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George Welcher
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, March 12, 2006 - 11:48 am: | 
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Well, the sticky mirror problem is fixed (see previous post), but the meter is off by about 2 stops. I checked it against a Lunasix and a Vivitar 45. For the light conditions measured both meters gave me readings of around 1/250 @ f2 (within a half stop). The Pentax gives me 1/250 @ f4. The difference is cosistent under various lighting conditions.
I did previously disassemble and reassemble the shutter/ASA dial, but it looks to me that unless you loosen the setscrew in the side (I didn't), it can only go back together the way it was before dissasembly, because everything interlocks.
According to Romney, there is a zero adjustment under the rewind knob, but I can't see anything like that through the access hole.
So, how do I proceed? Is there some sort of accessible variable resistor for adjusting the meter under the top? If so where is it located? What other approach should I take? Thanks for any advice. |
John Farrell
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 13, 2006 - 01:13 am: |
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The access hole is under the film reminder dial, around the rewind knob. Remove the rewind knob, and you can undo the slotted nut which holds down the dial. You will see the variable resistor through the hole. |
George Welcher
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 13, 2006 - 06:38 am: |
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Thanks John. I didn't recognize what I was looking at! The Pentax meter will now match my Lunasix at fairly low light levels (heavy overcast), but still underexposes by a stop or so at higher levels (table lamp on white sheet of paper). I'll see if I can find a happy medium that will work well enough for black and white and color print film. |
Donnie Strickland
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 13, 2006 - 08:15 pm: |
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Remember too that if you are metering something white -- i.e. a sheet of paper -- it would be natural for your meter to underexpose a little. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 14, 2006 - 05:37 am: |
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Always use a Grey Card for calibrating exposure systems. Mine were supplied by Kodak many years ago, but any good dealer will have a good choice.
The 18% card is the most useful and perhaps the only available one.
It is worth noting that all grey cards are not the same - for your requirements any 18% card will do - however for really accurate repro/photo work the spectral response of the cards surface finish is very important. My best card has a painted finish that is very delicate and requires careful handling, the others are of the more common printed form and are more robust.
The term 'card' is a bit of a misnomer as some cards are now made from grey foam. |
Brian Suh
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 15, 2006 - 07:02 pm: |
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George, I've got the same problem. My Voigtlander-Cosina VC II meter sees a sunny 16 scene at 1/250 @ f/16 for 200 speed film, but my Spotmatic SP1000 sees it as 1/60 @ f/16 at ASA200. How did you go about that process? I'd like to know very much 
Thanks! |
George Welcher
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 18, 2006 - 01:51 pm: |
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I followed John's instructions. Under the rewind knob on my Spotmatic (you also have to remove the film reminder dial) is an hole in the top plate. If you look carefully in good light, you can see a teardrop shaped switch or lever that pivots at one end, attached to a curcuit board. Your SP1000 may be set up somewhat differently. I then experimented with setting the lever at differnt positions and checking the results against a reliable meter.
A couple of hints:
* Small movements of the lever can have relatively large results.
* Use a non metalic tool so you don't scratch the curcuit board. I used a pared down bamboo skewer.
* compare readings under various light conditions. |
