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Something for nothing: Celestron C90

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#176 Sarkikos

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Posted 10 December 2013 - 04:59 PM

I stumbled onto this scope while perusing OpticsPlanet's website. They have a site-wide 10% off sale, bringing this package down from $164.99 to $148.49--great deal! Then I saw this thread... I had to bite!


I also recently grabbed up a C90. Mine came from the B&H site, at the same price, with free shipping, too. Great little scope!

I already have an L-bracket to use it with on the AT Voyager mount and will try it out with the same on the SLT Mount. It could be a match made in heaven for lightweight grab'n'go setup with the option to have tracking & GoTo or not, depending on the mount used. I am well aware that cooling issues will have to make a more 'pre-planned' grab'n'go but I am okay with that. I will use it on the Moon, planets and double stars mainly.


I also have an AT Voyager. But I think that mount is a little overkill for the C90. My C90 goes directly on a 1/4-20 screw on a 501HDV head and Bogen tripod. Very light, very agile, out the door in one hand, then down the stairs, along the side of the house, and 500' to where I set up on a hill ... all while carrying the C90 on tripod in one hand!

Mike

#177 Sarkikos

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Posted 10 December 2013 - 05:12 PM

I also put a 9x50 RACI finder on the C90, as in Syed's photos. This seems like a good combination with the C90, making it easier to find objects and giving a much lower magnification than the C90 could produce.

IME, though, a RACI alone is not the ideal finderscope. It's better to have a straight-through finder when initially getting in the vicinity of the object. (Actually, if all one is observing are bright planets or the Moon, a straight-through alone is good enough.) I'm considering which of my 1x finders to mount on the C90 to accompany the 9x50 RACI. The Telrad is immediately eliminated because of its large size. Maybe a QuickFinder or a red-dot? Then, exactly where to put it? :thinking:

However, one must beware of attaching too many add-ons to a small scope like the C90. IMO, that might vitiate the utility of a grab-n-go.

Mike

#178 t.r.

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Posted 10 December 2013 - 06:31 PM

Syed got me thinking...ya know what would be rad for a finder for the C90? The Baader Vario finder! That would be a mini dream package with the best of both worlds! Who's gonna do it?!? :grin:

Edit: Heck go all out and match it in black with a TV-60! :p

#179 azure1961p

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Posted 10 December 2013 - 07:42 PM

It seems like these little gem scopes not to be confused with GEM could benefit from a high quality mini finder - even 3x with a 25mm aperture - nice wide angle low profile. Trouble is tiny finders seem to get short shrift when quality is considered. Id love to have a nice high quality machined finder for my Ranger. The 18x is great but a five degrees would be better for locating things at times.

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#180 Sarkikos

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Posted 10 December 2013 - 08:31 PM

Syed got me thinking...ya know what would be rad for a finder for the C90? The Baader Vario finder! That would be a mini dream package with the best of both worlds! Who's gonna do it?!? :grin:

Edit: Heck go all out and match it in black with a TV-60! :p


Seriously, I was thinking about mounting one of my fast 70mm refractors on the C90. These are inexpensive and relatively light. I have one that's f/4.3 and another that's f/5.7. Neither is over-built, uber-heavy or relatively cumbersome like the ST80's and other similar small refractors.

But I'll probably stick with the 9x50 RACI and some lightweight little 1x finder. I really don't like the idea of loading a lot of heavy gizmos on these little grab-n-go scopes like the C90. That really wouldn't make a lot of sense.

Mike

#181 Mariner@sg

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Posted 10 December 2013 - 08:38 PM

Syed got me thinking...ya know what would be rad for a finder for the C90? The Baader Vario finder! That would be a mini dream package with the best of both worlds! Who's gonna do it?!? :grin:

Edit: Heck go all out and match it in black with a TV-60! :p


Someone might just end up wondering which is the main and which is the finder. :grin:


#182 Sarkikos

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Posted 10 December 2013 - 08:43 PM

It seems like these little gem scopes not to be confused with GEM could benefit from a high quality mini finder - even 3x with a 25mm aperture - nice wide angle low profile. Trouble is tiny finders seem to get short shrift when quality is considered. Id love to have a nice high quality machined finder for my Ranger. The 18x is great but a five degrees would be better for locating things at times.

Pete


That would be OK as long as the little optical finder is not a straight-through. :p

IME & IMO, straight-through optical finders are only good for quickly lining up the scope with a bright object like a planet, the Moon or a bright star. They are terrible for star hopping - again, IME & IMO. I'm speaking from my own experience here. RACI's are so much more comfortable.

