus and also consider the limitations of manual focus on your dSLR. When I first got my K10D, I was often disappointed with the sharpness from my legacy glass (most of what I own). That is, until, I figured out that I was missing focus much of the time.

Two quick points:
  • Focus confirm using the AF system is accurate, but not very precise (at least on the K10D). Much of the time, it is off (+/-) just a little.
  • Focus using the stock focus screen is also generally accurate, but not very precise. This is true even when the eyepiece diopter is properly dialed in. The apparent DOF in the viewfinder is about the same as with the lens aperture at about f/3.5. Translation? Fine focus is futile without a focus aid (split-image or microprism).
How do I know these things? I did some testing using both the stock screen and the aftermarket Katz Eye screen.

Steve

Last edited by stevebrot; 01-11-2010 at 04:58 PM.
01-11-2010, 05:31 PM   #11
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Unfortunately I trashed all of my fuzzy manual A lens shots as there was no reason to keep them.

I'm aware that the screen doesn't allow the precise focus of a split image. My film experience with "real" cameras goes back to 1969 so I'm not a rookie at this. I'm aware of the diopter issue. I use the focus confirm only as an approximation as I'm not confident of its accuracy and it rarely picks the plane of focus that I want. DOF is a possibility, but not convincing as I don't seem to have an issue when manually focusing D or D* lenses.

Case in point. When I received my first K-7, it wouldn't shoot more than three shots in rapid succession with autofocus engaged (it was defective and was replaced). I went through a good part of the shoot with it on manual focus with no problem.

Reading through all of the replies, the only thing I can come up with is that SR is a tad slower to engage with A series lenses mounted and I'm hitting the shutter release before it is ready. I'll watch for this in future.

To recap:

Tripod use with manual focus A, D or D* series lenses is not a problem (I use the 2 sec delay)
Flash use with manual focus A, D or D* series lenses is not a problem
Handheld manual focus with D or D* lenses is not a problem
Only handheld with series A lenses is a problem.

Last edited by Rusty Rat; 01-11-2010 at 05:39 PM.
01-11-2010, 05:33 PM   #12
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QuoteOriginally posted by Rusty Rat Quote
Unfortunately I trashed all of my fuzzy manual A lens shots as there was no reason to keep them.
.
Photo lesson #1 never throw anything away. you never know what you can learn form it
01-11-2010, 05:44 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
Photo lesson #1 never throw anything away. you never know what you can learn form it
Ridiculous, there was nothing more to learn from them. They were fuzzy. I see no reason to fill up HDD space with rejects.
01-11-2010, 06:02 PM   #14
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QuoteOriginally posted by Rusty Rat Quote
Ridiculous, there was nothing more to learn from them. They were fuzzy. I see no reason to fill up HDD space with rejects.
Not to sound too much like a smart ass here, but if we could review these totally useless photos perhaps we could have answered your question.

If knowwing what yoou are doing wrong is worthelss, OK fine by me
01-11-2010, 06:25 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
Not to sound too much like a smart ass here, but if we could review these totally useless photos perhaps we could have answered your question.

If knowwing what yoou are doing wrong is worthelss, OK fine by me
Why not have a more open mind and not automatically assume that is operator error.
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