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Something for nothing: Celestron C90

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#2701 Jaimo!

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Posted 16 August 2021 - 05:43 PM

What is the head in the picture?  A picture is not always worth a thousand words.  wink.gif

 

Will this head allow the C90 to point to zenith?  That's also not clear from the picture.

 

Mike

Kenko KDS mount, I believe it has been discontinued for a few years.  It is small and packs nicely.

 

It does not get all the way to zenith, but it comes close enough for what it is...   I can wait a few minutes then view if it is directly overhead, or if it is a special event I'll have a different scope and mount.  Most of the time it is pointing less than 45° because I like planets.  I have modified it to get closer to zenith (that is described earlier in this thread).


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#2702 Bowlerhat

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Posted 20 August 2021 - 07:13 PM

Focal Reducer: Celestron Reducer/Corrector f/6.3 (when this is installed I remove the SCT spacer ring and it threads directly onto the rear baffle & the diagonal)

Is this new C90?

 

There was a lot of questions about mounting a reducer here and last time I saw it you need an adapter from scopestuff etc to make it work. Can you just thread it directly now?


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#2703 Jaimo!

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Posted 22 August 2021 - 03:57 PM

Finally got a clear evening...  Inexpensive scope, inexpensive camera.

 

C90 @ f/14, CG-5 ASGT, Svbony SV305, SharpCap 3.2, AS!3, GIMP

 

2021-08-20-0249_9_lapl5_ap28_Drizzle15_conv.jpg

 

2021-08-20-0234_7_lapl5_ap52_Drizzle15_conv color.jpg

 

I got this camera for Christmas 2020, it was ~$125.  It has the Sony IMX290 CMOS chip similar to more expensive cameras.  The pixel size is 2.9 µm, going by the 5x rule the optimal f/ raito for imaging should be 14.5...  This cheap camera seems to be made for the C90 at f/14. The only down side to this camera is the limited USB2 data transfer.


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#2704 sevenofnine

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Posted 22 August 2021 - 07:11 PM

The C-90 benefits from a good mount. The high magnifications used in astronomy mean the mount has to be good or the vibrations will be annoying. If you don't want to spend more on the mount than you did on the scope then shop used. There are lots of good tripods out there. My old Bogen/Manfrotto 3033 does a great job. ($125 used) I can stand and look straight into the diagonal with the scope pointed at zenith!  waytogo.gif


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#2705 luke_conan

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Posted 22 August 2021 - 10:52 PM

Is this new C90?

 

There was a lot of questions about mounting a reducer here and last time I saw it you need an adapter from scopestuff etc to make it work. Can you just thread it directly now?

Hi Bowlerhat,

This is the newest C90, bought just over a year ago, it appears that there is factory flocking already. I think from other reports here this is one of the things found on newer models. The thread has not changed however and an adapter is still required. Here is a link to the correct one from Agena Astro, it does mention in the description that this does not fit the C90, this must be referencing the older models with a smaller thread, mine has the M44.5.

https://agenaastro.c...-telescope.html


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#2706 luke_conan

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Posted 23 August 2021 - 07:49 AM

+1 vote for the Celestron 6.3 focal reducer, Baader astro grade amici prism & the Televue Panoptic 24! This combination really feels like it can bring the most out of the C90. I was looking to purchase the Explore Scientific 24mm eyepiece instead of the TV, but I couldn’t find it anywhere in stock for purchase in Australia or the big online stores.
Very glad I ended up selecting this amazing eyepiece. Something I will cherish forever.

Can anyone help point me in the right direction to find a soft pouch, nylon or similar protective case to keep the Televue Panoptic in? The Baader Hyperion zoom case is perfect but not quite the right size. I keep everything in a camera backpack for mountaintop lookouts and want to keep it in an extra padded environment!

Also what have people done to protect their diagonals in this circumstance? I know most people would be keeping everything in a single large case but that doesn’t quite fit my criteria. The backpack has extra free space for things like a camping hammock, some food or clothes etc. My fold out chair, tripod and a water bladder straps to the outside, it all works really well for extended missions.

Cheers, Luke 


Edited by luke_conan, 23 August 2021 - 07:59 AM.


