104 replies to this topic

[25585]

70" eyepiece height at zenith is my comfort max, feet on ground. So 14" F5 would be largest I would go for. Faster means more collimation preciseness & anxiety.

[Kunama]

70" eyepiece height at zenith is my comfort max, feet on ground. So 14" F5 would be largest I would go for. Faster means more collimation preciseness & anxiety.

Preciseness of collimation and anxiety are easily solved, I use Penfolds Bin 389 or Bin 707 to soothe away any anxieties and OCDs while observing, works superbly well.....

[izar187]

Collimation anxiety.

Perhaps try less caffeine?

[Jon Isaacs]

Preciseness of collimation and anxiety are easily solved, I use Penfolds Bin 389 or Bin 707 to soothe away any anxieties and OCDs while observing, works superbly well.....

If I remember correctly, your scope is a 17.5 inch F/3.5.  For someone 6 ft. tall, an 18 inch F/4 can be flat foot and with a Catsperch Pro, it can be a 100% sit down scope.  I need no ladder with my 16 inch F/4.4 but it's right on the verge.  

 

The ladder comes along with a larger scope..  With the right ladder and the right circumstances, there is no reason to be afraid of a ladder..   There was a time when I was considering reworking my 22 inch with sub F/4 mirror but I decided I would be wiser just to put the effort into improving the ladder.  

 

Jon

[brentknight]

Part of the problem with the current mass-produced Dobsonians is the size and shape of the ground board.  From a logistical and physical viewpoint, round boards that extend out from the rocker box are just plain stupid.  If using a chair or a small ladder with them, you are forced to sit too far away from the eyepiece at most angles.  Square ground boards (or even triangular) eliminate most of this problem...