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Question about new C6A-XLT SCT??

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#1 tomcat141

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Posted 01 November 2013 - 11:12 AM

I just ordered a new Celestron C6 SCT OTA but have not yet received it. I have been reading everything I can find, and they seem to be highly regarded. The exceptions are the finder scope and the diagonal.

My main concern at this point is the diagonal. Do I need to replace it or is the stock diagonal pretty good?

Also, if I do replace it, is it worthwhile to go 2" or would it be a waste of money for this size scope?

Thanks in advance for your thoughts and experiences.

#2 LTE

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Posted 01 November 2013 - 11:45 AM

Regarding the finder, the supplied red dot finder gets one into awkward attitudes, difficult for older people (I am 72). Also, the red dot always seems too bright and the stars too faint. The fitting is non-standard, so replacement with a finder telescope is difficult. I plan to fit a StarSense camera, once these are fully developed and available here in the UK; this will also eliminate the need to align manually.
Tom.

#3 desertlens

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Posted 01 November 2013 - 12:41 PM

The visual back and the diagonal are pretty pitiful. I replaced mine with the following:
SCT-T thread adapter
T thread EP holder
GSO dielectric diagonal
This combo is only 3mm longer than the stock component.
I'm not sure which finder you have but the little 6x30 I received was replaced with this one:
MRF/Synta base
Enjoy the new scope.

#4 Bill Barlow

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Posted 01 November 2013 - 02:34 PM

The supplied visual back is okay, but when I owned one of the scope's a while back, I bought a 1.25" dielectric 99% reflective diagonal. I wouldn't use 2" eyepieces with is scope since the rear baffle tube's diameter is about 26mm. Enjoy your new scope.

Bill

#5 RTLR 12

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Posted 01 November 2013 - 02:42 PM

Regarding the finder, the supplied red dot finder gets one into awkward attitudes, difficult for older people (I am 72). Also, the red dot always seems too bright and the stars too faint. The fitting is non-standard, so replacement with a finder telescope is difficult. I plan to fit a StarSense camera, once these are fully developed and available here in the UK; this will also eliminate the need to align manually.
Tom.


The C6A-XLT comes with a 6x30 optical finder. It's still awkward to use though.

Stan

#6 kkokkolis

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Posted 01 November 2013 - 04:12 PM

I tried many finders and settled with a Rigel Quickfinder (excellent) and a Stellarvue F50 (magnificent, mainly used for objects that don't fit in C6's TFOV).
I also put a 2" dielectric diagonal with SCT thread. It is better; eyepieces fit better and it is sturdier. I use 2" eyepieces also with that and my most wide, a Hyperion Aspheric 31 doesn't vignette (but I was told that the 36mm does a bit). Some eyepieces like Naglers T4 and ES100s come in 2" format and I wouldn't be able to use them otherwise. So, a 2" diagonal opens your options.

#7 tomcat141

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Posted 01 November 2013 - 04:45 PM

Regarding the finder, the supplied red dot finder gets one into awkward attitudes, difficult for older people (I am 72). Also, the red dot always seems too bright and the stars too faint. The fitting is non-standard, so replacement with a finder telescope is difficult. I plan to fit a StarSense camera, once these are fully developed and available here in the UK; this will also eliminate the need to align manually.
Tom.


Thanks Tom. I will be 72 in a very short time. It is my understanding my version of the scope comes with the 6X30 straight through finder. I have a 90 degree finder which came with my dob, and possibly I can use it.

Thanks for the reply.

#8 tomcat141

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Posted 01 November 2013 - 04:50 PM

The visual back and the diagonal are pretty pitiful. I replaced mine with the following:
SCT-T thread adapter
T thread EP holder
GSO dielectric diagonal
This combo is only 3mm longer than the stock component.
I'm not sure which finder you have but the little 6x30 I received was replaced with this one:
MRF/Synta base
Enjoy the new scope.

Thank you. I will research your choices. Happy to hear what others are using. I like the look of your finder.

#9 tomcat141

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Posted 01 November 2013 - 04:58 PM

The supplied visual back is okay, but when I owned one of the scope's a while back, I bought a 1.25" dielectric 99% reflective diagonal. I wouldn't use 2" eyepieces with is scope since the rear baffle tube's diameter is about 26mm. Enjoy your new scope.

Bill

Did you notice much difference in the views after changing your diagonal? As I haven't seen mine yet (Monday I hope) I don't know how good or bad the diagonal will be. I read somewhere it is a plastic body.

There seems to be some differences of opinion on using a 2" lens on these small scopes. I understand the small baffles will limit the view, but some say their 2" EP's work well up to about 30mm. :confused: :grin:

Thanks for your input.

#10 tomcat141

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Posted 01 November 2013 - 05:15 PM

I tried many finders and settled with a Rigel Quickfinder (excellent) and a Stellarvue F50 (magnificent, mainly used for objects that don't fit in C6's TFOV).
I also put a 2" dielectric diagonal with SCT thread. It is better; eyepieces fit better and it is sturdier. I use 2" eyepieces also with that and my most wide, a Hyperion Aspheric 31 doesn't vignette (but I was told that the 36mm does a bit). Some eyepieces like Naglers T4 and ES100s come in 2" format and I wouldn't be able to use them otherwise. So, a 2" diagonal opens your options.


