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Something for nothing: Celestron C90

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#376 Patricko

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Posted 08 April 2015 - 04:15 PM

Given that the inner diameter of the primary baffle on the currently-produced Celestron C90 is between 16 and 17 millimeters, what's the largest diameter eyepiece field-stop that one can expect the scope's light-cone to fill at the stock visual-back, with the shortest light-path that the scope allows?

 

Does lengthening that light-path allow the light-cone to fill wider field-stops?

 

If so, at what cost?

 

Also, are there any after-market dual-speed focus-knobs mechanically compatible with the currently-produced C90's moving-mirror focuser?

Failing that, is anything like this available in a version compatible with the currently-produced C90?

My testing notes show any eyepiece with a field stop larger than 22mm will begin to vignette.



#377 SkyCruzr

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Posted 08 April 2015 - 10:00 PM

$159.99 at Optics Planet - 11% using 11BLACK code comes out to $142.39 with free shipping! Had to post, still a great deal. 

 

And a mere 4 months later it now costs $219.99. You guys went and made this scope too popular :bawling: I wore out the innerwebz today trying to find a "deal" on it.....none to be found. Only a handful of places selling the kit, and all are the same price. I'll try the 5% off code (FTZBX) that optics Planet plasters on their boxes. Upside, my wife says "Just go ahead and get it".



#378 Sarkikos

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Posted 09 April 2015 - 08:52 AM

Here is a C90 for $169.95.  http://www.adorama.c...CFS9o7AodQ04Ayw

 

Mike



#379 Steve C.

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Posted 09 April 2015 - 10:51 AM

It's still 169.95 at Amazon.



#380 t.r.

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Posted 09 April 2015 - 12:10 PM

Click on it too many times at Amazon though and the price goes UP!!! Wait  a day or two and it goes back down. There is no doubt in my mind they use some type of "hit program" for watching  items that become popular ("hot")!


Edited by t.r., 09 April 2015 - 12:11 PM.

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#381 Starman81

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Posted 09 April 2015 - 03:13 PM

 

$159.99 at Optics Planet - 11% using 11BLACK code comes out to $142.39 with free shipping! Had to post, still a great deal. 

 

And a mere 4 months later it now costs $219.99. You guys went and made this scope too popular :bawling: I wore out the innerwebz today trying to find a "deal" on it.....none to be found. Only a handful of places selling the kit, and all are the same price. I'll try the 5% off code (FTZBX) that optics Planet plasters on their boxes. Upside, my wife says "Just go ahead and get it".

 

 

Optics Planet has a zany pricing engine. I think it is driven by whatever current online coupon codes are live and circulating at any given moment. The $219.99 price is highly inflated from it's normal price, which is about $165 +/- $15. I do recommend them though. At times you can get some very good deals if you happen to combine one of their online coupon codes with a manufacturer's sale price and their shipping is fast and the customer service is good. 



#382 SkyCruzr

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Posted 09 April 2015 - 03:54 PM

Thanks for the replies folks. Since I am new to this hobby, I don't have an abundance of spare stuff laying around. Yet! That's why we wanted to get the kit package. We plan on leaving it in the back seat of the truck so it is always at the ready when we are out wandering around. So much more portable than the 6SE.

 

I found it strange that the kit with one eyepiece and no tripod actually costs more ($229.99) at OP than the kit with the tripod and 2 eyepieces. :scratchhead:



#383 Rmorales6

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Posted 22 April 2015 - 10:57 PM

 

Given that the inner diameter of the primary baffle on the currently-produced Celestron C90 is between 16 and 17 millimeters, what's the largest diameter eyepiece field-stop that one can expect the scope's light-cone to fill at the stock visual-back, with the shortest light-path that the scope allows?

 

Does lengthening that light-path allow the light-cone to fill wider field-stops?

 

If so, at what cost?

 

Also, are there any after-market dual-speed focus-knobs mechanically compatible with the currently-produced C90's moving-mirror focuser?

Failing that, is anything like this available in a version compatible with the currently-produced C90?

My testing notes show any eyepiece with a field stop larger than 22mm will begin to vignette.

 

This has been on my mind as well. I don't know if anyone has taken this scope apart, but is it possible to remove the primary baffle and widen the hole?



