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04-12-2020, 06:45 PM   #1
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K20D setting shutter speed manually using manual lenses?

Hey all,

I'm confused about how to set the shutter speed manually when I mount old manual lenses on my K20D.

When I set the mode dial to M, move the aperture ring on the lens where I want it, and then use the shutter speed dial to select the desired shutter speed and then take a photo the shutter speed often changes from what I set it to. In addition to this if I press the green button to stop down it chooses a shutter speed for me. Once again when I take the photo the shutter speed often changes.

In some other place on the internet someone suggested that there is a setting for the shutter half press to force exposure lock, but I can find no such feature anywhere on the camera.

Any help appreciated.

-Carl

04-12-2020, 07:11 PM   #2
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Hi Carl, it might help to know which lenses are you trying to use. Also, you don't mention if you have a user manual. The link below is to the PDF. Good luck.

http://www.ricoh-imaging.co.jp/english/support/man-pdf/k20d.pdf
04-12-2020, 07:54 PM   #3
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You might want to check out the use of the "green button" links on this site. I have used a K-20D with pure a pure manual lens and while it is not the best thing in the world, it is very doable.
04-12-2020, 08:03 PM   #4
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pressing the green button will stop down the lens to the set aperture and take a reading and set the appropriate speed.....so speed is certainly subject to change when doing so

as for the speed changing while pressing the shutter button in M mode......have no idea!

04-12-2020, 08:05 PM   #5
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QuoteOriginally posted by CarlGundel Quote
if I press the green button to stop down it chooses a shutter speed for me.
This is how the green button is supposed to work. However, the shutter speed shouldn't otherwise change from what you select using the e-dial (if you're in M mode). So, that part sounds rather strange to me.

Adam
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04-12-2020, 11:37 PM   #6
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QuoteOriginally posted by CarlGundel Quote
In some other place on the internet someone suggested that there is a setting for the shutter half press to force exposure lock, but I can find no such feature anywhere on the camera
There is an option on Pentax cameras to lock the exposure when focus lock has been achieved (half press of shutter button). But it is not common to have this selected, and is irrelevant when using M exposure mode.

In M mode there are only two occasions when the camera should change the shutter speed from what you have set:

1. When the green button is pressed.

2. If you switch on a flash mounted on the hotshoe (camera will change any speed faster than sync speed to the sync speed).

Is it possible that you are scroling with the front wheel to review images just taken, and somehow changing the speed yourself (after instant review has finished for example) ? I have done this many times myself.
04-13-2020, 01:30 AM   #7
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I've not checked the K20D specifically, but on my cameras there's an option in one of the menus to define what happens to the metering when the 'Green Button' (AE/L on earlier bodies) is pressed in Manual mode. I think the default is "Program Line", which can cause symptoms similar to those described. If you want the camera to set the shutter speed to suit your chosen aperture (or vice versa) there are alternative settings. Exactly what happens can depend which lens type is fitted, M42+adaptor, PK or PKA

04-13-2020, 03:04 AM   #8
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QuoteOriginally posted by kypfer Quote
I've not checked the K20D specifically, but on my cameras there's an option in one of the menus to define what happens to the metering when the 'Green Button' (AE/L on earlier bodies) is pressed in Manual mode. I think the default is "Program Line", which can cause symptoms similar to those described. If you want the camera to set the shutter speed to suit your chosen aperture (or vice versa) there are alternative settings. Exactly what happens can depend which lens type is fitted, M42+adaptor, PK or PKA
I have my K1 set up so that green button in Manual changes just the shutter speed , not the Aperture (when using a coupled modern lens).

But the OP is using a manual lens with no coupling, so green button behaviour will be to change shutter speed only. In Manual mode it is the only parameter the camera can change.
04-13-2020, 08:52 AM   #9
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I have just checked using my K20D and SMC M 135mm f3.5 lens. In manual, I set the aperture on the aperture ring then press the green button. This sets the shutter speed. I take the picture and the shutter speed remains the same as set by the green button. No idea what is happening with your camera.
04-13-2020, 09:37 AM   #10
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The old FAQ when Hoya was running the Pentax site suggested the following settings for using MF lenses on the K10D/20D:
Using aperture ring - Permitted
Preview Method - Optical Preview (default)
Green Button in TAv & M - Tv Shift

Note: In M mode you can "needle" match the exposure using the exposure bars in the viewfinder on non-A lenses by activating the Optical DOF. You can adjust the exposure with the eDial for shutter speed and the aperture with the ring on the lens.

If the EV of the scene has changed the shutter speed will most likely change if you use the green button to meter the scene again.

The shutter speed should not change unless you move the shutter speed eDial otherwise.

