8", f/8 Discovery dob or 9.25, what's more fun?

I did it again. I started looking for a campanion for my 140mm Vixen and I think you know how that goes. I've never owned a dob nor seen one in person. I kind of like the discovery "mars" dob but I could also get a C9.25 and mount it on my GM8. I've heard it is heavy for the GM8 and I've seen hands selling the 9.25 ota in carbon fiber, though more expensive. If I went with the dob I want a motor to track since I'm very used to it, but of course that will add some money - how much money? Would it be better to buy something else to use w/ the GM8? I really don't have all of the money to spend but I may just pull something out of my pocket, i.e. plastic (I think this is where the wife gets unhappy). Suggestions and info is appreciated and gracias in advance.
Don

Don - this is a no brainer IMHO...get the C9.25 and use it happily for visual on your driven GM8 mount. The larger aperture and quality optics of the C9.25 more than offset a narrower FOV and longer cooldown time compared to the 8" f/6 or f/7 Discovery PDHQ Dobs. The f/8 "Mars" version does not change the equation for me as the C9.25 is great on planets too.

Since you are likely using the GM8 with your Vixen, you will only be able to use one scope at a time. Advantage Dob.

Hello there Don,

I went to Discovery a few months ago to choose betweent the 8" f/6 or f/7 PDHQ (they didn't have the f/8 then). Being not a tall person, the f/7 is very much taller than the f/6 at the zenith; so I chose the f/6 and have been quite happy with this choice ever since (it also fit inside the cab of my pickup truck - just barely). So I imagine the f/8 would be even longer and higher.

I'm currently having two problems with my Discovery PDHQ: the mount and OTA balance with heavy eyepieces. Ryan who has the f/7 model doesn't seem to have this problem (so mine might just be the exception). I've improve on the sticky azimuth movement by waxing both the teflon and the elbony star. This helps a bit and I can track with one finger now but still not smooth as it overshoot often (so I'll try the milk jug trick after this). I'm solving the OTA balance problem with the ankle weight or buy one of those sliding weight.

Last but not least, the Discovery Mirror is incredible, I'll submit, in the short time I've been looking at the moon. Incredible contrast and sharpness (no nasty spider vane spikes on the moon). Since I'm so used to the view from my 4" TV-102 APO, I'd go out on the Lunar limb ;-) to say that the view is very "refractor like" (though I don't have an 8" APO for a side-by-side which might have a different result). I speculate that it might have to do with the enhanced coating, hand figuring done by Discovery (not massed produced machining) and the very small 19% secondary obstruction. (BTW, the view of the fairly bright to bright stars is *not* refractor like as the nasty spikes are very evident and on Mars at low power, but seemed to be much less noticeable on Mars at high power).

I still prefer viewing from the rear end when I went to the star party to look through several SCTs than through the side of the Newt ;-).

Good luck on your choice. BTW, do give Bill Larsen at Discovery a call; he does make custom mirror if you wish.

Ron B[ee]