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Something for nothing: Celestron C90

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#2326 Joe1950

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Posted 05 March 2019 - 04:50 PM

Same with me, Jamio. I’m in the fly over zone of a busy international airport, and just my luck, someone would see it. So I don’t even have one. I like star parties but not when the attendees arrive in cars with sirens and flashing lights! 


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#2327 Sarkikos

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Posted 05 March 2019 - 05:23 PM

Laser finders have always been a little counter-intuitive to me, we constantly avoid light pollution but have no problem shining lasers up in the air.  I know they do not add significantly to light pollution.  I also live in an area with 3 international airports, even if I am not pointing at air planes, the guy down the block does not know this when he is calling the cops...

 

Jaimo!

I have had no problem with laser finders either at home or at dark sites.  Planes and choppers fly over our house often.  But I just look out for them and avoid using the laser while they cross by.  Not a problem.  I doubt if anyone in my neighborhood even notices the laser in the light pollution.

 

The only person who has ever called the cops on me was a neighbor who thought I was kids out smoking dope and causing trouble.  When the cops arrived, I treated them to some eye candy in the sky.  Not a problem. grin.gif

 

I use the laser mostly at home.  It is too bright at dark sites, even the sapphire one that's supposed to be dimmer for astronomy.

 

Mike


Edited by Sarkikos, 06 March 2019 - 11:22 AM.

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#2328 Bejohnson

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Posted 05 March 2019 - 07:36 PM

Bejohnson - welcome to the club! I think you’ll love your C90!

A couple of things - you may want another eyepiece or two (cheap Plossls work fine in this scope - or a lot of us use a zoom eyepiece with it. The 32mm, a 24-8mm zoom, and a Barlow, and you’re all set for guerrilla astronomy, C90 style!

You’ll also want a 90deg astronomy diagonal - much more comfortable, and will really improve your views. You don’t need to spend much - I have the GSO mirror diagonal, and it works fine.

Make yourself a cheap dewshield - I used a couple of sheets of craft foam. Needed to block stray light even if dew isn’t a problem.

A lot of people on the thread have also flocked the baffle tube - easy to do with the really thin flock paper. Improves contrast - although a dew shield will get you most of the way there.

Finally, check the collimation on Polaris. Mine was out of collimation when I received it. I’m still not sure it’s perfect - but it’s close, and the difference on planets was noticeable.

Most of all - enjoy your C90!

Thank you for the quick rundown!

 

You'll probably also want the Celestron T-Mount to mount the Canon XS to the scope.  The threads on the inside of the T-Mount match up with the visual back.  The T-Mount also will attach to the Celestron 8-24 Zoom...

 

attachicon.gif Celestron Zoom 2.jpg

 

attachicon.gif Celestron Zoom 1.jpg

 

attachicon.gif Celestron Zoom 3.jpg

 

Have fun and welcome to the club,

Jaimo!

I just ordered the T-Ring and will be ordering a zoom also, thanks!

 

The one "mandatory" upgrade is the 90° diagonal, for better ergonomics when aimed at the sky. The Celestron 94115-A is a great fit, and not expensive.

Thanks for the suggestion, I will definitely will be adding a diagonal 90 to my list.

 

Agreed on the 90* diagonal, zoom EP, and I'll add a 1x Red Dot finder instead of the marginal finder supplied.  These and a solid tripod make C90 time fun.

Yep, I tried to locate anything in the finder it comes with, with little luck.

 

The C90 is a super scope with just a little modification. You can see small things that make a huge difference here:

https://www.cloudyni...ffle-mod/page-5

Thanks for the direct link I will be looking to do anything to get just a bit more out of the C90



#2329 Peter Besenbruch

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Posted 05 March 2019 - 09:24 PM

How would you (or have you) set up your C90 for use as a birding spotter?

I use my C90 a lot for birding. I have used a zoom and fixed eyepieces. Some general findings:

 

32mm Plössls and the like are not illuminated to the edge of the field when using a standard star diagonal. You lose roughly 5°.

