Mamiya Universal - 100mm lens f2.8 lens - need some confirmation on rangefinder issue please!

ajmiller · Oct 4, 2021

Just received the above camera and lens and everything is excellent apart from the rangefinder - I think!
I know the f3.5 lens needs to be pulled out from it's retracted position when used but is the f2.8 lens the same?
The rangefinder rings coincide ok at long distances but if I focus any nearer than 2 meters (8ft) the circles just seem to stop and do not coincide. Is this a rangefinder problem or associated with something I'm not doing correctly on the lens as asked above?
Thanks for any help.
Tony

Dennis-B · Oct 4, 2021

I don't think the 100 f/2.8 collapses. It's a 6-element Tessar-type, and the collapsible model only has 4 elements. It focuses down to @ 2 meters. Could be that the issue?

Have you downloaded the owner's manual? It may help, especially with focusing.

ajmiller · Oct 4, 2021

I did download the manual but obviously missed that part! I'll have a re-read. thanks for the advice.

Dennis-B said:
I don't think the 100 f/2.8 collapses. It's a 6-element Tessar-type, and the collapsible model only has 4 elements. It focuses down to @ 2 meters. Could be that the issue?

Have you downloaded the owner's manual? It may help, especially with focusing.

ajmiller · Oct 4, 2021

Doing some research it appears the minimum focussing distance is 3.5ft (1.06m) on the 100mm f/2.8 lens.

Mamiya_Repair · Oct 4, 2021

The 100mm f/2.8 should rangefinder couple down to its closest distance of 1 meter. I would check infinity with the lens to see if that works. If other lenses are working OK with the body, then the rangefinder cam on the lens has an issue.

ajmiller · Oct 4, 2021

Thanks. Infinity works ok. I don’t have any other lenses.

Mamiya_Repair said:
The 100mm f/2.8 should rangefinder couple down to its closest distance of 1 meter. I would check infinity with the lens to see if that works. If other lenses are working OK with the body, then the rangefinder cam on the lens has an issue.

Mamiya_Repair · Oct 4, 2021

ajmiller said:
Thanks. Infinity works ok. I don’t have any other lenses.

In that case, the lens rangefinder cam is OK. I would remove the lens, look into the lens mount and carefully push back the rangefinder coupling pin. I should move smoothly and come to rest on the back of the lens mount. My guess is that it is not fully coming to rest on the lens mount and something is sticking.

reddesert · Oct 4, 2021

You can also observe the operation of the RF coupling pin by putting the lens on, removing the film back, and watching the coupling pin as you turn the focus ring of the lens. The pin should ride on a brass ring on the rear of the lens, which is the lens's RF cam. It seems like it is failing to follow the cam as you focus close (lens gets further from body).

ajmiller · Oct 5, 2021

Thanks for your help. I've done what you suggest and I've attached a few photos. The rangefinder coupling pin seems to move back and forward ok - not exactly smoothly but returns ok. On the lens what is, I presume, the RF cam definitely doesn't follow focus. It does stop before I get to the minimum focus distance. So, it appears the RF cam is not set up for this lens? Maybe? Unless you can see soemthing else amiss. The other thing that strikes me is the lens doesn't look straight on - see second photo. Not sure if that's a problem? Thanks again.

Mamiya_Repair · Oct 5, 2021

ajmiller said:
Thanks for your help. I've done what you suggest and I've attached a few photos. The rangefinder coupling pin seems to move back and forward ok - not exactly smoothly but returns ok. On the lens what is, I presume, the RF cam definitely doesn't follow focus. It does stop before I get to the minimum focus distance. So, it appears the RF cam is not set up for this lens? Maybe? Unless you can see soemthing else amiss. The other thing that strikes me is the lens doesn't look straight on - see second photo. Not sure if that's a problem? Thanks again.
View attachment 287281 View attachment 287282 View attachment 287283[/QUFrOTE]
The problem is that the light baffle on the rear of the lens

ajmiller said:
Thanks for your help. I've done what you suggest and I've attached a few photos. The rangefinder coupling pin seems to move back and forward ok - not exactly smoothly but returns ok. On the lens what is, I presume, the RF cam definitely doesn't follow focus. It does stop before I get to the minimum focus distance. So, it appears the RF cam is not set up for this lens? Maybe? Unless you can see soemthing else amiss. The other thing that strikes me is the lens doesn't look straight on - see second photo. Not sure if that's a problem? Thanks again.
View attachment 287281 View attachment 287282 View attachment 287283

From your photos I can see that the light baffle on the rear of the lens is either loose or glued down incorrectly. The rangefinder cam lip is catching on the baffle and not allowing it to fully retract into the lens when focusing close..

ajmiller · Oct 5, 2021

It's fixed not loose so glued down incorrectly. I presume thats why it doesn't sit straight ( as in the 2nd photo)?
So, if it's glued it means it can't be straightened without causing damage?
Thanks

Mamiya_Repair said:
From your photos I can see that the light baffle on the rear of the lens is either loose or glued down incorrectly. The rangefinder cam lip is catching on the baffle and not allowing it to fully retract into the lens when focusing close..

Mamiya_Repair · Oct 5, 2021

If it was properly glued with something like Pliobond, then it can be carefully removed and re-glued correctly.

ajmiller · Oct 5, 2021

Ok thanks - there seems to be a loose edge at the top so I'll work from there. I do appreciate your help. Cheers

reddesert · Oct 5, 2021

The crooked rear baffle could also potentially vignette the corners of the image (I don't know if this would be visible on a 6x9 frame), so it should definitely be repositioned.

To clarify my previous comment about the "brass ring" rangefinder cam, some of the Mamiya Press lenses, mostly shorter focal lengths, have the cam surface as a ring at the rear of the lens that rotates as the focusing helical is turned. Others have a tongue that is driven in/out by a helical, turned by the focus helical at the correct rate to move the rangefinder coupling. Yours is the second kind. The 150mm lens is also like that.

ajmiller · Oct 6, 2021

Thanks for the useful info. I did also wonder about vignetting.
I’ll attempt to take the baffle off today and straighten it.
cheers
Tony

reddesert said:
The crooked rear baffle could also potentially vignette the corners of the image (I don't know if this would be visible on a 6x9 frame), so it should definitely be repositioned.

To clarify my previous comment about the "brass ring" rangefinder cam, some of the Mamiya Press lenses, mostly shorter focal lengths, have the cam surface as a ring at the rear of the lens that rotates as the focusing helical is turned. Others have a tongue that is driven in/out by a helical, turned by the focus helical at the correct rate to move the rangefinder coupling. Yours is the second kind. The 150mm lens is also like that.

hashtagquack · Oct 6, 2021

Not sure if this is of any help but just snapped a couple photos of my 2.8on a Press Universal

ajmiller · Oct 7, 2021

Yes, that is useful thanks. I’ve sorted the light baffle out - the glue hadn't had time to really set so it came off fairly easily. I’m out today trying the camera so i will have a better idea after processing the film. Thanks for the advice and photos.

ruilourosa · Oct 7, 2021

It´s a Planar not a tessar.

One of my favorite lenses!

These cameras rangefinder tends to go out of alignment, make shure to send the camera for CLA together with all the lenses you have

Mamiya Universal - 100mm lens f2.8 lens - need some confirmation on rangefinder issue please!

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