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Jaegers 6" f/15 Question

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#1 jragsdale

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Posted 21 December 2021 - 11:17 PM

Hello! I was selling a restored C8 scope locally, just a  standard sale. The buyer checked out the scope and asked if I'd be interested in a trade. As always I said it depends, he opened up the back of his van and inside was a 7 1/2ft tube of 7" OD with an unmarked black lens cell with a 6" clear aperture. A pair of simple baffles inside the tube that looks hand made. Rear port and focuser pictured. I found very comparable looking scopes from Jaegers so I assume that's what this is.

 

Buyer said he has had this scope for 20 years and the previous owner claimed it used to live in the Lick Observatory, not sure how long ago. He only brought the OTA, I'm going to check out the motorized mount tomorrow but it sounds like a pedestal. I'll update with that info tomorrow. But can anyone tell me any more about this guy? Approx vintage? Any interesting factoids? I don't know a lot about Jaegers scopes.

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#2 deepwoods1

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Posted 21 December 2021 - 11:26 PM

Can't help, but darn interesting..... Will you get to test? Scratch or???? on the objective at 5:30 o'clock? 



#3 ccwemyss

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Posted 21 December 2021 - 11:56 PM

The focuser looks like the 2” Jaegers that came on my 6” AP as a temporary back end while they finished making their first batch of 2.7” focusers. Although mine was painted black. But the cell doesn’t look like the smaller Jaegers that I’m familiar with.

 

Chip W. 


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#4 jragsdale

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Posted 22 December 2021 - 12:06 AM

Can't help, but darn interesting..... Will you get to test? Scratch or???? on the objective at 5:30 o'clock? 

It's a cobweb inside the tube, lens looks pretty good! All the foil spacers were present and looked unmoved.


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#5 jragsdale

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Posted 22 December 2021 - 12:07 AM

The focuser looks like the 2” Jaegers that came on my 6” AP as a temporary back end while they finished making their first batch of 2.7” focusers. Although mine was painted black. But the cell doesn’t look like the smaller Jaegers that I’m familiar with.

 

Chip W. 

You can tell the knobs were red before they did some hack spray paint job. *EDIT* (Maybe that's just a ton of dust?) My guess is the focuser body was black to start. I didn't get a caliper on it though. Looks like the 2" model though.

 

If I pick it up I'll be able to DPAC it.


Edited by jragsdale, 22 December 2021 - 04:03 AM.


#6 deSitter

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Posted 22 December 2021 - 12:16 AM

At f/15 a 6" will still have damaging CA on bright objects, so the main advantage of a refractor is lost at the outset. Now a Baader semi-APO filter will knock out most of the color, to be sure. You need to be at f/20 to be essentially colorless.

 

-drl



#7 Andrey Kobelev

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Posted 22 December 2021 - 12:22 AM

I have heard that F15 can be a good fit for the solar observation w/ etalon :)


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#8 deSitter

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Posted 22 December 2021 - 01:33 AM

I have heard that F15 can be a good fit for the solar observation w/ etalon smile.gif

It's going to be a very rare day when you can actually use 6" of aperture in direct sunlight. The atmosphere near the ground is too turbulent. That is why serious solar telescopes are built on towers.

 

-drl


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#9 gilbert80

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Posted 22 December 2021 - 01:36 AM

I had a 6" F/15 Jaegers, I had no problem with color!


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#10 Kasmos

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Posted 22 December 2021 - 01:52 AM

I'm sure it's a Jaegers. Their large focuser was a 2.7". The one thing that confuses me about Jaegers objectives is that my 4" has a thick ring spacer and I thought they all did, but I've see 6" objectives that don't. A photo of the outside of the cell might help. The outside has a groove/recessed area, but they might not if very old.

 

Here's a 6" f/15 in cell

 

https://www.cloudyni...gers-kit-scope/

 

and a f/10

 

https://www.cloudyni...-f10-objective/

 

BTW, AP used Jaegers focusers on the early scopes

 

https://astro-physic...oldfocusers.htm


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#11 jragsdale

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Posted 22 December 2021 - 03:34 AM

At f/15 a 6" will still have damaging CA on bright objects, so the main advantage of a refractor is lost at the outset. Now a Baader semi-APO filter will knock out most of the color, to be sure. You need to be at f/20 to be essentially colorless.

 

-drl

That's an easy step down. 5.2" or so should give 6" f/20 equivalent CA.


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#12 CHASLX200

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Posted 22 December 2021 - 06:50 AM

Gonna need a bigger boat to hold it.


