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Message |
    
Matthew Padden
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 14, 2004 - 04:45 pm: | 
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Hi folks,
The auto aperture pin and manual-auto selector on my Helios 44M seems to have no effect. The aperture ring and leaves work fine when moved manually, and the camera's auto-aperture actuator works fine when tested on other lenses. Is this a known issue and/or a straightforward fix?
Many thanks in advance for any advice.
Matt
Glasgow, UK |
Jan Dvorak
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, January 14, 2004 - 07:35 pm: |
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Matt,
Are the leaves closed to the working aperture when the lens is off the camera? If the auto aperture pin does not work, the diaphragm should stay open. If, as you say, the auto aperture pin and the manual-auto selector have no effect, I do not understand how the "leaves work fine when moved manually". Maybe I misunderstand you - if the diaphragm is closed to the working aperture ALL the time, than the problem might be a dislocated spring inside the lens, which should keep the diaphragm open. The diaphragm should only close when you push the auto aperture pin, or activate the manual-auto selector ring. The problem might be with the selector ring as well.
Good luck,
Jan |
Matthew Padden
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 15, 2004 - 02:59 am: |
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Hi Jan,
Sorry, I will try and explain a bit better what's going on. With the lens off the camera, the leaves will open and close as the aperture ring is turned, regardless of the manual-auto selector setting. The manual-auto selector also does not open the leaves when set to 'auto'. In addition, with the manual-auto selector in 'auto', pushing the auto aperture pin has no effect on the leaves. The pin and manual-auto selector control do move as expected though, which might seem to suggest that the problem is 'further inside' the lens?
Thanks in advance for any advice.
Matt
Glasgow, UK |
Jan Dvorak
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 15, 2004 - 10:42 am: |
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Matt,
The problem is definitely inside the lens. The diaphragm should stay open at all times, with the lens on or off the camera, regardless of the aperture set. It will only close at the moment of exposure - when the auto aperture pin is actuated, or when you set the auto - manual lever to manual. My 'over the ocean' diagnosis is a disconected spring inside the lens' auto aperture mechanism; this spring should hold the aperture open for wiewing.
Good luck,
Jan |
John Farrell
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 15, 2004 - 01:03 pm: |
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The aperture mechanism cover is held on by 4 screws, that you can see at the back of the lens. If you take the cover off, be careful not to remove the aperture ring - some of these lenses have 2 spring loaded balls under the ring, and replacing both is difficult. The aperture mechanism is straightforward to work on. Check the aperture pin - it has a screw adjustment, to change its length. If it is screwed out too far, the aperture stays stopped down. |
Matthew Padden
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 15, 2004 - 02:45 pm: |
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Thanks, Jan, for your suggestion, and thanks, John, for your mechanical tips (my lens had 3 screws holding the cover) and your warning about the aperture ring! I inspected the auto aperture mechanism in the lens and found it was somewhat 'sluggish'; the auto aperture linkage would move one way but then not return without some assistance. I applied a tiny bit of oil which improved things a lot. The lens now works properly, except for if I use an f16 aperture; then the aperture sometimes 'sticks' closed after I release the shutter button. I guess it's either still a little sticky, or the pin's screw adjustment is not quite right. Fixable either way though.
Thanks again for your wisdom.
Matt
Glasgow, UK |
Jim Brokaw
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, January 15, 2004 - 07:01 pm: |
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I note that you applied a small amount of oil. Often the reason for stickyness in aperture mechanisms is due to grease or oil getting where it is not supposed to be. My experience with most SLR lenses is that there is not supposed to be any grease/oil in the mechanical movements, although there may be some grease dampening the movement of the aperture ring itself. You might want to reconsider the oil in the mechanical linkages, this could cause problems down the line someday. If the mechanical linkages are straight and aligned as they should be, usually no oil is needed. |
Matthew Padden
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 17, 2004 - 04:16 am: |
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Thanks for your advice Jim. So far the lens is working Ok but I may set about removing the oil I applied at some point. There isn't any sign of bent or misplaced parts in the mechanism, but the lens had spent several years unused before I acquired it, so maybe it is simply stiff from lack of exercise?
All the best
Matt
Glasgow, UK |
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