Tweedledee Posted February 12, 2012 Share Posted February 12, 2012 Hi, Does anyone have an inkling what this beast of a scope is all about? />http://www.ebay.co.uk/itm/110824138242?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 Large Vintage Telescope with 5" WW2 Military Ross Lens At first look I thought someone had the description wrong and it was a search light, but it has an eyepiece at the back and an equatorial mount. Then I thought it was some sort of cat due to the unusual shape. When I looked at the curvature on the objective lens, it would seem to correspond with the tube length suggesting about F4! Certainly not your average frac. The F stops around the lens suggest a photographic application. Maybe someone built like Arnold Schwarzeneggar could use it as an RFT Puzzled, Pete. Link to comment Share on other sites More sharing options...
Doc Posted February 12, 2012 Share Posted February 12, 2012 Weird one this, it looks like the eyepiece goes in the funnel end of the scope and it has a 5" lens on the other end. Link to comment Share on other sites More sharing options...
Brantuk Posted February 12, 2012 Share Posted February 12, 2012 Here's some stuff about Ross lenses - nothing on scopes yet though: http://en.wikipedia.org/wiki/Ross_(optics) Link to comment Share on other sites More sharing options...
Tweedledee Posted February 12, 2012 Author Share Posted February 12, 2012 (edited) Cheers Kim, So, Ross are into wide angle photographic lenses. That would certainly fit with the pictures. Can't see any part where a photographic plate could be *simply* inserted, Just the four bolts to hold the large back plate on, but they don't look like they've seen much use with a spanner. Maybe the objective lens easily detaches to fit a photographic plate into a holder, but that would render the eyepiece unusable. Wonder what the air valve is for, if that is what it is? Maybe to pump in some inert gas to prevent condensation. Interesting bit of history... Ross being put in charge of the London Zeiss factory at the start of WW1 by the British government. Is it just me? I'm very intrigued by these unusual optical items. Pete. Edited February 12, 2012 by petersull Link to comment Share on other sites More sharing options...
Brantuk Posted February 12, 2012 Share Posted February 12, 2012 Yep - I also went off to a couple of other pages and discovered some famous names from the late 1800's associated with Carl Ziess and pre WW1 lens designs. The air valve is a total mystery. It sure is an intriguing trail to follow - can't believe I didn't find the scope yet - I'll try get some more on it later Link to comment Share on other sites More sharing options...
Doc Posted February 12, 2012 Share Posted February 12, 2012 I don't think it's wide angle photography as there is no place to insert a slide of film. I think it's a ships telescope that allows wide angle views, there is a purge valve on top to discharge the damp or sea air trapped inside. I would imagine originally it was secured onto a pier and at later date a tripod was adapted for it. Link to comment Share on other sites More sharing options...
Tweedledee Posted February 12, 2012 Author Share Posted February 12, 2012 If that's what it is Mick, I want it for a richest field telescope. Not quite grab-n-go though. Looking again at the ebay photo looking into the lens, it says 20" fl 6.3. So that gives an effective aperture of just over 3". Yet it does look more like 5" across the objective with some reducing sized baffles inside possibly going down to just over 3". The F stops surely must mean it is photographic, though. I don't know how they measure/calculate f ratios etc. with photographic lenses, maybe it's different to visual stuff. The main lens does look to have quite an extreme curve. But like you say, maybe someone has adapted it for astronomical use at a later date and put it on an equatorial mount. Your valve idea sounds right. I searched google for the lens no. REF.14A/4264 and found a german Westlicht Photographica Auction with the same lens (not the whole scope) - with 6 other much smaller lenses that sold as a lot for 312 Euros. Other than that I have drawn a blank. Link to comment Share on other sites More sharing options...
Tweedledee Posted February 12, 2012 Author Share Posted February 12, 2012 I just cannot figure out that funnel shape. Unless there are other internal lenses which fan out the optical path to a large concave mirror which reflects back to a small secondary convex mirror and back to the eyepiece. If that was the case it would certainly be some very weird catadioptric system. Link to comment Share on other sites More sharing options...
Tweedledee Posted February 12, 2012 Author Share Posted February 12, 2012 There's a likely looking bolt head just before the start of the funnel section on the tube that could be in the right position to hold a small secondary mirror inside the tube. Baffled Link to comment Share on other sites More sharing options...
Brantuk Posted February 12, 2012 Share Posted February 12, 2012 It coulda been slung under a reconaisance aircraft with a camera on the end of it for wide field ariel shots of bomb damage, or sub huntiing. Or possibly bomb sighting gear. Link to comment Share on other sites More sharing options...
Tweedledee Posted February 12, 2012 Author Share Posted February 12, 2012 It has certainly been slung somewhere with that dent in the objective cell Link to comment Share on other sites More sharing options...
philjay Posted February 13, 2012 Share Posted February 13, 2012 Its a reccy camera definately with the original body, the film holder removed and a plate with an RAS eyepiece fitted as an attempt to get a widefield scope. I had occassion to strip a couple of these for the lenses years ago and they make superb astrographs, a little wasted this one with just a narrow RAS eyepiece in the place of where the film would go. Scope manufacturers these days charge a fortune for flat fields the size of a 35mm sensor, whereas this does a guaranteed flat field across something like 6x4" imagine that. OK it'll be an achromat lens but hey if you can get even medium format film on the focalplane that would be a stupendous field of view. Ross are one of the best known optics manufactures for uk WD equipment, there are actually a couple of gun ranging scopes by Ross on ebay at the moment. In the 50s and 60s the ex WD was really the only way you could get decent kit and folks often built up scopes and cameras from stuff like this. This guy has just converted it to a scope and built up an eq mount from odds and sods. Its great to see the ex wd stuff again. I used to press my nose up against Wakefields Army stores window in Derby because they would have all the old gunsights and binos in there, I used to dream of all the scopes I could make with them, eeeeh those were the days Phil Link to comment Share on other sites More sharing options...
Brantuk Posted February 13, 2012 Share Posted February 13, 2012 Fascinating Phil - thanks for solving the mystery - you done some amazing stuff that abnormal folks like me wouldn't even think of lol Link to comment Share on other sites More sharing options...
Tweedledee Posted February 13, 2012 Author Share Posted February 13, 2012 Thanks very much Phil, That is a great explanation. I had hoped you might have something to say about it. It really had me racking my brains. With a modern focuser, and 2" eyepieces it could give some outstanding views, if a bit cumbersome. I will have do a bit of calculation and see just what sort of wide fields could be available with the right modifications on the eyepiece end. I wonder if that objective is being distorted by the dent? What do you think. Cheers, Pete. Link to comment Share on other sites More sharing options...
Tweedledee Posted February 13, 2012 Author Share Posted February 13, 2012 Just searched ebay for Ross gunsights. Some very interesting, bullet proof, pieces of kit on there. If I had the spare cash, I would love to collect some of this equipment. Link to comment Share on other sites More sharing options...
philjay Posted February 14, 2012 Share Posted February 14, 2012 I visit auctions and antique and collectors fairs regulary and see the Ross gunsight/alignnment scopes regularly. They are invariably brass, weigh a ton and you usually see them on stalls polished up so you can see your face in them. They arent a great deal of use astronomically (or even terrestrially IMHO) but look nice if you can find a period tripod to stick em on. Phil Link to comment Share on other sites More sharing options...
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