Reading mode: Light Dark

aperture ring problem

Go to last post
S

slide_scanner

Well-known member
Messages
124
Reaction score
12
Location
MI, US
I've got a problem and I'm wondering if there's something wrong with my camera or I'm just missing something.

When I try to set the aperture with the aperture ring, the diaphragm does not stop down (not with depth of field preview, and not with shutter release). However, the diaphragm works as expected when the aperture ring is set to "A" or on lenses with no aperture ring.

The two lenses I've tried this with are the 43 limited and an M 45-125 f/4, both on the K10D. The 43 only stops down when set to A and the 45-125 won't stop down no matter what I do. Yes, I have set the custom setting for the aperture ring to "permitted," and the shutter will fire, but all exposures are made wide open.

Can anybody tell me what I'm doing wrong?

Thanks
 
I've tried both Manual and Aperture priority mode -- exposure mode doesn't seem to have an impact.
  • mount a lens with an aperture ring (be sure custom setting for aperture ring is set to "permitted")
  • use manual exposure mode, set aperture to f/16, or other smallish aperture, and set shutter speed to whatever the camera meters
  • try depth of field preview to see if viewfinder darkens (it doesn't for me)
  • try taking two different shots with the same shutter speed but different aperture ring settings. They should have different exposures, but for me they are the same.
Thanks
 
K10d, fa43mm Limited, results below.
slide_scanner said:
I've tried both Manual and Aperture priority mode -- exposure mode
doesn't seem to have an impact.
  • mount a lens with an aperture ring (be sure custom setting for
aperture ring is set to "permitted")
Click to expand...
Done.
slide_scanner said:
  • use manual exposure mode, set aperture to f/16, or other smallish
aperture, and set shutter speed to whatever the camera meters
  • try depth of field preview to see if viewfinder darkens (it
doesn't for me)
Click to expand...
Done, and it does. f16, f22, different apertures, different levels of darkness (as I would expect).. DOF preview accomplished by pulling power switch to the right (just to be sure we're clear) and it's set for TTL not digital preview..
slide_scanner said:
  • try taking two different shots with the same shutter speed but
different aperture ring settings. They should have different
exposures, but for me they are the same.
Click to expand...
At f1.9, 1/60 second, a reasonably well exposed image. At f22, 1/60, complete darkness.

All of the above in Manual (M) mode btw.
slide_scanner said:
Thanks
Click to expand...
Something is wrong with one or more of your components (judging from this very unscientific test) or your lens is mis-mounted (a problem I use to have with an FA50 not being completely locked on).
--
http://photobucket.com/albums/v285/jjmel FZ20
http://s134.photobucket.com/albums/q109/jjkyle/ K10D
Still happy with the K10d (in spite of the pixel peepers)
Someone in Poland is enjoying my FZ20 now.
 
Take lens off the camera. Look at the back, if it's on A or f/22 you should see a fully closed aperture. DA lenses are in effect on A. See what happens when you push the aperture lever witha finger - the lens should open up and immediately flick closed when you release the lever (this won't happen with the lens manually set wide open). Often older lenses get oil onto the aperture blades (it drips down from the lubricated focusing helicoid etc, aperture diaphragms are supposed to be completely clean). Would then work as you describe. The camera lever forces the aperture open, so stuck irises are normally in the open position. Only closes under the strength of an internal spring, and if there's any resistance, nothing happens.

If the aperture closes and opens freely, you may have a lens mount or lens:camera communication problem. But otherwise and most likely, the lens needs servicing - it is quite expensive, must be disassembled and cleaned :-[

I have a cheapish lens in this state, uneconomic to fix - iow, about the cost of buying similar secondhand. But for an expensive or precious lens it's worthwhile.

RP
 
try setting K10 to M mode, with the custom green button in manual option set to program line.

With both M and A series lens, with say f16 selected on the ring, when you press the green button the aperture will be stopped down from fully open, you will both hear the operation and see the effect through the viewfinder (f16 will be more obvious than f2 of course) and yes I have the aperture ring option set to permitted

with A and F series lens when the aperture is set to A then the stop down does not happen when you press the green button, instead the program line metering is determined and displayed in the viewfinder - AFAIK the metering is done wide open and the camera will stop down the aperture when the pic is taken.

with an A series lens when A is selected on the aperture ring, the optical preview does stop down the iris, I didn't try this with any other lenses.

(Thanks to rplondon for the test of flicking the aperture lever on the lens, I learnt something new today :-) )
 
Thanks for trying -- I'm ruling out a mismounted lens because setting the aperture to "A" works fine, so I'm thinking there is something wrong with my camera.
 
I'm fairly certain the lens is not at fault: I've tried two different lenses with aperture rings and both work (or rather don't work) the same way. Plus the lenses with auto aperture work fine with the A setting. And as you suggested, I checked the aperture lever, and again, the diaphragms are responsive.

The really odd thing is that when I tried activating DOF preview with no lens mounted, the little switch that moves the aperture lever does move like it should! This suggests a problem with the way the lens is mounted, but if the lens wasn't mounted correctly, then the aperture shouldn't stop down properly when set to "A," either -- yet it does.

I'm really baffled at this point:

-it's not lens specific

-it's not sticky diaphragm blades

-it's not the lens aperture lever

-it's not a mis-mounted lens

-it's not the switch the camera uses to move the aperture lever

-it's not the aperture ring custom setting

Any other ideas?

Thanks
richardplondon said:
Take lens off the camera. Look at the back, if it's on A or f/22
you should see a fully closed aperture. DA lenses are in effect on
A. See what happens when you push the aperture lever witha finger -
the lens should open up and immediately flick closed when you
release the lever (this won't happen with the lens manually set
wide open). Often older lenses get oil onto the aperture blades (it
drips down from the lubricated focusing helicoid etc, aperture
diaphragms are supposed to be completely clean). Would then work as
you describe. The camera lever forces the aperture open, so stuck
irises are normally in the open position. Only closes under the
strength of an internal spring, and if there's any resistance,
nothing happens.

If the aperture closes and opens freely, you may have a lens mount
or lens:camera communication problem. But otherwise and most
likely, the lens needs servicing - it is quite expensive, must be
disassembled and cleaned :-[

I have a cheapish lens in this state, uneconomic to fix - iow,
about the cost of buying similar secondhand. But for an expensive
or precious lens it's worthwhile.

RP
Click to expand...
 
No luck.

I think I'm just going to have to contact Pentax and see what they can tell me, and possibly send the camera in. Thanks to everyone for the suggestions, though.
 
not many ideas left - er, have you tried cleaning the lens mount contacts? Do they look damaged in any way?

RP
 
hmmm, weird, hope you manage to get it sorted

just for info, if the custom setting for aperture ring is set = 1 and you take and FA series lens to say f8 by using the aperture ring on the lens, then you just get "F--" flashing in the viewfinder, even in manual mode. you can't even get the shutter to respond
 
You must log in or register to reply here.

Keyboard shortcuts

f
Forum
m
My threads
Mobile site
About
Editorial content
Cameras & Lenses
Community
All content, design, and layout are Copyright © 1998–2025 Digital Photography Review All Rights Reserved.
Reproduction in whole or part in any form or medium without specific written permission is prohibited.
When you use DPReview links to buy products, the site may earn a commission.
©GPS Media - Guides, Products, Services.
Back
Top