But then, RACI's really ought to be used in tandem with some sort of simple straight-through finder - usually a 1x - in order to acquire the initial line-up before star hopping in the RACI.

Also, there is the fundamental question of where to mount these finders on the OTA. I think it is just wrong-headed how these straight-through finders are intended to be mounted toward the bottom of the OTA near the visual back.

I like to sit while I observe. Set up one of the C90's - or any small Cat or refractor - so it will be at a comfortable height for seated observing, and then try to sight through a little straight-through finder mounted at the bottom edge of the OTA! Not very comfortable. A straight-through really ought to go near the upper end of the OTA. RACI's should go at the bottom, near the eyepiece in the main scope. But I guess I'm making too much sense. :rolling:

Mike

#183 Sarkikos

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Posted 10 December 2013 - 08:48 PM

Pete,

There is this. I have one like it. 7 degree TFOV. A little expensive for a 6x30, though. IIRC, I got it somewhere else for less. Also, it's not low-profile. It's on a tallish stalk, which can be helpful sometimes to keep from getting too cramped up against the main scope.

Black 6x30 Right-Angle Correct-Image Finder

Mike

#184 t.r.

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Posted 11 December 2013 - 11:24 AM

Well, I'm gonna put my money where my mouth is, or at least, Mrs. Claus will! I researched high and low for the right complimentary finder to my C90 as a Christmas gift. Every year I pick out some small astronomical item, last year it was the C90! Considered the 60mm Baader Vario, 70mm Orion Multi, SV 60mm & 50mm Deluxe and even the TV & Tak 60mm. Decided to ask the Mrs. for the SV 60mm! Looking at Syed's pics, 70mm seemed too big, 50mm too small. SV 60mm with RA correct image illuminated reticle, takes other eyepieces, helical focuser, built in dewshield...black of course to match the C90! Somewhere around 210 clams. I didn't want to pay more than the C90, but I think this SV60 will truly compliment the C90 and keep weight (22 oz) and mass down to what is intended for my little rig. If anyone has any better ideas, better tell me now before I hand in my "wish list"! :p

#185 Starman81

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Posted 11 December 2013 - 12:44 PM

As long as it balances without a problem, go for the 60mm! I like the look of the somewhat large finder flanking the OTA, kinda looks like a jet refueling in mid air!

(original picture included again for easy reference)

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#186 Sarkikos

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Posted 11 December 2013 - 12:57 PM

Here you go:

Celestron 70mm Rich Field Refractor OTA - Short & Compact Telescope - 400mm

Mike

#187 t.r.

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Posted 11 December 2013 - 01:25 PM

I did look at that C 70R but, it looks like a mounting issue, with the wide dew cap and the funny mounting block. I think it would need a regular set of finder rings to standoff the C90 abit for practical use...no? I think it may be too big in proportion to the 90 but if someone has made this work...I'm in for $44! :grin:

#188 Sarkikos

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Posted 11 December 2013 - 02:12 PM

I bought a C70R last week. I had been looking at these periodically for at least a year and finally decided to take a chance. A year ought to be long enough before pulling the trigger on a $44 item.

The optics, fit and finish look completely adequate. The collimation was a little off. There are no collimation screws at the objective, of course. I removed the focuser and extended a couple of the screw holes so I could adjust the collimation from that end. Using a refractor collimation cap, I was able to set the collimation right on the bull's eye before tightening the screws.

I already have 70mm finder rings on a Synta/Vixen mount. If the rings won't fit over the focuser, it shouldn't be a problem to take off the focuser and install the 70mm in the rings. I haven't done this yet. Instead of ending up on the C90, the C70R could be the next finder for my 10" Dob or might remain a little grab-n-go 'fractor. At f/5.7, it ought to give some pretty nice views, maybe like a shrunken C6R. :grin:

Now I have the C70R attached to my 501HDV head and Bogen tripod via 1/4-20 screw, awaiting a clear night for testing. It would also help if the ice and snow would melt away. :p

Mike

#189 orion61

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Posted 11 December 2013 - 06:42 PM

As long as it balances without a problem, go for the 60mm! I like the look of the somewhat large finder flanking the OTA, kinda looks like a jet refueling in mid air!

(original picture included again for easy reference)

What a great little combo. I love the SLT mounts. I think thay are seriously under rated, (IF you put them on a good tripod)
I have even had my C8 on mine and it worked just fine, also my 120mm F5 Refractor had no problems.
My C6 is the scope used on it now, My 127 Mak just found it's way to the classifieds today after putting off selling it for months.. I really love that Mak, they are superb optically.. I highly suggest you try one if given the chance! They perform much BIGGER than the Advertised 5"
on Planetary and Double Stars. The nice Flat field is a huge plus on the Moon too!
I love this thread.

