Is there life after aperture block failure?

Futax wrote:

TacticDesigns wrote:

Futax wrote:

TacticDesigns wrote:

Massao wrote:

...

I think both of you are right, but just happen to be talking about different things.

I want to test one thing on my Pentax cameras tonight with a Pentax-M lens and then I'll post. I want to confirm one thing with Pentax-M lenses in manual exposure mode. I also want to confirm something that someone told me a long time ago about how to make a Pentax-M lens act like an adapted lens to get a sort-of (not so consistent) aperture priority mode on Pentax dSLR cameras.

But the "one" question I have is . . . if a Pentax camera suffers aperture block failure, then when you press the shutter button (to take a picture) when the camera is in manual exposure mode, does the aperture block motor actuate and attempts to stop down the lens? Basically, I want to know if the motor moves, even if it is not doing exactly what it is supposed to do. And . . . even if the cameras suffers ABF, does it still let you take a picture in manual exposure mode.

Take care & Happy Shooting!

Please see my last post to flektogon. Basically, with an M lens, regardless of aperture block failure (and with any Pentax camera), in M mode, you will need to use the "green button" prior to the shot in order for the camera to stop down the lens and evaluate the correct exposure (but is subject to errors due to the metering having to work properly with varying apertures).

The aperture block failure just means that the camera will operate the stop-down lever FULLY all the time, instead of trying to control the exact aperture. Doesn't affect the above.

+1

I think LOL that is exactly what I was asking and trying to find out. Thank you!

Never mind, with M lenses the camera can't set the correct aperture anyway - those lenses control the aperture themselves - all that's required is that the camera operate the lever fully when taking the shot (like all legacy Pentax cameras). But the K-50 (though it isn't meant to) actuates the lever when taking a shot anyway - regardless of exposure mode.

That is interesting.

I have to try out my ist DS and K100d to see if it does that too.

Ok.

I tested this out on my Pentax ist DS and Pentax K100d.

For Av mode with Pentax-A lenses . . .

1. When I set the lens to "A", I can adjust aperture via. the e-dial and take a picture. Aperture changes.

2. When I try to set the aperture on the lens and take a picture in Av, all the pictures are taken at the largest aperture, regardless of where I have the aperture dial set on the lens. Aperture setting is not recorded in EXIF.

For Av mode with Pentax-M lenses . . .

1. M lenses don't have an "A" position, so not possible to set it to "A". LOL.

2. When I change the aperture on the lens, all pictures get taken at the same shutter speed, and all seem about the same brightness. So I am assuming that all the pictures, regardless of the aperture ring setting, are being taken at the largest aperture. Aperture setting is not recorded in EXIF.

For M mode with Pentax-A lenses . . .

1. When I set the lens to "A", I can adjust aperture via. the e-dial and then take a stopped down meter reading by pushing the AE-L button. (Green button on newer models.)

2. When I set the aperture with the aperture ring on the lens, I can take a stopped down meter reading by pushing the AE-L button. Aperture setting is not recorded in EXIF.

For M mode with Pentax-M lenses . . .

1. M lenses don't have an "A" position, so not possible to set it to "A". LOL.

2. When I set the aperture with the aperture ring on the lens, I can take a stopped down meter reading by pushing the AE-L button. Aperture setting is not recorded in EXIF.

When I take the lens off and push and put the camera in Av mode, when I press the AE-L (Green) button, the aperture lever does not move. When I fire the shutter, I can see the aperture lever move, but according to the testing above, it does not stop down a Pentax-A or Pentax-M lens.

So you take advantage of this by using Av mode. The camera doesn't know the aperture you set, so you have to compensate. Simple as that. An f4 lens set to f8 will need +2EV compensation.

+1

From my testing above. I don't think this is happening.

This is a very useful "feature" of the K-50 (and hopefully the K-30, K-500 etc.) as you get accurate exposure and more straightforward shot taking (arguably).

That makes sense. Like having to dial in the aperture setting twice. Once on the lens and once on the body.

Therebis another thing I was told . . .

I don't have any m42 lenses myself. I had one and then stupidly sold it. But someone told me that if you don't mount a Pentax-M all the way that it can act like an m42 lens on a Pentax dSLR.

They went on to say that if you want to use the Pentax-M lens like that on a regular basis that you can drill an extra hole in the mount to lock the lens in that position.

Yes, I think that works. The problem is that you will need to set the aperture wide open in order to focus accurately,

+1

Yes. This can be a pain. It is the way it was done before the Auto Pin on the m42 Pentax screw mount. But also, for this trick of drilling a hole in the Pentax-M lens mount, I found where someone told me that this was possible . . . and according to that post, this trick only works from wide open and maybe down to f/5.6 or max f/8 anyway. So the screen won't get that much darker. So might just forget about opening up to focus, unless you want to really lock down focus by having the aperture wide open.

then change the aperture ring to the desired aperture. That's why I don't like using M42 lenses (even if they have an Auto/Manual switch) - plus the fact that Catch in Focus won't work either.

I had forgotten about catch-in-focus.

My Pentax ist DS and Pentax K100d both have that feature.

I tried it on the Pentax ist DS with the Pentax-M lens offset on the mount, so acting like an adapted lens and . . . catch-in-focus worked!

Pity, as Takumars are a delight in the handling department - mind you, some of them don't need stopping down anyway (they're sharp when at max aperture).

Here is a link to where I originally asked about Pentax-M lenses on my Pentax ist DS camera. And where someone pointed out that I could drill that hole in the mount to make a Pentax-M lens act like an adapter lens. In other words, disengaging the aperture lever altogether.

https://www.dpreview.com/forums/post/55825335

Take care & Happy Shooting!