Posts Made By: Thomas Bennett

Neat comparison! I was out observing last night with my 10" Dob and TV85. The views look a lot like your 10" and 6". Don't think M13 was quite that bright in my 10" but the resolution is about right.

Hi Bill,

I know what you mean about the Chinese Achros. I briefly had a 5" F8 that was grossly under-corrected (~2/3 wave) and the color was just awful - it was sent back to the dealer. My TV85 has spoiled me on color correction in refractors :-). - Tom

Hi Robert,

If possible, I'd hold on to the TV85 for wide-fields, quick-looks, terrestrial, double stars and buy another scope for lunar and planetary. After owning both 6" Maks and 6" Mak-Newts, I've arrived at the conclusion that if I have to wait an hour for a scope to cool down, that scope is going to be bigger than 6".

My two most used scopes are the TV85 (Little Buddy) and 10" F6.5 dob (Goldmember).

My old (1996) MK67 has ample (maybe too much) back-focus. A binoviewer will come to focus straight-through while for single eyepices, I have to use a 2" diagonal (Intes) and a 2" extension to reach the sweet spot. Guess you won't know how yours is configured 'til it arrives but you might want to get a short extension if you don't have one already. I use 3mm, 4mm, 6mm Radians; 7-22mm Leica Zoom; and 30mm Widescan II all of which come to focus using the extension.

Good Luck, Tom

For high power viewing on my Telepod mounted (unguided) TV85, I like the 5mm Nagler for its wide field that allows more time for viewing without having to nudge the scope as often.

I use a 7.4-22mm Leica Zoom for mid-power. A zoom in this range covers a lot of bases for observing. If you don't mind a little color at the edge, the Apogee Zoom performs nicely and doesn't cost much.

For low power, I like my 30mm Widescan II for its superior light throughput/contrast and wider-than-Nagler FOV and lighter-than-Nagler/Panoptic weight. It doesn

Hi Mike,

I recently received a used Mewlon 210 and have been using it on my Vixen GP mount upgraded with wooden legs – works well for visual as long as the wind isn’t blowing! The Mewlon weighs 18 lbs but the weight is concentrated near the mounting plate at the back of the OTA so there’s not much of a moment arm. I’d guess your GM8 will handle the Mewlon somewhat easier than a C9.25 given the weight distribution.

The Mewlon collimation was a little tricky – for some reason I wasn’t able to collimate it adequately using a LaserMax collimator. However, once I got the secondary shadow centered in an out-of-focus star, the scope started performing up to expectation. The LaserMax shows it slightly out-of-collimation but collimation using the shadow-centering technique produced a better image. The laser and shadow-centering techniques agree when collimating my Newts but not the Mewlon.

Even though the Mewlon will work with a GP, my TEC6 is nearing completion and will be a more suitable match for the GP mount. The Mewlon 210 should be a great match for you GM8.

Good luck, Tom

Hi David,

I also have a GP mount with a 5”F8 (Burgess 1278) OTA and agree with Paul that you’d be pushing the capabilities of a CG5 mount with a bigger OTA – especially with the way the wind blows in this area! I also mount 8” F4.5 Newt, TEC6, and TV85 OTAs on the GP – the TEC being the best size/performance combo with this mount.

Could you elaborate on why you want to replace your N8 with a 6” Achro? You’d be giving up significant aperture and portability and I’ve seen lots of C8 OTA with nice optics. If piggyback photography is a desire, there’s a wedge available for the Nexstar that would allow you to try this out with your N8 rig.

Regards, Tom

Great performer in my F14 OMC140 Mak-Cass - excellent contrast and sharp to the edge. In my 80mm F6.25 Onyx ED refractor, star images are sharp within the middle 2/3 of the field and not too bad at the edge.

This is a big/heavy eyepiece and I'm still debating whether to also keep a 20mm Nagler T5 that's half the weight but with less field-of-view and eye-relief. I also prefer the tapered barrel safety feature of the ES20 instead of a recessed channel that always seems to catch when removing the eyepiece.

The ES20 makes a good companion to my 8mm and 13mm Ethos and there's not much motivation to acquire a 21mm Ethos at this point.

Hi William,

You might also consider a used Celestron Nexstar 11 GPS - the predecessor to the CPC 1100. It has the same optics in a carbon fiber OTA instead of metal and the power cord does not wrap around the tripod since its attached to the fixed portion of the base instead of the rotating portion like the CPC. I've seen a few of these sell at bargain prices lately.

Regards, Tom

Hi Paulo,

The position of the focuser knob depends on where the dovetail that attaches the OTA to the mount is located. If the dovetail is on the bottom (6 o'clock position looking from the back of the OTA), the knob will be on the right (3 o'clock position) of the visual back. If the dovetail is on the left (9 o'clock position) like on my C5+, the focuser knob is below the visual back making it harder to reach.

Tom