#384 jrbarnett

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Posted 28 April 2015 - 06:04 PM

 

 

There is "grab'n'go" and then there is grab'n'go. All my darn G-n-G's eventually gain so much weight that they really aren't G-n-G's anymore. Either the scope or mount gets upgraded to a point where the portability is compromised. Case in point: my SW 120ED. Meant to be a G-n-G... Not too heavy a scope overall, but long and large and with the AT Voyager Mount + extension pier + CG5 steel tripod --> somewhat of a beast requiring two trips. 

 

But like you said, the C90 on a lightweight mount/tripod combination is an 'ultimate grab'n'go'! I have a DwarfStar mount and now waiting on the Slik 700DX Pro tripod to come in. 

 

 

From my experience, I wouldn't consider any refractor as big as a 4" f/10 or bigger to be a grab-n-go scope.   They and the mounts they require are just too big, long and awkward for easy grab-n-go for many observers.   If you need to bring your mounted scope down stairs, out through a standard-sized house door and maybe down more stairs from the porch, forgetaboutit.  You're talking two trips unless you enjoy a struggle and like to live on the edge.  The only exceptions are if you park your mounted scope right beside the sliding doors to your deck or inside your garage.  Shoot, in those situations a 10" Dob could be a grab-n-go!

 

The C90 is a very nice grab-n-go scope.  Extremely compact and light.  I recently snagged a UA MicroStar on sale.  Sometimes I wish I still had my C90, because it would be the ideal little scope for that mount.

 

But so far IME the C5 is the ideal grab-n-go scope.  True g-n-g, not "open the sliding doors and schlep the scope onto the deck" g-n-g like your 4" and larger refractors.   I can put the C5 in a little padded bag or knapsack, sling a tripod and folding stool across my shoulders and walk the whole kit and kaboodle a couple miles to an observing site in my neighborhood.  Try doing that with a C102.  Well, you could do it, but it would be quite a work out.  

 

Mike

 

 

Mike, please be quiet with all this talk about the C5 being the ideal grab'n'go because you are just making way too much sense. The C5 is a nice step up from C90 in light gathering, nearly double (93%) and is still very small and lightweight, keeping mounting requirements modest. 

 

But I got the C90 for next-to-nothing and my C6 for a planned venture into EAA (which has not yet happened). Adding a C5 would be craziness. Who needs a quartet of C90/C5/C6/C8? That's what I would have if I added the C5... So... I'm not gonna hear it anymore!

 

:lalalala:

 

Now back to our regularly scheduled program of C90 news... Got the little guy on the DwarfStar mount + Slik 700DX camera tripod combo--nice!!

 

The C5 is "something", but definitely not "for nothing".  It costs as much as the larger C6, new, and about 3x as much as the C90 when the latter is on sale.

 

The C5 is a nice grab & go catadioptric for sure, but a C6 will show oh-so-much-more for the same cost.

 

The C90's beauty is really in its price.  It is a quality, non-toy, reasonably apertured scope with good optics for less than $160 new.

 

As a "something for nothing" proposition, the C90 is still secure in its crown.

 

- Jim



#385 Sarkikos

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Posted 28 April 2015 - 06:38 PM

I suggest trying to pick up a used C5.   That's what I did.  

 

The C6 will show a bit more but it also weighs quite a bit more and is longer and larger.  I can mount my C5 on a decent photo head and tripod.  Not a super expensive beefy photo head and tripod, but a decent light-weight one like a 501HDV and Bogen.  Personally, I think a C6 is too much for such a mount.  For the C6, you really need to move up to something like an AT Voyager, Vixen Porta Mount, or a NexStar SE 6/8.  

 

Also, the C5 is much easier to pack and carry for a walkabout.  I can fit a C5 in a little bag or mini-knapsack, carry a 501HDV and tripod, sling a folding camp stool across my shoulders, and walk several miles to a local observing site.  The C6 is much more of a bear to pack and carry along and requires a heftier mount.  Not a kit I'd want to walk with more than a short distance.  The C6 is a backyard scope.

 

The C5 is just so much better as a quick grab-n-go scope than the C6.   The C5 is also a good scope for long walkabouts.  And the C5 is not much more trouble than the C90.

