Celestron C6 and AZT6

[Ags]

I spent an enjoyable night tonight collimating my C6 and then pointing it at Saturn and Jupiter. On the subject of collimation, my considered opinion is collimating an SCT is waaaay easier than collimating a Newt. There are just three screws, a simple diffraction pattern, and you're done in a few minutes. There's just less moving parts than a Newt.

Freshly collimated, the C6 gave stunning views of Saturn and Jupiter despite their low altitude. Using a 13.4 mm eyepiece, 112x magnification gave a big, bright image, no floaters in sight. And all this from a little scope just over 3 kilos in weight! I had the scope sitting on a TS AZT6 travel mount, and wow, it was smooth with no backlash, it gave a better viewing experience than more expensive giro-type mounts I have owned.

So happy I am a C6 owner!

[newbie alert]

One thing to have in mind is that it's just as easy to get collimation wrong as it is right.. just in the direction of travel either side of focus.. here's a screen shot of the doughnut on both sides of focus.. one is wrong, the other is right

[Ags]

@newbie alert Not sure I understand what you are saying? Can you explain a bit more?

[newbie alert]

The top image is obviously wrong,bottom one right.. collimation is the same but the only difference is that they're at different sides of focus.

So you can easily get it wrong if you focus on the wrong side

Any help?

[Ags]

Still not following you. Why does the side of focus matter? The end goal is a concentric pattern and you can see that inside or outside of focus?

Edited September 8, 2021 by Ags

[CraigT82]

I think the point is the mirror may flop a little when you change focus direction. So if you moved focus inwards, then collimated, then move focus outwards the slight flop in the mirror changing direction may throw the collimation off. Some SCTs are bad for this and some hardly have any flop at all.

Aftermarket Crayford focuser solves the issue, if it's there. 

[Ags]

Ok, that makes sense. I don't think my mirror is very floppy. For example I get zero image shift, and collimation was stable when I refocussed.

[Guest]

Hello Ags. I like this topic you have posted. I to have a C6 and an concious of the need for collimation. May I ask what brand your 13.4 mm eyepiece is please. 

[Ags]

It is a Speers WALER 13.4, very nice but the eye lens tends to fog. 

I discovered recently I have been collimating wrong. Those collimation knobs are meant to be tight, and I've been keeping them loose. 

[Ags]

Just had another nice mini-session on Jupiter, followed by a couple of double stars. Collimation can be a wonderful thing!