#2707 luke_conan

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Posted 23 August 2021 - 07:51 AM

Lowepro Protactic BP 450 AWII

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  • E17BB717-56A1-4E2A-B013-00FB6404060B.jpeg

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#2708 luke_conan

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Posted 23 August 2021 - 07:55 AM

Setup

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#2709 Sarkikos

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Posted 23 August 2021 - 08:56 AM

Hi Bowlerhat,

This is the newest C90, bought just over a year ago, it appears that there is factory flocking already. I think from other reports here this is one of the things found on newer models. The thread has not changed however and an adapter is still required. Here is a link to the correct one from Agena Astro, it does mention in the description that this does not fit the C90, this must be referencing the older models with a smaller thread, mine has the M44.5.

https://agenaastro.c...-telescope.html

Factory flocking where in the C90?  Rear port?  Baffle tube?  The entire internal surface of the optical tube?

 

Mike


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#2710 Sarkikos

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Posted 23 August 2021 - 08:59 AM

The C-90 benefits from a good mount. The high magnifications used in astronomy mean the mount has to be good or the vibrations will be annoying. If you don't want to spend more on the mount than you did on the scope then shop used. There are lots of good tripods out there. My old Bogen/Manfrotto 3033 does a great job. ($125 used) I can stand and look straight into the diagonal with the scope pointed at zenith!  waytogo.gif

The only point I don't like is that you "stand" when you look into the diagonal with the scope pointed to zenith.  You have the tripod extended so much you can literally stand under the C90 and look straight forward into the diagonal?  Why don't you sit down?

 

Mike


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#2711 captaincook

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Posted 25 August 2021 - 04:05 AM

I started using my C90 on a standard photo tripod but got fed up with the pan and tilt head which wasnt up to the job. Bought a geared head and its much better but the accuracy is still only good in one axis and it doesnt like the cold. Went through a spell of not imaging anything and was considering my options: Better upgrade was then to get a flip mirror which helps a lot in finding the target- got par focus for my ZWO 120MC- and then switching to the camera; even with a x2 barlow and different focus I can get closer quicker than I did without it. Below is a summary of what I've done so far with the C90 all with the flip mirror in place (actually Mars was my MFT Olympus but everything else using this set up including for the sun it was a useful check of alignment by diverting onto cardboard).

 

planets6.jpg


Edited by captaincook, 25 August 2021 - 04:14 AM.

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#2712 Jaimo!

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Posted 25 August 2021 - 08:22 AM

Those are outstanding images.


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#2713 lorenzo italy

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Posted 25 August 2021 - 09:08 AM

Hi to all,
I started reading this thread several days ago, for now I have reached page 29 ...
Thanks to the reading I returned the desire to use my SW mak 90mm, I think similar to the C90.
Now I'll keep it mounted on the alt Voyager II mount, ready for a quick evening observation.
Like many of you, I have now surrendered to fatigue and practically no longer observe the evening.
I don't want to mount the C8 only to find that the turbulence ruins everything, I also have an acre of 127mm but in terms of bulk and weight it is similar to the C8.
Last night I tried the mak to observe Jupiter and Saturn.
Already with a Celestron Omni 32mm eyepiece the vision was very nice, I don't remember how long I hadn't used the small telescope on the planets (keep in mind that I bought the mak about 20 years ago ...).
I then tried a 9mm and a 5mm orthoscopic eyepiece.
With the 5mm on Jupiter the main bands were clearly visible, with the largest and most eye-catching one (sorry if I don't use the exact terminology) which appeared a faint brownish color.
The turbulence was visible, there were clouds passing fast, but the image was not very disturbed.
I certainly wouldn't have taken the C8 out on an evening like this, which makes me realize how useful a small portable telescope can be.
Useful to keep our passion always active.
I add a couple of photos, taken with a ZWO ASI178mm camera (the telescope was on a motorized eq5)
I must say that I did not believe in these results, and I enjoyed taking pictures.
And to think that I already had all the equipment, I just had to find an opportunity to use it.
Thanks to all of you for taking this discussion forward, which is very useful to all users of the small maks.

 

21_30_32Z_lapl4_ap116 300 c.jpeg

20_27_50Z_lapl4_ap72 300 d.jpeg

 

Lorenzo


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#2714 PeterAB

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Posted 25 August 2021 - 10:14 AM

Finally got a clear evening...  Inexpensive scope, inexpensive camera.