 

IME, the C5 is the best compromise of aperture and portability for easy grab-n-go.  That's why I still have the C5 and no long have the C6 or C90.  My remaining SCT's consist of an EdgeHD 8" and a C5.  So far that covers everything I want in an SCT.

 

Just because something's cheap doesn't mean you have to buy it. :shrug:

 

:grin:

Mike


Edited by Sarkikos, 28 April 2015 - 06:49 PM.


#386 Patricko

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Posted 28 April 2015 - 08:29 PM

All great points regarding the C5 Mike. I have both, the C5 and C6. The C5 acclimates in half the time. In fact it seems to acclimate about as fast as a 102mm doublet or a 90mm triplet. I can't say that about my C6. I've had a few examples of these 90mm (87.5mm) wonder Maks and they take longer to acclimate than the C5. Really there is nothing the C90 can do better optically than the C5. The C5 just makes more sense. Same focal length as the C90, wider rear baffle, a LOT more light gathering, better coatings, and better resolution. Only down side as Jim points out is the cost. I got mine new with a carry case included. 


Edited by Patricko, 28 April 2015 - 08:40 PM.

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#387 Usquebae

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Posted 28 April 2015 - 09:21 PM

 

 

Just because something's cheap doesn't mean you have to buy it. :shrug:

 

Hey, this is America!

 

:usa:


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#388 Quixylvre

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Posted 28 April 2015 - 11:43 PM


Just because something's cheap doesn't mean you have to buy it. :shrug:

 

:grin:

Mike

If it's the only option one can afford when looking to buy a telescope, on the other hand…


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#389 hardwarezone

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Posted 29 April 2015 - 12:37 AM

I think the C90 #52268 is a good option to keep the beginners away from the powerseeker and astromasters.


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#390 RodgerHouTex

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Posted 29 April 2015 - 08:51 AM

I like my 6se, but it's too large for my Versago II, and I'm not crazy about the 6se go-to mount.  So my C90 gets more use.  Plus it cools quicker and lets me know what it would be like to own a Questar.  Saved me from spending $5000 for a 90 mm Mak.


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#391 Sarkikos

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Posted 29 April 2015 - 09:21 AM

Well, sometimes I do think about getting a C90 for my MicroStar mount.  That mount is persnickity to balance.  So far the C5 does not play well with it.  A C90 might be the best scope for the MicroStar.  Now, if there is a really good sale on C90's ...

 

:grin:

Mike



#392 KarlL

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Posted 29 April 2015 - 10:42 AM

I've been playing with a NexImage 5 on my C90 for about a week. It's very cool. Although I am not yet tracking, I've taken a few good Lunar shots. Registax is my friend.

#393 t.r.

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Posted 29 April 2015 - 11:05 AM

Please post some pics KarlL!



#394 KarlL

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Posted 29 April 2015 - 01:56 PM

I have one in the Lunar Gallery. VERY rough, but it is a start. More to follow.

#395 Usquebae

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Posted 02 May 2015 - 02:04 PM

Last night was predicted to be thoroughly overcast here until 2 a.m., so I had no plan to observe.  The sky was a carpet of clouds at dusk, so I didn't bother setting any equipment out, and planned on a night indoors.  At halftime of the footie game I was watching, I poked my head out the door and found a brilliant Moon hanging in a clear and moderately steady (for here) sky.  So I put a few plossls in my pockets and headed out to use my ever-acclimated "boot scope" (C90 & DwarfStar mount I now keep in the trunk of my car).  Got great views of Jupiter at 125x, and decent Lunar views up to 147x.

 

I left the scope out while I grabbed a bite and finished watching Spirit spank Sky Blue FC (eat it, New Brunswick!), then I poked my head out the door again.  Still clear!  Luna was heading for my treeline but still well placed, and now Saturn had joined the party.  The clouds eventually arrived around 2am - the hour at which the sky was supposed to be clearing, according to the weather prediction.  Were it not for the C90 in my trunk, I would not have done any viewing at all.

 

I used the boot scope again this morning to check whether the Sun was spotty enough to warrant bringing out a bigger scope & BV for white solar viewing.  It was not, and I was saved some time and disappointment.

 

Other scopes like 80 ED may be more a more versatile grab&go options than the C90, but only the C90 is so cheap that I was required by law to buy one.  And I'm glad I did!

 

:jump:


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