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Something for nothing: Celestron C90

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#2401 fcathell

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Posted 31 August 2019 - 06:39 PM

Nice compact setup Jaimo, but don't you just hate for the focus knob to be on the top?  I have the same situation when using my old GT mount and it makes me want to move the Vixen rail to the other side of the scope.

 

By the way - what kind of alt-az head is that?  Looks nice.

 

Frank



#2402 PXR-5

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Posted 31 August 2019 - 07:36 PM

I use an Orion L bracket, this keeps the finder and focuser in the intended position ;)
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#2403 Jaimo!

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Posted 31 August 2019 - 10:24 PM

Nice compact setup Jaimo, but don't you just hate for the focus knob to be on the top?  I have the same situation when using my old GT mount and it makes me want to move the Vixen rail to the other side of the scope.

 

By the way - what kind of alt-az head is that?  Looks nice.

 

Frank

I don't mind the focuser on top, most times I use a Cat on a GEM where the focus knob moves throughout the evening.

 

Kenko Alt-Az, I removed one of the spacers.  I like the knobs for the X and Y movement but the downside is it cannot reach the Zenith, but I rarely look straight up.

 

Jaimo!


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#2404 Jaimo!

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Posted 02 September 2019 - 01:20 PM

Jaimo!'s Celestron C90 Hack #2

 

I love Cats and Casses, and a majority of my scopes are of this type...  But I hate dew shields.  For the C90, and others, I simply use a piece of craft foam from the art store, ~$2.00, and this is nothing new...  But I secure it to the scope with a velcro and elastic band (like THIS) and it works quite nice, mine is 28" long and wraps all the way around the OTA, you can certainly go shorter. The craft foam is soft enough to roll up small and fit in my bag, and the band is always wrapped around the OTA.  Easy peasy lemon squeezy.  Here is a post with the shield in action.

 

IMG_20190902_134955.jpg

 

IMG_20190902_135146 - small.jpg

 

IMG_20190902_135224 - small.jpg

 

Jaimo!


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#2405 Sarkikos

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Posted 02 September 2019 - 01:25 PM

So, you hate dew shields … unless you make them yourself?  scratchhead2.gif

 

I've made plenty of dew shields.  But they're never as good as a professional job with sewn-on Velcro to secure the edge and padding where it rests on the OTA.  If I can buy a nice dew shield that fits, I buy it.

 

grin.gif

Mike


Edited by Sarkikos, 02 September 2019 - 01:29 PM.


#2406 fcathell

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Posted 02 September 2019 - 02:10 PM

What is dew? (LOL)

 

Frank

Tucson


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#2407 Jaimo!

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Posted 02 September 2019 - 02:21 PM

So, you hate dew shields … unless you make them yourself?  scratchhead2.gif

 

I've made plenty of dew shields.  But they're never as good as a professional job with sewn-on Velcro to secure the edge and padding where it rests on the OTA.  If I can buy a nice dew shield that fits, I buy it.

 

grin.gif

Mike

Never said I liked the ones I make...  But I like it much better than the commercially available dew shields.

foreheadslap.gif



#2408 Sarkikos

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Posted 03 September 2019 - 06:00 AM

What is dew? (LOL)

 

Frank

Tucson

It's kind of a wet dust.

 

:grin:

Mike


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#2409 Sarkikos

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Posted 03 September 2019 - 06:05 AM

Never said I liked the ones I make...  But I like it much better than the commercially available dew shields.

foreheadslap.gif

Why?  Many commercially available dew shields have nice sewn-on Velcro, good flocking and a padded section that grips the OTA. 

 

I don't sew.  I have to glue the strips of Velcro on my home-made dew shields.  After multiple nights of use under dewy conditions, the Velcro strips start to come loose.  Sewn-on Velcro doesn't.

 

The commercially available dew shields are just better.  The only problem with them sometimes is when I can't find one to fit a particular scope.

 

I don't love or hate dew shields.  But I accept they are useful to help keep dew off and shield the optics from ambient light.

 

Mike


Edited by Sarkikos, 03 September 2019 - 06:09 AM.

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#2410 azure1961p

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Posted 03 September 2019 - 05:14 PM

I just get a package of HotHands hand warmers and rest it on the corrector. It's disklike so it stays on.

 

 

Pete



#2411 fcathell

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Posted 03 September 2019 - 11:33 PM

I remember when I lived near the coast in San Diego many years ago and would have to have a hair drier on extension cord running out of my apartment into the yard where the C-8 was set up. What a PIA, but boy were those planetary views incredible in that humid air!

 

Frank 


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#2412 Sarkikos

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Posted 04 September 2019 - 05:48 AM

I just get a package of HotHands hand warmers and rest it on the corrector. It's disklike so it stays on.

 

 

Pete

lol.gif



#2413 Sarkikos

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Posted 04 September 2019 - 05:53 AM

I remember when I lived near the coast in San Diego many years ago and would have to have a hair drier on extension cord running out of my apartment into the yard where the C-8 was set up. What a PIA, but boy were those planetary views incredible in that humid air!

 

Frank 

Then you have to take the time to blast the corrector with the hair dryer ...  over and over again.  It's much better to prevent dew with warming strips than to deal with the problem after the fact ... over and over again.

