Voigtlander 125 APO Lens Problem

[Michael Erlewine]

I am trying to use a CV-125 APO with a Pentax K mount. I have other Voigtlander lenses (90mm APO [2 types], 40mm Ultron) in the Pentax mount, and they work fine. When I mount them, I turn the aperture dial to the narrow end, press a little tiny button, and move it to the "A" spot. At least this is what the Pentax folks call it. Once I have done that, I can change aperture and shutter. However, on this CV-125, I move it to the "A" spot, but nothing happens. Is continues to only show up as wide open. Any ideas please?

[Roland Vink]

On the Pentax aperture ring, A=Auto. Use it when shooting in Shutter priority or Programme mode. If Pentax cameras work the same as Nikons you might also have the option to control the aperture using the aperture ring or command dial. If you choose the command dial you must also set the ring to A. I generally prefer setting the aperture ring manually.

From memory, if you turn the aperture ring you should see the aperture blades close down, same as Nikon lenses but I might be mistaken (Pentax 645 lenses are different, they stay wide open regardless of the aperture ring setting, the aperture only closes down when the camera presses the lever at the rear of the lens).

What happens when you take a pictures at various apertures? If the exposures turn out ok I wouldn't worry about it.

[Michael Erlewine]

On the Pentax aperture ring, A=Auto. Use it when shooting in Shutter priority or Programme mode. If Pentax cameras work the same as Nikons you might also have the option to control the aperture using the aperture ring or command dial. If you choose the command dial you must also set the ring to A. I generally prefer setting the aperture ring manually.

From memory, if you turn the aperture ring you should see the aperture blades close down, same as Nikon lenses but I might be mistaken (Pentax 645 lenses are different, they stay wide open regardless of the aperture ring setting, the aperture only closes down when the camera presses the lever at the rear of the lens).

What happens when you take a pictures at various apertures? If the exposures turn out ok I wouldn't worry about it.

I will try this out. When focus stacking many layers, the inability to see anything but wide open, narrow DOF, makes it very difficult. I will keep working on this.

Thanks.

[Roland Vink]

Not entirely sure I follow ... if you only shoot wide open (for shallow DOF) the aperture ring becomes irrelevant.

If you do need to stop down - whether you use the aperture ring or command dial - take a few snaps wide open and stopped down. No need to focus stack, just take some quick random shots. If the aperture is not opening or closing properly you'll quickly see if you get exposure errors.

[Michael Erlewine]

Not entirely sure I follow ... if you only shoot wide open (for shallow DOF) the aperture ring becomes irrelevant.

If you do need to stop down - whether you use the aperture ring or command dial - take a few snaps wide open and stopped down. No need to focus stack, just take some quick random shots. If the aperture is not opening or closing properly you'll quickly see if you get exposure errors.

For sure, I can do that. I am trying to work a new camera and other Voigtlander lenses work fine, so this one may be damaged in some way.

[Dr Klaus Schmitt]

For sure, I can do that. I am trying to work a new camera and other Voigtlander lenses work fine, so this one may be damaged in some way.

Did you get the Pentax K1 ??

[Michael Erlewine]

Did you get the Pentax K1 ??

I did. Just posted something on the Camera section about it.