4" F/9 or F/7 ED refractor on AZ mount?

[tico]

Hello, Thinking of a 4" refractor, perhaps the Skywatcher 4" F/9 model or perhaps the 4" F/7 model..., possibly the latter is shorter and more manageable, and with less weight... although less corrected ...?? All this to ask you, how would they work with a manual AZ mount? Anyone with this experience? Thank you. 

Tico

[Bivanus]

Hello @tico , my usual setup is either a102mm or a 80mm  refractors both F/7 on AZT6 mount. I found out that the key in using the longer and heavier 102mm tube is equilibrium by weights. I very much prefer the lighter 80mm , however, the big boy is by no means unused. 

Based on my experience I would say that unless that AZ mount is a bit on the heavy duty side , one might have a tad of trouble with the longer F/9 , that does not mean it's not doable, it just that the cash flow must also take into account a sturdy mount like the Rowan AZ100. It would be interesting to hear from someone that uses a Rowan AZ75 how does it deal with longhish refractors.

Bellow my team on horseback  😄  the 80mm is also set-up with a counterweight because of the binoviewer, otherwise it doesn't requires it.

EDIT: My main use for this set-up is visual , single exposure DSLR  pictures, and when lazy also a bit of planetary EAA 

Edited August 20 by Bivanus

[Elp]

Tripod, tripod, tripod. As long as they're mounted to a strong tripod you'll have little issue. In fact I use my SF102 on my Tecnosky Cubo on a CF tripod standing tall, dampens down fine. 

[Bivanus]

@Elp is right , the tripod I use for the 102mm is the EQ6 heavy version.

Also , I now something about the F/7 being less corected than the F/9. That would aply like that only for non ED glass , both my scopes are Photoline series doublets with one lens FPL53 and the other Lanthan glass and I have yet to see any CA on bright objects. To compare , the SW72ED I had before the 80mm did show some violet traces even in visual.

Edited August 20 by Bivanus

[Elp]

You can use none premium glass refractors perfectly fine if the issues don't bother you personally, but from my experience, just buy the decent glass in the first place, many options out there which are non fluorite.