Auto bellows M metering

I've recently acquired a set of Pentax Auto Bellows M off ebay, and I'm struggling a bit with metering. With my trusty A 50mm attached my K10d only seems to offer me Aperture priority, manual, X-sync and bulb.
Obviously aperture priory isn't going to be of any use as there is no mechanical or electrical linkage and the green button seems to max out at 1.5 secs whether the aperture is wide open or stopped down, resulting in grossly under exposed pictures.
I have set the camera to permit aperture control and also set the green button to adjust the shuter speed with set aperture, but to no avail.
The only way I get reasonable results is using the camera set to X-sync (and using a sheet a A4 paper to bounce the built-in flash) and simply by guessing the exposure in manual.
What am doing wrong?
I've added one of my more successful shots.
[IMG]http://i246.photobucket.com/albums/gg93/callumsj/rose.jpg[/IMG]

I have taken a lot of closeup/macro shots and a whole lot of flowers.
All I can say is "I wish I had taken that one"
Breathtaking!
Geoff

Hi,
My thoughts,
You refer to your trusty A50, have you de-selected the aperture ring from the "A" setting and manually pre-set the f number you want to use. Are you using the cable release to shut down the aperture before pressing the green button to set the exposure. I use the "M" mode.

Greg

Greg,
Yes, I have taken the aperture ring off "A" and stopped down to f16 or f22, I have then shut down the aperture (the auto bellows have a handy lock on the aperture stop-down button), then I have pressed the green button. The trouble is, I get exactly the same shutter speed even if I don't shut down the aperture!

Callum

Aperture Priority is fine as you are working in stop down mode. Forget the green button and use Av. Set the aperture you want on the lens and the camera should deliver the appropriate shutter speed for the lighting conditions.

You will have to enable use of aperture ring in the Custom menu to ensure the camera shutter releases.

A silly question, are you sure that the aperture actually closes down when you press and lock the aperture button Is there enough light to take a reading in the first place.

To check myself I've just run a quick test as follows.

Camera set to use aperture.

"M" Mode on K200D
Lens off "A" position. Press in and lock aperture button on bellows unit.
Set f stop, press green button, my camera selects a shutter speed.
Change f stop, press green button, gives new changed shutter speed.

"AV Mode on K200D
Lens off "A" position. Press fully in and lock aperture button on bellows unit.
Now as I change the f stop on the lens the camera gives a continuously variable shutter speed.

I have no idea what your problem can be

Greg

Greg,
The aperture is certainly stopping down, a quick look at a virtually black viewfinder confirms that. I'm just wondering if, maybe, there isn't enough light to get an accurate reading. As I said in my original post, I've just got them and had only a brief play about with them (in a very subduely lit lounge).
One thing a forgot to mention, was that, when I tried using the flash in anything other than x-sync, I get grossly underexposed shots when the lens is stopped down and grossly overexposd shots if I leave it wide open.
I think I'm going to have to put an evening aside and try and get to grips with them. The thing is, I do have experience with bellows (used to own a lovely set of Minolta auto belows III, shift and swing, which were even nicer than the Pentax set).

Are you covering the viewfinder (either with your eye or hand) when you take the meter reading? If not, the light entering the viewfinder through the eyepiece will influence the meter reading, leading to under-exposure.

Just a thought.

Dan

I think you are hitting the limits of the metering system, I have the same problem using stop down lenses in low light on both my K10D and DL2, it never selects a shutter speed slower than 1.5 seconds.

I think it's just too dark at that point to get an acurate reading, remember the meter is designed to work with the lens wide open.

Well I never! Just tried it with my K10D, and found the same. Well, I say the same, but I got 3s when I first tried it, but still underexposed. Checked my ISO, I had it at 100, changed it to 200, now only get 1.5s, 0.7s at ISO400 etc. So yes, it's the limits of the metering.

So the only option is to use manual and experiment with shutter speeds if you're using natural light. You could try an angle-poise lamp for aditional lighting, which may reduce your exposure times (just remember to alter your white balance to suit), or invest in a cheap flashgun and play around with that.

Dan

I'm hoping Santa will bring me a shiney new Metz 48 AF-1 at Christmas, so I think I'll be going down the flash road (just need to construct some kind of flash bracket). I'll see how I get on outdoors, in brighter available light, in the the meantime.
Thanks, so far, for all your advice and suggestions.

Callum.