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Equipment Discussions >> Reflectors

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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: older 8" blue sonotube dob new [Re: Jon Isaacs]
      #6100189 - 09/25/13 11:43 AM

Quote:

Is your friend still making mirrors/telescopes ? I have a sneaky suspicion the answer is yes..

Jon



Yes. Mirrors, both primaries and secondaries. Mostly contract work. No scopes.


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: Calypte]
      #6101179 - 09/25/13 07:54 PM Attachment (26 downloads)

I forgot to take pics before I started, but the mirror cleaned up perfectly. There must be something protective about NM dust, because this is now the second mirror that I've bought that had years of local dust accumulation on it that was in fabulous shape underneath!

The blue-green hue of plate glass is clearly visible, as well as the particle board cell.

I taped between the cell and mirror to prevent water from getting in between them. Is there any reason not to leave the tape in place?

Next job is to center spot it (with the photo centering technique, of course!).

Oh, and in the background is my 16" mirror which just arrived with a new figure and new coat...


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: precaud]
      #6101186 - 09/25/13 07:57 PM Attachment (25 downloads)

In the off chance that someone might recognize the components and identify where this kit came from, I'll post a couple more pics. Here's a view of the OTA front.

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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: precaud]
      #6101191 - 09/25/13 08:01 PM Attachment (25 downloads)

And one of the 4" molded plastic altitude bearings. The previous owner thought it moved too easily and had wrapped duct tape around it for resistance. The tape adhesive had hardened long ago and was a pain to remove. Also visible is where the original kit builder had misplaced the bearings and covered up the gap with blue marker pen... sigh.

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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: older 8" blue sonotube dob new [Re: precaud]
      #6101466 - 09/25/13 10:58 PM

It could still be a gem despite the rough around the edges mechanics . You might want to spray the tube with Kilz to coverup ink before you paint to prevent pigment seepage. I'm curious to see how this one performs.

Pete


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: azure1961p]
      #6101603 - 09/26/13 12:51 AM

Good idea on the sealing primer, Pete, thanks. This one is definitely rough around every edge, but the mirror is superb. I was just out with it, collimated it on a star (what a pain... first order of business is to put a center spot on this thing so I can use tools!). I compared it to my AD10 on several targets, and this mirror is excellent. Sharper, and better contrast, background is just plain darker with less "haze" around stars. When viewing M31 tonight, I could clearly see M110 in this scope, whereas it was barely discernible in the AD10 (without CC). A diamond in the rough.

I really don't like seated viewing from the left side. My body was protesting the whole time. It doesn't like being contorted that way. I'm going to move the bearings over for right-side viewing. That would be a good time to repaint the tube.


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: older 8" blue sonotube dob new [Re: precaud]
      #6101810 - 09/26/13 08:06 AM

Interesting as Im a dyed in the wool left side observer - always have been. Something to consider - and its simple and cheap with big pluses - mount a 100mm DC powered fan suspends by rubber bands behind the primary. It speeds cooling but more than that, helps get rid of the heat within the tube and it shows in the tighter star images - even at low power .

Pete


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: azure1961p]
      #6102014 - 09/26/13 10:19 AM

I suppose it could just be poor focuser and finder placement that is the cause of the discomfort.

Interesting you mention cooling, I was wondering about that very thing last night as I watched tube currents morph the star test image. There's no way to get air to the back of the mirror when it's glued to the particle board cell. Is it still worthwhile having a fan back there?


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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: older 8" blue sonotube dob new [Re: precaud]
      #6102096 - 09/26/13 10:56 AM

Quote:

I suppose it could just be poor focuser and finder placement that is the cause of the discomfort.

Interesting you mention cooling, I was wondering about that very thing last night as I watched tube currents morph the star test image. There's no way to get air to the back of the mirror when it's glued to the particle board cell. Is it still worthwhile having a fan back there?




It's worthwhile have a fan back there.. some holes in the cell, a new cell..

