Pentax LX shutter problem and also batteries


Snapper_UK

Link Posted 28/12/2012 - 22:04
I wonder if anyone can advise with regard to another pentax LX problem I am having.


If I shoot with fresh batteries in manual mode 4 seconds shutter speed is 4 seconds. However, if I do it in Automatic it seems always longer, perhaps 6 or 7 seconds. I wondered whether this was actual not a fault but something to do with OFT although the shots were taken under controlled circumstances and I dont think that the light was changing.


I am hoping that the meter isnt playing up in auto and surely if it was it would play up in manual too?


Incidentally the AG13 batteries seem to drain very quickly after a couple of weeks or so and I fear the worse but wonder whether there are any better batteries I could be using?


John

K10D

Link Posted 28/12/2012 - 23:53
I would not worry about the timing/metering difference between manual and auto. The metering is from the film plane in auto.

The AG13 is an alkaline button cell under the general LR44 group of batteries. An SR44battery is Silver Oxide and has a slightly higher capacity as well as voltage-link

Best regards

Helpful

Snapper_UK

Link Posted 28/12/2012 - 23:59
Thanks.

K10D

Link Posted 29/12/2012 - 00:06
I forgot to ask if you had actually compared the results between manual and auto for an identical shot situation.

Best regards

Snapper_UK

Link Posted 29/12/2012 - 00:21
No but I will. Thanks

I am a bit perturbed though that if the camera says 4 but the film says 7.. Doesn't that make the camera way out or is this infact a massive advantage as opposed to disadvantage?

John

johnriley

Link Posted 29/12/2012 - 00:27
Alkaline batteries should happily last for 6 months and silver oxide for 12 months, so unusual battery drain could indicate a fault.

When using auto exposure, also bear in mind that the speeds are seamlessly variable and that the speed indication is only an approximate value. The camera will deliver, for example, 1/213s if that is what is needed, but the speed indicated will be approximate.

In practical terms, where one stop is a doubling or halving of exposure, the difference between 4s and 6s is really quite small.
Best regards, John

Helpful

Snapper_UK

Link Posted 29/12/2012 - 02:10
Thanks John

JohnMcD

Link Posted 09/01/2013 - 21:52
In automatic mode the camera reads the light reflected off the film plane. Assuming you're trying this without film in the camera and the back closed then the meter will be reading what's reflected off of the back which is black, certainley a lot darker than film which is usually a kind of yellowish tan colour. Therefore it will over expose.

If I could find my book on the LX ( which I can't at the moment ) it says that Pentax did a lot of testing regarding the reflectivity of all different kinds of film to come to the settings they have done.
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