Bent fin

[MattSett]

Merry Christmas all!

So my long wait for my first scope is over, I unpacked it, thanked Santa, and set it up. However when struggling to collimate I noticed that 2 of the fins holding the secondary mirror are bent. At risk of sounding stupid, this isn't normal is it? I guess not as I can't get the red collimator dot anywhere near the centre of the primary mirror.

So tonight if it does clear i shall have to use the naked eye, while standing next to my nice telescope!

Cheers Matt

[Bizibilder]

It doesn't sound normal at all - what scope is it? If you can post a picture as well that would be great - you will get some advice pretty quickly.

[brantuk]

Matt it depends on what you mean by "bent". If it's just slightly twisted then you can losen the screw that holds it in place at the edge of the tube - gently turn it straight - then tighten up again holding it firmly at a right angle to the primary mirror.

So long as you ensure all three "fins" are exactly the same length from the tube edge to the secondary so it stays dead center. You may have to slacken and retighten all three, one at a time, with equal pressure.

[MattSett]

Hopefully this link works, trying to do this on my phone!

[MattSett]

Ok the link disappeared! Will have to try again later.

Matt

[Tinker1947]

Its hard to suggest a remedy, but clamping between wood might straighten them or gently remove a kink on a engineering block, just depends on the degree of damage..

[MattSett]

It is kind of twisted. However I've tried loosening and tightening all of the screws that hold the fins to the tube and it hasn't got the dot any closer to the centre. I'm not too sure about taking it out and trying to flatten it, as I don't want to nullify the warranty.

[brantuk]

If the fins are now straight - then to center the dot on the primary you use the four screws on the top of the secondary to do that. Just slightly slacken the center one half a turn being very careful not to undo it fully. It holds the secondary on and you don't want it to come off and drop on the primary.

Best to do this with the scope horizontal. Then tweak the three screws around the center one till the dot falls dead center of the primary. Then retighten the center screw to hold it all firmly in place. Ensure you don't turn the secondary away from the focuser tube at all while you do this.

Finally tilt the primary using the three adjustment screws under the mirror - you'll need to loosen the locking screws to do this. Once the beam goes straight back up to the secondary and through the focuser tube to hit the target dead center you're there. Re tighten the locking screws and the jobs finished.