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04-10-2012, 05:34 PM   #1
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Does LX choose intermediate shutter speeds in auto?

Hi, The subject line says it all. If the meter determines that a perfect exposure is in between 250th and 500th sec in "auto" mode, will it adjust? Or will it just choose one or the other? If it adjusts, this might make it better to shoot in auto most of the time?

04-10-2012, 05:43 PM   #2
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Yes, cameras with aperture priority will select (adjust to) any shutter speed between the highest and lowest that the camera supports.

Phil

Last edited by gofour3; 04-10-2012 at 05:49 PM.
04-10-2012, 06:17 PM   #3
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Thanks!

QuoteOriginally posted by gofour3 Quote
Yes, cameras with aperture priority will select (adjust to) any shutter speed between the highest and lowest that the camera supports.

Phil
I've mostly been a nikon shooter, didn't know if Pentax did this...
04-10-2012, 06:46 PM   #4
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I believe all the aperture priority auto exposure cameras will select precise shutter speeds not limited to the shutter speed selection switch when in auto mode.

The differences are how long will it stay open for and if it will vary according to changes in lighting of the scene. Since you may be familiar with Nikons, I can say that all the manual focus Nikons with aperture priority will keep the shutter open for a very long time determined at the time of the shutter release. The LX uses Integrated Direct Metering (off the film metering) and while it will also keep the shutter open for a very long time, it will continuously monitor the scene in real time for changes in light and make adjustments accordingly. You can easily test this by firing the shutter with the lens cap on, removing the cap and pointing it to a light source. The Nikons will continue keeping it's shutter open regardless of this change while the LX will immediately close the shutter.

04-10-2012, 07:41 PM   #5
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Thanks Les..

Yes, I have made myself familiar with the unique features of the LX in the last few days. Things like learning not to "test" the shutter speeds by dry firing since reflectivity of the plate is different from film etc. The IDM metering is what really interested me. There are two nikons that I'm aware of, the FA and the FE that have a closed loop exposure system, but I'm not sure how that differs (for better or worse) than the system in the LX.
04-10-2012, 08:09 PM   #6
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That feature was my main interest so I tested practically all the manual focus aperture priority auto exposure capable cameras from Canon, Nikon, Minolta, Olympus and Pentax lineup. Canon is straight up ends at 30 seconds. Minolta it depends but not much longer then 30 seconds. Olympus OM2 & OM4 also employed off the film metering but holds the shutter open only for minutes. In the Pentax lineup this feature is apparently unique only to the LX. In testing, I have successfully auto exposed film for greater then 2 hours with the LX.
04-11-2012, 05:57 AM   #7
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BTW, if you haven't already, you can get a copy of the LX PDF at http://www.lensinc.net/manuals/Pentax_LXL.pdf
In page 18, it specifically states that the LX provides stepless shutter speeds from 1/2000 down to 125 seconds. The 125 seconds is probably based on the meter's sensitivity to EV -6.5 at ASA 100 with an f1.2 because we know that the LX will hold it's shutter open for as long as the battery lasts or it accumulates sufficient exposure - whichever comes first.
04-11-2012, 10:48 PM   #8
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Reciprocity failure...

QuoteOriginally posted by LesDMess Quote
BTW, if you haven't already, you can get a copy of the LX PDF at http://www.lensinc.net/manuals/Pentax_LXL.pdf
In page 18, it specifically states that the LX provides stepless shutter speeds from 1/2000 down to 125 seconds. The 125 seconds is probably based on the meter's sensitivity to EV -6.5 at ASA 100 with an f1.2 because we know that the LX will hold it's shutter open for as long as the battery lasts or it accumulates sufficient exposure - whichever comes first.
This is interesting to me. When the meter is "summing" up the exposure, how does it handle reciprocity failure? The reason I ask is that on one of the LX's that I had shipped to me, I put the camera in auto at the end of the day in and took a shot of my bedroom...still end of day light coming from the outside but basically pretty dark. The camera held the shutter open for about 8 seconds or so and when I developed the film the shot was very underexposed. I thought that it was reciprocity failure and wondered just what "off the film" metering really means. Does this mean that with different films that have different tendencies that the meter, since metering off the film will AUTOMATICALLY handle reciprocity failure?

04-12-2012, 04:42 AM   #9
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The LX metering is not sophisticated enough to account for any film's reciprocity characteristic and I am not aware of any camera that can.
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