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The Scope that Jack built...


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I was hunting a few things out on ebay and by accident of the rubbish search engine that ebay used I found this..

http://www.ebay.co.uk/itm/240mm-diam-9-5-F3-5-800mm-refractor-Leitz-Weszlar-objective-/171021173162?_trksid=p2045573.m2102&_trkparms=aid%3D555003%26algo%3DPW.CAT%26ao%3D1%26asc%3D33%26meid%3D6959066041269854883%26pid%3D100034%26prg%3D1031%26rk%3D2%26

(Moderators:-Why can't I add this as a Hyperlink to shorter text??)

Whilst a 240mm lens may be nice for building a telescope, I am not sure that a cinema projector lens is an ideal choice, this is very short and I would image that the doublet construction may have a problem with chromatic aberration at the edges of the field....further, although the seller accepts this may not be the best built scope, if you look at it the appearance is as if it isn't even joined together behind the lens mount..

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Ha! This is going back to the "good old days" of my youth when purpose-built telescopes of any real aperture were rare and well beyond any but the well-heeled.

Lots of amateurs built their own out of war-surplus lenses and whatever else they could scrounge.

If I wasn't strapped for cash I would take a punt on this for old-times sake. Bit ironic really, not being able to afford a cut-price job,

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I actually doubt it is only a doublet. My guess would be a Petzval derivative.

We're looking at a Zeiss cinema projection lens. It will be designed to project a flat plane (The film) onto a flat plane (The screen), a scaled up version of an enlarging lens and not a trivial exercise.

Also we're talking cinema. Want to know ho much cine kit costs? Your Apo 'fract is small-change by comparison.

The more I think about this, the more I'd like to take a punt for building a fast astro-cam.

I won't, of course. I don't have a current Ebay account, not to mention the time and finances to pull it off.

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I'm struggling to convince myself that it would make a genuinely good telescope. Certainly not at £160, anyhow. At £16 I might give it a punt just to see how well it worked...

James

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Sorry, I thought it was Zeiss, it's not. The ring says Leitz Wetzlar.

And they don't put their name on bottle-bottoms!

Even at £160 I'd still take a punt if I had the resources, mainly for the fun of making a fast astro camera.

Regrets...

Have a look here

http://www.creativevideo.co.uk/index.php?t=category//lenses/pl+mount+cine+lenses

To get an idea of how much cine lenses can cost. Note some are marked "call us" that's 'cos they don't want casual viewers having heart attacks! :eek:

Edited by DaveS
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