Dollond rangefinder - any info?

lindsay

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I have this Dollond external rangefinder that I came across in my Dad's box of camera bits. I've played with it a bit and can't see two images overlapping so I don't think it is functioning. Has anyone got any more info on such things and suggestions as to whether I can fiddle with it usefully to get it working ok?
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It needs a bit of a clean, anyway, but is there anything else I might do if I start trying to dismantle it? I'm no handyman so I don't want to completely ruin it if it might be of use.
 
Some where on here I started a thread about Gnome rangefinder, which was also my Dad's. It looks similar to yours and I had a bit of a fiddle getting it apart, when I did I found that the silvering on the mirror had gone hence no double image. HTH
 
@sirch Chris that's really helpful thanks, I reckon you're right about the silvering. As they are selling for £9.99 in good working order, I think I can afford to dismantle it like you, and ditch it if no good.
 
just looking at your photos, the end caps are knurled (got grooves on) so they might unscrew rather than just being a push fit like the gnome.
 
I've tried pulling and twisting with no success. I might try using pliers, but I think they are glued in place judging by a slight discolouration at the edges of the join
 
Using pliers will likely do nothing more than make a mess of the knurling - those parts look to be aluminium, which is soft.

Try undoing a screw or two and pulling at one of the bits. The knurling could be decorative (on bits that don't rotate). Given that the main tube is square, it's much more likely that the internal shapes match that and are held in place by screws.
 
If the problem is that the mirrors have become tarnished or desilvered, maybe an old, dead SLR's mirror could be repurposed to replace them.

WRT the knurling on the ends, I would guess (but it IS a guess!) that it's to help keep the device pointed in the right direction without twisting in the fingers.
 
I do plan to unscrew and investigate it, but it has to be said it's for just curiosity, as I just don't get on with rangefinder technique somehow, so not something I'm going to actually use even if I got it working.
 
If the problem is that the mirrors have become tarnished or desilvered, maybe an old, dead SLR's mirror could be repurposed to replace them.

WRT the knurling on the ends, I would guess (but it IS a guess!) that it's to help keep the device pointed in the right direction without twisting in the fingers.
Rangefinder mirrors are generally much, much thinner than SLR mirrors. The extra thickness would ruin the calibration.
 
In mine it was the half-silvered mirror that had lost it's silvering or else it might have been salvageable, it probably is but not really worth it.
 
For those who might be interested: I dismantled the rangefinder just now. I discovered that Chris @sirch (@Nomad Z @Nod) was correct. the silvering had all gone from the mirror, hence why it wasn't working. I also discovered that the knurled and pieces did in fact unscrew. So I now have it all in pieces, but I'll put all the bits in a component bag just in case I decide to reassemble it - how does one re-silver a bit of thin glass? (rhetorical question really).
 
If you want to do it, Google will throw up a load of advice on how to do it. Can't remember how we did it at school but it involved a silver salt (? silver nitrate?). Might be easier to source a bit of first surface mirrored glass the right thickness than to get the necessary smoothness of mirror yourself.
 
For those who might be interested: I dismantled the rangefinder just now. I discovered that Chris @sirch (@Nomad Z @Nod) was correct. the silvering had all gone from the mirror, hence why it wasn't working. I also discovered that the knurled and pieces did in fact unscrew. So I now have it all in pieces, but I'll put all the bits in a component bag just in case I decide to reassemble it - how does one re-silver a bit of thin glass? (rhetorical question really).


Plenty of demo's on YouTube for resilvering glass.
 
For those who might be interested: I dismantled the rangefinder just now. I discovered that Chris @sirch (@Nomad Z @Nod) was correct. the silvering had all gone from the mirror, hence why it wasn't working. I also discovered that the knurled and pieces did in fact unscrew. So I now have it all in pieces, but I'll put all the bits in a component bag just in case I decide to reassemble it - how does one re-silver a bit of thin glass? (rhetorical question really).
Should be golded, I suspect, rather than silvered. Gives a clearer spot in the image.
 
I have a few ancient rangefinders but the only one still in good usable condition is the rather better voigtlander one.
It seems that this is usually the case, and why they hold their price so well. the others have all lost most of their silvering.
 
Should be golded, I suspect, rather than silvered. Gives a clearer spot in the image.
You are very likely correct there John, as the mount for the mirror is brass and it did look rather like the glass was more yellow than silver round the edges.
 
TBH, I wouldn't expect a gold coating to tarnish while a silver one will. Inside a "sealed" unit, wear shouldn't be a factor although a gold coating would be softer and more susceptible to wear should it be touched.
 
I do not know of any pocket rangefinders that were ever gold coated. when these were made no one was thinking forty or fifty years down the road.
It is not so much the quality of the silvering, it is the quality of the sealing lacquer.
 
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Here's the offending article:
IMG_0483.jpg
 
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