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Equipment Discussions >> ATM, Optics and DIY Forum

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Binojunky
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Reged: 12/25/10

Re: Jaegers objective new [Re: dawsonian2000]
      #4695548 - 07/16/11 01:43 PM

A fair chunk of change for a item that may be very iffy, JMHO, DA.

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martym
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Reged: 02/15/10

Re: Jaegers objective new [Re: Binojunky]
      #4696477 - 07/17/11 12:28 AM

Yes, it's not dirt cheap, but low enough to take a chance. SS gives 10 days after receiving the item to evaluate and return for full refund if desired. I've returned some things and SS refunded my Paypal payment no problem, and full amount. I think that the lens would be as least as good as the mass produced Chinese glass that's being bought- some ain't too good.

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martym
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Reged: 02/15/10

Re: Jaegers objective new [Re: martym]
      #4696486 - 07/17/11 12:39 AM

Also, I forgot to mention Roland Christen's statement. If you have ever met him (and I have) you need to understand that he is not going to speak well of anything that does not come near to optical perfection as possible; so the comment on Jaegers is understandable. Whatever glass comes from his shop is going to be as good as possible, and that is slow to make. So you are not going to get an AP lens out of a Jaegers shop, no matter what you paid. So if you can live without 100X per inch of diameter, than maybe a Jaegers might be OK.

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DAVIDG
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Reged: 12/02/04

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Re: Jaegers objective new [Re: martym]
      #4696506 - 07/17/11 01:07 AM Attachment (228 downloads)

Here is a picture of the 4" f/15 Jaegers lens I just purchased from Surplus Shed being tested via Double pass autocollimation. The pictures is taken on the outside of focus. A perfect lens would show perfectly straight lines. This one has the lines curving inward indicating overcorrection of around 1/4 wave.

- Dave


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DAVIDG
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Reged: 12/02/04

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Re: Jaegers objective new [Re: DAVIDG]
      #4696517 - 07/17/11 01:18 AM Attachment (169 downloads)

Just to compare, here is a picture of a very good 3" f/15 Selsi objective from $60 Ebay telescope with about 1/10 wave error. Note the straightness of the ronchi lines. I can barely detect any bowing of the Ronchi lines as I pass from inside to outside focus. While on the Jaegers lens the bowing is very easy to see.

- Dave


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neo
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Re: Jaegers objective new [Re: DAVIDG]
      #4696625 - 07/17/11 04:55 AM

So glad I've passed the temptation test ok .

Is there a way to correct a bit the Jaegers lens without refiguring? Maybe different spacing between the lenses?


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tim53
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Reged: 12/17/04

Loc: Highland Park, CA
Re: Jaegers objective new [Re: neo]
      #4696952 - 07/17/11 11:08 AM

I was reminded that I have a thread on my 6" f/15 Jaegers, that at least shows it has 3 foil spacers and no spacer ring: 6" f/15 Jaegers construction

-Tim.


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Napersky
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Re: Jaegers objective new [Re: dawsonian2000]
      #4704709 - 07/21/11 12:30 PM

Sean,

I need to PM you.

Mark


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Sean Cunneen
Let Me Think
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Reged: 08/01/07

Loc: Blue Island Illinois
Re: Jaegers objective new [Re: DAVIDG]
      #4704905 - 07/21/11 02:09 PM

Quote:

Just to compare, here is a picture of a very good 3" f/15 Selsi objective from $60 Ebay telescope with about 1/10 wave error. Note the straightness of the ronchi lines. I can barely detect any bowing of the Ronchi lines as I pass from inside to outside focus. While on the Jaegers lens the bowing is very easy to see.

- Dave




Dave, how large is your flat? From it's shape I'd assume your using a secondary?

Sean


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ccaissie
professor emeritus


Reged: 09/13/10

Loc: Whitefield, Maine
Re: Jaegers objective new [Re: neo]
      #4705175 - 07/21/11 04:53 PM

Alex:

According to an OSLO experiment, increasing the spacing undercorrects the lens, both in spherical abberation and color correction.


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DAVIDG
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Reged: 12/02/04

Loc: Hockessin, De
Re: Jaegers objective new [Re: Sean Cunneen]
      #4705692 - 07/21/11 09:58 PM

Quote:

Quote:

Just to compare, here is a picture of a very good 3" f/15 Selsi objective from $60 Ebay telescope with about 1/10 wave error. Note the straightness of the ronchi lines. I can barely detect any bowing of the Ronchi lines as I pass from inside to outside focus. While on the Jaegers lens the bowing is very easy to see.

