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Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 230
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 05, 2013 - 01:53 pm: | 
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I just picked up a minty Minolta XG-M with 50mm lens from a 2nd hand store, loaded it with fresh batteries, and tested the meter, only to find that it's about 2 stops off. E.g., using the sunny f/16 rule (yes, it's bright and sunny outside right now), instead of 1/125 @ f/16 @ ISO 100, I'm getting 1/30 second @ f/16. The camera looks to have been babied its entire life -- even still has the protective plastic film on the base.
Is there a likely culprit for this? I've never had an XG-series Minolta apart before, so I'm a noob at this one. Nice little camera, though, and I'd like to get it working properly. Any suggestions are welcome. |
Aerowoof
Tinkerer
Username: Aerowoof
Post Number: 74
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 05, 2013 - 03:04 pm: |
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is the aperture ring on the camera moving with the lens aperture or is it sticking? |
John_s
Tinkerer
Username: John_s
Post Number: 113
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 05, 2013 - 03:37 pm: |
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I would do some more accurate checks before starting to take it apart, against another camera or exposure meter. It might not be as far off as you think. I've often found exposure meters and cameras disagreeing with each other, its tha actual results on film which matter. Actually its one and a half stops off, and could the light have been a little duller than "full sun"? If you confirm it's out of acceptable limits you could just change the ISO setting to compensate. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 231
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 06, 2013 - 02:51 am: |
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Thanks for the responses, guys. Aerowoof, the aperture ring rotates without sticking. The LED readout in the window changes precisely as I move the ring when in Aperture priority auto.
John, I'll admit that I did a quick and dirty check without using another meter of known accuracy. But I've been guesstimating exposure based on the sunny f/16 rule for -- oh, about 25 years or so I guess, and I've gotten fairly comfortable with it. All you gotta know is where 18% gray is when you're outdoors. The blue sky away from the sun is 18% gray. Green grass is 18% gray. I checked the Minolta's meter readout against both empty blue sky and green grass and got the same reading. It was quite bright today when I tried it out, but even if it had been "a little duller," it wouldn't have been two stops worth. That would have required significant overcast.
I guess I count f/stops differently from you: 1/125 to 1/60 to 1/30 is two stops to me, not 1-1/2.
I've also run into instances where a camera's meter will disagree with an accurate hand-held meter, but this is almost always because of a metering pattern that is set on the camera which causes it to read the scene differently from the way the hand-held is.
The XG-M has an EV adjustment dial: +/- 2 stops EV. I can dial in -2 stops of EV and it reads correctly. But that's cheating. I want it to read the scene the way it's supposed to.
Look I appreciate the well intended advice guys, I really do. But can we assume please that the meter is indeed off so I can find out what I need to do to correct it? I don't suppose there's anything convenient under the top cover like an adjustment pot is there? |
John_s
Tinkerer
Username: John_s
Post Number: 114
Registered: 07-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 06, 2013 - 12:07 pm: |
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I meant that the actual shutter speed suggested by the sunny 16 rule would be 1/100 (which isn't available on many cameras) rather than 1/125. This is somewhat less than two full stops from 1/30, if not exactly 1.5.
I wasn't doubting your experience at estimating exposure, its a skill I should practice more.
I'm sorry, I've no idea how to adjust it. |
Msiegel
Tinkerer
Username: Msiegel
Post Number: 329
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 07, 2013 - 04:46 am: |
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THere is a service manual here:
http://ebookbrowse.com/minolta-xgm-service-manual-pdf-d176728056
Description of shutter speed and LED adjustments are found from page 50 (or so) onwards.
I am more or less completely lost regarding electronics - but it seems that the actual shutter speeds and the speeds indicated via the LEDs are to be adjusted seperately. So maybe it's worth seeing if the actual shutter speeds are off or not.
But as I said that's guesswork on my side.
Hope it helps
Martin |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 232
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 07, 2013 - 05:55 pm: |
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Martin, thank you thank you. I d/l'd the manual and have been studying it. It looks like a simple meter adjustment is more complicated than I thought. Involves installation of a "temporary top cover," soldering of test leads to points on the camera's circuitry, and other stuff I don't even feel like messing with. Why couldn't they just have a little pot there to tweak?
Too much trouble. I'll just dial the EV compensation all the way to -2EV and not worry about it anymore  |
Msiegel
Tinkerer
Username: Msiegel
Post Number: 331
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 08, 2013 - 02:29 am: |
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I don't know how you use your camera - in aperture priority mode or metering and setting speeds manual.
But as the manual describes different procedures for the shutter timing and the LEDs adjustment it is possible that the shutter speeds you get in "A" mode are different than the ones shown by the meter LEDs. So it may be worth checking if the shutter actually works at the same speed as the LEDs indicate. In low light this could be done quite easy I guess - you should hear or see the difference between 1/4 and 1 second.
So if the shutter works correctly there's no need to use the EV compensator.
If not you might want to consider using the ISO settings dial to adjust. Thus you still have the EV compensation when needed. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 233
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 08, 2013 - 04:11 am: |
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Good point about the ISO settings vis-a-vis the EV dial. But since I usually shoot in manual mode, I've never seen the need for dialing in EV adjustments.
I would have noticed right off if the shutter speeds differed from those indicated. I can gauge pretty accurately by ear speeds up to 1/30 second. So, I'd have to say that they're in agreement. But since I wasn't specifically looking for this, I'll need to go check it and make sure (past my bedtime right now, it'll have to wait til the morning).
Usually I prefer shooting in manual, at least until I've come to trust a camera a bit more. I don't know it well enough yet to trust it with its AE mode, so it's manual for now. And the slower speeds sure do sound like the ones indicated. |
