Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Something for nothing: Celestron C90

  • Please log in to reply
1208 replies to this topic

#1001 andycknight

andycknight

    Vostok 1

  • -----
  • Posts: 153
  • Joined: 13 Aug 2010
  • Loc: UK

Posted 05 February 2016 - 01:13 PM

 

 

[snip...] I actually prefer using the Kellner!

Same here. With my 127 I spent part of one evening doing a shootout between the cheap 25mm plossl that came with my 90 and the cheaper 25mm Kellner that came with the 127. Both were satsifactory, but ever so slightly, the edge went to the Kellner.

Need to post that in the EP forum lol ;)

 

 

I wouldn't dare ! :lol:

 

Regards

 

Andy.



#1002 XyrcesFenol

XyrcesFenol

    Explorer 1

  • -----
  • Posts: 75
  • Joined: 05 Aug 2011

Posted 05 February 2016 - 02:32 PM

Balancing the surrounding costs for the C90. 

 

Weight and mount cost:

- Duck tape, piece of wood and a hammer on the ES Twilight II mount. :grin:

 

Cost balanced and most used EP:

- AT 20mm in binoviewer.

(please disregard the counterweight with green text on the back of the scope...)

 

Winged Eyecups:

- Bicycle tube, cut to snug fit on my face.

They block 100% light from the sides. (The street light at my house is like a close encounter with a white dwarf.)

Works really fine, they also help keeping my eyes centered in the EP, so no blackouts or continuous searching to find the sweet spot. Allows a much more relaxed viewing. Never leave home without one, my best update so far along with the binos.

 

See attached pic.

Attached Files


Edited by XyrcesFenol, 05 February 2016 - 04:07 PM.

  • jrbarnett, rocco13, Patricko and 1 other like this

#1003 Patricko

Patricko

    Gemini

  • *****
  • Posts: 3091
  • Joined: 30 Jan 2007
  • Loc: New Mexico, USA

Posted 05 February 2016 - 04:23 PM

Winged Eyecups:

- Bicycle tube, cut to snug fit on my face.

They block 100% light from the sides. (The street light at my house is like a close encounter with a white dwarf.)

Works really fine, they also help keeping my eyes centered in the EP, so no blackouts or continuous searching to find the sweet spot. Allows a much more relaxed viewing. Never leave home without one, my best update so far along with the binos.

Excellent idea!



#1004 Joe1950

Joe1950

    Apollo

  • *****
  • Posts: 1159
  • Joined: 22 Aug 2015
  • Loc: NJ

Posted 05 February 2016 - 06:53 PM

Congratulations JRB on another topic of epic proportions! 

 


Edited by Joe1950, 05 February 2016 - 07:09 PM.

  • jrbarnett and Crow Haven like this

#1005 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 06 February 2016 - 10:34 AM

Well, I had no Dos Equis Light, so I had to celebrate with an ouzo and water ... after a couple hours out with the C90. 

 

I never drink while observing.

 

:grin:

Mike


  • Joe1950 likes this

#1006 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 06 February 2016 - 10:37 AM

Balancing the surrounding costs for the C90. 

 

Weight and mount cost:

- Duck tape, piece of wood and a hammer on the ES Twilight II mount. :grin:

 

My, that 2x4 and hammer balances the mount, but it would kinda kill the C90 as a grab-n-go.  :thinking:

 

:grin:

Mike



#1007 Joe1950

Joe1950

    Apollo

  • *****
  • Posts: 1159
  • Joined: 22 Aug 2015
  • Loc: NJ

Posted 06 February 2016 - 12:20 PM

Just wondering about the hammer. Where did the ball-peen part go?  :confused:



#1008 PowellAstro

PowellAstro

    Surveyor 1

  • *****
  • Posts: 1640
  • Joined: 14 Oct 2009
  • Loc: Tennessee

Posted 06 February 2016 - 12:21 PM

He may of had to cut it off as it was to much weight :)
  • Sarkikos likes this

#1009 Joe1950

Joe1950

    Apollo

  • *****
  • Posts: 1159
  • Joined: 22 Aug 2015
  • Loc: NJ

Posted 06 February 2016 - 12:23 PM

Ah, yes! The price of a precise balance!  :waytogo:


  • XyrcesFenol likes this

#1010 Joe1950

Joe1950

    Apollo

  • *****
  • Posts: 1159
  • Joined: 22 Aug 2015
  • Loc: NJ

Posted 06 February 2016 - 12:31 PM

Well, I had no Dos Equis Light, so I had to celebrate with an ouzo and water ... after a couple hours out with the C90. 

