[icy]

Hi,

I am using a Helios 44m-4 with Pentax K-r. I notice that when I switch to Av mode, the output image is darker than image captured in M-mode (as you can see in the first image below). The expect result is as in the 2nd image, which is taken with M-mode (green button is pressed to measure the light source.)

My question is: Why does the Av-mode report wrong light parameter? Am I using Av mode in wrong way? Does the Av mode work with Helios lens?

Thank you very much.

Demo:

The first image: f/2.8, 1/45s, Av mode, link = http://vonhudieu.net/zen/picture.php?/381/category/18
The second image: f/2.8, 1/15s, M mode (green button pressed to measure light source.), link = http://vonhudieu.net/zen/picture.php?/382/category/18

[bobpur]

Hi

Un documented rule, when using M42 screw mount manual aperture lenses that do not have a clean metal mount
that grounds out the contacts" add +1.7 ev
Forget that Green button thing it just adds to your shutter count and makes you do 2 steps for each Pic !
Pentax should have had a metering on the half press shutter button or proper metering in Av mode,
My Sony A33 works with any lens and meters without the stopdown thing

[Philoslothical]

Hi icy, as I mentioned in your last thread, you need to use old m42 lenses in M mode with green button metering to get a proper exposure. The camera has no way of knowing what aperture you're using with these lenses, so it makes the best guess it can on exposure, but it is not accurate.

Forget that Green button thing it just adds to your shutter count and makes you do 2 steps for each Pic !

What on Earth are you talking about? The shutter doesn't fire when metering with the green button. That's just bad info.

[jezza323]

What on Earth are you talking about? The shutter doesn't fire when metering with the green button. That's just bad info.

the rest of the info is pretty accurate in my experience, but yeah not the green button bit!

[icy]

Hi icy, as I mentioned in your last thread, you need to use old m42 lenses in M mode with green button metering to get a proper exposure. The camera has no way of knowing what aperture you're using with these lenses, so it makes the best guess it can on exposure, but it is not accurate.

Oh I see it now Thank you very much!

[eddie1960]

well question has been answered.
but
holy smoke that tak looks like it's been through several war zones how's it performing