 

Mike


Edited by Sarkikos, 04 September 2019 - 06:04 AM.


#2414 nicoledoula

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Posted 06 September 2019 - 06:54 PM

I have the same setup - C90 on a Twilight 1 mount. The dovetail on the scope is on the bottom - but the Twilight mounts from the side - you just put the scope in sideways, tighten it down, and rotate the diagonal. The arm for the mount needs to be on the left (it's moveable) if you want to use the finder - otherwise it'll be on the bottom of the scope - not very useful. 

 

Telescopes with diagonals on mounts are like celestial objects in the Universe - there is no true top or bottom - it all depends on your reference point :-)   

When I use the C90 with the Twilight 1 the focusing knob is on the bottom and my RACI finder is useful and turned to the same angle as the diagonal. It's a stable platform for the C90 although the dovetail is a wee short so care in mounting is advised. If someone wanted to make right angle finder mounts they could sell a few. Having the focuser knob on the bottom solves some clearance issues and helps with stability while focusing IME. 


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#2415 Jaimo!

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Posted 08 September 2019 - 12:41 PM

Now here is a deal. Same as the C-90 (Synta made).

 

https://astromart.co...-wcarrying-case

 

FC

That Levenhuk scope showed up again for $80...

 

Jaimo!


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#2416 johnhudson922

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Posted 03 October 2019 - 08:00 PM

I pulled the trigger on a used C90, on its way. I'd like to use it for Planetary photography, maybe closeup lunar and stitch the photos together, etc. Would the ASI120MC-S (color) be a good camera to get? 


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#2417 Jaimo!

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Posted 03 October 2019 - 08:49 PM

I pulled the trigger on a used C90, on its way. I'd like to use it for Planetary photography, maybe closeup lunar and stitch the photos together, etc. Would the ASI120MC-S (color) be a good camera to get? 

Yes!

 

The ASI120MC-S is a color camera, the ASI120MM-S will have better resolution as it is a mono-camera, but you will have to capture images in 3 or 4 wavelengths to get a color image requiring 3x more work capturing images and procession. 

 

The only other camera I can recommend it the ASI224MC, which can capture images significantly faster with less noise, but is an extra $100.

 

The other important consideration is what mount are you planning on using? 

 

Jaimo!



#2418 johnhudson922

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Posted 03 October 2019 - 09:02 PM

Yes!

 

The ASI120MC-S is a color camera, the ASI120MM-S will have better resolution as it is a mono-camera, but you will have to capture images in 3 or 4 wavelengths to get a color image requiring 3x more work capturing images and procession. 

 

The only other camera I can recommend it the ASI224MC, which can capture images significantly faster with less noise, but is an extra $100.

 

The other important consideration is what mount are you planning on using? 

 

Jaimo!

AVX



#2419 Jaimo!

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Posted 03 October 2019 - 09:26 PM

AVX

waytogo.gif  Can't wait to see your photos!



#2420 BillP

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Posted 08 October 2019 - 09:19 AM

This thread has been going on for years!  OpticsPlanet has the C90 w/tripod for $155 + 12% off through 8/25 and shipping.  As inexpensive as ever!laugh.gif

 

That is a crazy deal!  Will be interesting comparing/contrasting this instrument against my 65mm Pentax Spotter and 81mm Apo. 


Edited by BillP, 08 October 2019 - 09:20 AM.

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#2421 Paul Lennous

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Posted 08 October 2019 - 09:51 AM

The C90 and AVX make a great little pair. I used that combination this past weekend to show a troop of boys and other campers the moon, Jupiter, Saturn, and a host of brighter DSO’s. 


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#2422 Jaimo!

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Posted 08 October 2019 - 12:34 PM

That is a crazy deal!  Will be interesting comparing/contrasting this instrument against my 65mm Pentax Spotter and 81mm Apo. 

Bill, 

I have bought a few of these packages for myself and friends, hard to find a better deal.

 

The C90 is my current scope as I broke my hand last week...  it is small and lightweight, I can take my scope, mount and tripod out with one hand.

 

J


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#2423 Sarkikos

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Posted 08 October 2019 - 12:38 PM

Has anyone wrapped their C90 in Reflectix?  I've noticed that my C90 is prone to tube currents, which display as a flare on one side of the diffraction pattern.  It tends to make every star look like a close double star until the scope acclimates.

 

Mike



#2424 BillP

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Posted 08 October 2019 - 01:18 PM

Has anyone wrapped their C90 in Reflectix?  I've noticed that my C90 is prone to tube currents, which display as a flare on one side of the diffraction pattern.  It tends to make every star look like a close double star until the scope acclimates.

 

Mike

 

What was your temp differential?  Don't these little things take only 20 minutes to acclimate generally? 


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#2425 Sarkikos

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Posted 08 October 2019 - 01:29 PM

The flare / tube currents are most obvious during cold weather, of course.  But I've had the C90 on the porch for a half-hour or so, start observing and I still see the flare a bit for a while after.  Definitely tube currents.

 

I especially notice the flare if I'm trying to split double stars.  You might as well give it up if just about every star looks like a close double.

 

Mike


Edited by Sarkikos, 08 October 2019 - 01:31 PM.



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