Do you have ISO set to Auto? Set it to a fixed ISO.
04-13-2020, 10:37 AM   #11
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Thanks for all the answers. I did go back to the manual and between that and your help I am learning. I didn't understand how to use the exposure lock button (which does not lock the shutter and aperture, but only the exposure), and the setting of the green button to Tv Shift is interesting. Also the use of Optical DOF is interesting.

I do not have the ISO set to automatic, ever.

However, even trying all these things, I don't understand why there seems to be no settings to do the following.

Mount a Pentax K or KA lense.
Set the aperture using the lens aperture ring.
Set the shutter speed using the e-dial
Press the shutter button to take a photo
...and the shutter speed remains where I left it. This does not happen with any of the settings I have tried.

I just want the camera to do what I tell it and not try to be 'helpful'. Very annoying.

Thanks again.

-Carl
04-13-2020, 10:38 AM   #12
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QuoteOriginally posted by Not a Number Quote
The old FAQ when Hoya was running the Pentax site suggested the following settings for using MF lenses on the K10D/20D:
Using aperture ring - Permitted
Preview Method - Optical Preview (default)
Green Button in TAv & M - Tv Shift
I don't know where manual focus applies here, but that advice is pretty good for when the aperture ring is used to control the iris opening. I wrote "pretty good" because TAv mode defaults over to Av on the K10D/K20D the same as with other auto-exposure modes or at least it did on my camera. Similarly, Tv-shft is the only green button option for M mode when the body cannot set the aperture (page 4 and page 210 in the K10D manual).

I concur that auto-ISO is best turned off. With M, X, and B modes, the camera does this for you, but when in Av mode with a manual aperture (always stopped down) lens, sudden ramping of ISO may be unexpected and probably undesired.


Steve

Last edited by stevebrot; 04-13-2020 at 10:43 AM.
04-13-2020, 11:01 AM   #13
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QuoteOriginally posted by CarlGundel Quote
Any help appreciated.
QuoteOriginally posted by Adam Quote
This is how the green button is supposed to work. However, the shutter speed shouldn't otherwise change from what you select using the e-dial (if you're in M mode). So, that part sounds rather strange to me.
What Adam said is how my K10D worked and is the expected behavior on the K20D as well. If your camera behaves otherwise, it has a problem that is probably not addressable by any setting. That said, conventional wisdom is to make sure the firmware is the most recent release (1.04 for the K20D and 1.31 for the K10D). If up-to-date and still misbehaving, a common suggestion is to do a full reset using...
Menu --> Custom Settings --> Reset Custom Settings
followed by
Menu --> Setup --> Reset
With a few exceptions,* doing the above will restore all settings to their default values and has been known to magically cure bad behavior in the past. If still not behaving properly, it is probably not something that is fixable for a reasonable amount of money.


Steve
04-13-2020, 11:58 AM   #14
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QuoteOriginally posted by CarlGundel Quote

However, even trying all these things, I don't understand why there seems to be no settings to do the following.

Mount a Pentax K or KA lense.
Set the aperture using the lens aperture ring.
Set the shutter speed using the e-dial
Press the shutter button to take a photo
...and the shutter speed remains where I left it. This does not happen with any of the settings I have tried.




-Carl
If twhat you describe does not happen in M exposure mode then your camera is broken

Please confirm the mode dial is set to M.
04-13-2020, 02:09 PM   #15
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QuoteOriginally posted by CarlGundel Quote
Thanks for all the answers. I did go back to the manual and between that and your help I am learning. I didn't understand how to use the exposure lock button (which does not lock the shutter and aperture, but only the exposure), and the setting of the green button to Tv Shift is interesting. Also the use of Optical DOF is interesting.

I do not have the ISO set to automatic, ever.

However, even trying all these things, I don't understand why there seems to be no settings to do the following.

Mount a Pentax K or KA lense.
Set the aperture using the lens aperture ring.
Set the shutter speed using the e-dial
Press the shutter button to take a photo
...and the shutter speed remains where I left it. This does not happen with any of the settings I have tried.

I just want the camera to do what I tell it and not try to be 'helpful'. Very annoying.

Thanks again.

-Carl
What happens if you this: mount a KA lens. Set the aperture ring to A
Set the Mode dial to M.
Set the aperture with the rear dial.
Set the shutter speed with the front dial.
Set the iso to anything but Auto.
Take a picture.
Do you get the same result, that is, does the shutter speed (or {in this case as the aperture is set through a dial} the aperture) change from your original setting?

" In addition to this if I press the green button to stop down it chooses a shutter speed for me. Once again when I take the photo the shutter speed often changes."

If you use the green button a shutter speed is set and after taking the picture the lightmeter indicates the shutter speed and again you have to push the green button to properly setting the shutter speed. So the changing of the shutter speed directly after using the green button is normal behaviour. I tried this out on different Pentaxes, They all work in the same way.

Last edited by Unregistered User; 04-16-2020 at 02:52 PM. Reason: Additional information.
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