As some here might expect I can't help but mention that slightly bloated and out of focus stars are usually not a problem when taking data. In fact, in some cases bloated and out of focus stars can even be a plus. patrick :) On 31 May 2014, at 18:41, Don J. Colton <djcolton@piol.com> wrote:
Hi Steve,
Star bloat has nothing to do with collimation but is caused by poor seeing or focusing. Getting accurate focus is not trivial and without Focus Max or a similar program it can be difficult to achieve - particularly with a fast system like yours. If you have round star images throughout the frame your collimation is good. Poor collimation will result in oval images with one side "pinched". This image of the Pelican http://www.slas.us/gallery2/main.php?g2_itemId=3968 was taken with the same scope you have - FSQ106 at f/5 and I used the FSQ reducer on this one: http://www.slas.us/gallery2/main.php?g2_itemId=3896 . Click on both images for enlarged version.
The best way to check for collimation is use a high power eyepiece on a 2nd or 3rd magnitude star and see if you get concentric diffraction rings. Also, be sure the image is centered in the field of view.
Clear Skies,
Don
-----Original Message----- From: Utah-Astronomy [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of gazebo4sale@comcast.net Sent: Friday, May 30, 2014 10:47 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] M8 unguided with Murphy
Dear Utah-Astronomy Folks,
Thanks for the nice comments and input.
Don I was very careful with my focusing this time and as you can see star bloat is an issue. I suspect my previous issue was soft focus and wind.
I thought that it would be a good night to learn how to use the Polar Alignment Routine in "Backyard EOS" instead of Image but Murphy did manage to throw a nice wrench at me and I couldn't have been more accurately Polar Aligned out of the gate:The stars would not drift so I decided to Image.
Chuck to me anyone who imaged with film had to be an Astronomical Hero. I know that in the back of a previous film images mind there has to be the thought that this stuff is child's play compared to what one had to do when shooting film and hand guiding. It is just astounding to me in that for every 10 good sub frames I acquire I get 1 bad one on a good night and because I can shoot and immediately see my results the learning curve is simpler. I did have a programmable cable for the Canon but I did not have a memory card in the camera..duhh.
My big brother, who accompanies me suffers from a great deal of cognitive problems that come free with his nasty case of Parkinson's disease gave me hell for not bringing along the Old Film EOS and a few rolls of Color film. It was a pretty profound thought for him but he use to image with film also.
Dave your words are kind and I wish I could keep Murphy at bay but I know the sukkah loves to eat "Driver's". I think he has a taste for DIL..lol.Good luck with the commet. I will be on the beach in California with grandkids.
I selected the Lagoon Nebula for three reasons that night: 1. I have never gotten a decent image of it. 2. It is easy to find 3. It is very bright and lends itself to shorter exposures.
I like to participate on Yahoo User Group "dslr_astro_image_processing". Mike Smythers who is the Pixisite expert in the group processed my image and this is his version:
https://www.dropbox.com/s/nux7sizrzuxres8/Steve%27sM8.png .
Thanks for the comments.
Steve Gallenson