Posts Made By: Doug Scobel

Joe, that's exactly the setup I have on my circa 1984 13" Dob. When I get a better shot of it I'll post it.

Here's a not so good shot, but you can see one of the latches that hold the cell on, and where the split is (about six inches up from the bottom). The main reason I did this was because the scope had to fit into the Dodge Omni I had at the time I built it. It was the only way to make the tube short enough to fit in the car. I got my inspiration from Richard Berry's plywood tube 20" that he had built back then. In his both the mirror cell and secondary cage were removable.

Sounds like a good idea to me!

Doug

Carey, what Rick and Walter said. I would add what I’ve done with mine after peeling the waxy paper is to seal the inside surface with a couple coats of shellac to waterproof it. I observe in an area where dew can get really bad and it makes the now bare cardboard surface nearly impervious to moisture. I then follow up with Krylon ultra flat black spray. Also, be sure to seal any unfinished edges (like the hole for the focuser, or the ends of the tube) with shellac or waterproof carpenter’s glue. On the exterior of Sonotubes I have used Krylon’s polyurethane enamel with great results. After years of use and a lot of dew there’s no deterioration at all. You may have to shop around for it, or order it from a paint store tho.

Doug

My wife tells me that the moon's gravity sucks the clouds away. I find it hard to argue with her.

*sigh*

Doug

Maybe that's why you see a lot of binoviewers but few binoscopes.

Doug

Thanks for sharing, Michael. Our club is still buzzing about it.

Doug

I just did a similar thing, Floyd. I just purchased a 1/25 wave (P-V) 1.3" flat from Antares for my 8" f/8. In looking at the test data, most of the error is around the extreme edge, so with a high power eyepiece, where the edge is not being used, it will be more like 1/50 wave. The nice thing about an Antares flat is that they test the flatness after it's coated, so it's definitely an accurate measurement. It may be overkill, but I will never again have to wonder if my secondary mirror is causing any image degradation.

Speaking of coatings, I was surprised to see that it has an enhanced aluminum coating. The test data they provided shows that it averages better than 95% reflectivity across the visible spectrum, as measured at 45 degrees. I was expecting just a standard aluminum coating. Plus I ordered it Friday, it arrived Monday. What a great company to deal with!

All I need now is for my Protostar curved vane (single semicircle) secondary support to arrive so that I can install it. The scope currently has a standard four vane with a "mystery" secondary that I've had in my 6" f/8 for years. I have no idea how flat it is or isn't.

I'll report once I get it all put back together.

Cheers,
Doug

Very nice, Steve. What's the aperture?

When you compare blowing in/out be sure to post your results. I'm considering a similar setup in my next scope.

Thanks for sharing,
Doug

I still have my homemade 6-inch f/8 from 1969. I've since replaced the primary mirror, secondary mirror, tube, and finderscope, but it's still essentially the same scope.

Regards,
Doug

David, according to the AL's write-up (http://www.astroleague.org/al/obsclubs/herschel/hers400.html) all objects are visible in a 6 inch or larger scope, under mildly light-polluted skies (NELM 5.5 at zenith). However, I just finished the list, using a 13 inch scope under similar skies. I think that some of the objects will present a challenge in a 8 inch unless you observe under quite dark skies.

IMO what is equally important is to have really good charts. Either use Uranometria 2000 or Millennium Star Atlas, or print up detailed charts from some software package like The Sky or something similar. In some fields you will need the detail to positively identify your target. Sky Atlas 2000 is definitely not sufficient.

Good luck!
Doug

Mark, just lean over and look through it. It really is that simple.

Count me as one of those dinosaurs who still use a straight-through. Mainly because I am cheap and don't see the need to spend the $$$ to replace something that works for me. If I actually tried a right-angle w/amici then I might have a different opinion.

Besides, it helps keep the neck limber!

Best regards,
Doug