Lens advice for medium format

[Mike Chalmers]

See the photo I've uploaded below, which is a copy of one you uploaded earlier, to which I've added some cyan and red markings.
The screwhead I have circled in red may have been added to keep the lens from turning in the threads. Try taking it and any other similarly located screw out.
The black area I have marked in cyan may be the retaining ring, or it may be a part of the mount - I can't tell.

Thanks Matt, appreciate your advice.

First off, I don't think the cyan is a retaining ring, see photo of the SIRIOPLA below. On mine the lens, probably the threading, protrudes slightly above this ring:

Next, there's several screws here on the rear of the lens, but I'm slightly concerned they're more to do with lens construction than locking the thread, but really not sure:

 

[MattKing]

Here is a picture of the lens itself:

You can see the threads on the back end, which either screw into the mount, or go through the mount and are attached using a retaining ring that screws on to them.

 

[Mike Chalmers]

Taken from an eBay listing for my exact model - seems like I should be able to just unscrew but I physically can't.

If a screw is used, I've no idea which one or ones, or where to start. Tried to find a manual but no joy yet.

 

[Mike Chalmers]

You can see the threads on the back end, which either screw into the mount, or go through the mount and are attached using a retaining ring that screws on to them.

Ah we're on the same path! Yeah if you look at the images I posted, it doesn't SEEM like the screws would have any affect on threading.

 

[MattKing]

Thanks for your last post. The photos there tell me that the threads on the mount are either on the inside edge of that ring I marked in cyan here:

Or they are lower down in the mount, but at the same location.

There is a small but distinct chance that someone has used something like loctite to fix that lens to that mount.

I'm afraid you are going to need to have someone chime in who has experience with this exact combination of lens and mount.

 

[Mike Chalmers]

There is a small but distinct chance that someone has used something like loctite to fix that lens to that mount.

Never considered this, but I think it's a definite possiblity. I'm gonna look for the previous owner's email and see if he can shed some light..

 

[Paul Howell]

You can put a drop of nail polisher remover on the screw and see if that will loosen it up. Never seen loctite on an enlarger part, but seems to common on camera bodies I am working on swapping out the pentaprism and focusing screen on a Sigma SA9 with a unit from a past repair SD9, about 1/2 the screws had loctite nail polish remover allowed for easy removal.

 

[MattKing]

I'm wondering if that mount and that lens might have spent some time in a Durst commercial printer. If so, the relatively unusual lens and mount pairing and loctite wouldn't surprise me.

 

[Mike Chalmers]

I'm wondering if that mount and that lens might have spent some time in a Durst commercial printer. If so, the relatively unusual lens and mount pairing and loctite wouldn't surprise me.

I don't believe so Matt, the guy I bought it from had all original manuals and things stored meticuously and I got the sense he'd owned all his equipment from new.

You can put a drop of nail polisher remover on the screw and see if that will loosen it up. Never seen loctite on an enlarger part, but seems to common on camera bodies I am working on swapping out the pentaprism and focusing screen on a Sigma SA9 with a unit from a past repair SD9, about 1/2 the screws had loctite nail polish remover allowed for easy removal.

I've asked the previous owner, hopefully he responds before I get restless and jump the gun.

 

[Mike Chalmers]

With some advice I managed to get it off, using the rear lens and some rubber gloves with grip (careful not to grip the aperture ring).

My new Rodagon 105mm arrived today too and looks good.

Now if anyone can point me in the direction of a VEGABOX 667 mixing box, I might be good to go!

Thanks everyone

 

[Paul Howell]

Question, is what you have a lens board for a 50mm, do you need a lens cone for the longer lens? I've only owned one Durst which used a different lens cone for the 80mm.

 

[Mike Chalmers]

Question, is what you have a lens board for a 50mm, do you need a lens cone for the longer lens? I've only owned one Durst which used a different lens cone for the 80mm.

Hi Paul, a quick test was successful, in that I could get the print sizes I wanted to and could focus on the grain. The image itself was slightly cropped (maybe the outside 25%. Now it seems to me that it's likely caused by the VEGABOX35 and the larger mixing box might correct this.

So, to answer your point - I think for some reason the previous owner had the medium-sized lens mount (SIRIOPLA) which still worked okay for 50mm - despite being designed for 80mm - and similarly might cover my new 105mm at the sizes I want.

 

[MattKing]

So, to answer your point - I think for some reason the previous owner had the medium-sized lens mount (SIRIOPLA) which still worked okay for 50mm - despite being designed for 80mm - and similarly might cover my new 105mm at the sizes I want.

The problem with using the SIRIOPLA with 50mm and longer than 80mm lenses isn't a problem with coverage.
It is a problem with:
1) limitations respecting the range of magnifications you can achieve; and
2) in some cases, with some longer lenses, physical interference between the back of the lens and the enlarger/negative.

 

[Mike Chalmers]

1) limitations respecting the range of magnifications you can achieve; and
2) in some cases, with some longer lenses, physical interference between the back of the lens and the enlarger/negative.

Yeah this was my hope and in that case likely totally fine for my purposes. There's a lot of clearance between lens and neg.

Cheers

 

[Mike Chalmers]

Just a quick update for anyone interested - thank you all for your help, I now have a lens and managed to get the Sixma 67 and anti-newton glass for cheap