Some questions for Dob users

[Piero]

On my SW Dob 200 F6, the primary mirror has 3 adjustment screws and 3 locking hex screws. 

Could someone tell me whether the following procedure for collimating the primary mirror is correct, please?

1) slightly unlock the locking hex screws,

2) collimate use the primary mirror using the adjustment screws,

3) lock the locking screws 

Another related question is: are these locking screws really required or can they be permanently removed?

I do not really understand what their purpose is.. 

Different topic.

Do you remove your newton tube from your dobson base when the telescope is not used, or you just leave the tube in vertical position on the base?

Thanks for your help,

Piero

[Gazabone]

Re the bolts; yes, undo (but don't remove) the locking bolts and then re tighten once collimated (nb, you should collimate the secondary mirror first). The locking bolts are required to be in place, they help keep the collimation (although you'll find it won't keep collimation that well if you keep moving the scope, which most people do).

My 10" stays in the mount 24/7. Personally I think it's better protected (and will keep collimation better) like that.

Happy viewing

[John]

I don't use the locking screws on my 12" dob unless I'm transporting the scope in the car. I have them slackened off during normal use.

As said above, you collimate the secondary first, then the primary. The secondary usually does not need touching for fairly long periods. I tweak my primary each time I set the scope up but it's only the smallest amount of fine tuning, if any, that is required.

My dob tube sits on it's base in the corner of the dining room, pointing upwards.

[laudropb]

It's best to gently tighten the locking screws after collimation. This definitely helps keep collimation. My Dob sits on the base permanently. Have done this for 2 years without any detrimental effect.

[niallk]

On my SW Dob 200 F6, the primary mirror has 3 adjustment screws and 3 locking hex screws.

Could someone tell me whether the following procedure for collimating the primary mirror is correct, please?

1) slightly unlock the locking hex screws,

2) collimate use the primary mirror using the adjustment screws,

3) lock the locking screws

Another related question is: are these locking screws really required or can they be permanently removed?

I do not really understand what their purpose is..

Different topic.

Do you remove your newton tube from your dobson base when the telescope is not used, or you just leave the tube in vertical position on the base?

Thanks for your help,

Piero

Hi Piero,

1: Yes loosen a decent bit so that they do not constrain any collimation adjustments.

2. Yes!

3. Yes - though I lightly turn until I barely detect that they make contact. I don't 'tighten' whatsoever. I recheck my chesire when I'm done with the lock screws, and iterate again if I find that I've affected collimation.

Note I'm assuming your scope is similar to mine - 250px. I think others might chip in to say the locking screws can be taken out - just collimate before every session.

I often recheck my scope, and it rarely needs adjustment - even after carrying out and in several times - and it gives great views.

Re storage - yes I leave mine vertically on the base. One suggestion (which I don't do, but makes sense) is to put an elasticated shower cap on the mirror cell end to keep dust out. Don't tell anyone, but I've never washed my mirror: its a bit dusty as is normal, but still works well - so I keep leaving it. One of these days... (It's been like >6 yrs! This is probably not good practice).

Also if you get a Telrad - I leave mine on permanently, and the sticky baseplate has not moved in all that time - still rock solid like a limpet.

Best of luck!!

[Piero]

Thanks for your comments! On my old Newt 114mm, I always checked the secondary first (adjusted 2 times in 17 years) and then the primary before each observation. However, the locking screws on the primary of that scope have always been loosen, so I never touched them. On this 200 they were tighten instead. 

I will follow your advices which all make sense! 

Thanks! 

[niallk]

Thanks for your comments! On my old Newt 114mm, I always used to check the secondary first (adjusted 2 times in 17 years) and then the primary before each observation. However, the locking screws on that scope have always been loosen, so I never touched those. On this 200 they were tighten instead.

I will follow your advices which all make sense!

Thanks!

I spent a while aligning the secondary on my 250px,and tightened down the hex nuts. Took patience, but when alligned and tight - it hasn't had to be touched for literally years.

I do both secondary and primary every time on my truss dob though - it's not that I'm lazy about collimation - the solid tube 250px just holds it so well.

[Mr Fiery Jack]

Good sound advise own offer, as always