#190 t.r.

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Posted 29 December 2013 - 05:09 PM

"Christmas... IT CAME! Somehow or other, it came just the same!"

So, Mrs. Claus delivered! In my stocking was a nice box from Orion telescope. Inside was the new 70mm MultiFinder with rings and attachment bracket. It looks identical to the TV 60mm scope. This is the "poor mans" TV60 at $99. Out came my C90 mounted on the EQ2, off went the straight thru finder and on went the 70mm...plug and play. I wanted to try this as an alternative to the 8x50 finders!

It is a nice light weight unit just over a pound at 1.2. It weighs the same as the 8x50RA units. I mounted a nice light Celestron diagonal, 5 ounces, that comes with scopes these days and a lightweight 25mm ELux, again very light weight at 5 ounces. Combined weight at 29 ounces, then add the C90 at 3.7lbs for total package weight at 5.5lbs. Nice. Balance was achieved, helical focuser unscrewed to achieve focus providing a nice 4.6 degree fov @ 11x. It says that eyepieces over 20mm may not come to focus but a 32 and 40mm plossl did anyways. All my eyepieces, orthos,plossls,swa and ultras focused. I think this alternative to the typical 8x50RA is gonna work out well. Variable magnification and fov options. Contrary to the dismal review on Orion about alignment, I had no issues and the image looks clean although curvature is obvious at F3.9.

The helical was full of goo-lube however. Swapping eyepieces will be a chore too, in that each requires a different focal point and the helical focuser must have a set-screw loosened first to move the focuser to a new position. But, I intend to pick one eyepiece and leave it in providing a very wide complimentary view to the C90 primary and to act as the finder. A delux finder with enough oomph (twice the light gathering over a 50mm finder)to begin to show deepsky with a 15mm/18x eyepiece! I'll post a pic when I can. I can't wait for first light! :grin:

#191 Sarkikos

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Posted 29 December 2013 - 08:37 PM

t.r.,

I wish I'd known that Santa was going to bring you the Orion 70mm MultiFinder. I could have sold you mine. I thought you were going to get the SV60.

I've tried my Orion 70mm MF on the 10" f/4.8 Dob at my dark site. The image is good, considering it is working at f/3.9. That's even faster than f/4.3 of the old 70mm "toy" achromat I've been using as my optical finder. Images are pretty similar, too.

However, I do not like the helical focusing on the Orion MF. I prefer the standard dual-knob r&p focuser on the 70mm "toy." I wear glasses. Sometimes I want to view through the finder with glasses on, at other times without glasses. This requires refocusing. The helical focuser makes the diagonal turn in the focuser. Not too convenient. It's much more convenient to focus using an old style r&p. At this point, I'm about to sell the Orion 70mm MF and go back to my old 70mm "toy."

I received the Celestron C70R a few days ago. I gave it first light this past Saturday at my dark site, using it as the optical finder on my 10" Dob. This 70mm is an f/5.7. The view did look sharper across the field compared to the Orion MF and the 70mm toy scope. But the scope itself is also several inches longer, which brings the eyepiece farther down along the 10" Dob's OTA. This makes for a less comfortable experience. Also, it's more difficult to reach around and over this longer 70mm finder to look through my Telrad. I might try to mount the C70R finder closer to the sky-end of the OTA to compensate for the longer length. In addition, I prefer the even faster f/3.9 or f/4.3 of my other 70mm's, compared to the f/5.7 of the C70R. As a rough rule of thumb, the lower the power and the wider the field the better when it comes to star hopping. True, I might do the last little bit of star hopping through the main scope, but most is done in the optical finder.

So the C70R will probably end up as another of my little grab-n-go scopes rather than a finder scope.

As it stands now, IME, my old 70mm f/4.3 "toy" finder beats out both the Orion 70mm MF and my new C70R f/5.7. Well, you never know until you try.

Mike

#192 Sarkikos

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Posted 29 December 2013 - 08:54 PM

t.r.,

You mentioned that some users have had problems aligning the Orion MF. Yes, I definitely had more problems getting a close alignment with the main scope when using the Orion MF than with either of my other two 70mm's. For the other two 70mm's, they were mounted in two rings that are wider in ID and more widely spaced than the rings for the Orion. IME the Orion rings are too close together and too narrow for easy alignment. To make up for that, you probably have to get lucky with attaching the finder shoe just right.

