Reccomend me a collimator for sw 300p dob

[johninderby]

Not a problem with my dob. 

[davhei]

For the normal everyday (night) collimation I use a long cheshire/combo tool. It really is all that I need. Noticed however that I find it more difficult to align the primary (centering the dot) than the secondary (centering the donut) due to the crosshairs obstructing in the middle. Not so much a problem when done in daylight but in the dark it is more difficult.

Because of this I sometimes use a cheap laser with the barlowed laser method to confirm primary alignment. Easy as pie.

For the rare collimation of moving the secondary up and down the tube and larger adjustments to the secondary mirror angle I also have a cheap collimation cap. Can’t see the mirror clips in the cheshire/combo tool but the cap works fine. Sometimes I have snapped a picture with my phone camera through the cap (in daylight) and measured with a ruler on the camera screen to confirm equal distances on each side of the secondary mirror outline. Pretty rough method but if I take care to center the camera decently when taking the picture I think given the tolerances the results are ok. Again this is done very rarely.

All in all pretty cheap methods that give good results.

Would highly recommend replacing the allen screws on the secondary mirror holder with bob’s knobs and adding milk jug washers (lots of info available on the forum). Helps a lot. Really does.

[BGazing]

Looking through some friends' dobs and through the one I recently acquired, I'd say that collimation and thermal management are the most important things. Nowadays most of the mirrors are at least decent, but even the best mirror will be worthless if not collimated and cooled actively.

My dob is built from scratch every time so I went for Farpoint combo (laser for secondary and cheshire for primary). I will probably do barlowed laser in the future for primary and just subsequent check with cheshire as it makes life easier collimating alone and not getting sore knees going up and down all the time. 

Using lasers requires relatively good focusers and registering laser in them the same way every time. I learned that lesson quickly. Stock focusers on dobs can be flimsy. Cheaper lasers are not that good and might misalign secondary if they themselves are not collimated.

[garryblueboy]

Hotech works for me