 

I never drink while observing.

 

:grin:

Mike

 

You should give it a try, Mike! It's amazing what you can see with inverted vision!   :blink:



#1011 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 06 February 2016 - 02:03 PM

Well, I had no Dos Equis Light, so I had to celebrate with an ouzo and water ... after a couple hours out with the C90. 

 

I never drink while observing.

 

:grin:

Mike

Mike:  "I do not always drink Ouzo, but when I do, it's Metaxa."

 

:grin:

 

- Jim


  • Sarkikos likes this

#1012 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 06 February 2016 - 05:58 PM

Yes, so do I!  :waytogo:  Besides, my wife likes the licorice smell on my breath.

 

:grin:

Mike



#1013 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 06 February 2016 - 06:14 PM

Yes, so do I!   :waytogo:  Besides, my wife likes the licorice smell on my breath.

 

:grin:

Mike

I have Metaxa Ouzo in the Butler's Pantry, in fact.  Great stuff.

 

Congrats on being number 1000 too.  It's been a fun ride.

 

Regards,

 

Jim


  • Sarkikos likes this

#1014 duck2k

duck2k

    Messenger

  • -----
  • Posts: 427
  • Joined: 03 Sep 2015
  • Loc: Sun Devil Country

Posted 07 February 2016 - 12:50 AM

After going for over a month without the "little guy," I was jonesin' to bring the C90 out to play.  I wanted to test some new eye pieces I got today, on Jupiter. I used both my Apex 127, and my C90.  I ordered the AT Paradigm ED series (5mm, 8mm, 12mm, 15mm, and 18mm).  I did not do the 25mm, because my ES 68 24mm being a favorite.

 

The C90 performed well with the 32mm for scanning and targeting Jupiter.  Using a light blue filter, I tested the 8, 12, 15, and 18mm EP's.  With the C90 (for me anyway), I found the 12 to 18mm good, the best being with the 15mm.  that is the same EP that performed well on my 127 (the 12mm was good as well on the 127, but that is what worked for me).

 

Man, I forgot how fun the C90 is to use. :sct:


Edited by duck2k, 07 February 2016 - 02:48 AM.


#1015 PowellAstro

PowellAstro

    Surveyor 1

  • *****
  • Posts: 1640
  • Joined: 14 Oct 2009
  • Loc: Tennessee

Posted 07 February 2016 - 01:28 AM

I've used mine at 265x on the moon many times and it is razor sharp. Just a great little/rugged scope!
  • duck2k likes this

#1016 jgraham

jgraham

    Hubble

  • *****
  • Posts: 15611
  • Joined: 02 Dec 2004
  • Loc: Miami Valley Astronomical Society

Posted 07 February 2016 - 01:29 PM

Olde school C90...

 

Attached File  Celestron C90 (2-6-2016)-2.jpg   180.96KB   30 downloads

 

It's a little different beast than the modern 90s, but still a fun little scope. I had this one out last night star-hopping from central Orion south through Lepus. I'm gonna try putting a 50mm RACI on it, though I'm not sure how the ergonomics of that will work out. (I'll find out.) The 32mm HightLight Plossl gives a nice 1.7 degree FOV, though the eye relief is a tad tricky. For daylight use it makes a fantastic spotting scope.

 

Fun stuff.

 

 


  • Sarkikos, Laika, ron2k_1 and 2 others like this

#1017 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 07 February 2016 - 08:32 PM

What is the L-bracket that you have in the fork?

 

Mike



#1018 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 07 February 2016 - 08:43 PM

I've used mine at 265x on the moon many times and it is razor sharp. Just a great little/rugged scope!

I was messing with mine today after finishing my spring refractor cleaning session.  I tested it on my artificial star.  It is *slightly* out of collimation.  I'll touch it up on Polaris during the week ahead if I catch a clear night.

 

Regards,

 

Jim



#1019 ron2k_1

ron2k_1

    Ranger 4

  • *****
  • Posts: 390
  • Joined: 28 Jun 2015
  • Loc: Belize, Earth, Solar System, Milky Way, Virgo Supercluster

Posted 07 February 2016 - 09:09 PM

I was messing with mine today after finishing my spring refractor cleaning session. I tested it on my artificial star. It is *slightly* out of collimation. I'll touch it up on Polaris during the week ahead if I catch a clear night.