- Dave




Dave, how large is your flat? From it's shape I'd assume your using a secondary?

Sean




Sean,
My small autocollimation flat, which is the one I'm using in the picture is 7" x 11". It was government surplus and is mounted on heavy aluminum mount. I tested it and it is good to 1/10 wave with no edge problems. My large flat is 11" x 15" and also good to 1/10 wave. The flat does not have to be very flat just smooth. You can have many waves of error in the flat, again along as it is smooth and it adds an extremely small error to test.

- Dave


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dawsonian2000
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Loc: Riverview, FL, USA
Re: Jaegers objective new [Re: dawsonian2000]
      #4719245 - 07/29/11 09:55 AM Attachment (136 downloads)

Just received my 6" f/10 objective on Monday and it is definitely uncoated. Here is a photo showing the date and some other numbers on the side of the flint element, which I am hoping someone can elaborate on.


Mel


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dawsonian2000
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Reged: 07/26/06

Loc: Riverview, FL, USA
Re: Jaegers objective new [Re: dawsonian2000]
      #4719250 - 07/29/11 09:57 AM Attachment (95 downloads)

Here is another photo of the other side of the 6" f/10 flint element with number values inscribed in pencil.

Mel


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dawsonian2000
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Reged: 07/26/06

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Re: Jaegers objective new [Re: dawsonian2000]
      #4719263 - 07/29/11 10:05 AM Attachment (90 downloads)

This is a side shot of the crown element showing number values.

Mel


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dawsonian2000
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Reged: 07/26/06

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Re: Jaegers objective new [Re: dawsonian2000]
      #4719267 - 07/29/11 10:06 AM Attachment (85 downloads)

...and the other side of the 6" f/10 crown element.

Mel


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dawsonian2000
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Reged: 07/26/06

Loc: Riverview, FL, USA
Re: Jaegers objective new [Re: dawsonian2000]
      #4719278 - 07/29/11 10:10 AM

I understand that the line markings on the sides of lenses are to be used to align both elements, but it would be great to know more about the number values. A couple of number groupings looks like dates, but they may have a totally different meaning from the perspective of an experienced eye.

Mel


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Pinbout
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Reged: 02/22/10

Loc: nj
Re: Jaegers objective new [Re: dawsonian2000]
      #4719286 - 07/29/11 10:15 AM

Quote:

Here is a photo showing the date and some other numbers on the side of the flint element, which I am hoping someone can elaborate on.







Isn't everyone at stellafane this weekend?


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dawsonian2000
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Reged: 07/26/06

Loc: Riverview, FL, USA
Re: Jaegers objective [Re: Pinbout]
      #4719300 - 07/29/11 10:23 AM




Isn't everyone at stellafane this weekend?




Wish I were! One day I will take the journey to visit during a convention. I would love to bring along my 10" f/5.6 fork mounted Newtonian.

Mel


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martym
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Reged: 02/15/10

Re: Jaegers objective [Re: dawsonian2000]
      #4724238 - 08/01/11 08:36 AM

Mel,
Are you planning to use postage stamps for spacers, and did you buy the 6" Jaegers cell for $50 also at SS ?

marty


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dawsonian2000
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Reged: 07/26/06

Loc: Riverview, FL, USA
Re: Jaegers objective [Re: martym]
      #4724707 - 08/01/11 01:12 PM Attachment (102 downloads)

Hi Marty,

I will be using aluminum duct tape for my spacers. Below is a photo of the roll of tape (2.5" wide) I purchased years ago from Home Depot. Atop the roll, you can see a small cutoff section of tape is peeled back to show the adhesive backing partially removed from the piece. I have, and will use this tape for other refractor objectives. Also it stays in place yet comes off cleanly despite having excellent adhesion to the glass surface. Another cool thing is that you can stack layers to make tabs to suit you spacing needs. For this, I recommend stacking easy to handle sized sections (2" x 2" with the adhesive backing left on the bottom sheet ), then cutting the tabs from the pre-stacked sheet.

As for the cell, I am hoping to have one custom made. But, if that does not work out, I will purchase the one for $50.00.


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