Yep – that about sums up my experience too Clive and I guess that’s the beauty of astronomy as a hobby – it’s a pleasant pastime that we can enjoy however we practice it; with different telescopes, focal lengths, cameras, accessories, preferences, skills and capabilities. Each person will adopt what works for them.
On no, please don’t do that….if you didn’t write another word, how would we all know that we are indeed different…and how would we continue to learn from each other about the assorted equipment and diverse techniques we use!
This whole discussion prompted me to go looking for some data on focusing and finding the Lodriguss website provided an interesting read.
My lack of patience and skills mean that I prefer focusing aids such as the Bahtinov Mask, but kudos to others who just eyeball it, or use other techniques; there is always something to be learned, and more often un-learned, through discussing these topics on Ice In Space.
This is proving to be quite an informative discussion. I found an interesting write up on “Focusing Methods for Astrophotography” on the website of Jerry Lodriguss. Out of the 17 methods of focusing that he discusses, he lists the eye as the least accurate method whilst the Bahtinov Mask only comes in at #6, with the Hartman Mask a lowly #4 on his list. The low ranking of these masks surprised me!
Using Software Metrics was judged to be the most accurate, placed at the top of the list at #17.
I had a quick read of this article. The trouble with his discussion of the Bahtinov and Hartmann masks is that he is talking about using them through the camera viewfinder, whereas most of us download the image and look at it on the computer screen.
Good points. I do remember some while ago playing around during a couple of imaging sessions where I compared the focus accuracy of the Bahtinov mask by eye versus using CCDSoft Focus Tools. Unfortunately, the results were polluted by an ill-fitting mask and some (since) discovered slop in my focuser.
However, even with the above anomalies, I judged that to all intents and purposes, eyeballing focus via the Bahtinov Mask on my computer display was as accurate as using the Focus Tools panel in CCDSoft, where the software produces a graph indicating best focus. This was based on using a manually operated, motorized focuser, not a fully automated software controlled process.
Having now got a well made mask and having since solved the focuser slop, I haven’t yet re-run run the tests. Like you, my previous experience leads me to believe that the Bahtinov Mask would appear much higher up on my own list, when viewed on a computer display.
In other experiments, I found that even using the Canon 40D in-camera “Live View” at x10 zoom gives a superb focusing image using a bright star.
Dennis mate, I didn't mean that I would never speak again, but just not on this subject.
To my needs and purposes the mask is of no value to me, considering my set up, the FSQ is so sharp, one can see it snap into focus. and do It's diffraction thingy.
LOL! I knew that – you’re too much of an old hand at photography and astro photography and a strong character to boot!
When I find myself at variance with a particular view in a post, I am trying to leave a footprint that kind of says “that’s okay - what works for you doesn’t necessarily work for me” rather than “x is right and y is wrong” or “mine is the only way”.
Experience reminds me that several times, I’ve been out of order, plain wrong or just not understood the issues fully, (and not surprisingly this will continue), so my views are only what I understand right now, with the gear and techniques I have at my disposal.
we all do it differently, which is good, so from this point on I will not mention another word 
but just not on this subject.
