2 replies to this topic

[MasalaDav]

Hi,

I'm considering buying a Explore Scientific 12" Dob. I was told that the scope needs collimation very frequently. As frequently as a couple of times in a night of observing. Collimation done during dusk will not hold for more than a few hours. Also, as you go higher in Altitude, the scope loses collimation. The reason being, the metallic rocker box as against wood or plywood rocker boxes in other Dob designs.

I typically do a rough collimation before heading out to dark skies. And do a finer collimation before starting my observation session for the night. This I'm fine. But re-collimating again in a span of a few hours is a pain.

Would like to know if that is really the case.

 

Thanks very much and wishing clear skies

MD

[Whiteduckwagglinginspace]

I will start by saying that others on this forum has much more experience. I don't know it exactly about the Explore Scientific 12 inch, but in general this sounds very often. What I found out by now is that some people in this hobby are much more precise on collimation than others. So, I expect different answers. Some newtonians holds collimation longer than other newtonians. I guess You have F5 which is in the middle of being sensible for collimation. I follow this topic, because I'm curious what others will say.

[Bener]

I have this scope and don’t find it needs “frequent” collimating. I do it at the beginning of every session. If I have not taken the scope apart for transportation in a vehicle, it typically only needs minor adjustments if any.  If using it for a long session, I sometimes check the collimation during the night and rarely have had to tweak it.  Because collimating the primary mirror can be done from the topside, it does make collimating take less time than in a traditional dob where the collimating adjustment is located at the bottom of the scope.

Taking it apart and moving it does mean one has to do a bit more, but not much, collimating. Maybe a couple of minutes.

I have found that cooling the mirror makes a big difference in viewing. The two fans that are in the scope are really boundary layer fans, so effective cooling means having it outside for a couple of hours to cool or, if you have power, I point a box fan at the bottom of the mirror to cool it down faster before starting my observing session.

Edited by Bener, 03 December 2024 - 10:55 AM.