Topic: Pentax ME Super, 35mm dark lens and odd metering

[subcolour]

Hey all,
I'm a reasonably novice shooter.  I have a pentax me super which I've been shooting mostly with the 50mm f1.7 lens in aperture priority mode. I have a 35mm f2.8 lens, which makes the viewfinder seem much darker I assume this is down to the higher f stop. The odd part is that when in aperture priority mode the metering always seems like the 35mm lens needs way more light to work (at least 5 more stops at the same aperture).

When I look through the 35mm lens I can't see any fungus and the lens seems totally clear.

Can any one help shed any light on this? (pun intended)

[Francois]

Does the lens really open wide?
I don't know but there might be a depth of field preview button on the camera that is depressed. That would explain the darkness.

Usually, while a lens with a smaller aperture will be darker in the viewfinder, it won't be that much.

You can usually check the lenses by hand by simply removing them from the camera and depressing the aperture switch on the back. You will see the blades move and get an indication of how good things are.
It could be a lens problem.

[subcolour]

the aperture lever seems ok ish, there is a little 'second stage' to the lever throw that just requires a little more pressure to move.

I've just checked my 50mm and it doesn't have the same issue

[johnha]

Is it the M series 35mm f/2.8 (will have 'Pentax-M' around the front)? There is a common problem with the aperture sticking on this particular lens (doesn't seem to be anything as prevalent with the other M series lenses). With the lens mounted on the camera and set to f/22 the aperture blades (seen from the lens front) should be fully open. As you fire the shutter they should stop down to the set aperture, then open fully again.

The camera should hold the aperture fully open for metering/focusing by holding the lens aperture lever down. During exposure it releases the lever - letting springs in the lens close the aperture down as selected on the aperture ring. The M35mm f/2.8 blades or springs seem to start sticking over time (mine stops-down fine but fails to open 'snappily').

John.

[Francois]

This could be related to the oil they use that has either thickened or simply dripped on the blades.
I had a lens with a similar problem that I dismantled, cleaned the blades and put back together.
It's usually not hard to do but unless you have some experience taking lenses apart, you better start with something you don't care much about.

[subcolour]

It wasn't a pentax lens, I don't have it to hand but I think it was a tokina. I've bought a pentax m smc 35mm and a pentax smc 28mm to play with. I will take the original 35mm lens apart and see if I can fix it, I've also thought about using it as the bases of some lens experiments. Although I've just got my hands on a instant back'd holga fn so that will be my lofi experiment for a while.

The metering seems normal on the 35mm lens, so it was definitely a lens problem.

[Francois]

If you do decide to open it, just one word of caution:
They all have a tiny ball bearing in the aperture ring that's pushed with a spring to make the aperture click. And when you take it off, it will jump out.
The best thing I've found so far is to take a sheet of paper and make a roll that surrounds the lens before pulling it.
Also work on a terry cloth towel. That way you run fewer chances of dropping that elusive little screw on the floor.