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C5 or C6 For SLT

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#1 Jeff Lee

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Posted 07 December 2019 - 10:06 AM

I've seen (perhaps for Europe?) a SLT/C6 combination. I do EAA and want to add a scope that is bigger than my ST80 for EAA (4-8 second exposures). The C6 appears to be just a bit too heavy for the specs of the SLT but it is a inch larger than the C5.


Which would you get and why?



#2 MrRoberts


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Posted 07 December 2019 - 11:25 AM

I love my C-6, aperture always wins with everything else being equal in this sport, but will have to wait for others with the slt to say what their experience has been.

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#3 mclewis1


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Posted 07 December 2019 - 11:28 AM

Safer with the C5, but with care the C6 can work. Are you willing to spend some extra time fine tuning your balance? Will you keep the configuration mostly static (not moving back and forth with visual work and very different weight/balance setups)? Will you not be too upset if your SLT dies a little prematurely?


If yes then you can probably get away with the C6.

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#4 mikenoname


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Posted 07 December 2019 - 05:30 PM

My SLT runs quite well with a ~10# load and will keep perfectly round stars up on up to 4-second exposures. There are three things to keep in mind to make that happen:


Strong tripod. The weak link of the stock SLT is not the mount, it's the tripod. Replace it with a heavier one (I made mine inexpensively) and the mount will work happily at above Celestron's 8# rating.


Strong voltage. If you use a battery, use an external battery that is kept well charged. The motors are strongest and work most efficiently at 12V. Make sure you have a power supply that keeps it there.


Balance. Set your OTA on a table, load it up with camera and all the gear that normally rides on it, place a marker/highlighter/pencil underneath it and move it back and forth until you find the balance point and mark it on the scope. Then set in in the mount such that you are either *slightly* nose-heavy or tail-heavy depending on how you have your GoTo Approach set on the mount. The better you get this, the easier you make it on the mount's motors.


Imaging Setup 130_SLTs.jpg

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#5 Michael_Swanson


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Posted 08 December 2019 - 08:33 PM

The SkyProdigy mount is/has been sold with the C6.  That mount is essentially the same as the SLT so Celestron thinks it can be done ;-)


But, I agree the tripod isn't really up to it.  Many years ago I moved my SLT mount to a NexStar 4SE/5SE tripod (see page 191 of my book) and the difference is significant.  Unfortunately that tripod isn't sold separately though you might find one available on the used market occasionally.


Best regards,
Mike Swanson
Author of "The NexStar Users Guide II"
Author of "The NexStar Users Guide"
Author of "NexStar Observer List"

#6 Jeff Lee

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Posted 09 December 2019 - 10:52 AM

Thanks all. I have my SLT on a set of carbon fiber legs rated for a true 22 pounds, very steady and vibrations from touch  the scope die under 1 second. Since I only do EAA with this setup I am thinking that a 6 would be as good as a 5 - whichever comes up on the B&S in January. Thanks all for the input, and I've been using this mount for about 10 years and do mark my vixen rails for balance point and set the mount up and use the proper front/back settings. Since  I have the ZWO224/FR3.3 and the 290MC/FR6.3 to use I am very tempted to go for the 6 and use 3-5 second exposures. Every inch of aperture of course makes a difference in these smaller scopes. Worse thing that could happen is having to look for a used SE mount.


I do use an external battery and can get 6-8 hours before it drops voltage.


I have the NSX(?) software loaded on both HC's and have found the mount to be very useful for my travel and long distance star parties. If my C90 (USA rubber coated) could use the FR's (can come to focus at infinity with them) I'd not be looking for a larger scope.

Edited by Jeff Lee, 09 December 2019 - 11:12 AM.

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