Opinion on GSO/Bintel BT200 CF astrograph

[LewisM]

Looking for opinions of the GSO/Bintel f/4 BT200 CF tube astrograph - pros and cons. Mirror quality (shape etc), collimation holding, baffling etc.

It's going to be either that, or a 2nd hand Vixen R200SS.

[tlgerdes]

I have the AL not the CF

Holding collimation - need to upgrade to stronger springs for the mirror, a flip will through it out. Secondary works fine.
Baffling - none, definitely worth flocking. I went from 90sec to 180sec subs in inner Sydney before light pollution became problematic after flocking. Also worth creating a light shroud for the front for the same reason.
Focuser - worth upgrading, electric focuser makes imaging so much better. Standard focuser can lift 500gms easy enough (low end DSLR).
Coma - need a corrector.
Dew - not a problem, never had the main dew up, never used fan or heater.

Mine started at $500, but I have spent another $600 to get it to a good point. I believe all these things will be the same things you will want to upgrade even on the Vixen, so factor that in either way.

You will need a better collimation technique than a simple laser at F4. Catseye tools are a must, for either the R200 or the GSO.

On the plus side
Focal Length - really useful @800mm, with an APS chip you get 1.5deg*1deg FOV, team it with an 80mm F5 guidescope with QHY5/SSAG autoguider and it is really easy to point as the FOV of guider matches.

[LewisM]

Trevor,

The CF tube is baffled and looks at least VERY matt painted internally.

[tlgerdes]

The AL was matt black painted as well, but when you shone a light on it, it looked decidedly grey. Once flocked with Protostar flocking, it looked black under light.

[LewisM]

Bintel is out of the CF tube model, and selling the Alu tube model at the same price.

Hmmmm. Don't know yet.

[Peter.M]

I 100% would never buy the AL tube if the carbon one was the same price. But on their site it is listed at 799 for the carbon and 499 for the AL tube. From my experience the mirrors themselves are fine but the mechanical components are not up too scratch when trying to keep the thing collimated.

[LewisM]

No longer interested in GSO - made an offer on ANOTHER VC200L :)

[UniPol]

They're are both great scopes

[LewisM]

Don at Bintel clarified today that the alu tube model is NOT baffled, and is $449, not $799 as he erroneously first told me.

The CF astrograph is out of stock, and is $799 when available.

No matter for me anyway - got an R200SS and a VC200L. :)