 

Purchasing an SCT adapter, along with a Celestron .63 reducer and 1.25" visual back, produces a view with at least some illumination to the edge of the field. A 32mm gives you about 25x with this setup, as opposed to nearly 40x without it.

 

I have also used a Baader zoom with the reducer and achieved a low to mid 30s magnification. The is little to no noticeable vignetting.

 

The best results are with the Barsta Flat Field 27mm. Vignetting is modest. The true field is wider than the zoom, and the apparent field is wider than either the Plössl or the zoom. It yields about 30x. The true field is about 1.7°.

 

I like the Orion 6x30, correct image finder. The optics are good, and it is very good for sweeping large areas.

 

I mount the scope on one of those side mounting alt-az mounts, making sure that the finder points down and to the left. This results is essentially perfect balance, regardless of where you point, or how loose the altitude bearing is.


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#2330 Jaimo!

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Posted 05 March 2019 - 10:46 PM

I have had no problem with laser finders either at home or at dark sites.  Planes and choppers fly over our house often.  But I just look out for them and avoid using the laser while they cross by.  Not a problem.  I doubt if anyone in my neighborhood even notices the laser in the light pollution.

 

The only person who has ever called the cops on me was a neighborhood who thought I was kids out smoking dope and causing trouble.  When the cops arrived, I treated them to some eye candy in the sky.  Not a problem. grin.gif

 

I use the laser mostly at home.  It is too bright at dark sites, even the sapphire one that's supposed to be dimmer for astronomy.

 

Mike

Mike, 

I know there is nothing wrong with using one, if used responsibly.  I just have a hard time wrapping my head around it...

 

I use a $20-ish dollar red dot sight, from post #1917.

 

Jaimo!


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#2331 Jaimo!

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Posted 05 March 2019 - 10:54 PM

Thank you for the quick rundown!

 

I just ordered the T-Ring and will be ordering a zoom also, thanks!

 

Thanks for the suggestion, I will definitely will be adding a diagonal 90 to my list.

 

Yep, I tried to locate anything in the finder it comes with, with little luck.

 

Thanks for the direct link I will be looking to do anything to get just a bit more out of the C90

Be,

Before you get carried away, check out this LINK.  It is a presentation from a gentleman who is a professor from Princeton who does astrophotography with a 3.5" Questar Mak.   It is amazing what can be done with such a small scope.

 

Jaimo!


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#2332 Joe1950

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Posted 06 March 2019 - 01:23 AM

...and the right ancillary equipment. Not saying tons of knowledge and skills must be developed. A good camera is almost as important as the scope, imho.

 

He has an excellent presentation, especially showing the differences between a single frame and a processed stack. Nice link Jamio!

 

Is deconvolution done by an available software? 



#2333 Jaimo!

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Posted 06 March 2019 - 11:01 AM

...and the right ancillary equipment. Not saying tons of knowledge and skills must be developed. A good camera is almost as important as the scope, imho.

 

He has an excellent presentation, especially showing the differences between a single frame and a processed stack. Nice link Jamio!

 

Is deconvolution done by an available software? 

I am sure deconvolution is available via a software package, I just do not know which one would be best.  I am still just doing lunar and planetary imaging using Autostakkert! and Registax, but after going over the presentation, I am seriously considering trying some globular clusters with the C90.

 

Jaimo!


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#2334 Adun

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Posted 06 March 2019 - 03:34 PM

I use my C90 a lot for birding. I have used a zoom and fixed eyepieces. Some general findings:

 

32mm Plössls and the like are not illuminated to the edge of the field when using a standard star diagonal. You lose roughly 5°.

 

Purchasing an SCT adapter, along with a Celestron .63 reducer and 1.25" visual back, produces a view with at least some illumination to the edge of the field. A 32mm gives you about 25x with this setup, as opposed to nearly 40x without it.

