Group - I am attempting to apply Roddier analysis to my 10 inch f/6 Newt. Two questions in this regard have arisen: 1. Roddier has an entry field for the...
Hi Mick, ... f/6 ... report a ... Yes. ... effect? My feeling is that the spider will not have much effect. It will show similar patterns on both sides of...
Dr. Biretta - thanks much for the inputs on Roddier and Newts. My initial trials have yielded indications of really bad performance (P-V 1.9, 0.82 Strehl)...
Hello again Mick, I would ignore the P-V=1.9 result. The P-V is extremely sensitive to any small spot on the optic with a large error. It is the same way for...
... Dr. Biretta - thanks again for the useful inputs. I don't remember this afternoon what the RMS was but it was (to me) unspectacular, less than 10. The...
... with ... as ... the ... holding ... Mick, you have to remember that Roddier tests not only telescope in question, but the whole shebang - collimation,...
... Bratislav - I have posted (Files section, folder "Newtonian 10 inch") the intrafocal and extrafocal images for the first set of Roddier tests (two camera...
... Bratislav - I have posted (Files section, folder "Newtonian 10 inch") the intrafocal and extrafocal images for the first set of <<< Out of curiosity since...
... took a ... overcorrected ... this is ... sounds ... running a ... because ... edges. In ... as the ... differential ... Mr. Bartels - thanks much for...
... the start, and perhaps 5 deg lower after another 1.5 hours. The fan is an exhausting type that pulls air from the mirror back (and the tube sides) and...
... (or ... haven't ... Mick, I've had a quick look and run the Roddier test myself just now. First, the bad news. I agree with Mel about overcorrection and...
... diagonal ... of focus ... doesn't ... interpose any ... introduce ... looks ... Mr. Bartels - on the above points: 1. I installed the fan as an exhaust...
... Bratislav - thanks for the personal examination of my images, and for the "culprit" analysis. See my reply to Mr. Bartels above for the steps I intend to...
Well if Bryon says its OK for your setup, then I'm sure it is. I'd work on finding the cause of the 'stig. The mirror can rattle 1 mm in its cell, just to...
I should point out that if I remove coma and trefoil errors in WinRoddier, the residual Strehl jumps to 0.935 (1/24 wave RMS). And even those actions don't...
Hi Mick, I got a look at your images. The primary mirror clips may be too tight. I can just barely see the clips in the images, and the trefoil warp lines up...
... Dr. Biretta - thanks much for looking at my images. My next steps are to loosen the primary in its cell (both clips and nylon centering screws) and also...
Mick, I have one of the Parks mirror cells and I can say that it is very easy to pinch the mirror with out knowing it has happened. I'm assuming the cell you...
... easy to ... cell ... in place ... screws ... in the ... nylon ... face and ... minimally. Drill ... screws in ... mirror ... pinching. The ... support ( ...
Group - in a further effort to put the investigation of my 10 inch Newt on a systematic basis, last night (Mon 4 Aug 08) I took four sets of intra/extra...
Mick, This is very good news. It seems you are measuring the optics indeed, and not something else (chromatic problems, seeing, etc.). Onward to mechanical...
... Dr. Biretta - thanks, it is certainly good news. It's always good to pass a sanity check. I will certainly do the write-up you suggest as soon as I have...
... Dr. Biretta - update to the above: I have loosened both the sec mirror (in its shroud) and the primary (in its cell); primary is now floating on the...
... Not unexpectedly, new problem: the scope is not holding collimation as its angle is changed from vertical. A laser collimator dot which is centered in the...
Hi Mick, I agree with Mel. The collimation problem is likely the secondary is now too loose. Probably need to put some more stuffing behind the mirror, etc. ...
... Dr. Biretta, Mr. Bartels - thanks much for the advice. Before the latest check on collimation shift (late this afternoon) I put a couple of small shims...
... Dr. Biretta, Mr. Bartels - progress report on collimation shift and sec mirror movement: I redid the sec mirror shroud by placing small thin plastic...
Really, from my vantage point, you seem to be distracted into a touch of analysis paralysis. Simply loosen the primary mirror's restraining clips a bit, then...
... clips a ... alignment ... flexing, ... might ... Mr. Bartels - thanks much for the insights and advice. I do tend to fall into a pattern of trying to...
Hi Mick, This 0.1 inch shift will have almost no effect on the image quality. What I would do is collimate at say 20 degrees off the vertical, and let it go...
Having problems with message search?
Fill out this form to ensure your group is one of the first to be migrated to the new message search system.
