153mm DIY refractor ebay

[Joseki]

Since I've got a bad ebay habit I've been watching this diy refractor.

http://www.ebay.co.uk/itm/310590816922?_trksid=p5197.c0.m619

even the sellers name seems to morph into "stay away" to my eyes, but then it's not far away and I know someone who works around there. I guess I'm curious as to what sort of lens that is. I vaguely remember hearing about some old military lenses which might explain it. Knackered old telescopes and telescope bits are very interesting to me so I'd be interested to know whether you could in theory do something with one of these.

cheers

[Joseki]

Other than the CAPS, it's described as a terrestrial scope. Actually I should talk to my neighbour about this as I remember him saying something about getting hold of an RAF survey photography lens in order to make a telescope only to encounter some problems (that I didn't quite follow).

[John]

I think it is an ex-military lens. The native focal ratio of the lens seems to be around F/4.5. The iris will reduce the effective aperture to between 4.3 inches (F/6.3) and 1.2 inches (F/22). If F/6.3 is as wide as the aperture gets then it's effectively a 4.3 inch scope. Could be OK as a rich field scope I guess.

[Joseki]

Ok, thanks that's interesting to know

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[cantab]

Wow, that's a thing!

[Centus]

He DOES say "COLLECTION ONLY" which, to me, spells, can't be used for actual visual work.

[Centus]

Scratch that... just realized it means no postage...

[DaveS]

I don't think I'd touch that with the proverbial

[Moonshane]

I think it depends on the price. if it goes for a small sum then it might make an interesting project but at £100+ you might possibly be better with a 102mm f5 SW frac which I think go for about that for the OTA.

one thing's for sure, it looks a heavy old beast.

[Peter Drew]

It's one of the standard ex WD 36" F6.3 four element photographic objectives, I've had several over the years and even had a binocular with two of them. They have a fair bit of off axis coma and CA but if stopped down to 4" or less with the built in iris the images are quite good. Very heavy construction!