 

I have also used a Baader zoom with the reducer and achieved a low to mid 30s magnification. The is little to no noticeable vignetting.

 

The best results are with the Barsta Flat Field 27mm. Vignetting is modest. The true field is wider than the zoom, and the apparent field is wider than either the Plössl or the zoom. It yields about 30x. The true field is about 1.7°.

 

Thanks for the feedback!

 

 I do have a Baader zoom and a .63 reducer. An a fluid head tripod.

 

I use 30x to 40x a lot with my camera, so "mid thirties" sounds good to me. Maybe if I feel the need of a spotting scope on the field, I should get an SCT adapter then



#2335 Peter Besenbruch

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Posted 06 March 2019 - 10:27 PM

I am sure deconvolution is available via a software package, I just do not know which one would be best.  I am still just doing lunar and planetary imaging using Autostakkert! and Registax, but after going over the presentation, I am seriously considering trying some globular clusters with the C90.

If not available natively, some packages will do deconvolution via add-ons. GIMP, of all programs, has at least two approaches to deconvolution: The Linux nerd approach with a bewildering array of settings, and one with quite a few presets. They often get bundled into the gimp-plugin-registry package. You can't argue with the price of the GIMP, but you may want to do all your processing at higher bit depths than what the GIMP is capable of. RawTherapee works with high bit depth images, and offers RL Deconvolution.

 

Another package I hear about a lot is Maxim DL. I have no experience with it.



#2336 Peter Besenbruch

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Posted 06 March 2019 - 10:35 PM

Thanks for the feedback!

 

 I do have a Baader zoom and a .63 reducer. An a fluid head tripod.

 

I use 30x to 40x a lot with my camera, so "mid thirties" sounds good to me. Maybe if I feel the need of a spotting scope on the field, I should get an SCT adapter then

Give it a try. You can always use other eyepieces later. Along with the SCT adapter I can't stress an optical finder enough for wide angle sweeping.


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#2337 Messierthanwhat

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Posted 08 March 2019 - 07:03 AM

I am sure deconvolution is available via a software package, I just do not know which one would be best.  I am still just doing lunar and planetary imaging using Autostakkert! and Registax, but after going over the presentation, I am seriously considering trying some globular clusters with the C90.

 

Jaimo!

 

If you're using Registax and its wavelet sharpening, you're already using a deconvolution method somewhat more advanced than the VanCittert method mentioned in that presentation from 2002.


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#2338 Bejohnson

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Posted 27 March 2019 - 01:23 PM

So I have done a little bit of upgrades of the C90. I purchased a Celestron Star Finder, an inexpensive SVBONY mirror diagonal, Canon T-Ring adapter, Celestron 2x Barlow, 1.25 ND Filter and a Meade 8-24mm zoom here in the classifieds. Eyecrazy.gif


ybYm1tV.jpgtegNJC1.jpg

 

When I have been able to get some nights without an clouds, I've taken some time to get used to the C90 and have been observing the moon and really haven't attempted anything else than some of the brightest stars. I'm starting to get a nice feel for it now with positioning and eyepieces.

 

cnMoon

 

With all of the excitement of taking photos I was able to get some nice shots of the full moon this past week with the Canon attached directly to the C90. I haven't had too much success with attaching the Meade zoom, more practice and I think I'm getting some vignetting at 24mm?, Jaimo, maybe you has some insight on this?

 

I have yet to start down the path of flocking, but I have gone back and read the threads on it and I will be doing it sooner than later.


Edited by Bejohnson, 27 March 2019 - 10:18 PM.

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#2339 Jim1804

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Posted 27 March 2019 - 09:48 PM

The flocking makes a small but noticeable difference - use the really thin paper referenced in the threads - easy and fully reversible.
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#2340 Drew57

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Posted 28 March 2019 - 06:58 PM

Finally resolved the finder issue with my C90 MAK with some custom walnut machining...perfect. What a great little scope!

