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06-25-2010, 10:11 AM   #1
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Z-1P / KAF2 "A" aperture problem

Hi there,

I have a Pentax Z-1P with a problem.
When selecting aperture "A" on the lens, and e.g. 22 on the body, the aperture does not close all the way when taking a picture.
When selecting aperture 22 on the lens, it does close all the way.

I suspect this to be a communication problem between lens and body? Does anyone have an idea which contacts could be involved?
Does anyone have a better idea?

It's not the lens - it works fine on another Z1-P and a K10D.

Any help appreciated!

Best regards,

Rudolf

06-25-2010, 10:18 AM   #2
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Sounds like there might be something wrong with your camera. Were you testing yours in M mode?
06-25-2010, 10:25 AM   #3
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are you sure it is showing F22 on the body, maybe it is just reading the contacts for aperture incorrectly. Since it shows F22 for stopped down, what does it show as wide open? Maybe it thinks the lens is slower than it is wide open, and this is causing the problem.

the other possibility, is that the activation lever is not moving the entire distance. This sounds less likely since in manual it is letting the lens stop down fully.

SInce you say the lens works fineon other cameras, I assume you have a couple to test, and compare the activation lever movement?

BUT first check and see what it shows as maximum aperture. It may be the lens / camera body contacts need cleaning, or the lens mount is deffective. Can you check with more than one lens also
06-25-2010, 11:56 AM   #4
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An update: Afaik hyper program won't let you pick a setting that underexposes, so make sure you're in M mode

06-25-2010, 12:13 PM   #5
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QuoteOriginally posted by Adam Quote
An update: Afaik hyper program won't let you pick a setting that underexposes, so make sure you're in M mode
interesting point, are you suggesting that F22 with the lighting and ISO film th eOP has selected, that the reading is bleow the exposure limit?

didn;t thnk of that. But he says other lenses go to F22?
06-25-2010, 12:36 PM   #6
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I'm not sure, as there can be several factors. Here's a possible senario, however: you're testing indoors in low light. At the lowest possible shutter speed, the smallest compatible aperture is F20- however, this is rounded up in the viewfinder and displayed as F22 when the user selects it.

I don't have my PZ-1 handy right now, so I can't confirm or deny this or any malfunction for sure
06-25-2010, 12:59 PM   #7
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I will try later with an FA power zoom lens, with my FA-J 18-35 it will stop down to F27 in hyper program no problem it will flash below minimum calculated exposure limit.

edit note

Good call on the last point adam

with the FA 28-80 F3.5-4.7 it limits the aperture to the exposure limit, I put the ISO manually to 100 and pointed the camera under my desk, only got to F6.7, point it at the ceiling and it goes to F27

seems to be in the software to limit idiots. Looks like manual is meant for idiots
06-26-2010, 04:22 AM   #8
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Hello again,
you guys are incredible. So many answers in so little time ;o)

But unfortunately, I was trying with all kinds of programs. Manual in bulb setting is ideal for testing, as I can then watch the aperture close, the shutter open and back again.

It might indeed be a communication problem the camera does not seem to be able to tell the lens, what the selected aperture should be (in "A" mode).

Communication from lens to camera seems to work: if I choose an aperture on the lens, it show correctly on the body.

Does anyone have information about the contacts in KAF2? Maybe a link to a description?

A repair manual for Z-1P would be great...

Thanks for your enthusiastic help!

Rudolf

06-26-2010, 03:29 PM   #9
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QuoteOriginally posted by Rudz Quote
Hello again,
you guys are incredible. So many answers in so little time ;o)

But unfortunately, I was trying with all kinds of programs. Manual in bulb setting is ideal for testing, as I can then watch the aperture close, the shutter open and back again.

It might indeed be a communication problem the camera does not seem to be able to tell the lens, what the selected aperture should be (in "A" mode).

Communication from lens to camera seems to work: if I choose an aperture on the lens, it show correctly on the body.

Does anyone have information about the contacts in KAF2? Maybe a link to a description?

A repair manual for Z-1P would be great...

Thanks for your enthusiastic help!

Rudolf
I don;t think you have a problem, as Adam correctly suggested and I confirmed with my camera, the PZ-1 will limit the aperture if there is not enough light to give a minimum exposure within the range of Hyper program.

but if you want to find out about contacts, search on Mark Roberts pentax , and you will get a good review of the K mount and the lens contacts for all mount types
06-27-2010, 02:38 AM   #10
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Thanks for your post, Lowell.
Unfortunately I do have a problem.
As I wrote, I have tried all kinds of programs, and the aperture just wont close far enough. I have not stayed with the USER setting or Hyper programs, I have tried all kind of manual programs (bulb is pretty manual), and I have checked all the Pentax specials - nothing is set to anything wrong.

I have a second Z-1P, where it works nicely, as it is supposed to. The aprture closes all the way, when 22 is selected on the body.

I'll check Mark Roberts pages next...

Thanks for your help!

Rudolf
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