collimating query

[coffee_prince]

FLO Quote

Please note, for any laser collimator to be effective it needs to be fitted to a well-made focuser. The regular rack-and-pinion style focuser fitted to many beginner/intermediate telescopes lacks precision and rigidity. If in doubt please contact us for advice.

How true is this statement for the Skywatcher 200 dob, it comes with crayford focuser, it is a little loose to be honest

[Moonshane]

you should be fine with a crayford but you need to ensure your laser is itself collimated.

[todd8137]

what part of it is a little bit loose ?

[coffee_prince]

hard to explain, you can turn the focuser in its place, and there is some ability to jiggle it about, looking through a 10mm ep it is a large movement. It doens't jiggle in normal use, unless I move it

I did a star test yesterday and I think it is off as the black circle was not in the middle (still got some nice views though).

I'm currently using a homemade collicap

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Can I confirm secondary alignment, mirror needs to look like a perfect circle, and be placed in the middle of view?

[Skiddins]

If you can move the entire focusser it sounds like you need to tighten up the mounting bolts.

I had the problem on mine where the rack and pinion system was a bit loose, but after tightening up the four screws on the adjuster section it works far better.

[coffee_prince]

the actual focuser itself is scewed into the ota tightly, the grey tube that extends in and out when focusing can be rotated and jiggled about

[johninderby]

There are "cheaper" crayford focusers and then there are the better quality crayfords. The one that comes standard on the 200 dob is certainly better than the rack and pinion, but not as good and solid as the replacement crayfords.

However you should be able to adjust the focuser on your scope to get rid of most the excess movement.

John

[coffee_prince]

there only appears to be a screw which locks the focuser in place, i've tried every other screw lol

is this focuser accurate enugh for a laser?

[daz]

You should be able to adjust the tension on the drawtube (the grey tube that moves in and out) - usually by tightening some screws (they may be behind a plate on the front) on the focuser itself.

If you're not sure, take a close up image and we'll help out there (not sure of the exact focuser on that scope, but there will be a way to adjust the tension, which may help to take out some of the play)

When using a collimated laser, use it in the SAME orientation each time and use the same screw to lock it in place in the focuser.

And yes, your focuser is fine!

[coffee_prince]

i'll post a pic/vid later on, i find collimating fiddly so a laser would help so i don't have to keep going back and forth

if the black middle in the startest isn't central, what does this mean?