Iris on the Minolta Rokkor 58mm 1.2

sbaechler · Joined: 01 Jan 2013 Posts: 10

Hi

I bought a Minolta Rokkor 58mm 1.2 off of ebay and noticed that the iris is not perfectly round (or octagonal) when closed. Which results in odd shaped blobs when shooting small out-of-focus lights at night.

I had a look at other lenses on ebay (picture) for this issue as well and found it on some, but not all of them had it.

Is this a common issue? Does anyone who owns this lens has a perfect aperture?

Regards
Simon

M. Valdemar · Joined: 14 Nov 2008 Posts: 93

It won't make any difference.

As long as the blades open and shut quickly without sticking or binding there is no problem.

sonyrokkor · Posted: Tue Jan 01, 2013 4:17 pm Post subject:

First. My rokkor 1,2/58, serial Nª 259xxxx (second version), has the aperture blades in perfect form.

Second. I saw and had a lot of lenses with the blades like you show here.

Third. Effects? I don't know if one or more. But think that if the lost of adecuate form occur when the aperture is small (F/11 or so), the effect can be minimal.

Lightshow · Joined: 04 Nov 2011 Posts: 3666 Location: Calgary

It may be caused by heavy usage wear, or just out of tolerance parts, it wouldn't take much(a .001") to cause a visible difference.
a lens tech may be able to fix it just be swapping blades around.

sbaechler · Joined: 01 Jan 2013 Posts: 10

It actually does make a difference. The effect is visible on blurred point light sources already at f/2.0.
I wouldn't complain if this was a 100$ lens, but those lenses are 450-500$ in mint condition. A lot for a 45 year old lens. If this issue is caused by wear it's something to be aware of when looking for one on ebay.

M. Valdemar · Joined: 14 Nov 2008 Posts: 93

Nonsense.

hifisapi · Joined: 25 Sep 2012 Posts: 941 Location: USA

aleksanderpolo · Joined: 24 Jan 2010 Posts: 684

I can take it off your hand for $100 so you can hunt for a mint one Wink

sbaechler · Joined: 01 Jan 2013 Posts: 10

Attila · Expire: 2025-11-18

skida · Posted: Wed Jan 02, 2013 7:13 pm Post subject:

It is hardly noticeable on a shot just of OOF highlights, so is likely to be of no importance with a properly focused and interesting subject. Sometimes I feel that I would like to meet the man who popularised the term "bokeh" and punch him in the face, hard. Shocked

sbaechler · Joined: 01 Jan 2013 Posts: 10

The actual question is to owners of this lens if the issue with the blades is age/usage related.

I don't really mind if you notice the effect it has (or think that it does not have one).

fermy · Joined: 17 Feb 2012 Posts: 1974

Some people are perfectionists, nothing wrong with that. It also bugs me a bit if something does not work quite right even on $10 lens and even though I can work around it easily.

dan_ · Expire: 2016-12-19

One of the blades came out of its place and slipped under others. I had more lenses in this situation. If it is not fixed back it will make other blades came out of their place and the iris will be soon unusable. I have managed to fix some of them myself but I have never tried with a Minolta lens.

David · Expire: 2013-01-25

All the itis blades look like they're in the right order to me. It looks more like either a manufacturing error on the blade shape or on the connection to the diaphragm ring (more likely.) If it bothers you, b all means sell it and pick up a different one. I can see the asymmetry you're talking about in the OOF shot, but I see that more as the lens having character than a flaw.

tromboads · Expire: 2015-10-01

dan_ · Expire: 2016-12-19

The blades are there, they are in the correct order, but one of them is no more moved by the diaphragm ring. It is dislocated from its place on the diaphragm control mechanical part and is moved by friction with the others only. Therefor is moving aleatory and its fixing rivet could dislocate other blades on its move. I don't think it could be a manufacturing error.
The repair isn't so difficult and wouldn't cost much more then a CLA.