Mike

#193 t.r.

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Posted 29 December 2013 - 09:50 PM

The work around I used for alignment was to leave the forward ring screws alone, simply supporting the tube, and did the alignment adjusting the aft ring screws...easy. COuldn't justify the price for the SV...over $200 clams, more than the C90 itself, didn't make sense. This setup so far is $250! I had the accessories. ;)

#194 Sarkikos

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Posted 29 December 2013 - 10:01 PM

Well, I will give the Orion MF another try in the field before I decide to sell it. I do like the fact that it has the lowest f number for a 70mm finder, AFAIK. And it does have good optics and good coatings.

I'm also going to try focusing the difference between glasses-on and glasses-off by moving the diagonal in-or-out a bit, rather than turning the helical focuser. I'll just set the helical for the farthest in-focus I need and leave it there.

Mike

#195 t.r.

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Posted 30 December 2013 - 07:50 AM

Yeah, I didn't like the little set screw to lock in the helical and it is necessary as the weight of an eyepiece in the diagonal will rotate the helical unless the screw is completely tightened. It is either locked or unlocked to rotate! Sliding the diagonal works too. So while this might not be an on-the-fly SBS refractor, it is about as close as one can get for the C90 with keeping it in proportion and it is nice to have so many options of magnification and FOV with it. The setup still looks rather svelt! ;)

#196 Sarkikos

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Posted 30 December 2013 - 09:34 AM

I bought my Orion MF before they started installing the set screw. I solved the diagonal rotation problem by wrapping a little plumber's tape inside the helical focuser. Now the helical focuser turns smoothly and grips tightly.

Having to deal with another screw in the setup does not sound like a good solution to me. You already have the screw to hold the diagonal in the focuser, and another screw to hold the eyepiece in the diagonal. Enough already. Sounds like we're getting screwed here. :thinking:

But in any case I do not want to focus with a helical focuser at my dark site, especially when a diagonal is in the focuser. Besides the diagonal rotating, there is also the problem with the wire from the dew heater strip. Rotating focusers are a royal PITA.

Last night I walked outside with the Orion MF to set the focus permanently. I set it for when I do not wear glasses. This is the farthest in-focus setting. Now when I put my glasses on, I just need to move the diagonal out a touch to be back in focus. I'd rather do this than focus with the helical.

By the way, Orion's Belt and M41 looked sharp in the finder. I'm using the Orion 20mm illuminated eyepiece. There was some FC toward the EOF ... but probably not as much as I saw in the ES 82 14mm eyepieces!

Mike

#197 Sarkikos

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Posted 30 December 2013 - 09:41 AM

For dual telescope use with the C90, I'd think about putting my Baader Zoom in the Orion MF. Or maybe my Titan-II 40, which has the largest TFOV for a 1.25" eyepiece. When used as an optical finder, though, I'd stick with the Orion 20mm illuminated eyepiece.

Mike

#198 t.r.

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Posted 30 December 2013 - 09:50 AM

It's nice to know that Orion looked sharp...I can't wait to first light the little bugger. I wonder how far the magnification holds up? The reason I got this was that looking for DSO's in the tight fov of the C90 is a challenge, while the light gathering of this 70 is twice what the 50mm finders provide, I'm asssuming that DSO locating and maybe even viewing will be easier/nicer than the C90. I thought it would be a nice, cheap compliment to the 90. I was originally gonna SBS the 90 with my C80SS to have the best of both worlds, but that combo is too heavy to be a nice compact rig. The 70mm fits as a finder better...We'll see. :grin:

#199 Sarkikos

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Posted 30 December 2013 - 10:01 AM

Oh, I know for a fact that DSO locating and viewing is easier in the Orion MF. I didn't even have the Orion MF on a mount last night. I just held it in my hand. An Amici RACI type diagonal was in the focuser. I always prefer a correct-image non-reversed view when locating objects. Why complicate things more than necessary?

True, Amici prisms are said not to hold up under high magnification. They are said to show a line in the FOV, too, but I have never noticed that with my Amici when viewing DSO. Also, isn't higher magnification what the C90 is for? I'd reserve the Orion MF for low-power, rich-field, wide-field views.

Mike

#200 mattyfatz

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Posted 31 December 2013 - 03:44 PM

Has anyone compared the optics of the modern day C90 to the ETX90 (UHTC type)?
I'm very happy with my ETX optically. IT seems that the C90 has more versatility though. Meade doesn't make many of the older adapters, the finder scope is useless..


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