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Equipment Discussions >> Cats & Casses

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: stevenf]
      #5575509 - 12/17/12 10:48 AM

Quote:


You might want to consider going with a 20mm instead of the 15mm, if you're getting the barlow, since a barlowed 32mm will give you 16mm, and you're duplicating eyepieces. With a 20 and 32 you'll get four options, 32, 20, 16, and 10mm.



Perhaps Steve's way is best for now. Just get a 20mm and a barlow.
Update:
I went ahead and ordered the GSO 90-deg 99% Dielectric mirror diagonal, GSO 1.5x X 2x barlow, and a GSO 20mm plossl. Now all I need is to order the mount and I'll be in buisness!

Edited by RafaelP (12/17/12 04:37 PM)


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MrJones
Pooh-Bah
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Reged: 09/15/10

Loc: Indiana
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5576444 - 12/17/12 09:21 PM

Grats. I didn't mean to poopoo it too much. It's a good terrestrial scope and ok for astronomy. Hopefully you got the 90 degree diagonal and not the 45. I used my Smart Astronomy 19mm EF (same as Orion Edge On 19mm) in my mom's - nice EP for sure and good in the C90 too.

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mmclure
professor emeritus
*****

Reged: 12/30/10

Loc: Sacramento, CA USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: MrJones]
      #5577354 - 12/18/12 01:53 PM

My C90 arrived last night and I took it out to the sidewalk for first light on the Moon and Jupiter. Here's my first impressions:
  • The OTA feels very solid and well constructed. Can't say the same about the finderscope, though.
  • Views of the Moon and Jupiter with the included 32mm plossl (40x) were nice and sharp, even with the included erect image prism diagonal. All four of the Galilean moons were sharp, and both of Jupiter's equatorial bands were easily visible even at 40x. Haven't tested with greater magnification yet.
  • There is quite some flare when bright objects (Moon, Jupiter) are just out of the field of view or near the edge. Whether this is due to the prism diagonal or something else I don't know.
  • The finder is not very nice to use. Not a lot of eye relief and the crosshairs aren't in focus. I'll be attaching the spare base from my Rigel Quikfinder so I can transfer it from my Astroscan to the C90 as needed.
  • Surprised that there were no end caps included with the 32mm plossl.
  • The tripod I put it on (Velbon Videomate 607) is definitely not up to the challenge and was a pain to use. Planning to buy Manfrotto 055XB legs with a 128RC head to use with this scope.

In general, once I get a better tripod and a proper star diagonal (probably the GSO one) I think I'll like this little scope quite a lot.


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: mmclure]
      #5577805 - 12/18/12 07:30 PM

I think cassegrain systems in general with the long baffle eminating from the center of the primary can be prone to off axis glare from the moon. My c6 does the came when the moon is shining in the inside if the baffle tube - bit not directly down the center. Its a shrug thing to me as the design is so successful on so many other levels.

You seriously need more oculars. Fir that scope magnifications between 100x and 130x would be ideal on Jupiter. Coming Saturn would be great 150x on steady air nights.

Pete


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mmclure
professor emeritus
*****

Reged: 12/30/10

Loc: Sacramento, CA USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: azure1961p]
      #5577842 - 12/18/12 07:58 PM

Quote:

You seriously need more oculars. Fir that scope magnifications between 100x and 130x would be ideal on Jupiter. Coming Saturn would be great 150x on steady air nights.




I have more eyepieces, but given how frustrating it was to use even 40x on my current tripod, I decided that more magnification without a better mount was pointless. When I have the better tripod I'll test my 11mm ES82 with it.


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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: mmclure]
      #5578172 - 12/18/12 11:53 PM

You can focus the finder, by the way. It has a huge TFOV and on a driven GOTO mount works well for alignment purposes.

The flare is not due to the diagonal. It's a common feature with Celestron scopes. At least the smaller ones - C5, C6, C90.

Regards,

Jim


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JIMZ7
Pooh-Bah
*****

Reged: 10/22/05

Loc: S.E.Michigan near DTW
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: jrbarnett]
      #5578531 - 12/19/12 08:14 AM

Does the Orion 90mm,102mm % 127mm Maks have the same flaring problems as Celestrons?

Jim


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mmclure
professor emeritus
*****

Reged: 12/30/10

Loc: Sacramento, CA USA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: jrbarnett]
      #5578909 - 12/19/12 01:20 PM

Quote:

You can focus the finder, by the way. It has a huge TFOV and on a driven GOTO mount works well for alignment purposes.




I can focus what the finder is looking at, and already have, but the crosshairs remain out of focus even though stars seen through the finder are sharp.


