Optolyth 30x70 vintage draw tube scope (1 Viewer)

Hello,

I could not find a place to post this. Perhaps the moderator could move it for me.

Does anyone have specifications for this old model that they could post here or by snail mail?

thanks

The-Wanderer

I own a 30x75 Optolyth telescope which I bought second hand around 20 years ago and a Swarovski CTC 30x75 which I bought new five years ago.
Unfortunately I have lost an old Optolyth catalogue so this is the best I can do:-
Weight 2lbs 10 oz (kitchen scales).
Length 47.5 cm extended, 30cm closed.
The field of view appears similar to that of the Swaroski at around 41metres at 1000 metres.
The significant difference and disadvantage with the vintage Optolyth is the close focussing distance which might be in the region of 50 feet or more. I had my Optolyth cleaned and the close focussing adjusted, but this now requires moving the draw tube about a centimetre for close and distance viewing.I found this inconvenient and it gave me the excuse to buy the Swarovski, which I very much enjoy using.

Dear Robert,

Thank you for responding. Yesterday I received the Swarovski, a second hand purchase that I did not want to miss! I still have the Optolyth.

I was mainly interested in eye relief and, while I still do not get the full field, it is marginally better than the Optolyth... The image is brighter on my ATS80HD, I guess by more than the increase in objective area would suggest - perhaps this is due to the HD glass.

I must admit I find the focussing easier on the Swaro draw tube.

However, the Optolyth seems still to be very good.

Watch out tough that you do not strain the hot shoe mount on the Optolyth.

Best wishes,


The-Wanderer

The-Wanderer said:

... Watch out tough that you do not strain the hot shoe mount on the Optolyth...

The-Wanderer

Click to expand...

I remember quite distinctly that the tripod mount, which is what I think is meant here, was a particularly weak point on Optolyth scopes. Several of my Optolyth-owning birding buddies, back in the days when they were popular, suffered scope damage at this point with very little force involved.

Dear Rotherbirder,

Hello,

I must apologise for nor responding sooner but the reason will become clear below.

Before that, though, thank you for correcting my mistake - why I didn’t write tripod shoe I don’t know but I find myself increasingly forgetful with advancing years!

I had previously found references through Google of problems with the tripod mounts on Optolyth draw scopes, and I appear not to have bought an unusual example. I bought my 30x 75 Ceralin from the son of a deceased owner. It would appear that the latter had made a steel cage of interconnecting circlular bands that surrounded the rubberised scope body and which provide a strong support for the scope on a tripod. It was, however, heavy at 485 grams.

I then thought of other options, a bespoke collar from SRB, perhaps, or the made in China collars that I had for my Canon “L’ lenses, though their diameters would be too small. Nevertheless I searched on Google and found collars for the Canon 70-300 ‘L’ lenses that had 78mm internal diameter which seemed about right but a little on the large size. I bought one from Amazon ‘Eggsnow Aluminum Tripod Lens Mount Ring for Canon EF 70-300mm f/4-5.6L IS USM ZOOM Lens” For £10.99, including delivery.

It arrived this morning and, with the enclosed broad elastic band it fits, but not tightly. I have used some 1mm thick double sided stick foam tape and that enables the collar to grip the scope tightly.

Another advantage is that the collar can be located to suit the centre of balance of the extended scope.

I will tether the scope to the tripod for a while to satisfy myself as to the robustness of the collar, but I do not foresee any problems as it seems sturdily made and it has a positive clasp mechanism.

It seems an economical and practical solution to my problem and the scope is now serviceable again - and the collar weighs 165 grams.

The-Wanderer

No problem Wanderer, you and me both! Good solution. It would be a shame not to be able to use the 30x75 as it is optically still a very good scope, particularly for sea-watching - good enough to 'turn' many a birder away from zoom to fixed power eyepieces back in the day as I recall.