9.5" f3.5 Leitz-Wetzlar triplet

[LDUNN1]

Anyone here have any experience with this lens cell? I've just bought one with the intent to build it up into a scope, I've had a rudimentary daylight visual & imaging test through the lens cell just hand-holding eyepiece & camera around the focal plane of the lens cell, with the lens cell propped up pointing at a distant tree against a bright background sky, & the chromatic aberration (CA) seemed pretty well controlled considering the size & speed & age of the lens cell. I'd love to hear from anyone else that has one or has looked through one, I know its a long shot as it is probably a rare lens cell, but someone here might know something about them.....

[michael.h.f.wilkinson]

I must say I do not know that lens. Can you post images or links?

[davew]

Does it have "EPIS" written on it ?

Sounds rather interesting,

Dave.

Just thought. Does the 9.5" refer to the focal length or diameter ?

[LDUNN1]

Dave, yes it does have 'EPIS' on the lens cell, but it doesn't have the lever sticking out of the side of the lens cell which runs is an angled slot that I have seen on other Leitz Wetzlar lenses marked EPIS.......I'm not sure what that lever is for, I presume either a focus or zoom controller, but my lens cell doesn't have this - it looks like a normal telescope lens cell, albeit a bit on the large & heavy side!

Michael, I attach images of the lens cell, some have an ST80 (with extension tube, lodestar & dew shield attached) included in the photo to help with scale.

I've only done the most basic of tests so far - propping the lens cell up on a bed & aiming it at a distant tree then handholding an eyepiece, & then a camera (with lens) roughly at the focal plane so I could look at the image of the tree (against bright sky backdrop which usually shows up chromatic aberation pretty well), & then photo the tree. I'll attach images of this too.

I'm trying to get a feel for how good or other wise this lens cell would be to use as a scope (visual &/or imaging), ahead of specing any componentary to go with it. If someone out there has experience with something very similar, then it might give me a better idea on how much I should put into the tube & focuser. It looks surprisingly good from my quick looksee test, but due to the size & wieght, I can't easily test this lens cell on a night sky, so its a bit of an unknown.

Thanks guys for showing an interest in this post, this is an interesting lens to me, & I am looking forward to eventually building it up into something useable.

[davew]

That's a monster !

The EPIS bit refers to an Episcope. The angled slot and lever you've seen on other lenses was to focus by sliding the cell forward and back. We had a similar one at school but not so big.

I can't help with it's suitability but have my doubts due to the focal ratio. In an Episcope you need all the light throughput you can get but I have a nagging feeling it will have aberations under the stars.

If you get it working do please show it off, I'm very interested

Dave.

[LDUNN1]

yes, I had my doubts about it too......after I had won it, but before I'd seen it in the flesh........The big aperture & fast focal ratio not being condusive for colourless views.

.......however, once it arrived & I started looking at it, & more importantly, through it, I've been gaining confidence in the purchase.

despite the rudimentary method, if you look at the image above of the tree through the lens with a bright background, the chromatic aberation seems to be pretty well controlled.........it is certainly much better than I thought it would be, but time will tell, it's going to be a fun & interesting experiment!

[DaveS]

Ha! Is that the one that was on ebay a while ago? There was a thread on it in The Astro Lounge I think as I posted in it. I might have bid myself if funds weren't so tight.

Didn't the original seller think it was a cinema projection lens?

Might be worth trying it out as an astro cam, not sure what you'd mount it on though.

Do keep us posted, it looks an interesting project.

[LDUNN1]

That's the one DaveS.

I took a bit of a gamble on it......seemed an interesting bit of glass.

From what I've seen so far, I'm happy I took the gamble, the colour seems reasonably well controlled for such a large fast lens. Once I build it up into a proper scope if there is still a bit of residual colouration, I can still revert to a minue violet filter to clean it up, but currently it is not looking like it will need it. Might be a different case once I get it out under stars mind.

If a minus violet filter doesn't tame things, I can still use it for imaging with NB filters - & SII & OIII will sure appreciate the f3.5........can't wait to add the focal reducer to that ;-)

[DaveS]

Will be very interested to see images through it.

This takes me back to the old days when hard up amateurs would build telecopes / astro cameras from all sorts of salveged optics.

As I said in the original thread it's from Leitz, the real one in Wetzlar (Not Panasonic produced re-brands), and they don't put their name on bottle-bottoms!

*** Contemplates how much APM would charge for a 9.5" f/3.5 APO triplet ****

[michael.h.f.wilkinson]

It does look like a projection lens. Interesting project I would say.

[LDUNN1]

From what I've Googled on it (& the fact it has 'EPIS' written on its nose) I am sure, as DaveW has said above, that it is from an episcope, but it does not have the focus lever mentioned above that I've seen elsewhere on the web - it looks like a typical 'scope lens cell.....just a lot bigger!

DaveS - I had the same sort of thoughts -

a) Leitz were a quality manufacturer, so the optics are probably half way decent - albeit not benefiting from latest tech.

how much would a 9.5" refractor cost me these days, even if it were not a full-on APO (the clue being, I probably couldn't afford it! ;-) )

I had one further thought too though.

c) even if the optics were only of achro quality (& from the little I've seen so far, I suspect they would actually be described as at least semi-apo), then as something like an ST150 costs approx £500 today & thats only a 6" f5, & refractor prices seem expotential with aperture, then that puts a 9.5" f3.5 significantly over the cost of something like the ST150. Plus if the optics were at least semi-apo, I could combat a little colouration with filters (for both visually & imaging)

.....hence why I ended up getting this lens cell I guess.

I have a star party in May, so I am contemplating knocking something quickly together in wood just so i can have a look through this cell (I have a large focuser avaialble from another scope that's currently out of action), but I've started making enquiries about CF tubes for this lens cell long term, think it will be some months before I can afford to complete the build alng the lines I'm thinking long term though.

[E621Keith]

Have you consider giving Mark at Moonraker Telescope a call? I think he can make a custom tube for your lenscell.

[LDUNN1]

cheers Keith, no I have not considered that as I didn't know about Moonraker telescope. Thanks, I will look into it.