Calling All Flextube Owners!

[Damo636]

Hi guys. I am wondering how well does the flextube system on the above hold collimation? (12") I have read Ade Ashfords review where he repeatedly put it and down and it held collimation perfectly but in the real world how do you guys find it?

[Space Cowboy]

Holds collimation very well. I use mine for planetary imaging and it only needs the tiniest tweak even after transporting in the car. For visual use I doubt it would need adjusting every time.

[brantuk]

I check collimation at the start of every session with a star test. It's never more than a tiny tweak out, unless after a long journey where a screw may have sometimes vibrated loose (eg travelling to a star party). But mostly it holds collimation really well imho

[Damo636]

Thanks guys. I cannot make my mind up on whether or not to go flex or solid tube. TS now have the flextube 12'' priced cheaper than the solid tubed 12''. Am i right in saying that other than portability the flextube has no other advantage over the solid tube version?

These are the 2 scopes i am considering.

GSO Dobsonian 980 - 300/1500mm Telescope - Tension Control

Skywatcher Skyliner-300PX / 12' f/5 Gitterrohr Dobson

I like the look of the alt/azi bearings on the GSO but the flextube would be easier transported on those rare occasions (only got away once this year) we do head for a really dark site. Decisions decisions

I am also not ruling out the 10" version as my 4 year old also likes to participate now and again and he is already using a box to stand on with my 8'' dob. My only concern with the 10" would be would i get any additional wow factor

Has anyone made the jump from 8-10" and wish they had went for the 12'' ?

[robbieince]

I have a flextube 12 and find it keeps collimation very well in use. As many others it seems, I Collimate each time I set it up and usually only need the slightest of tweaks.

Try putting a 12 inch solid tube widthways in the boot...... I f I had wanted a 10 inch, I would say go solid tube, but at 12 inches or more, the advantages of the shorter stored tube size outweigh the stiffer solid tube.

Regards

Rob

[Gweedo]

Mine seems to hold its collimation very well. I've made some finger adjustment screws to replace the grub screws that adjust the secondary, but so far, I've not had any need to adjust them from their original setting. I think that the storage for the flex tube is an attractive option, and that was a major influence on my purchase.

[stuartm]

Mine only goes out slightly, but i can colimate it in under 30seconds, so i do everytime.

[umadog]

There are two factors to consider regarding how something holds collimation.

Firstly, how long will it maintain collimation? So does it gradually loose collimation over the course of a night (perhaps due to temperature changes or perhaps due to screws untightening [this happens]). Will it need to be re-collimated every time you pick it up and move it?

Secondly, how rigid is the OTA? Does axial alignment alter as the scope is moved through elevation range? It's easiest to use an accurate collimation tool to assess this. Will heavy eyepieces cause flexure? Can it cope with a bino-viewer or a coma-corrector (should you want to use those)?

A scope that needs to be re-aligned once or twice a night is hardly a bother. One that can't maintain collimation across different elevations or conditions could be a real pain. Often problems in the second category are correctable and can be due to stuff like a secondary support that isn't under sufficient tension. Truss designs can be remarkably rigid if well designed, so this needn't be a concern.