... Thank. I made a silly mistake (I did not click the calculator button to compute the intra/extra defocus). BTW what is that number, the distance of intra...
... to compute the intra/extra defocus). ... It is the distance from best focus to where you were focused for the intra- and extra- focal images. The software...
Hey guys, I tried to do the roddier on my C9.25 again and uploaded the tifs in my folder. I followed the directions in the howto and the resulting .fits gave...
Hi, I'm having a heckuva time trying to get nice, round, stars when imaging through my recently new TMB 152/1200 (APM). It's riding on a fairly new AP1200 and...
What does a star look like in focus at very high power? _____ From: roddier@yahoogroups.com [mailto:roddier@yahoogroups.com] On Behalf Of Jim S. Sent:...
Hi Jim, Just back from WSP. Still unpacking, but I'll give a quick read on your results. The Roddier results look about as I would expect. The green images...
Mike, ? Excellent suggestion. ? Jim, you are going to need a minimum of 300X for a good look. 350X to 500X will be even better. ? - Gene ... From: Mike C To:...
Hi Mike, You mean, like, actually LOOKING THROUGH the telescope with an eyepiece or something, rather than with a camera? I read about doing that somewhere,...
Remember: The Roddier test will only characterize the on-axis performance of an optic. It will not help with understanding off-axis distortion. From the...
Hi, Thanks much everyone for the help, analysis, and suggestions. What follows is a long (sorry <g>) summary of the experiments I've performed thus far,...
Hi Jim, I'll try to provide some comments below. ... at ... elongated ... better ... adapters ... 2" ... the ... in a ... OK, so the problem is not in the...
Hi John, Thanks much for the thoughtful reply(s) to my tales of woe. I very much appreciate the comments and suggestions you've provided. When we get a break...
... strips ... up ... I have seen two TMB lenses that pinched in cold temperatures, but they always made 3 spikes that extend away from the star. Seems a bit...
Thanks John. An aperture mask I shall try. <g> Do you have a recommendation on "where" to put the dew strip? Thomas himself recommended "just behind the dew...
... Thomas ... tube ... cell. ... wondering ... better ... being ... I don't have any well-tested proof that one method is better than any other. Certainly a...
Hi, Can I use the USB camera that came with a Meade AZ70-A to take pictures of a defocused star on a CPC1100 and to do startesting? Images inside and outside...
Hi Mike, Welcome aboard! It likely that your USB camarea can be used. The brightness scale needs to be linear to get accurate results, and not all cameras...
Group - back in Dec 07 I posted some results from Roddier tests on my Celestron (Synta) C6R using an artificial star as the source; see post #276 and the...
Mick, Thanks for posting the results. They seem very nicely done and well-documented! Testing a scope with this much chromatic aberration is certainly a...
... Mr. Biretta - thanks for the kind words about the C6R tests and even more thanks for taking the time to examine and critique them. My main "hidden"...
Hi Mick, Thanks for the picture of the focuser collimation blocks. Very clever! I sometimes have put small plastic or tape shims between the focuser mount and...
... Mr. Biretta - thanks profoundly for the very complete and detailed reply; almost makes me want to try to learn how to use Aberrator. The collimation...
Bits, A/D, D/A and Signal to noise ratio. This is something which I have studied, albeit long ago. The only, repeat, ONLY thing more bits in an A/D (Analog to...
Philip, Thanks for the interesting discussion on bit levels. I personally still wonder how the 1 bit sampling on audio CD players works.... Will have to look...
Hi I am new to the group. The attached file do not seem to load into the program. Could some one please tell me what is wrong with them. The files are for a...
Roddier program is very particular about which flavor of FITS you give it. I reformatted the images in K3CCD and FV, and put them in Files/Walker. Seems like...
Thanks for the help. The files load now but I am still having some problems. I will e-mail "zeissnut" directly. For general interest: I am working with a Canon...
Hello Scott, Great that you are trying using new types of equipment for getting the data for a Roddier test. One of the most important items for this test is...
... Dr. Biretta - I do plan to give the experiment a try. I will make a mask that fits snugly inside the outer part of the lens cell and will drop the clear...
Scott, I am using the "old" version Beta 0.4 of Roddier. It all runs fine for me. I put the results in that same folder. Are you using the newest version? I...
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