Tasco 66TE-5 <- now with the grandkids Meade ETX-70EC <- they got this one too! Tasco 7TE-5 Meade 300 Celestron C8-SGT Advanced Jaegers 103mm, F15
Every week I do something new to reduce light pollution. Eyes on the Sky is at 600,000+ views so far; more views = more awareness. Please consider sharing with others.
Quote:Bob, nice looking baffles. I was going to suggest you ditch the last one as three with such a slow F stop is all that's really needed.Also, I suggest using only the middle baffle to set the actual fully illuminated field size and position the others slightly further down the light path than the drawing would suggest. This way only the center edge of the middle baffle actually intersects the primary light cone and diffracts that light. The other baffles, being now set further down the light cone, don't touch the primary light cone and therefore don't diffract light from it. A baffles job is to reduce stray light, and not generate it. Positioning the baffles this way reduces to a minimum any stray light their inner edges may generate. Of course, I'd bet a months pay, such diffracted light scatter would be difficult to measure, let alone see, however, why not eliminate it if you can. It's soooooo easy to do and keeps with the idea of maximizing contrast, which is a refractors strong suit to begin with.Jeff
Quote:I also recently completed a 4" F15 scope but with a rare Ebay find of a Edmund lens and cell. I used 4" PVC for the tube and baffles were fashioned from 3" pipe couplings, one by itelf and one with a 2" pipe coupling insert. Nice thing about these is that they are a 'jam" fit down the 4" tube.To stablize the long tube I fashioned a 'Hargrave" strut.To make the lens colimatable I placed it in two 4" PVC pipe couplings with one set of three drilled and tapped holes in each. The Edmund metal cell fits loosly in the pipe couplings and is colimated by six allen screws.I opted for a nice old all metal 1.25" focuser from an old Tasco as a 2" focuser is rather unneeded for a long focus planetary scope.
Quote:Bob, you wrote: " . . . I think my thought process is correct? I think I'm going the proper way with my dimensions. Long FL eyepieces need less focuser travel than short FL eyepieces, correct?"
I don't think you can generalize that. It depends on where the eyepiece field stop (AKA "eyepiece focal plane") is located relative to the barrel flange that abuts the focuser tube. Some eyepieces of different focal lengths are parfocal, having no travel needed between them. Garrett SWA's of 20mm, 26mm, 32mm. and 38 mm are like this and have their field stop inside the barrel at the same position as the flange outside the barrel. (Those are also the same eyepiece series as the Orion Q70 and the Agena SWA.) In comparison, I have an Edmund orthoscopic 6 mm that needs 7.9 mm more "in" focus than the Garrett SWA's and a Galoc 16.3 mm FL that needs 21.4 mm more "out" focus than the SWA's. Best measure the eyepieces you plan to use. and make sure you have the focuser travel range to accommodate them. Check with a Barlow, too, if you plan to use one. Televue lists this information for their eyepieces in a table on their website, but most ocular manufacturers don't. It is pretty simple to measure if you have another finished scope on hand, though. For eyepieces with the focal plane below the field lens, you can even make this measurement without a telescope by pushing a thin strip cut from a note card up from the bottom of the eyepiece until its upper edge is focused sharply. (Don't use a ruler or anything that might damage the field lens!) Then transfer that distance from the bottom of the eyepiece to the outer barrel (mark temporarily with a soft pencil) and measure how far the mark is from the flange. This method does not work with many complex wide field eyepieces like Naglers, Ethoi, Pentax XW, etc, because they have the field stop between lenses where it is not accessible for measurement. Do those by comparison of focus position with other eyepieces in a finished scope.
Hope this helps. There's nothing any more frustrating than building a scope and then finding out there's not enough "in" focus to allow use of some of your favorite eyepieces. - Bill
Quote:Very Nice! Hope to see some planet pics soon.I am finishing a 128mm F5.5 project and painting that darned tube is turning out to be the hardest thing. I may eventually do a wrap (work smarter not harder) like you did. It looks great.
Quote:So sorry about the dec encoder. Is that a CG5? I have had good luck with the AVX I bought this Spring but should I worry about encoder issues? They are probably the same motor/encoder.
Clear Skies, Forever! The Vega Sky Center 254mm F/5.65 Homebuilt Fork Mounted Newtonian Reflector 152mm F/10 Jaegers Homebuilt Refractor 127mm F/9.4 SS Homebuilt Refractor 100mm F/13 Carton Homebuilt Refractor 114mm F/8 Tasco 11te-5 Newtonian (under restoration) 60mm F/16.7 Tasco 7te-5 Refractor 60mm F/15 Jason Discoverer 313 Refractor http://www.vega-sky-center.com
Quote:Congratulations on the completion of your Jaegers 103/1545, Bob! Very impressive with its carbon fiber tube. You should be very proud of this auspicious accomplishment. I have one to build myself. It is going to be interesting to compare it to the Carton 100/1300 I previously built.Sorry to read about the ills of your EQ. I hope you can get it operational as soon as possible. In the interim, I wish you a successful First Light session. Look forward to reading your report.Mel
Quote:The tube is not carbon fiber. It's plain old 6063 aluminum. I didn't feel like doing all the sanding, filling, sanding again, etc., etc. steps to get a good looking tube.So I went with the vinyl wrap. Because the tube is longer than the stock width of the wrap, I had to go with a really large piece and cut it down. I went with 3M Gloss Black DI-NOC Flex Wrap.The wrapping went ok. At first I thought I was going to mess it up but it worked out eventually. You just have to make sure the edges of the piece of vinyl are square.The replacement encoder diode is on its way to me. If I can't replace the one I have and get the new one working I will order a replacement motor/encoder assembly directly from Celestron.-Bob