| Author |
Message |
    
Dean Cruikshank
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 26, 2004 - 09:50 pm: | 
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My Pentax Spotmatic SP Light meter seems to have malfunctioned. Here's the problem: At 100 ASA setting the meter works fine for all shutter speeds (1-1/1000 s). From a film speed setting of about 200 ASA and beyound (400, 800 etc.) and at shutter speeds of 1/4 s and slower (1/8 to 1 s) the light meter arm (ammeter?) moves to the bottom as if it shorted out. The battery is fine. I am presently trying to trouble shoot and have had a look inside (cover off). Could it be a short somewhere, the CdS sensors, corrosion? Please help. Thanks, Dean Cruikshank |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 27, 2004 - 03:54 am: |
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Sorry for stating the obvious, but are you sure that the meter is not simply trying to tell you that with that film sensitivity and at such slow speeds, no iris opening is going to provide a correct exposure? If you deliberately exceeds the limits of the correct exposure range, what is the meter arm supposed to do? |
Sam Styles
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 27, 2004 - 05:45 am: |
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Ive had exatly the same problem with my Nikon FG. The LED's in the meter skip out the lower shutter speeds. The higher the ISO setting the more they skip out, although if I set the camera on a shutter speed manualy, the metering works fine for all ISOs.
I took it to a camera shop and they explained it exactly as Ezio just has, but if you think about it, the camera should always display the shutter speed for the set aperture, even if it is a slow speed.
Now, Im 100% sure that this problem came on, and the camera certainly hadnt been doing it in the past. The chap in the camera shop looked at me as though I was stupid.
Im not sure what it is, but my camera still takes photos. Would be nice if it worked properly though. |
Sam Styles
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 27, 2004 - 05:49 am: |
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...I asked for help with my problem on the following linked page a while ago, but to no avail.
http://www.amphot.co.uk/photo-portal/forum.asp?FORUM_ID=27&CAT_ID=7&Forum_Title=Film+Cameras
The mystery meter problem continues.... |
Henry
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 27, 2004 - 07:03 am: |
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Just a thought...try cleaning the resistor tracks for the ASA dial and aperture position. Use electrical contact cleaner to dissolve any corrosion.
Henry |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 28, 2004 - 04:57 am: |
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Dean, there is a very simple way to check whether I'm correct or you do really have a problem. When the camera does its act and the meter arm moves to the bottom, try to partially cover the front lens with your hand so as to darken the scene. If the meter arm suddenly springs to life, then I'm right - the poor thing was simply trying to tell you that with such a slow speed, even the smallest aperture would produce an overexposed photo. If the meter stays where it is, then there is a problem which however is beyond my limited knowledge. |
Steve Roberts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 28, 2004 - 05:26 am: |
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Dean,
As I recall the SP handbook gives a table showing the range of shutter speeds for which the meter will read at a given film speed. As film speed increases, so the the longer shutter speeds fall off and as film speed gets slower, so you begin to lose the faster shutter speeds. Whetrher this was a limitation imposed by the electronics of the day or whether it was designed like that on the basis that no right-minded person would expect to be shooting at 1/1000th with 12ASA film, I don't know. Might be worth checking with the handbook (downloadable from the Pentax website)to see if this is the case or whether your situation is more severe!
Steve |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 28, 2004 - 08:50 am: |
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Yes, Steve above is correct. I also finally found the time of cheking it out with my own SP, and sure enough this is not a defect or a malfunction - it is just the way the meter was designed. |
Andreas Berg
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 28, 2004 - 09:31 am: |
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An afterthought: The meter in my Zeiss Icarex works in the same way. As far as I know, both the Icarex and the Spotmatic (as opposed to most cameras) have bridge-coupled meter circuits, which are insensitive to battery voltage, and therfore work fine with 1,5V batteries - a great advantage these days! |
Dean Cruikshank
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 29, 2004 - 08:00 am: |
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Thank you very much to everyone who responded. It's comforting to know help is out there. I will check the handbook (on-line) to see if there is inherent limitations but this would mean one could not take night shots (?). (I often use 100 ASA film and then back calculate the time to expose at night by setting my ASA dial to a higher exposure say 400,800 etc. and then back to 100 ASA)
Henry, is there a procedure for cleaning contacts with contact cleaner? Any precautions?
Thanks again Ezio, Sam, Henry, Steve and Andreas.
Dean Cruikshank |
David
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 30, 2004 - 10:45 am: |
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You can take whatever shots you want! Just don't rely on the meter. There are tables of suggested exposures published for various types of night shots (fireworks, floodlit buildings etc. etc.). Just use a tripod and expose for 1 or 2 seconds is a good starting 'guess'. If you dont have the slowest speeds you use the 'B' setting with a cable release. |
Ezio
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 30, 2004 - 12:08 pm: |
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Actually, you would need more than 1 or 2 sec. exposure for night shots. Unless you really know what you are doing, the only way to ensure acceptable results is bracketing - that is, taking several photos with different times. Based on my (limited) experience, a landascape in full moonlight (not including the moon itself) will require anything from 2 to 5 MINUTES. Of course, this only works with things that don't move. I seem to believe that there are hand-held light meters that can actually read such low light levels. |