 

P3280108.JPG


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#2341 Simon B

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Posted 19 April 2019 - 06:18 AM

Just thought I would share this soft case I found for my Orion 90 mak, it fits like a glove! Thick padding too - and it's only $11.99 on Amazon:

 

https://www.amazon.c...m/dp/B078LXYVR7

 

 

 

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#2342 Sarkikos

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Posted 19 April 2019 - 11:46 AM

Great find!

 

They have a Large I, Large II, Medium and Standard.  Which one fits the C90?

 

I wish these companies would give internal dimensions!  mad.gif 

 

Mike


Edited by Sarkikos, 19 April 2019 - 11:49 AM.

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#2343 Simon B

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Posted 19 April 2019 - 11:56 AM

Great find!

 

They have a Large I, Large II, Medium and Standard.  Which one fits the C90?

 

I wish these companies would give internal dimensions!  mad.gif

 

Mike

 

Yeah I agree they should provide more info : )  it's the 'Large II'


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#2344 BFaucett

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Posted 19 April 2019 - 12:39 PM

Just thought I would share this soft case I found for my Orion 90 mak, it fits like a glove! Thick padding too - and it's only $11.99 on Amazon:

 

https://www.amazon.c...m/dp/B078LXYVR7

 

THANKS!  waytogo.gif  That looks to be just about perfect and at a great price. 

 

Cheers!  Bob F.  smile.gif


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#2345 Simon B

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Posted 19 April 2019 - 01:02 PM

THANKS!  waytogo.gif  That looks to be just about perfect and at a great price. 

 

Cheers!  Bob F.  smile.gif

 

No problem : )  but hang on, how long is the C90 OTA? I know it's longer than the Orion.... I just tested the bag for size and it will fit a 13" OTA, but probably not a 13.5"

 

Edit: I used some spacers at the bottom of the bag to see how long of an OTA would fit, and yeap, 13" fits, 13.5" doesn't..! The Orion is around 11.2"


Edited by Simon B, 19 April 2019 - 01:13 PM.

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#2346 BFaucett

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Posted 19 April 2019 - 01:23 PM

It looks like it should work.  (I realize I'd have to take the finder off but that's not a big deal.)  Thoughts?

 

Thanks.  Bob F.

 

 

gallery_230527_10968_855885.jpg

 

gallery_230527_10968_2176119.jpg



#2347 Simon B

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Posted 19 April 2019 - 01:32 PM

It looks like it should work.  (I realize I'd have to take the finder off but that's not a big deal.)  Thoughts?

 

Thanks.  Bob F.

 

Perfect smile.gif  I thought the C90 was considerably longer, nevermind! It'll fit no problem

 

Speaking of manufacturer misinformation - Celestron state the C90 as being 16" long.... I'm assuming that's with the supplied 45° diagonal + eyepiece attached, but someone reading the specs sheet wouldn't know that! They might assume the OTA itself was 16 inches. I knew it wasn't 16", but it made me think the OTA was maybe 13"


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#2348 BFaucett

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Posted 19 April 2019 - 01:36 PM

It never hurts to double check things!  And now I know it will definitely fit thanks to your measurement info on the case.  Thanks for that also!  waytogo.gif  And maybe this will help some other folks on here that are thinking about getting one of these cases. 

 

Cheers!  Bob F. smile.gif


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#2349 Jaimo!

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Posted 19 April 2019 - 10:17 PM

I love that the ruler is taped to the OTA for the photo...  grin.gif

 

Jaimo!


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#2350 BFaucett

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Posted 19 April 2019 - 10:30 PM

I love that the ruler is taped to the OTA for the photo...  grin.gif

 

Jaimo!

 

Well, that was the first way to do it that came to mind in order to show the length (as opposed to just stating the length).  I seem to recall some old saying about a picture is worth a thousand words...  shrug.gif

 

Bob F.  smile.gif


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