I was thinking I would try my Telrad if it is not too large for the 6" scope. I like it on the dob. Your experience using 2" ep's differs from the earlier post, adding to my confusion. As with nearly everything else, opinions vary. I am just trying to get an idea which way to go when I change out the diagonal. I presently have both 1.25 and 2" lenses.

Does the APOF of the lens have a bearing on which will work and which will vignette?

#11 Dave L

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Posted 01 November 2013 - 05:19 PM

I have a C6. The diagonal is fine for a beginner. I would not change it yet. The diagonal give good views. I think you need to familiarize yourself with the scope. It is a fine tool. Once you comfortable with the hobby and scope, it is then time to think about improvements to the tube, or the purchase of a larger scope.

#12 jrbarnett

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Posted 01 November 2013 - 05:20 PM

The stock diagonal is "okay". I would not, however, make replacing the diagonal a top priority if I was budgeting. Like all SCTs, dew control is essential. You can go passive in the form of a dew shade, which buys you a little time before the corrector dews up, or active in the form of a dew heater strip and a dew heater controller and suitably large battery to battery to power it, or combine the passive and active (best) and observe dew free pretty much year-round.

Personally I think going 2" on a C6 is a waste of time. It has a straw-diameter central baffle and very little real estate on the rear cell. A 2" diagonal crowds the focuser knob.

I dislike straight through finders of any kind, whether RDFs or magnified. I strongly prefer a right angle correct image magnified finder. To add one to the C6 you'll need to but a finder shoe that fits the C6 and a finder. I like the Orion 6x30 RACI on the C6 as it's light weight and has a large 7-degree field of view. The bigger 8x50 and 9x50 finders work, but are awfully large in proportion to the size of the OTA. They also have smaller fields of view than the 6x30.

Regards,

Jim

#13 mclewis1

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Posted 01 November 2013 - 05:53 PM

What Jim said ... 100%

I bought the nice little Orion right angle 6x30 finder and use it with the original mounting brackets on my C6. I've tried 2" accessories on my C6 and while the big and solid attachment of an SCT threaded 2" diagonal is nice, it doesn't buy me much. The downside is that the back of a C6 doesn't have a lot of real estate, things are quite close together. The focuser knob ends up very close the the larger diagonal and can sometimes really be a problem depending on how I orient things, and I have to do things like removing the thumb screws on my 2" visual back in order to thread it onto the rear cell.

I have some nice 2" gear but I really like using my C6 with 1.25" accessories and sometimes the SCT f6.3 focal reducer.

#14 Eric63

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Posted 01 November 2013 - 07:19 PM

I have a Telrad on my 127mm Mak and it fits perfectly.

#15 brianb11213

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Posted 01 November 2013 - 07:55 PM

The stock diagonal is "okay". I would not, however, make replacing the diagonal a top priority if I was budgeting. Like all SCTs, dew control is essential. You can go passive in the form of a dew shade, which buys you a little time before the corrector dews up, or active in the form of a dew heater strip and a dew heater controller and suitably large battery to battery to power it, or combine the passive and active (best) and observe dew free pretty much year-round.

+1

Personally I think going 2" on a C6 is a waste of time. It has a straw-diameter central baffle and very little real estate on the rear cell. A 2" diagonal crowds the focuser knob.

+1. Also a 2" visual back & diagonal extends the optical path beyond the point the scope optics are designed for. The standard 1.25" back & diagonal used with a 32mm Plossl shows as much true field of view as the scope can usefully deliver (in fact there is significant vignetting even with this setup).

I dislike straight through finders of any kind, whether RDFs or magnified. I strongly prefer a right angle correct image magnified finder.

-1. I find it almost impossible to point a scope using a right angled finder, just as I'd find it almost impossible to drive a car, at speed, in traffic with all the windows except the one in the passenger door blacked out. If you really must have a right angle finder you need a Telrad type finder as well, to get you pointed close enough to see the target in the finder.

The 6x30 inverted image, straight through finder is a good match to the C6 tube.

#16 Jan Owen

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Posted 01 November 2013 - 08:10 PM

While they don't add much to the aesthetics of the telescope (no matter what scope they're on), the Rigel is still a favorite of mine. It's really light, easy to adjust, easy to use, and reliable. And batteries last a long time (as long as you remember to turn it off when you're done observing)... I have Rigels on three of my scopes...

#17 dpippel

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Posted 01 November 2013 - 10:04 PM

Personally I think going 2" on a C6 is a waste of time. It has a straw-diameter central baffle and very little real estate on the rear cell. A 2" diagonal crowds the focuser knob.


