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Old Sep 16, 2006, 5:36 PM   #1
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I think I am missing some basic concepts regarding stopping down a manual lens on my *ist DS.

OK, so I focus with the lens wide open, the camera is set to 'Av' and I have made the change to the firmware to allow use of manual aperture. I press the button and everything else is automatic in that the camera meters the light and sets the exposure time, or so I understand it. Have I missed anything yet?

Now suppose I want to stop the lens down. I start the same way, lens fully open for focusing then I manually stop the lens down and push the button? What is different that the camera needs to know about?



Thanks



P.S. so far I have always used wide open for manual lanual lenses.


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Old Sep 16, 2006, 5:46 PM   #2
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John Hill wrote:
Quote:
OK, so I focus with the lens wide open, the camera is set to 'Av' and I have made the change to the firmware to allow use of manual aperture. I press the button and everything else is automatic in that the camera meters the light and sets the exposure time, or so I understand it. Have I missed anything yet?
Quote:
I don't think this procedure will work except to shoot at wide open aperture. You must set the camera to "M" and use the procedure you have outlined in the next paragraph.
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Now suppose I want to stop the lens down. I start the same way, lens fully open for focusing then I manually stop the lens down and push the button? What is different that the camera needs to know about?
Quote:
Since pre-"A" lenses have no electronic communication with the camera the only meteringthat will work at the aperture you choose is stop down metering. Kjell reminded me that you can press the AE-L button to set exposure but a more accurate way is to turn on the DOF previewand then use the control dial to set the exposurevalue shown in the viewfinder to 0.0 (or any other value you choose for the shot).
Quote:
Thanks



P.S. so far I have always used wide open for manual lanual lenses.
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Remember, set camera on M, not on Av or all you can do is shoot wide open. BTW I use Av mode with my mirror lens because it doesn't have an aperture setting anyway.
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Hope this helps
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Ira

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Old Sep 16, 2006, 6:08 PM   #3
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Thanks Ira, now I really am getting confused!

I am pointing my camera out the window with screw mount Tele Lentar 1:65 450mm circa 1971.This lens has no mechanical nor of course electrical connections of any kind to the camera.

With camera set to Av andwith the lens full open (6.5), shutter speed is indicated as 1/1000, while still holding the button and turning the aperture ring to 32 the indicated shutter speed slows to 1/45.

This seems so easy so what is it I am missing that makes this whole subject sound so complex?




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Old Sep 16, 2006, 6:08 PM   #4
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Not to hijack the thread but heres a related question. When using an "A" lens in Av mode, do I need to adjust the exposure or hit the AE-L button or is that done automatically? Ive got some decent shots with the lens so far just adjusting the ap setting in camera(with the wheel) and shooting.But I'm wondering if I should be doing some other steps to improve my outcome? Thanks.
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Old Sep 16, 2006, 6:54 PM   #5
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John Hill wrote:
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Thanks Ira, now I really am getting confused!

I am pointing my camera out the window with screw mount Tele Lentar 1:65 450mm circa 1971.This lens has no mechanical nor of course electrical connections of any kind to the camera.

With camera set to Av andwith the lens full open (6.5), shutter speed is indicated as 1/1000, while still holding the button and turning the aperture ring to 32 the indicated shutter speed slows to 1/45.

This seems so easy so what is it I am missing that makes this whole subject sound so complex?

Sorry John

I didn't realize you were using an M42 lens. That means the procedure you used here will work. Just leave the lens stopped down to take the picture.

Ira
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Old Sep 16, 2006, 7:11 PM   #6
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Thanks Ira, I thought I must have been going nuts and not seeing something obvious.



So the next question, when does using a manual lens require those complicated procedures I see being described?
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Old Sep 16, 2006, 7:33 PM   #7
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John Hill wrote:
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Thanks Ira, I thought I must have been going nuts and not seeing something obvious.



So the next question, when does using a manual lens require those complicated procedures I see being described?
I definitely don't qualify for expert status but I will try to answer.

A-series lenses with the A setting on the aperture ring work just like the AF lenses except they focus manually of course. Earlier K-mount lenses do not have electronic contacts, and since Pentax chose to take out the mechanical link they used to have in their early K-mount cameras, then the only way to meter is to stop down the lens.

To facilitate that they made a relatively simple procedure,
1- set the exposure mode to "M",
2- focus,
3- compose,
4- set the aperture on the lenses aperture ring and then
5- press the AE-L button to set the exposure.

Not really very complicated at all. Using the DOF preview and control wheel is just an alternate method that may prove more accurate in low light.

Hope this helps.

Ira
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Old Sep 16, 2006, 8:13 PM   #8
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OK, the light is beginning to glimmer in my pea-brain. None of my heritage lenses are from the era of electric contacts, they are either M42 or slightly later such as the Pentax 1:2.0 50mm that came with my K1000, apparently I could no understand the problem because I had never faced it, thanks for clarifying that.
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Old Sep 16, 2006, 9:07 PM   #9
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All answers here:-
http://www.geocities.com/ricehigh/K_...ure_Bases.html

John Hill wrote:
Quote:
I think I am missing some basic concepts regarding stopping down a manual lens on my *ist DS.

OK, so I focus with the lens wide open, the camera is set to 'Av' and I have made the change to the firmware to allow use of manual aperture. I press the button and everything else is automatic in that the camera meters the light and sets the exposure time, or so I understand it. Have I missed anything yet?

Now suppose I want to stop the lens down. I start the same way, lens fully open for focusing then I manually stop the lens down and push the button? What is different that the camera needs to know about?



Thanks



P.S. so far I have always used wide open for manual lanual lenses.

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Old Sep 16, 2006, 9:27 PM   #10
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I think there is one more bit here - at least this is how I do it on my DL, using my old K100 lenses...

To facilitate that they made a relatively simple procedure,
1- set the exposure mode to "M",
2- focus,
3- compose,
4- set the aperture on the lenses aperture ring
5- press the depth of field preview


6 - adjust the shutter speed using the thumbwheel and the exposure indication in the viewfinder

7 - release the DOF, and shoot.

I use this with my K-1000 135mm and it works great!

Rick
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