 

C90 @ f/14, CG-5 ASGT, Svbony SV305, SharpCap 3.2, AS!3, GIMP

 

attachicon.gif2021-08-20-0249_9_lapl5_ap28_Drizzle15_conv.jpg

 

attachicon.gif2021-08-20-0234_7_lapl5_ap52_Drizzle15_conv color.jpg

 

I got this camera for Christmas 2020, it was ~$125.  It has the Sony IMX290 CMOS chip similar to more expensive cameras.  The pixel size is 2.9 µm, going by the 5x rule the optimal f/ raito for imaging should be 14.5...  This cheap camera seems to be made for the C90 at f/14. The only down side to this camera is the limited USB2 data transfer.

Hi Jaimo!

 

I would be interested is knowing the steps you used to acquire and process these pictures.    They turned out great.  

 

I have basically the same setup that you used.

 

Thanks,  Peter



#2715 SandyHouTex

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Posted 25 August 2021 - 10:31 AM

I started using my C90 on a standard photo tripod but got fed up with the pan and tilt head which wasnt up to the job. Bought a geared head and its much better but the accuracy is still only good in one axis and it doesnt like the cold. Went through a spell of not imaging anything and was considering my options: Better upgrade was then to get a flip mirror which helps a lot in finding the target- got par focus for my ZWO 120MC- and then switching to the camera; even with a x2 barlow and different focus I can get closer quicker than I did without it. Below is a summary of what I've done so far with the C90 all with the flip mirror in place (actually Mars was my MFT Olympus but everything else using this set up including for the sun it was a useful check of alignment by diverting onto cardboard).

 

attachicon.gifplanets6.jpg

Nice work.


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#2716 sevenofnine

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Posted 25 August 2021 - 07:45 PM

I agree that sitting with the C-90 is very enjoyable. However, if I'm in the sitting mode then the Apex 127 is better so why not? For me, the C-90 is the perfect stealth scope. It fits in a small backpack with the tripod over your shoulder. With it you can hike anywhere for a better view. Unfortunately, the chair becomes an encumbrance IMO. A tall tripod like the Manfrotto 3033 can be cranked up very high and be rock solid. No awkward bending or crouching. Just something to consider for this amazing little scope. waytogo.gif


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#2717 Sarkikos

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Posted 25 August 2021 - 08:00 PM

I agree that sitting with the C-90 is very enjoyable. However, if I'm in the sitting mode then the Apex 127 is better so why not? For me, the C-90 is the perfect stealth scope. It fits in a small backpack with the tripod over your shoulder. With it you can hike anywhere for a better view. Unfortunately, the chair becomes an encumbrance IMO. A tall tripod like the Manfrotto 3033 can be cranked up very high and be rock solid. No awkward bending or crouching. Just something to consider for this amazing little scope. waytogo.gif

For me, sitting while observing is always more enjoyable!   Except maybe when I'm lying down and observing with binoculars.  grin.gif

 

My previous home was a condo with no private yard.  I often hiked to a nearby golf course with a C90 or other small scope, a photo tripod and ... a chair.  The chair was a fold-up camping stool which I slung across my shoulders.

 

Nothing beats a good sit. grin.gif
 

Mike


Edited by Sarkikos, 25 August 2021 - 08:01 PM.

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#2718 Jim1804

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Posted 25 August 2021 - 08:19 PM

Hi to all,
I started reading this thread several days ago, for now I have reached page 29 ...
Thanks to the reading I returned the desire to use my SW mak 90mm, I think similar to the C90.
Now I'll keep it mounted on the alt Voyager II mount, ready for a quick evening observation.
Like many of you, I have now surrendered to fatigue and practically no longer observe the evening.
I don't want to mount the C8 only to find that the turbulence ruins everything, I also have an acre of 127mm but in terms of bulk and weight it is similar to the C8.
Last night I tried the mak to observe Jupiter and Saturn.
Already with a Celestron Omni 32mm eyepiece the vision was very nice, I don't remember how long I hadn't used the small telescope on the planets (keep in mind that I bought the mak about 20 years ago ...).
I then tried a 9mm and a 5mm orthoscopic eyepiece.
With the 5mm on Jupiter the main bands were clearly visible, with the largest and most eye-catching one (sorry if I don't use the exact terminology) which appeared a faint brownish color.
The turbulence was visible, there were clouds passing fast, but the image was not very disturbed.
I certainly wouldn't have taken the C8 out on an evening like this, which makes me realize how useful a small portable telescope can be.
Useful to keep our passion always active.
I add a couple of photos, taken with a ZWO ASI178mm camera (the telescope was on a motorized eq5)
I must say that I did not believe in these results, and I enjoyed taking pictures.
And to think that I already had all the equipment, I just had to find an opportunity to use it.
Thanks to all of you for taking this discussion forward, which is very useful to all users of the small maks.

