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11-27-2006, 08:17 AM   #1
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Third party lenses question...

I have a question about the 3rd party lenses on Pentax k100D or k10D (waiting on body to arrive still).

From what I read in the online PDF manual on SR system of these two cameras, it requres for the lens to let camera know the focal lenght the lens is at a the moment of the shot.

I know most later model lenses from Tamron and Sigma (such as 17-70, 70-300 etc) do convey the focal lenght information, at least to my Canon 350D (as I can see it in the exif data)... At least that is how I understand what is says in the manual (pages 69-71 of the document http://www.pentaximaging.com/files/product/K10D_Manual.pdf )

In the real world, if you have any AF third party lenses, does SR work automatically or are you prompted every time to enter the focal length manually into the camera?

Thanks for your time!

Regards,
D

EDIT - I was not sure to post here or in the lens section (since it involves the body and SR of the DSLR...)


Last edited by Duh_Vinci; 11-27-2006 at 08:22 AM.
11-27-2006, 08:23 AM   #2
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SR work fine with my Sigma EX 180 APO Macro. I do not have to enter any focal length info as the lens does send this info to the camera.

hth

Don
11-27-2006, 08:58 AM   #3
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Thank you for comfirming that, Don! Much appreciated!

Regards,
D
11-27-2006, 12:52 PM   #4
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SR on my K100D works fine with my Tamron 28-300 zoom (model A06). On my older manual lenses, I have to input the focal length, and then that info also shows up in the extended exif info.

11-27-2006, 01:15 PM   #5
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QuoteOriginally posted by rfortson Quote
SR on my K100D works fine with my Tamron 28-300 zoom (model A06). On my older manual lenses, I have to input the focal length, and then that info also shows up in the extended exif info.
just in case I pick up some old lenses, do you mean you have to put in the focal length of the entire range of the lens, or do you have to change the focal input every time you change the focal length with the telephoto?

hope that make sense ")

thanks
11-27-2006, 01:40 PM   #6
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QuoteOriginally posted by slipchuck Quote
just in case I pick up some old lenses, do you mean you have to put in the focal length of the entire range of the lens, or do you have to change the focal input every time you change the focal length with the telephoto?

hope that make sense ")

thanks
Makes perfect sense. I only have one manual focus zoom, so I enter the focal length that I plan to use it at. If I change the zoom, then I reenter the new focal length. Alternatively, you could just set it somewhere in the middle and figure it's "good enough". I've never really checked it out to see if it makes much difference.
11-29-2006, 07:11 PM   #7
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I was going to ask the same question as slipchuck, as I am thinking of buying a relative's disused Tamron 70-300 lens from the 1980s (?) for use with my K100D. I know it should work, but I han't considered the SR implications.

Hmm, that could be a pain, especially as I'll need SR much more at longer focal lengths. How many button presses is it to change the focal length? I don't have the camera here. Does anyone have feedback on how painful this is? Or how well SR works e.g when FL is 300mm but I tell the camera 200mm?

My options are (1) buy this used lens for maybe A$50, or (2) get a new Samsung/Schneider (rebadged Pentax DA) 50-200mm for A$200. I'm not sure I want to pay 4x as much just for this reason, and get a shorter lens into the bargain. Not sure about the optical quality difference.
11-29-2006, 10:51 PM   #8
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I don't know how many button presses it is. I just cycle the power and it asks me first thing. In fact, I usually leave the camera on and just let it power down on timer. Then, when I press the shutter, it will come to life. However, with a manual lens it will always ask first about the focal length. It does remember the last setting so all it takes is a press of the OK button and I'm good to go.

It sounds much worse than it is. In practice I don't really even notice it.

11-30-2006, 12:06 AM   #9
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QuoteOriginally posted by rfortson Quote
I don't know how many button presses it is. I just cycle the power and it asks me first thing. In fact, I usually leave the camera on and just let it power down on timer. Then, when I press the shutter, it will come to life. However, with a manual lens it will always ask first about the focal length. It does remember the last setting so all it takes is a press of the OK button and I'm good to go.

It sounds much worse than it is. In practice I don't really even notice it.
Same here, I leave it on the "on" position all the time and use the half-press to bring it back to life, and when a manual lens is on, the first thing on the screen is the focal length input. BTW anyone knows how much does the accurate focal length info matter? I've only got a 50mm 1.4 manual at the moment, but haven't tested much with that focal length input + SR thing.
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