Depends. If you already have a few 2" eyepieces then a 2" diagonal is a good investment IMO. I can go up to a 2" 31mm Baader Aspheric in my C6 with no noticeable vignetting, and the 2" GSO SCT diagonal I have doesn't crowd the focuser knob at all on an alt/az mount. YMMV of course on a GEM, where rotating the diagonal is often necessary to get an optimal viewing angle.

#18 tomcat141

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Posted 01 November 2013 - 10:14 PM

I have a C6. The diagonal is fine for a beginner. I would not change it yet. The diagonal give good views. I think you need to familiarize yourself with the scope. It is a fine tool. Once you comfortable with the hobby and scope, it is then time to think about improvements to the tube, or the purchase of a larger scope.


Thank you for the advice. It is good to hear the diagonal is not too bad. I will have a chance to look it over on Monday if the tracking info is correct. I was concerned about it when I read it was plastic.

BTW, I do have a 10" dob also. My reason for buying this C6 was to use it as a grab and go scope, one I could take when camping, etc.

#19 dpippel

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Posted 01 November 2013 - 10:16 PM

I bought mine specifically for use as a grab-and-go too, and it works admirably in that role. What are you going to mount it on?

#20 tomcat141

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Posted 01 November 2013 - 10:25 PM

Jim, Thanks for the information. I like the idea of not having to buy a new diagonal right away. You are correct on the dew control. I have had problems with my dob with dew, especially on the Telrad.

I'm not sure what I will end up with for a finder. I really like the Telrad best on my dob, next to the setting circles I have just recently installed. They seem to get me on target pretty well. I find I have difficulty with the right angle finder. Just my lack of experience I guess. With the telrad, I can better see the area of the sky where I want to observe.

Thank you for your comments. I appreciate all the advice here.

#21 tomcat141

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Posted 01 November 2013 - 10:35 PM

Thanks Mark and Eric. With the straight through finder coming on the C6 and my RACI and Telrad from the dob, I should be able to find what is best for my needs. I think the Telrad or the straight through finder may be awkward with the 90 deg. diagonal. Will have to wait and see.

For the time being, I will use the scope on a heavy duty tripod with a fluid head. If the height is adjusted properly, I may not have too much trouble bobbing around sighting and observing. :grin: :grin:

Mark, it is interesting and encouraging to hear you like your scope with 1.25 accessories.

#22 tomcat141

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Posted 01 November 2013 - 10:40 PM

Brian, thank you for the comments. I agree at this point with your opinion of the right angle finders. I have always found them difficult to use. I normally just rely on the telrad.

Jan, I have looked at the Rigel finders and have always wondered if I would like them as well as the telrad. Both are rather large, IMO. Thanks for the comment.

#23 tomcat141

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Posted 01 November 2013 - 10:51 PM

Personally I think going 2" on a C6 is a waste of time. It has a straw-diameter central baffle and very little real estate on the rear cell. A 2" diagonal crowds the focuser knob.


Depends. If you already have a few 2" eyepieces then a 2" diagonal is a good investment IMO. I can go up to a 2" 31mm Baader Aspheric in my C6 with no noticeable vignetting, and the 2" GSO SCT diagonal I have doesn't crowd the focuser knob at all on an alt/az mount. YMMV of course on a GEM, where rotating the diagonal is often necessary to get an optimal viewing angle.


There you go, confusing me again :grin: :grin:. Reading all this advice, I have pretty much decided to try the diagonal that comes with the scope, and then if I think the views would improve, go for a better quality 1.25 diagonal. I only have two 2" EP's but my barlow is also 2 inch. I am not so worried about having to rotate the diagonal, as this scope will most likely always be on some sort of alt-azimuth mount. I may buy a T mount to attach my Nikon dslr for terrestrial use, but I don't forsee trying astro-photography or even a GEM.

#24 tomcat141

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Posted 01 November 2013 - 11:04 PM

I bought mine specifically for use as a grab-and-go too, and it works admirably in that role. What are you going to mount it on?


Glad you asked! At first, I will mount it on a HD photo tripod or I also have an Orion Paragon Plus tripod. I also have a bogen fluid head which I may try. I have used it with the 25X100 binos which weigh around 10 lbs. Oh, another crazy idea I have is to try the OTA on the parallelogram I built for the 10 lb binos. I can move them anywhere, and any direction with one finger, and they just hang where ever I let go of them.

Like I said in a previous post, I have recently installed degree circles on my dob and a digital level which makes finding objects fairly easy. I use Stellarium to get the locations.

I like to tinker, and although it may sound foolish, I may try to build a table top dobsonian type mount where I can use degree circles just like my 10" dob. I may even be able to adapt this little mount to a pier in my backyard or use it on a picnic table at camp. Sounds crazy, huh?

#25 tomcat141

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Posted 01 November 2013 - 11:12 PM

Well, you're all probably tired of my ramblings, but seriously, I want to thank everyone for the sound advice. Different ideas and opinions is what I was looking for, and you all came through. I hope I did not miss recognizing anyone, but I want to thank each and every one for the comments. Thank you :bow: :bow:






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