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04-14-2008, 07:16 PM   #1
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OK, is this it or .... (LBA)

Alright, this is getting scary now. I was out looking at 70-210 and 80-200 lenses today.

Pentax A 70-210mm f/4 (looked in ok shape)
Pentax M 80-200mm f/4.5 (mint)
Tokina "A" 80-200mm f/4.5 (worst PF I have ever seen)
Vivitar 70-210mm f/3.5 (good condition, at almost 900g and twice the cost of the above M, I opted out)

The winner was the Pentax M 80-200mm f/4.5 due to mint condition and the 'feel' of the lens. Bojidar Dimitrov's page says there are 2 versions of this lens. Mine looks like the version 2 when looking at the images of each lens. However, version 2 is stated to have; "a linear aperture-coupled lever, a feature of the KA and later lenses." I put the camera in Av mode, it doesn't show the F Stop, just F-- ...just like all my other M lenses. Not a big deal, curious if that "aperture-coupled lever" is indeed on my model. Any ideas?




Last edited by metalfab; 04-14-2008 at 07:31 PM. Reason: forgot to add image :)
04-14-2008, 08:16 PM   #2
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SR is not always needed.

SR is great but, I find it a pain on M Zoom lens so I just turn it off. No difference or lost shots so far.

Both at 200mm, f/4.5, 1/250, 100% crops.

SR Off;



SR: On;

04-14-2008, 09:21 PM   #3
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This is what his tech page has to say about the linear diaphram actuator (taken from the page about the KA mount):

"The least-noticeable change is in the movement of the diaphragm actuator. In the original K-mount its displacement is proportional to the diameter of the diaphragm opening. In the KA mount, it is proportional to the area of the diaphragm opening, and thus to the selected f-stop. This leads to an identical stop-displacement between any two consecutive f-stops, and thus greatly simplifies the operation of the body in the Tv and P operating modes. All KA lenses have the same stop-displacement.

The diaphragm actuator's change in operation does not lead to any incompatibilities with older camera bodies. This is because the diaphragm release of these bodies always moves all the way up, and allows unrestricted travel of the lens' diaphragm actuator."

I don't pretend to fully understand what that means, but it doesn't sound like it's talking about being able to use Av mode on the crippled mounts- it seems that that only occurs when you have an A lens that transmits the aperture data electronically.
04-15-2008, 08:16 AM   #4
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QuoteOriginally posted by clawhammer Quote
This is what his tech page has to say about the linear diaphram actuator (taken from the page about the KA mount):

"The least-noticeable change is in the movement of the diaphragm actuator. In the original K-mount its displacement is proportional to the diameter of the diaphragm opening. In the KA mount, it is proportional to the area of the diaphragm opening, and thus to the selected f-stop. This leads to an identical stop-displacement between any two consecutive f-stops, and thus greatly simplifies the operation of the body in the Tv and P operating modes. All KA lenses have the same stop-displacement.

The diaphragm actuator's change in operation does not lead to any incompatibilities with older camera bodies. This is because the diaphragm release of these bodies always moves all the way up, and allows unrestricted travel of the lens' diaphragm actuator."

I don't pretend to fully understand what that means, but it doesn't sound like it's talking about being able to use Av mode on the crippled mounts- it seems that that only occurs when you have an A lens that transmits the aperture data electronically.

Thanks for the info, and the link. I'll have a read when I'm more awake

-

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