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#13 bobhen

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Posted 22 December 2021 - 07:10 AM

Many years ago at one of my club’s star parties, I observed Jupiter through a 6” F15 Jaegers refractor. On that night I had my AP 152 F9 triplet nearby. Sorry, there was no comparison. Plenty of color with the Jaegers and a general softness when compared to the zero color on the AP with its much sharper delineations between features, etc., etc.

 

Unless the Jaegers was dirt-cheap or was a project scope, I would rather have one of the low cost 150mm ED doublet refractors produced today.

 

Bob


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#14 deepwoods1

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Posted 22 December 2021 - 08:21 AM

We’re talking a trade for a C8. Restored, so you have time and effort. The Jaegers is certainly a classic and has value within that context. Certainly a statement piece. If the offer was for an 152 triplet, jaws would have dropped. And cash would have to be added. While certainly it would be nice to try, I personally couldn’t handle to weight nor do I have the storage space. I would NEED an observatory. Heaving that on to a mount wouldn’t be something I would do often. That being said, even an AP 152 would lose out on use over a lighter weight instrument. I guess I need more Wheaties! 


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#15 Jeff B

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Posted 22 December 2021 - 08:23 AM

You can tell the knobs were red before they did some hack spray paint job. *EDIT* (Maybe that's just a ton of dust?) My guess is the focuser body was black to start. I didn't get a caliper on it though. Looks like the 2" model though.

 

If I pick it up I'll be able to DPAC it.

And there you go.  As you know, DPAC does not lie.  However, as the seller is local, I'd insist on DPAC first.  There is also value in that DPAC knowledge for the seller too.  Now if it looks great, well that's where the fun begins.

 

Let us know the outcome. 

 

Jeff


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#16 apfever

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Posted 22 December 2021 - 09:12 AM

As usual, most of the negative comments about CA come from those discussing apo, ed, triplets, etc. They are DIFFERENT scopes, not better or worse but DIFFERENT. 

Those zeroed on less CA then put regular achromats is the wrong light with a lack of cognitive awareness. Here is a chart widely accepted (norm) for CA.  A 6" F15 rates very nicely for such a large refractor, and a simple fringe filter would make for awesome.

 

I have a couple of 6" refractors, I think both are in the F8 to F9 area with the specifics not being where I dwell. I have a 120mm F5 refractor finder scope. They all have color and the 120ST can make a bright object look like a messed up Rubik's Cube. If I have to have a oober clear limb on the moon or dot stars then I'll get a different scope, not a 'better' one because it cost more - and it will.  I have a fringe killer. It makes the bigger ones very very nice. It makes the 120ST piggyback very nice for more than just a finder. 

 

Fringe killers.  They block the blue and red side some since these are the biggest culprits. They favor blue blocking since this is the side our eyes have more difficulty with. They do surprisingly little for reducing brightness because we are less sensitive to the ends of our visual spectrum. They DO reduce brightness enough to not get used when I need the 120 ST as a faint fuzzy finder. I then keep the filter installed in my main option eyepiece instead of the focuser. 

 

jragsdale, the CA is not 'damaging' from my standpoint, it is subjective but I think you will find that far from a normal opinion. NICE scope. Dealing on this level you probably already know how to enjoy it to a totally giddy level.  CONGRATS!

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#17 deSitter

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Posted 22 December 2021 - 09:37 AM

I am not particularly bothered by CA, but I just wanted to point out that f/15 isn't a magic number, the aperture is involved. My 5" ED is vastly better than the 5" achromat it replaced on low-contrast objects, and both are around f/9.

 

-drl


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#18 jgraham

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Posted 22 December 2021 - 10:00 AM

I have several EDs (80, 100, and 152mm) and long refractors (60mm f/15, 90mm f/10, 130mm f/9, 150mm f/8). The EDs are just amazing, but I find using a long achro to be pure magic. There's something special about sitting under a yard canon pointing skyward. I find the CA in my long achros to be only visible around bright objects and invisible on pretty much everything else. When observing bright objects the Baader semi-Apo filter does a nice job knocking it down. I have 6" f/10 and f/15 Jaeger's objectives in storage for retirement project scopes. I'm really looking forward to tinkering with them.

 

I look forward to seeing how you progress with this scope!

 

Enjoy!


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#19 CltFlyboy

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Posted 22 December 2021 - 10:27 AM

Count me in that club who just finds a big piece of glass up front magical, especially if it's a light cannon. I really need to get off my keister and finish my Jaegers 6" f/5 build while I'm on Christmas vacation.... I've posted this before, but I just have to share it in this thread:

 

 

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#20 YourNotSirius

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Posted 22 December 2021 - 10:52 AM

My turn!