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t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: mmclure]
      #5578994 - 12/19/12 02:03 PM

Can anyone confirm the new C90 OTA dimensions? The specs say 16.5" long, but I'm unclear as to whether that is with the 45 degree diagonal and eyepiece, I believe it has to be. The tube should be about 11.5" without accessories if I'm not mistaken. Also, what is the OTA diameter? Help a Bro out...Thanks ahead...The darn thing is sittin' under my Christmas tree wrapped, but the wife won't let me go near it! I feel like a kid again.

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: t.r.]
      #5579029 - 12/19/12 02:20 PM

I don't have my C90 here, but it is more 11.5 rather than 16.5. I can measure it when I get home.

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JIMZ7
Pooh-Bah
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Reged: 10/22/05

Loc: S.E.Michigan near DTW
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: t.r.]
      #5579057 - 12/19/12 02:34 PM

Santa likes cold milk & cookies. Who knows
-maybe you can get even closer?

Jim


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

Loc: Petaluma, CA
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: JIMZ7]
      #5579180 - 12/19/12 03:49 PM

Dunno as I haven't used either of those, but the 6" Orion MCT would show a bit of flare with the Moon positioned just out of the field of view.

- Jim


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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: jrbarnett]
      #5580367 - 12/20/12 10:21 AM

So the OTA dimensions are:
4.25" (not including dovetail bracket)
11.5" (the tube itself is 9.75")


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t.r.
Post Laureate
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Reged: 02/14/08

Loc: Upstate NY
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5580560 - 12/20/12 12:20 PM

Thanks...

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: t.r.]
      #5583083 - 12/21/12 07:27 PM

I received my eyepieces and diagonal. Now I just have to wait for it to stop being cloudy...

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LateViewer
Pooh-Bah
*****

Reged: 11/17/05

Loc: Manhattan
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5584195 - 12/22/12 02:31 PM

Sunday night Jupiter in Central Park?

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RafaelP
super member


Reged: 12/01/12

Loc: NYC
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: LateViewer]
      #5584893 - 12/22/12 11:44 PM

Sounds good! It looks like it will be cold and clear.

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Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Which 90mm Mak for tiny Apartment and travel? new [Re: RafaelP]
      #5585112 - 12/23/12 05:16 AM

If you are using an Amici prism diagonal, there will be significant flare on objects.

If there are other sources of stray light reflection in the telescope, they are actually easy to track down and fix:

While indoors, take the telescope and point it near a lit lamp (this is going to be your moon simulator).

Set up the telescope with everything in the optical train you have been using, except the eyepiece.

Now, look in the diagonal where the eyepiece would go. Look around the features of the telescope and components visible from this location. If there is a bright reflection off of something, it will look bright instead of dark. Anything which looks dark isn't a problem.

Usually the culprit in SCTs is not really part of the telescope; the visual back, which will have a flat perpendicular to the optical path, which is a basic optics no-no. And obviously this flat becomes less important on the scale of the telescope as the telescope gets bigger. This can be corrected with a thin coat of Tamiya XF-1 flat black paint (really black, really flat, and removable with isopropyl alcohol if needed, someday).

Anyway, look for any surfaces flat to the optical path. Another way of doing this is to point it at an overhead light fixture and look in the front for anything reflecting light back. The original C90s had a flat on the fronts of their center baffles, and show remarkable image improvement if this is made flat black. (I did this with a little tool I made by taping the end of a Q-tip to a thin wood dowel to make a 90* paint brush I could put in from the back).

I haven't played with the newest C90, otherwise I'd be able to tell you where to look if there are any reflection points.

For good practice blackent the front edges of the diagonal's collar and the one on the eyepiece. These can be chromed, and as you will see from the exercise of looking in the back, they are visible to the eyepiece.

All in all, this is a perfect activity for a cloudy night.

-Rich


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azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Which 90mm Mak for tiny Apartment and travel? [Re: Starhawk]
      #5585246 - 12/23/12 09:08 AM

Hey guys tonight might be the last clear night for a good number of days in the northeast. Just passing it along.

Pete


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bsim
Carpal Tunnel
*****

Reged: 01/04/08

Loc: Miskatonic
Re: Which 90mm Mak for tiny Apartment and travel? [Re: azure1961p]
      #5585292 - 12/23/12 09:52 AM

I've joined the 90mm MAK club. I've been eyeing the C90 on Amazon for $150, but never bought it. I picked up a new Orion Starmax 90 for $79.99 on eBay. It was a pricing error, but Orion honored it.

Has anyone compared the Orion 90mm MAK with the Celestron C90? Optically it should be similar, but one thing which I like is that the Orion has less metal hardware than the Celestron. It should cool faster.


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