Jump to content


Photo

older 8" blue sonotube dob

  • Please log in to reply
40 replies to this topic

#26 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 25 September 2013 - 11:51 PM

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.

#27 azure1961p

azure1961p

    Voyager 1

  • *****
  • Posts: 10462
  • Joined: 17 Jan 2009
  • Loc: USA

Posted 26 September 2013 - 07:06 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

#28 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 26 September 2013 - 09:19 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?

#29 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 44731
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 26 September 2013 - 09:56 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?


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

#30 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 26 September 2013 - 10:23 AM

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.

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.

#31 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 26 September 2013 - 02:08 PM

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

Attached Files



#32 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 44731
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 27 September 2013 - 04:41 AM

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

#33 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 27 September 2013 - 10:08 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!

#34 Calypte

Calypte

    Apollo

  • -----
  • Posts: 1168
  • Joined: 20 Mar 2007
  • Loc: Anza, California

Posted 27 September 2013 - 12:21 PM

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

#35 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 29 September 2013 - 07:44 AM

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.

#36 azure1961p

azure1961p

    Voyager 1

  • *****
  • Posts: 10462
  • Joined: 17 Jan 2009
  • Loc: USA

Posted 29 September 2013 - 06:56 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

#37 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 15 November 2013 - 10:14 AM

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

Attached Files



#38 herrointment

herrointment

    Aurora

  • *****
  • Posts: 4923
  • Joined: 12 Mar 2011
  • Loc: East of Poskin

Posted 15 November 2013 - 04:47 PM

Late 1970's Novak?

Attached Files



#39 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 15 November 2013 - 09:46 PM

Interesting... it looks identical.

#40 Space_Girl1234

Space_Girl1234

    Explorer 1

  • -----
  • Posts: 93
  • Joined: 06 Mar 2011

Posted 15 November 2013 - 11:00 PM

Is a Pirate telescope a good one?

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

#41 precaud

precaud

    Surveyor 1

  • *****
  • Posts: 1664
  • Joined: 05 Dec 2012
  • Loc: north central New Mexico

Posted 15 November 2013 - 11:51 PM

Ahhh, now that's more like it!

A huge thank you to the CN forum member who, in response to my wanted ad, sent this UO cell to me and refuses to accept payment for it. What an amazing group we have here.

Attached Files








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics