Telekit Dobsonian

[Singlin]

The quality of the wood is first class and it arrives with a suprisingly good level of finish which makes the first sanding down very quick.

When the manual arrived I was a bit awe inspired when I saw the list of all the parts. When I opened the boxes I relaxed as all the hardware is divided into labeled platic sacs relevant to eaxh chapter in the manual. On each sac label is a description of each .

Whenever I was not sure I gave Randy Cunningham a ring at 08:30 colorado time (any later he is in his workshop and dies not answer)and he would be very helpfull.

[Singlin]

Added a small wooden knob for moving the scope.

 

[Stu]

Great stuff Simon. Don't forget to update your signature  

 

[faulksy]

nice one, lovely scope and lovely views

[Gina]

Lovely   Great stuff

[wackyscot]

Just tremendous - view is spectacular also wow

[Singlin]

I started building a centry box for the scope.still have the door and sloping roof to do.

 

[jabeoo1]

This thread is admirable. Well done its lovely work.  

[Singlin]

Shed finished.

 

[estwing]

fantastic...well done on a great project from start to finish.....clear skies!

[Singlin]

I calculate that a 4.5mm offset is needed with my setup.

Should I apply this and if so how do I offset away from the focuser without distorting the spider vanes.

[Singlin]

When I do a star test the rings are perfectly consentric but the blck circle in the middle is slightly off center, What is the reason for this?

[Moonshane]

The offset is 'fixed' when the secondary is glued to the secondary stalk, so no need to adjust it, assuming you offset it when gluing the secondary in place. I say gluing, I mean siliconing of course.

The secondary will show in the very centre of a star test only when exactly centred in the field. I find star tests very hard to decipher and as a result tend to rely on a physical collimation only. If the views are good then don't worry too much. Splitting close doubles and high levels of lunar/planetary detail are good enough for me.

Wonderful project and location. You clearly have a good eye and skilled hand.

[Singlin]

My secondary is not glued but placed in a holder that has a flange and packed with synthetic cotton wool type material.

[Moonshane]

If the secondary is reasonably tight in the holder (I.e. no real way to adjust the position within the holder) then the offset will have been set when the holder was made/fixed to the stalk.

Maybe ask Telekit?

[Singlin]

Thanks Moonshane.

I have just been on the phone with Randy from Telekit and he said for scopes that are F4 and above not to bother with the offset as visualy you would not see a difference and collimation is more complicated. The  stalk therefore has no offset built in.

 

[Moonshane]

I tend to agree. The secondary collimation affects the views hardly at all. As long as it's okay and close enough it matters not. The primary is both easier to adjust and more critical;  a most unusual but convenient combination!

[andrew s]

A Newtonian can be perfectly collimated with or without secondary offset. The only difference is that with offset the optic axis and mechanical axis are aligned and without offset they are not.

Regards Andrew

[niallk]

FWIW, I've the same type of secondary holder, and Dave Kriege's recommendation is the same as what the guy from Telekit told you, and as Shane and Andrew say.

BTW, nice job on the storage shed

[faulksy]

i bought the astrosystems spider and holder for my build, randy put the offset on mine, which orion optics specified . apparently when using dsc you should use offset

[Singlin]

john Nichol asked me for the distance from the center of the secondary mirror to the lip of my focuser where the eyepiece slots in and calculated the my secondary was big enough not to warrent offset.

Sorted.

[Singlin]

I am preparing the scope for our local starparty this weekend and have been making some arrangments.

I moved the rocker box limit screws further back as my mirror cover would drop out when i put the scope horizontal.

 

[Singlin]

I also made a cover out of a damp course floor liner and car cover.

 

[Singlin]

I used a rucksack rain cover to protect the opening of the secondary cage.

 

[Singlin]

I put 4 plastic feet on the bottom of the mirror box which stops chaffing of the mirror box bottom when resting it on the ground.