MF lenses on a Pentax K-x

[peterqd]

I'm a long-time Pentax fan but my only experience is with film cams and I'm a bit ashamed to admit this, but my son's new K-x has me beat. With Bill's help I bought him an M42-K Pentax adapter and I'd like to give him one or two of my lenses, but we can't work out how to use them.

When a MF lens is mounted the shutter won't fire and the display seems to be asking for information about the lens. It shows "F - - -".

Could some kind soul please explain what we need to do. Is the cam asking for the focal length or the aperture setting? And how do you enter the value?

Thanks

[8310]

You have to allow your camera to make use of the aperture ring. "Using Aperture Ring" in the custom functions menu is what you are looking for.

If you are using M42 lenses that is all you need to do for being able to shoot away in Av at working aperture.
Pentax K mount pre-A series lenses are to be used in M with the Green Button for exposure measuring or wide open only in Av.

The camera will keep showing "F--" either way. No way to change that, at least not without modifying the lens. The only thing the camera wants you to tell it is the focal lenght when using SR.

[ludoo]

Av mode with M42 lenses on the K-x is often off. Manual works better, set the dial to M then let the camera set the exposure by pushing the exposure compensation button (on the left of the shutter release). Adjust with the wheel if you have to compensate.

[mo]

Does the K-x have the "green button"?
I have the K200D...I set it to M,set my aperture on the lens...hit the green button and it works...you still focus etc Look on the Pentax forums under beginners corner and it helps explain a lot of things.
http://www.pentaxforums.com/forums/pentax-beginners-corner-q/

Peter make sure you give him lenses with the A/M switch

[kuuan]

Peter check out these instructions made for the use of manual lenses on a Pentax K100D:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=24921509

the basic information there, e.g the essential setting of the camera to: allow "Using Aperture Ring" as mentioned by 8310 and all the other most important is covered there.

as noted Av mode is too much off on the K-x ( the early *ist cameras did a much better job in Av mode ) If you want to camera to choose shutter speed set it to M mode and meter by pushing the green button. However the metering still may be off, depending on aperture and lens used. Generally one may say the wider open the lens the more accurate the metering. To correct for a second shot after the first came underexposed ( which is the usual mistake ) turning the wheel will adjust the shutter speed.

generally work flow is: put lens wide open for brightest viewfinder = focusing, stop down lens to desired aperture, push green button, release

[peterqd]

Thanks all for the great answers! I've just found out the camera is still in Paris until Tuesday, so I'll have to wait a couple of days before I can play around with the settings.

I only have three K-mount lenses at present - M1.7/50, M2.8/28 and the cr*ppy 28-80 A zoom, so I wasn't planning to give him any of those. I've made up a cheap set of M42 lenses for him to start with - Viv 2.8/28, Mir1B 2.8/37, SuperTak 2/55 and Jupiter 37A 3.5/135 and he can progress from there if he wants. He's having fun with the AF 18-55 kit lens and a 70-300 but I'm hoping he'll see the light!

Mo, thanks for the tip about the A/M switch. I forgot about that. I was actually planning to give him a Tamron zoom with an M42 mount, so your tip was timely.

I'll report back when I have the camera here.

[kuuan]

[peterqd]

[Laurence]

I use the Pentax 645 lenses on my k-mount Pentax ZX-5N.
The images are sharp, and I let the camera meter without
reverting to Manual. Focus confirmation works (at least the
little beeping sound). I'll post some pix from the setup later.

[peterqd]

OK, everything is working as expected now, exactly as you explained. Thanks for all the really helpful advice.

I've only tried a very few shots for testing the metering so far, but with M42 lenses and using the green button in M mode, the results have been very good indeed - even better, I would say, than the camera performs on fully auto with AF lenses. We haven't looked at the metering options yet, I'm sure that will make a big difference (I'm very eager to try out the spot metering ) but on the multi-segment factory setting, the camera seems to have struggled with some of my son's shots. I'm extremely impressed with the low-light functions - we took some night shots of the Eiffel tower while we were away and the K-x blew away my 400D completely.