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Posts Made By: Doug Scobel

July 22, 2004 01:42 PM Forum: Telescope Making

BORED (Pictures Please)

Posted By Doug Scobel
Okay, Ian. Here's something you don't see every day. Here's my circa 1984 homemade 13" Dob. Nothing out of the ordinary you might say, until you see the picture in my next post...

Doug

July 26, 2004 08:27 PM Forum: Telescope Making

fans - front or back

Posted By Doug Scobel
Dan, here’s what I have on my 13" dob. Two 3" Radio Shack fans blowing across (from below), out vents at the top of the mirror box. I control their speed (to tune out vibration) with a 25 ohm rheostat also from Radio shack. I'm planning a third fan on the back, haven't decided yet whether blowing in or out is better. Easy enough experiment, though, just turn the fan around.

The next photo shows the vents from inside and out.

Please excuse the dirty mirror. shocked

Regarding your fan sizes, 4" sounds a little big to me for blowing across, 3" for exhausting out the back sounds a little small. You could probably use 3.5" fans in all three positions to good effect. Probably not critical, tho.

Doug


July 27, 2004 01:28 PM Forum: Equipment Talk

Clausing Mirror Coatings "Diamondbright"

Posted By Doug Scobel
In our club, I know of two folks who have had similar experience with Clausing coatings. In one case they damaged the face of the mirror while stripping the old coating and the poor owner had to have the mirror reground and refigured. The other guy's mirror started to get pock marked like yours after less than a month. Don't know if they were Diamondbrite or not.

We also have our 24" mirror Beral coated. After a couple years it starts getting translucent.

I don't use Clausing.

Doug

July 27, 2004 06:34 PM Forum: Pictures of Me and My Telescope and........

Scopes please Scopes

Posted By Doug Scobel
OK, here's my 8-inch f/8 homemade Newt (including primary mirror) I made for last year's Mars opposition. I call it the "Mars Scope".

Doug Scobel

July 28, 2004 01:14 PM Forum: Telescope Making

Wacky

Posted By Doug Scobel
Alan, double check the positions of your altitude trunnions, and the races in which they ride. Make sure they are parallel, plus make sure they are not skewed somehow. I suspect that one or the other (or both) are not directly opposite each other. Obviously, double and triple check everything for squareness, too, in all directions.

Good luck,
Doug

August 3, 2004 09:28 PM Forum: Equipment Talk

Nagler 4.8 vs 5mm ? differences

Posted By Doug Scobel
Howard, I used to own a 4.8 (Type 1). My complaints were that it was a little soft sharpness-wise, and the eye relief was a contradiction in terms. Never compared it with a 5mm Type 6, tho (don't even know anyone that owns one!). But I think I've heard that the 5mm Type 6 is better WRT both shortcomings.

I've since replaced it with a 5mm Radian and never regretted it.

Doug

August 3, 2004 09:31 PM Forum: Equipment Talk

Eye dilation. (It's more intresting than it sounds)

Posted By Doug Scobel
I don't know, I don't know, I do, probably.

grin

Sorry, it's late here at the office. I should go home.

Doug

August 4, 2004 01:24 PM Forum: Equipment Talk

Mirror is back!

Posted By Doug Scobel
Happiness is a freshly coated mirror. grin

Enjoy your "new" scope!

Doug

August 5, 2004 02:06 PM Forum: Equipment Talk

6.5 inch APO ???

Posted By Doug Scobel
Technically, because “APO” is short for apochromatic, which means “truly without [artificial] color”, then all Newtonians, obstructed or not, are indeed apochromatic. But I agree with the others that it is misleading, since “APO” has come to be generally understood as “apochromatic refractor”, and all that it implies.

My $.02.
Doug

August 9, 2004 12:40 PM Forum: Solar System Observing

Sunspots 08-Aug-2004

Posted By Doug Scobel
Here's an image of the spots on the preceding limb.

Doug

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