Gary, I think your post helped me understand what Wally maybe have been saying - and it's different than what I have been trying to explain. 1) If I...
20213
walter kennison
walterkennison
Apr 22, 2012 3:36 am
your absolutely right,,, the boundry layer exist,as in aviation,,, nevertheless its effect on the mirror and optics is dependent on the humidity and...
20214
Robert Bunge
bungerob
Apr 22, 2012 4:15 am
I'm likely barking up a different, and perhaps wrong tree here. I'm guessing most of us store our large dobs (ok, I'm defining this as something with a mirror...
20216
Neil
lowentress
Apr 22, 2012 9:11 am
Hi Kai Very interesting to see what has been done there with 25mm Borofloat, Do you know of people in Germany using the Suprax glass disks that are made there...
20217
garyk9rx
Apr 22, 2012 2:27 pm
Having a 30 in an observatory that is one thing I had always planned on doing. Putting in a portable AC unit with a hose to the mirror box with some sort of...
20218
walter kennison
walterkennison
Apr 22, 2012 2:44 pm
I would like to bring something up again,,, when we think of equalibrium ,,, we can separate two issues,,,and approach them separately for common denominators...
20220
ceroxyd
Apr 22, 2012 2:56 pm
Hallo Walter, it's done with Dale Easons OpenFringe Software. Interferometric test after every polishing session. It's very intuitiv und straight forward. ...
20221
atmpob
Apr 22, 2012 4:49 pm
For several years I have had a 16 x 1 inch mirror with a fan on the back and small 1 inch fans that blow across the font and so had not noticed the following...
20222
nwstars2002
Apr 23, 2012 2:16 am
I am traveling to Germany June 2 and will be in Berlin for the transit of Venus, do you know if there is a public viewing event scheduled for Berlin? Kevin, in...
20223
Neil
lowentress
Apr 23, 2012 9:13 am
Hi I prefer F5 because I think it is more feasable for me to reach a very accurate mirror surface 1/8 pv or better at F5 rather than F4 or even F4.5 I also...
20224
abellhunter
Apr 23, 2012 7:38 pm
BigDob group, this spring a 28" f4.1 Starmaster w/Kennedy optics has been installed in a new astro village 30mi south of Silver City, New Mexico. Last night...
20225
Ali Khan
ak6666666
Apr 24, 2012 3:11 am
Very impressive collection of pictures!...
20226
careysub
May 1, 2012 11:18 pm
The Cruxis Mirror Edge Support Calculator shows that two-point mirror edge support performs nearly as well as a 180 degree cable sling, with similar degrees of...
20227
Jan van Gastel
janvangastel
May 2, 2012 6:24 am
It is much easier and better to make supports that support the mirror exactly at the COG plane then making the 'line supports' you suggest, because for such...
20228
Robert Houdart
rhoudart
May 2, 2012 8:22 am
Jan is spot on. With a cylinder support, how can you guarantee that the support is perfectly distributed over the thickness of the mirror? Take into account...
20229
tsulmer1
May 2, 2012 9:18 am
Hey everyone. I have acquired some PTFE strips 1/8" thick x 1" wide x 9 ft long. I can cut these into any length you desire. And if you need 3/4" wide, I...
20230
dobson 2005
pierredesvaux
May 2, 2012 10:09 am
As for edge supports, having tried many systems, including cable slings, I now use 2 ball bearings, the axis of which is horizontal. In this case, the contact...
20231
Jan van Gastel
janvangastel
May 2, 2012 10:17 am
Another solution is to place the supports on the part of the mirror cell that moves with the mirror when collimating. They will always stay in place that way....
20232
careysub
May 2, 2012 11:47 am
... Yes, I built a 13.1" mirror cell that does exactly that also. Here is the key motivation for this question: sandwich mirrors. Hubble Optics or Normand...
20233
careysub
May 2, 2012 12:34 pm
I just unboxed the newly arrived Hubble Optics 18" mirror and find that the bottom mirror disk is smaller than the top disk. It the top is 18", then the...
20234
Robert Houdart
rhoudart
May 2, 2012 12:39 pm
If a support at the COG is impossible, you can directly support the edge of the front and back plate if you make sure that the load is correctly distributed...
20235
Nils Olof Carlin
nilsolofcarlin
May 2, 2012 2:20 pm
Carey, ... cylindrical supports, would seem to support mirrors quite accurately for the tests to be useful. There have been many very good replies already....
20236
atmpob
May 2, 2012 4:13 pm
I just did an interferometry test on an 18 inch HO mirror and I was worried about how to support it on the test stand. Turns out the mirror had much more...
20237
careysub
May 2, 2012 4:47 pm
Do you know the exact focal length? That would tell us if it was the same mirror. It doesn't matter is this particular mirror is not up to snuff (I'll be...
20238
dobson 2005
pierredesvaux
May 2, 2012 5:12 pm
For Hubble Optics mirrors or similar ones with 2 plates, the best is to make two vertical weefle-trees. For each weefle tree, put 2 rollers or ball bearings,...
20239
careysub
May 2, 2012 5:59 pm
Thanks - I think the vertical whiffle tree you refer to is the same as the pivot arm scheme I was beginning to settle on. A pivoting arm, with pivoting...
20240
careysub
May 2, 2012 10:08 pm
I just did a check of refiguring prices - and even if I had the mirror refigured by Steve Swayze (which in my book makes it premium) the combined cost of the...
20241
Tim Ulmer
tsulmer1
May 3, 2012 12:54 am
Yep. I bought a 16" HO and had it refigured to premium (0.97 strehl) and took care of the turned down edges etc. HO price plus refiguring was about 1/2 (HO...
20242
careysub
May 3, 2012 1:01 am
Who did your refiguring?...
20243
atmpob
May 3, 2012 2:05 am
3683 mm give or take 10mm. I forgot to get the exact ROC during Foucault testing. I would have gone back except the astig and surface roughness were the...
