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03-16-2019, 02:35 PM - 1 Like   #46
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QuoteOriginally posted by swanlefitte Quote
Are you sure it stopped down dismounted? My 55-300 seems alway open. I could be wrong.
I'll take you're word for it. That would mean KAF4 lenses are wide-open only on legacy bodies.

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03-16-2019, 03:48 PM   #47
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QuoteOriginally posted by swanlefitte Quote
Are you sure it stopped down dismounted? My 55-300 seems alway open. I could be wrong.
If itís always open, thereís no point to dismounting the lens, then.

-Eric
03-16-2019, 05:23 PM   #48
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QuoteOriginally posted by GregL65 Quote
A workaround for KAF4 lenses on incompatible bodies would be to partially dismount them, which stops down the aperture (also turns them into manual focus).
QuoteOriginally posted by TwoUptons Quote
Wouldn’t partially dismounting them stop them all the way down?
Nope...KAF4 has no physical actuator lever. Stop-down is done using an in-lens motor with the lens wide-open when not stopped down for exposure or DOF preview; the same is true when not mounted to a compatible camera.


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03-16-2019, 05:34 PM - 1 Like   #49
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QuoteOriginally posted by stevebrot Quote
Nope...KAF4 has no physical actuator lever. Stop-down is done using an in-lens motor with the lens wide-open when not stopped down for exposure or DOF preview; the same is true when not mounted to a compatible camera.
This sounded like the Canon EF workaround not the Pentax KAF4 workaround. On a Canon you set the aperture, preview and then dismount. Stopping down a Canon EF lens ? Photocritic Photo School As far as I know there is no method similar to this for KAF4 lenses.

03-16-2019, 06:38 PM - 1 Like   #50
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QuoteOriginally posted by UncleVanya Quote
As far as I know there is no method similar to this for KAF4 lenses.
AFAIK, I believe you are correct: there is no KAF4 work around. If the body is not compatible, the lens plays dead and stays wide open as in the photo below from the D FA* 50/1.4 detailed review. From all reports, the aperture is wide open unless it is both powered and purposefully being stopped down.

https://www.pentaxforums.com/reviews/hd-pentax-d-fa-50mm-f1-4-sdm-aw/constru...-handling.html




Note the lack of mechanical couplings.



Steve

Last edited by stevebrot; 03-16-2019 at 07:24 PM.
03-16-2019, 07:02 PM - 1 Like   #51
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QuoteOriginally posted by GregL65 Quote
A workaround for KAF4 lenses on incompatible bodies would be to partially dismount them, which stops down the aperture (also turns them into manual focus). That was the workaround for M and earlier lenses on "cripple-mount" bodies before the Green Button solution appeared.
Ummmm...no...

Green button metering or its equivalent has been a feature of all Pentax dSLRs since the beginning. I believe the same is also true of many crippled mount film camerasEdit: NOT. The partial dismount hack allows stopped-down use (full manual aperture) of Av mode with non-A lenses K-mount lenses, something the green button cannot do.


Steve

Last edited by stevebrot; 03-16-2019 at 07:18 PM.
03-16-2019, 07:10 PM   #52
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QuoteOriginally posted by angerdan Quote
So not many lenses before the first DA lenses with SDM have them.
Just those FA series lenses with power zoom: four seven* models?


Steve

* Thanks @angerdan (comment below)

Last edited by stevebrot; 03-17-2019 at 10:02 AM.
03-16-2019, 07:34 PM - 1 Like   #53
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QuoteOriginally posted by stevebrot Quote
Ummmm...no...
Green button metering or its equivalent has been a feature of all Pentax dSLRs since the beginning.
Yes, but I said "cripple-mount bodies", not DSLRs.

QuoteOriginally posted by stevebrot Quote
I believe the same is also true of crippled mount film cameras.
There were cripple mount film bodies before there was a green button solution. I had thought that the film *ist had the green button but it seems I was mistaken. The flagship MZ-S had a green button but it didn't have the cripple mount; it was used for other green button purposes.

There used to be a website that spelled it all out pretty clearly but it's long gone. Here's one that shows it though. It shows four film models including the film *ist with cripple mount but no green button. See the last column and the M footnotes. M''', shown for all the DSLRs, means it had a green button solution to cripple mount:

The Pentax Camera Lens Compatibility Chart

03-16-2019, 09:36 PM   #54
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QuoteOriginally posted by GregL65 Quote
Yes, but I said "cripple-mount bodies", not DSLRs
I believe that category includes Pentax dSLRs, every single model. Sorry about the confusion with those vs. the four film slrs having crippled KAF mount. I am not sure, but I believe that the "rotate out of mount" hack only works with two of those (MZ-50 and *ist).

QuoteOriginally posted by GregL65 Quote
Here's one that shows it though. It shows four film models including the film *ist with cripple mount but no green button. See the last column and the M footnotes. M''', shown for all the DSLRs, means it had a green button solution to cripple mount:

The Pentax Camera Lens Compatibility Chart
That page is very useful and is maintained by the Pentax Forums owners. That being said, the matrix has a few errors, one of which is pertinent to this discussion. The MZ-30 is only compatible with A and AF lenses, while the MZ-60 is only compatible with AF lenses.


Steve

Last edited by stevebrot; 03-16-2019 at 09:47 PM.
03-17-2019, 12:27 AM - 1 Like   #55
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QuoteOriginally posted by stevebrot Quote
Just those FA series lenses with power zoom: four models?
3x FA* and 4x FA:
Pentax Lens Search | PentaxForums.com
03-17-2019, 10:00 AM   #56
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QuoteOriginally posted by angerdan Quote
Cool! I have not used the lens compatibility search and it looks to be a great tool to ferret out this sort of information.


Steve
03-17-2019, 10:33 AM - 1 Like   #57
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QuoteOriginally posted by stevebrot Quote
Ummmm...no...

Green button metering or its equivalent has been a feature of all Pentax dSLRs since the beginning.


Steve
Not quite, this function only came in with the first firmware revision for the *istD, v1.10.
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