 

It's a Jeagers. No doubt about it. We have several of them. I grew up using a six inch Jeagers. The old man and mom would go to many public events and set it up for viewing. The color issue is way overblown. Yes, things have improved and yes, you can get filter to help. However, it's not really that much of an issue. Although, on really bright objects, such as Sirius or Vega it can be one but, how often does anyone look at those as a main object? Really?!

 

The focuser is also from Jeagers. We have at least one laying around here somewhere. They are actually decent focusing units. When cleaned, lubricated and adjusted properly they can do very well.

 

I will be very interested in seeing what mount comes with it. I'd jump all over that trade if it were local and offered to us and I have a sand cast C-8 sitting right behind me. It's not been outside in four years mostly because New Hampshire has such horrible weather and the old man can't drive at night because of cataracts. Of course, free time is also required and never seems to coordinate with the weather. It must be a government conspiracy or something. LOL

 

Those lenses went out of production in the mid 1970s, I believe. Since they were almost identical throughout their production run there is no way to really date them. At least, not of which we are aware. We know when two of ours were made because we bought them from the original owners. One was 1965 and the other was 1967. We also have a 1910 Mogey 6 inch f/15 but, that's a horse of a different color. LOL

 

I can tell you that these are wonderful telescopes for deep sky work. We have seen the central star in M-57 multiple times with our 6" f/15 Jeager as well as with our 4" f/15 Jeagers. Using the 6" Jeagers the old man and one of his friends  managed to score the Horsehead Nebula once. It was on a brutally cold night with no Moon, in a very dark area of the state, no lights anywhere at all, a big blanket to shield them from every other source of photons plus, lots and lots of patience. From what they told me it was the observing challenge of their lives.

 

So, you have a change to get a really fine instrument which will wow people much more than that old C-8. One of the best parts about a big refractor is the WOW! factor when people see them. It is what people expect when they come to public events and time after time people would line up at our refractors and ignore larger reflectors for that very reason. Yeah. That was fun!

 

Take the trade! You won't be sorry!

 

Q


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#21 Sean Cunneen

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Posted 22 December 2021 - 11:19 AM

F15 is the shortest focal length that won't vignette in a 2-inch focuser. A 6" f15 is point-of-fact the largest aperture and shortest tube that one person can manage as a refractor. It also has the lowest CA. I know, I have built 4 of them! You need to spend 3x more to get a shorter scope with less color!

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#22 photiost

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Posted 22 December 2021 - 11:35 AM

F15 is the shortest focal length that won't vignette in a 2-inch focuser. A 6" f15 is point-of-fact the largest aperture and shortest tube that one person can manage as a refractor. It also has the lowest CA. I know, I have built 4 of them! You need to spend 3x more to get a shorter scope with less color!

Thats a great looking setup !!


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#23 Kasmos

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Posted 22 December 2021 - 01:20 PM

Many years ago at one of my club’s star parties, I observed Jupiter through a 6” F15 Jaegers refractor. On that night I had my AP 152 F9 triplet nearby. Sorry, there was no comparison. Plenty of color with the Jaegers and a general softness when compared to the zero color on the AP with its much sharper delineations between features, etc., etc.

 

Unless the Jaegers was dirt-cheap or was a project scope, I would rather have one of the low cost 150mm ED doublet refractors produced today.

 

Bob

Lets see, typical C8 sells for about $450-$650. Trading one for Jaegers 6" then comparing that with a AP 152? Remember we are talking classics here.


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#24 Terra Nova

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Posted 22 December 2021 - 01:31 PM

The focuser looks like the 2” Jaegers that came on my 6” AP as a temporary back end while they finished making their first batch of 2.7” focusers. Although mine was painted black. But the cell doesn’t look like the smaller Jaegers that I’m familiar with.

 

Chip W. 

I have a black wrinkle finish Jaegers Newtonian focuser on my 6” reflector. The color of the knobs tells the tale. Jaegers were red bakelite, Edmunds were black.


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#25 Kasmos

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Posted 22 December 2021 - 01:31 PM

 

 

Those lenses went out of production in the mid 1970s, I believe. Since they were almost identical throughout their production run there is no way to really date them. At least, not of which we are aware. We know when two of ours were made because we bought them from the original owners. One was 1965 and the other was 1967. We also have a 1910 Mogey 6 inch f/15 but, that's a horse of a different color. LOL

 

 

I don't have all of my old S&Ts so I can't say when they stopped, but not long ago I was thumbing thru them and I believe an issue from '94 still had a Jaegers ad with the objectives still being offered. I was surprised. BTW, My 4" was purchased from them in '78




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