Regards,

Jim

You don't trust the artificial star for collimation? I have a Hubble branded on which I use to collimate my other scopes.

On Beetlejeuce my C90 is slightly off as well but I'm intimidated on trying collimation on this scope. I fear I may leave it worst than it is now. You have any online resource on tips how to collimate Maks?

Ron


Sent from my iPad using Tapatalk

Edited by ron2k_1, 07 February 2016 - 09:13 PM.

  • Sarkikos likes this

#1020 jgraham

jgraham

    Hubble

  • *****
  • Posts: 15611
  • Joined: 02 Dec 2004
  • Loc: Miami Valley Astronomical Society

Posted 07 February 2016 - 09:23 PM

"What is the L-bracket that you have in the fork?"

 

That is the mount from my trusty old Meade DSX-90, so it came that way. The DS-2000 mount is essentially a repackaged ETX mount and it does a great job with the little C90 on it. I took a look at installing a 50mm RACI finder on the C90 today and I'm not sure that going to work out, so having it on a GoTo mount is a nice option to have.

 

Fun stuff.


  • Sarkikos likes this

#1021 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 07 February 2016 - 09:36 PM

 

I was messing with mine today after finishing my spring refractor cleaning session. I tested it on my artificial star. It is *slightly* out of collimation. I'll touch it up on Polaris during the week ahead if I catch a clear night.

Regards,

Jim

You don't trust the artificial star for collimation? I have a Hubble branded on which I use to collimate my other scopes.

On Beetlejeuce my C90 is slightly off as well but I'm intimidated on trying collimation on this scope. I fear I may leave it worst than it is now. You have any online resource on tips how to collimate Maks?

Ron


Sent from my iPad using Tapatalk

 

Nope.  I get better results using a real star and very high magnifications on a steady night.

 

Here's one method:

 

http://www.company7....kcasscollim.pdf

 

The small grub screws push the primary and the large ones pull it to tilt the mirror.

 

If instead of the daylight method described in these instructions you elect to use a star, the process is the same except the way you select your first screw is by choosing the rear screw on the opposite side (while looking at a defocused star) of the thinner part of the "donut", idetified by holding your finger in front of the corrector pointing at the center hole across the thin side of the donut.

 

If the indicated screw is a small one, you turn it CCW and then turn the two adjacent large screws CW by the same amount, and then move to the other three screws, turning the opposite large screw CCW the same amount and then finish up by turning the adjacent two small screws CW by this amount.

 

Regards,

 

- Jim


Edited by jrbarnett, 08 February 2016 - 10:20 AM.

  • Laika and Joe1950 like this

#1022 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 08 February 2016 - 06:53 AM

Nope.  I get better results using a real star and very high magnifications on a steady night.

 

Here's one method:

 

http://www.company7....kcasscollim.pdf

 

The small grub screws push the primary and the large ones pull it to tilt the mirror.

 

If instead of the daylight method described in these instructions you elect to use a star, the process is the same except the way you select your first screw is by choosing the rear screw on the opposite side (while looking at a defocused star) of the thinner part of the "donut" by holding your finger in front of the corrector pointing at the center hole across the thin side of the donut.

 

If the indicated screw is a small one, you turn it CCW and then turn the two adjacent large screws CW by the same amount, and then move to the other three screws, turning the opposite large screw CCW the same amount and then finish up by turning the adjacent two small screws CW by this amount.

 

Regards,

 

- Jim

 

 

An artificial star should work just as well as a star in the sky.  Why shouldn't it?  This is collimation, not a star test, in the sense of actually "testing" the optics.  All you're doing is making sure the optics are aligned properly, not testing to see if the scope has SA or a turned edge or roughness or whatever.

 

I place a Hubble artificial star up high on a photo tripod and position the scope down low at the farthest position where I can get a direct line of sight.  I know many observers complain that collimating the telescope when it is horizontal will not give good results when you take the telescope out to look at the sky.  This is why I position the artificial star high and the scope low when I collimate.

 

You need a certain minimum distance when using an artificial star for testing a telescope, or there will be induced SA.  But this isn't testing, just collimating.  All you need to do is make sure the rings are concentric.  

 

Besides, inside the house, the scope is already acclimated.  You don't have to wait for the image to settle down.  You can put in a short focal length eyepiece right off the bat for high power if you want.   And you don't have to fumble around in the dark.  

