Posts Made By: Rob Mackie

Mark Harry 8" mirrors are outstanding. I've got one and it never ceases to impress me. Best views with 8" aperture I've ever experienced.
Rob Mackie

I use my Maks on a Giro Alt-Az mount. Attached is a photo of my MN61 Mak Newt on a Giro. It's important to use a rock solid tripod with the Giro. I also have a MK67 MCT which I use with the Giro. When the Giro is mounted atop a Bogen 3036, it's unsatisfactory at high power. But mounted atop the surveyor's tripod shown in the photo, it's very stable no matter the power.
Rob Mackie

I've done side by side comparisons of a Zeiss/Baader vs a Denk Std in various refractors. In every case the Zeiss/Baader gave brighter views with more contrast, more pinpoint stars and a generally more aesthetically pleasing and involving view. To my eye the differences were not subtle. This may not be the case with the Denk II vs Zeiss/Baader. Construction quality, fit and finish of the Zeiss was far better than the Denk std. The dedicated 2" diagonal that comes with the Zeiss is especially appealing. The strengths of the Denk std are 1)lower cost and 2)highly flexible optical correctors that enable use of the Denk std in most any type of ota. Also, the Zeiss/Baader is scarce while the Denk std is widely available both new and used.
Rob Mackie

Joe,
I think you would miss the ease of use and wide fields of your TV. Yes, the C9.25 would go deeper, but then you'd have to worry about cooling, dew, collimation etc etc. If it were me, I'd keep the TV AND get the C.9.25 rig. These scopes are radically different instruments. They will compliment each other, so if you can swing it, keep the TV and get a C-9.25 to keep it company.

Rob Mackie

And here is another photo of a barely awake Milo.

Rob Mackie

Here is another photo by Charlie Ryder. I know nothing about the pictured scope, but Charlie labeled the photo "best scope".

Rob Mackie

I've owned many different scopes of all types, ranging from 3"-16" aperture. If I was forced to live with one scope (there's a thought)it would be an 8" dobsonian-mounted tube reflector utlizing a premium (Zmbuto, Royce, Spooner, Harry)mirror. Why?

1. Enough aperture for decent deep sky performance

2. Great planetary performance if it uses one of the aformentioned premium mirrors.

3. Reasonably short focal length means I don't give up wide field views. My 8" F5 has a 1015mm F/L (1160mm when used with a paracorr). This yields a 2+ degree FOV with a 31mm Nagler.

4. Very fast setup, faster than any other scope/mount combo. This is a big deal for me. Setup is almost instantaneous and not a backbreaker at all. I do spur-of-the-moment viewing when the gas giants are up. No need to fiddle with mounts and alignment, just place the tube on mount and start viewing.

5. Easy and hassle free transport in back seat of my car to dark sites. No fiddling in dark with mounts, trusses etc etc.

6. No corrector plate to dew up or retard cooling. This is a big factor in ease of setup and quickness with which one can start viewing.

Pictured is my 8" F5 Royce reflector built by Chuck Fellows. I use it with a Paracorr. It's beautiful to look at as well as look through, and images are pinpoint and contrasty with very little coma. This is the third tube dob I've owned, and it's my opinion that 8" (either F5 or F6) is the sweet spot for a tube dob. I store the scope so the mirror is at or near outside ambient temperature most of the time, which minimizes cooldown.

Rob Mackie

I've been using a JMI DX2 focuser with 8" dobs for several years. It's a very good focuser and I haven't felt the need to upgrade. If you're using a fast dob (F/4.3, for instance) then a 2 speed focuser like the Feathertouch is a worthwhile upgrade, though not a cheap one. If you're using a JMI DX2 and your dob is F/5 or slower, stick with it until you get more experience.
Rob Mackie

Herre's a closeup of focuser shaft. I suspect that mirror shift is caused by the shaft's being offset from central mirror axis.
Rob Mackie

Here's another photo of the mirror cell