Green Button on M-series lens

[chongmic]

Recently I bought 2 lenses without the "A" settings. This is the first time I use lenses without "A" on DSLR. The lenses are the M-135 F3.5 and a Tokina ATX 28-85 F3.5-4.5.

On my Kr, when I pressed the green button, the VF will dim out for a while and the shutter speed with be selected by the camera.

While on the M-135, as I pressed the green button, the VF will NOT dim out, however it still set the sutterspeed, the only problem is the shutter speed selected by the camera will treat my lens at max aperture, regardless my aperture ring setting. Isn't that the green button suppose to dim out the VF for a while and set the shutter speed in stop down metering?

Still have no time to test out both lenses to their potential yet, but the Chinese New Year holidays is around corner, I hope to get some interesting shot during the festive season.

Regards,
Mike

[blackcloudbrew]

I don't know the Kr but I believe with an M lens you will have to be in manual mode. That's how it works on the K5.

[chongmic]

I did set to M mode for both lenses, only the Tokina will do stop down metering, and quite accurate.

The Pentax-M always meter at max aperture. For example, eventhough I set the aperture ring at F8, the sutterspeed setting given by the camera will always be as if the ring is set at 3.5. If I use the shutterspeed given by the camera, I always get under exposed. Thefore, I have to slowdown the shutterspeed by 2 stop to get the correct exposure.

Hope anyone with M lens and Kr can share their experiences.

PS: After some initial test shot in my in-law garden, I started to like the Tokina a lot.

Regards,
Mike

[blackcloudbrew]

Again, I don't have a Kr to test this but in reading the Kr manual pages 312-314 says that 1. you need to be sure that Custom Menu setting 22 is set to permitted, and that you use the optical preview initiate metering. That's not the green button on the Kr per the manual. Anyway, that's what your manual says. Give it a read.

[davidhampshire]

you have the ' allow using aperture ring '  set to 'permitted'   in the custom menu ,  yes?    and the  ' afs, c,  mf ' switch set to mf ?  yes?   and the metering set to center,   and the focus point set to center?      with those set ,   aperture ring should control the f-stops.   pacerr ?   where are you ?     

[chongmic]

Yes, I got all the settings right before the trials on both lens, that's why I was wondering why only the Kr would only do stop down metering on the ATX and not the M lens.

BCB, I gave a further reading on the manuals and it mentioned something like the M lens will perform open aperture metering regardless of the ring setting. It also says exposure error may occur. I guess I just have to live up with the limitations of using the M lens with the Kr body. I have started to getting use to adjusting the shutter speed setting given by the green butter in relation of the aperture ring setting.

Thanks everyone for your input.

[chongmic]

Guys, I posted the problem on Pentaxforums and finally got it resolved. It seems to be the problem caused by some glue residue left over by the piece of tape. The previous owner had a piece of tape on the lens mount around the area where the body contact pins mated on the mount. I removed it the moment I received the lens, but I didn't expect the glue residue was thick enough that it insulated the pins from shorting to the lens mount.

Solution is some lens cleaner to dissolve the residue, and cotton swap to scrap them off. Now it can stop down metering now and quite accurate.

Hopefully this will be valuable information for M lens user.

My current work load put me off for outdoors activities, hopefully I can get some good shot very soon with these 2 "new" lenses very soon.

[blackcloudbrew]

Great. Glad to hear it. Never would have thought about that. Love to see some shots when you can post them.