Left versus right.. I have scopes both ways.. it really doesn't matter but focuser and finder location are critical for comfort. Looking at the photos, it looks to me like the focuser is at maybe 60 degrees, nearly vertical. I think something closer to 40 degres is much more comfortable.

Jon


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: Jon Isaacs]
      #6102149 - 09/26/13 11:23 AM

Quote:

It's worthwhile have a fan back there.. some holes in the cell, a new cell..




Thanks Jon. I definitely see the disadvantage of not being able to wash air over the back of the mirror to cool it. A new cell eventually, perhaps, but not anytime soon.

Quote:

Looking at the photos, it looks to me like the focuser is at maybe 60 degrees, nearly vertical. I think something closer to 40 degres is much more comfortable.




Viewing the OTA from the front as a clockwise circle with 0* being straight up, the focuser is at about 330* and the finder is about 355*, not even at the top, and sitting too close to the tube. So you're right, the focuser is sitting too far atop the tube, no question.


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precaud
Pooh-Bah
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Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: precaud]
      #6102525 - 09/26/13 03:08 PM Attachment (19 downloads)

Took the 2ndary out for cleaning. Does anyone know who makes this? It looks like a unique design.

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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: older 8" blue sonotube dob new [Re: precaud]
      #6103526 - 09/27/13 05:41 AM

Quote:

Took the 2ndary out for cleaning. Does anyone know who makes this? It looks like a unique design.




I can't put my finger on who made it but it looks pretty standard, it could even be an AstroSystems, I have two of them and they are both different.

Jon


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: Jon Isaacs]
      #6103941 - 09/27/13 11:08 AM

Thanks Jon, you're right. Looking at the photos on their website, it was never clear to me if that angled piece was a shroud that fit over the 2ndary or an angled sleeve that it attached to.

I center-spotted the primary mirror and collimated it yesterday. I definitely need to replace those Philips head 2ndary adjustment screws! Ugh!


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: older 8" blue sonotube dob new [Re: precaud]
      #6104227 - 09/27/13 01:21 PM

It looks identical to the secondary holder in my 1973 8-inch Cave Newt.

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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: azure1961p]
      #6107066 - 09/29/13 08:44 AM

Quote:

Interesting as Im a dyed in the wool left side observer - always have been.




Pete, are you either left-handed or a left-eye observer? It became clear to me last night the two ergonomic reasons why I prefer right-side observing.

: Left hand guides the OTA, right hand works the focuser.
: The right arm comes in roughly parallel to the OTA and just feels more comfortable.

The one thing I'll say for left-side observing is that it predisposes me to use both eyes - left eye for the finder, right eye for the eyepiece.


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: older 8" blue sonotube dob new [Re: precaud]
      #6108102 - 09/29/13 07:56 PM

I'm a left eye observer. I'm right handed so I guide with that arm . I focus with my right too. Left hands for holding another eyepiece or filter.

Pete

Edited by azure1961p (09/29/13 07:57 PM)


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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: azure1961p]
      #6196240 - 11/15/13 10:14 AM Attachment (7 downloads)

This is the old cell. It provides a good wavetrap (absolutely no reflections around the mirror), but it also provides absolutely no cooling!

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herrointment
Post Laureate
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Reged: 03/12/11

Loc: North of Hwy. 64
Re: older 8" blue sonotube dob new [Re: precaud]
      #6196832 - 11/15/13 04:47 PM Attachment (5 downloads)

Late 1970's Novak?

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precaud
Pooh-Bah
*****

Reged: 12/05/12

Loc: north central New Mexico
Re: older 8" blue sonotube dob new [Re: herrointment]
      #6197257 - 11/15/13 09:46 PM

Interesting... it looks identical.

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Space_Girl1234
member


Reged: 03/06/11

Re: older 8" blue sonotube dob new [Re: precaud]
      #6197428 - 11/15/13 11:00 PM

Is a Pirate telescope a good one?

My grandpa has a big one that is taller than me.


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