[Boris_Akunin]

Hi,

I recently found a Vivitar Series 1 28mm f/1.9 (M42) with the aperture stuck wide open. After taking it apart until I reached a set of screws that I couldn't get loose and reassembling it, the aperture now works unless the lens is focused at infinity. When the focus ring reaches the infinity-mark, it tightens up and keeps the aperture from beeing closed. This happens about 3mm before the focus ring reaches infinity, at that point the aperture can still be opened up but when it is stopped down nothing happens. As soon as the lens is focused a little closer, the aperture snaps where it belongs.

Secondly, the focus scale seems to be off, when I focus at a building that's ~100m away with the split-prism of my Minolta XD-7 or my Pentax Super A (both with adapters with the correct flange distance), the focus scale on the lens shows ~1,2m.

The point where the aperture gets stuck is at about 10m on the focus scale, so I could adjust it if it wasn't for this:
(shown is the K-mount version, mine doesn't have the second set of F-stop number on the aperture ring)

The position of the focus mark can be adjusted but the position of the aperture mark is changed at the same time so I'm looking for a way to independently adjust the focus scale.

Maybe someone here can help me.


Edit: I have now move the focus/aperture mark by one stop so the set f-stop now shows on the left instead in the middle. It works as long as I remember the change but it's not exactly ideal.
(It now has half-stops from f/16 to f/2.8 and is effectively stepless from f/2.8 to f/1.9)


regards
Jan

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Last edited by Boris_Akunin; 08-03-2013 at 01:44 PM.

[bobpur]

Remove the rubber grip there i usually 3 small setscrews that hold the focus ring. When they are loosened the ring can be repositioned.

[Boris_Akunin]

Remove the rubber grip there i usually 3 small setscrews that hold the focus ring. When they are loosened the ring can be repositioned.

Are you sure about that?
As I said, the metal ring that has the focus/aperture mark and the dof markings on it can be repositioned, it has the usual 3 setscrews.
I wouldn't want to damage the rubber unnecessarily, the entire front of the lens (focus ring, grip, filter thread) seem to form one solid piece.
The are a few lenses in the early "Series 1" line that share this construction (i.e. the 135/2.3).

[nater]

I wouldn't want to damage the rubber unnecessarily, the entire front of the lens (focus ring, grip, filter thread) seem to form one solid piece.

I can't speak to this lens at all, but when I have removed rubber grips (usually to clean them on older lenses I've acquired), I typically use a toothpick to slip underneath the grip so I can start to pull it up over the lip of the lens barrel. I work my way around slowly, lifting and pulling a little bit at a time evenly across the circumference, sometimes taking many minutes to get the rubber up and over. On this lens, it looks like the body is somewhat conical, so I would work the rubber down toward the mount since I imagine the rubber is molded in a conical form and would be difficult or impossible to pull up and over the top of the lens.

[Boris_Akunin]

I can't speak to this lens at all, but when I have removed rubber grips (usually to clean them on older lenses I've acquired), I typically use a toothpick to slip underneath the grip so I can start to pull it up over the lip of the lens barrel. I work my way around slowly, lifting and pulling a little bit at a time evenly across the circumference, sometimes taking many minutes to get the rubber up and over. On this lens, it looks like the body is somewhat conical, so I would work the rubber down toward the mount since I imagine the rubber is molded in a conical form and would be difficult or impossible to pull up and over the top of the lens.

Thanks, I'll try that some time but I think I'll try to live with my makeshift solution for a while.
I still have to decide whether I'll keep this one or my Kiron 24/2, I don't need both.
I I decide to sell it, I'll try and fix it up nicely...

regards
Jan

[Boris_Akunin]

Remove the rubber grip there i usually 3 small setscrews that hold the focus ring. When they are loosened the ring can be repositioned.

I finally found the time to try that and it worked.

In case someone else has the same problem:
There are 4 setscrews underneath the lower rim of the rubber grip that can be loosened to adjust the focus scale and another 4 setscrews underneath the upper rim. When the upper screws are loosened, the edge of the focus ring can be turned and removed. The upper and lower limit of the focus ring can be adjusted by turning the edge.

I've used the opportunity to clean all the lenses and the Vivitar is now ready for sale.
I'll post some testshots comparing the Viv 28/1.9, the Kiron 24/2 and the 18-55WR Kit, I'll probably sell both the Vivitar and the Kiron and get a Sigma 17-50/2.8.

If anyone's interested, send me a PM (shipping only inside EU/EFTA for now)

EDIT:
The Vivitar and the Kiron are now for sale:
http://www.dslr-forum.de/showthread.php?t=1330075
http://www.dslr-forum.de/showthread.php?t=1330076


regards
Jan