 

Thanks for the PDF manual to collimate Maks.  I've never collimated any of my Maks.  They've always been right on.  I have had to collimate SCTs.

 

Mike


Edited by Sarkikos, 08 February 2016 - 07:06 AM.

  • ron2k_1 and Joe1950 like this

#1023 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 08 February 2016 - 10:26 AM

 

Nope.  I get better results using a real star and very high magnifications on a steady night.

 

Here's one method:

 

http://www.company7....kcasscollim.pdf

 

The small grub screws push the primary and the large ones pull it to tilt the mirror.

 

If instead of the daylight method described in these instructions you elect to use a star, the process is the same except the way you select your first screw is by choosing the rear screw on the opposite side (while looking at a defocused star) of the thinner part of the "donut" by holding your finger in front of the corrector pointing at the center hole across the thin side of the donut.

 

If the indicated screw is a small one, you turn it CCW and then turn the two adjacent large screws CW by the same amount, and then move to the other three screws, turning the opposite large screw CCW the same amount and then finish up by turning the adjacent two small screws CW by this amount.

 

Regards,

 

- Jim

 

 

An artificial star should work just as well as a star in the sky.  Why shouldn't it?  This is collimation, not a star test, in the sense of actually "testing" the optics.  All you're doing is making sure the optics are aligned properly, not testing to see if the scope has SA or a turned edge or roughness or whatever.

 

I place a Hubble artificial star up high on a photo tripod and position the scope down low at the farthest position where I can get a direct line of sight.  I know many observers complain that collimating the telescope when it is horizontal will not give good results when you take the telescope out to look at the sky.  This is why I position the artificial star high and the scope low when I collimate.

 

You need a certain minimum distance when using an artificial star for testing a telescope, or there will be induced SA.  But this isn't testing, just collimating.  All you need to do is make sure the rings are concentric.  

 

Besides, inside the house, the scope is already acclimated.  You don't have to wait for the image to settle down.  You can put in a short focal length eyepiece right off the bat for high power if you want.   And you don't have to fumble around in the dark.  

 

Thanks for the PDF manual to collimate Maks.  I've never collimated any of my Maks.  They've always been right on.  I have had to collimate SCTs.

 

Mike

 

I get better results when my light source is at infinity.  I also think the more pronounced poisson point I get using a real star at night helps accuracy of collimation.

 

FWIIW, Orion's new instructions suggest you can do it in day from the rear with no star using a collimating eyepiece.  I haven't tried daytime collimation using any form of sight tube/Cheshire combo on an MCT.

 

- Jim



#1024 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 22204
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 08 February 2016 - 10:35 AM

A collimating eyepiece for a Mak?  What would that look like?  Could you use the usual collimating eyepiece that is available for refractors?  The home-made collimating eyepiece described in the Orion manual sounds like the cheap collimating cap that is thrown in with some telescopes.  

 

Mike


Edited by Sarkikos, 08 February 2016 - 10:39 AM.


#1025 jrbarnett

jrbarnett

    Eyepiece Hooligan

  • *****
  • topic starter
  • Posts: 24980
  • Joined: 28 Feb 2006
  • Loc: Petaluma, CA

Posted 08 February 2016 - 10:47 AM

A collimating eyepiece for a Mak?  What would that look like?  Could you use the usual collimating eyepiece that is available for refractors?  The home-made collimating eyepiece described in the Orion manual sounds like the cheap collimating cap that is thrown in with some telescopes.  

 

Mike

The only collimating eyepiece Orion sells is a combo sight tube/Cheshire.  It doesn't grok with me actually.  I don't see how it would work in a MCT.  The daytime "center the mirror reflections from the front" method actually makes more sense, though I seriously doubt its accuracy; it's hard to keep your eye exactly centered, and if th eeye isn't centered on the secondary, your estimate of whether and how much the alignment is off will be wrong.

 

It's worth noting that folks swear you can use the Tak refractor collimating eyepiece to collimate the Mewlon 210 too.  It works on the 250 very easily because the 250 has a center spot on the secondary.  The 210 does not.  I've never been able to make it work, which is sad because the Mewlon 210 is hard to collimate once it's out of whack and performs poorly if not collimated properly.

 

- Jim


Edited by jrbarnett, 08 February 2016 - 10:48 AM.

  • Sarkikos and ron2k_1 like this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.







Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics