Is there life after aperture block failure?

Futax wrote:

TacticDesigns wrote:

Futax wrote:

peterpainter wrote:

TacticDesigns wrote:

Massao wrote:

peterpainter wrote:

Futax wrote:

You could also try using Av mode. On my K-50, the camera still stops down the aperture as defined by the ring. Since the camera doesn't actually know that aperture, you need to get it to provide the correct exposure, and you can do that by using exposure compensation. If you're shooting wide open, then exposure is correct without compensation. Otherwise use the appropriate compensation.

Seems to be a much more accurate method for getting the correct exposure than using the green button in M mode. Also, can make shooting off several frames a lot quicker.

The camera is pretty-much always et on AV mode and was when I was getting odd exposures using just the shutter button rather than the green button. As I mentioned in another comment, I'll experiment further but from limited testing today the green button seems to work better - and frankly, I can't understand why it should!

Ok, then I wonder whether you have done these changes in settings as recommended by PF. See here .

If your Aperture Block failed, will stopped down metering work with Pentax-M or Pentax-A lenses?

I was just thinking about that.

I pulled out my Pentax K100d and tossed a Pentax-M lens on it.

To do stopped down metering, since I don't have a "Green" button, I push the AE-L button instead.

But . . . I can hear the lens being stopped down.

If the Aperture Block motor has failed, how can the camera stop down a Pentax-A or Pentax-M lens?

Take care & Happy Shooting!

I think the only way would be to do stop-down metering on A and M lenses (but I don't have any that I can test with) - can't see how the camera could set the aperture. I'm using it (stop-down metering) with my screw mount (Carl Zeiss Jena) lenses and it's a pain, really, but I suppose people got used to it in the old days.

If you're using M42 lenses, they'll almost certainly have black anodised rears. This means you have to use stop-down metering (and you can't use Catch-in-Focus). With the K-50, it seems that you can use Av mode (as well as Catch-in-Focus) - with most K-mount lenses. That's because they mostly have bare metal rears. The camera will detect the conductive rear, and act accordingly.

Aperture block failure just means the camera can't stop down an "A" type lens (i.e those without an aperture ring, or one which has been set to "A") to the correct aperture - it will always stop it down to the smallest aperture. A lens which sets the aperture using the aperture ring will limit this stopping down, such that the correct aperture results when you take the shot. And since the camera doesn't know what aperture you set - it'll assume wide-open - you have to compensate using EV compensation.

So, if a camera suffers aperture block failure, the camera still stops down a Pentax-M lens? (Which means if you are using the stop down metering option this will still work with a Pentax-M lens, or a Pentax-A lens set to one of the aperture settings and not set to "A"?)

So it just can "stop" at the chosen aperture if a Pentax-A lens is attached and set to "A"?

Take care & Happy Shooting!

Hope that clears everything up - everyone take note!

No, it won't stop down correctly if you set it to "A" (which is the equivalent to F22 or whatever as far as your camera is concerned). That would be just the same as using a lens without an aperture ring.

+1

Yes. Exactly.

I actually stated  . . . "not set to "A", above.

Just set the aperture ring to your chosen aperture (which might well be an aperture which maximises sharpness), and in Av mode it will stop down to that aperture (at least with my K-50 it will).

Since the exposure metering is done just before you take the shot, and the camera assumes the aperture is wide open (it knows no different, as the aperture ring doesn't communicate back to the camera), the camera will overexpose unless the aperture is actually set to be wide open.

So you have to use exposure compensation to counteract this. For example, if it's an F4 lens and you set the aperture ring to F8, you will need +2EV compensation.

Give it a try, and report back, because that is how my own K-50 behaves, and I'm assuming it applies to all K-50s. It'll hopefully be of help to a lot of people!:-)

I think we are talking about 2 different things.

I'm not talking about aperture prioirty.

Instead I'm talking about stop down metering.

For my Pentax ist DS (or K100d), I can toss on a Pentax-M lens. Set it to whatever aperture setting I want. (For instance f/8). And then, when my camera is in manual exposure mode, I press the AE-L button and the camera "stops down" the lens, takes a meter reading with the lens stopped down, and then sets the shutter speed for a normalized exposure.

Take care & Happy Shooting!