 

attachicon.gif21_30_32Z_lapl4_ap116 300 c.jpeg

attachicon.gif20_27_50Z_lapl4_ap72 300 d.jpeg

 

Lorenzo

Welcome (back) to the 90mm club!

 

I've said many times - hot, sticky, stormy summer nights - I wouldn't see much of the summer planets if it weren't for the C90. On a small tripod it's the perfect combination. 


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#2719 Jaimo!

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Posted 25 August 2021 - 08:46 PM

Hi Jaimo!

 

I would be interested is knowing the steps you used to acquire and process these pictures.    They turned out great.  

 

I have basically the same setup that you used.

 

Thanks,  Peter

Peter, 

There are a couple of key points I have learned along the way...

  1. Polar alignment is key.  I used to get a close polar alignment a watch the planet drift across my field.  When imaging with the C90 I used an old CG-5 ASGT the Celestron all star polar alignment is easy, takes only a couple of minutes, and good enough for planetary work.  I am sure other brand of mounts have similar features or old school drift alignment...  figure out something that works and is quick.
  2. I use a flip mirror to center/find the planet.  I have spent many frustrating evenings trying to get the planet centered on the tiny chip, it's a nice crutch.  Mine is from Omegon and is plastic and light weight, the good thing about this flip mirror is it is small enough to stay out of the way of the focuser, I have a couple of others and this one works best with the C90.  For the eyepiece, I have a second hand Kellner with the crosshairs, that is missing the illumination, but it works good enough.
  3. The Svbony camera is limited to using SharpCap (I prefer FireCapture, but that's another story) set the gain for the SV305 to 30 (max), choose the exposure that gets you about 80% on the histogram, more or less.  I am less familiar with SharpCap and many of my images end up with weird colors, these planetary images were definately greenish in tone and I have done some moon imaging that ended up blue...  This can be fixed in GIMP under the menu 'Colors' than 'levels' then even everything out.  I don't have this problem with ZWO cams and FireCapture.
  4. After collecting images in SER format, which will vary depending on the planet's brightness (i.e. exposure time) and capture size I like 320x320 .  I can collect up to 10,000 images of Jupiter at 7-9ms exposure, and 80-100 ms for Saturn...  I don't remember how many images, but it was significantly less than Jupiter due to the longer exposure.  And to reiterate, the good ploar alignment allows for smaller capture size and more FPS.
  5. After that into, Autostakkert!3, sharpen with the wavelets in Registax, and adjust color or crop in GiMP.  All of these programs are free.
  6. Most important is seeing.  They call this technique "Lucky Imaging", but part of that is getting out and imaging as often as possible and when the seeing is favorable you will be glad you did.
  7. Also, you don't need much computer power for the acquisition, my "outside" computer is an old Acer ES1-512 Celeron manufactured in 2014.  Although I switch to my "inside" computer for the analysis...

 

If you have any other question feel free to ask, I may or may not know...  But I do know the IMX290 and IMX 462 chips for the C90 is a good match as this requires no Barlow for optimal f/ ratio for the scope and chip, 5x rule.

 

 

 

PXL_20210826_011729210 - small.jpg


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#2720 barbie

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Posted 25 August 2021 - 08:53 PM

Same for my Meade ETX90 and Skywatcher 90mm Maksutovs. After just over 50 years of observing with many types of instruments, large and small, I've found that my 90mm Maksutovs are now the perfect size scopes for my typical 1 hour observing sessions of the moon, planets and brighter double stars. I observe when the weather is warm so thermal acclimatization is not a problem with these two wonderful 90mm Maksutovs during my primary observing times of spring and summer. For cold weather, I use my 7x50 binoculars whenever it's clear here in Ohio.


Edited by barbie, 25 August 2021 - 09:00 PM.

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#2721 Jim1804

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Posted 25 August 2021 - 09:16 PM

 For cold weather, I use my 7x50 binoculars whenever it's clear here in Ohio.

I grew up in Ohio - it's not clear very often!!


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