MX metering doesn't work on all Speeds and ASAs


Taliety

Link Posted 16/03/2004 - 21:13
I've just aquired an MX, came with a marked screen, but that came off with soapy water (yes, I did take the focus screen out of the camera first).

I've noticed that the meter only works from 1 second and faster if the ASA is set to 100 or slower.

ASA200 at 1 second doesn't work
ASA 400 at 1/2 second or slower doesn't work
ASA 800 at 1/4 second or slower doesn't work
ASA 1600 at 1/8 second or slower doesn't work.

When not working, the red Underexposure led illuminates.

Is there something wrong with the speed dial switches, or is this just a normal limitation with this camera? I don't think this will be much of a limitation, as I can always meter at a faster speed, and then slow down, if that's what I need.

Cheers

Taliety
Cheers

Malcolm

Life? Don't talk to me about life!

Kimbo

Link Posted 16/03/2004 - 22:08
Have you tried pointing the camera to a bright subject to counter the underexposure warning?
I've never used an MX but as the readings are incremental, I would suggest that the meter is working correctly - unless it's doing the same thing no matter how bright the subject!
TBH, I'm not totally sure that I understand the question
Die my dear doctor, that's the last thing I shall do!

George Lazarette

Link Posted 16/03/2004 - 23:42
This camera's meter works between EV1 and EV19.

I think you are pretty much at the camera's limit at the values you are using, assuming you are using a fast lens wide open.

Kimbo

Link Posted 17/03/2004 - 09:35
From the figures given, I would expect the meter to give the same reading (same EV) but surely you'd need to have the lens cap on or at least be set at minimum aperture with a dark subject for ASA200 at 1 second to be underexposed?
I would have thought that an OVERexposure was more likely!
Die my dear doctor, that's the last thing I shall do!

johnriley

Link Posted 17/03/2004 - 18:27
In the MX instruction book there is a table that indicates the MX metering range.

At 200 ASA 1 second will be outside the meter's range
At 400 ASA 1 sec and 1/2 sec will be
At 800 ASA 1, 1/2 and 1/4 will be
At 1600 ASA up to 1/8 will not meter
At 25ASA 1/500 with an f1.4 lens will be unrelaible at f22 and 1/1000 will be unreliable so should be used with caution
At 50 ASA a similar caution with the f1.4 lens at 1/1000

This is a normal condition of the meter and is not a fault - it reflects the limits of operation effectiveness of the meter.
Best regards, John

Kimbo

Link Posted 17/03/2004 - 20:35
Yep, I know the type of table you mean John, Pentax are very good at providing that sort of info.
As I suspected, the meter would appear to be working correctly - interesting topic though!
Die my dear doctor, that's the last thing I shall do!

Taliety

Link Posted 17/03/2004 - 22:25
Thanks for the help. Now I have obtained a copy of the manual, I can see the table you refer to. I can see now that the meter is working axactly as described, although I haven't tried the other end of the range. These are extreme measurements, and metering can nearly always be taken at a different speed.

Having just obtained the camera, I was just trying all combinations I could in the available light, with an f1.7 mens on. I haven't tried the f1.4 one yet, and I haven't got a f1.2.

Cheers

Taliety
Cheers

Malcolm

Life? Don't talk to me about life!
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