From: Alan Friedman <alan@greatarrow.com>
Date: April 27, 2010 7:41:36 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Ha efforts from Ray
Hi Ray,
Daytime seeing is certainly an overwhelming factor in solar observing and imaging. Many say that solar observing should be done before 10:00am. Unfortunately I can only see the sun before 10:00am from my backyard for a couple of months during the year. The good thing is that seeing during the day can change very dramatically over short periods of time. Our buildings are mostly wood frame in Buffalo - the houses adjoining my backyard are 100 feet away. They have asphalt roofing that stores heat beautifully and radiates heat all year long. In the winter, the heat escapes through the roofs making a mess of the low riding sun. But in the brief passage between the houses, the air settles down and allows imaging to happen. We just have to get outside often to hit these brief stretches of steadiness.
Transparency is also very important for solar imaging. Thin clouds make for big headaches in image processing. That said, when something of note is happening on the sun, I almost always give it a shot.
But the biggest challenge by far to daytime imaging is our families. They seem to think it more valuable for us to have a job and go to work.
best wishes,
Alan
Alan Friedman
president
Great Arrow Graphics
2495 Main St. suite 457
Buffalo, NY 14214
716. 836. 0408 ext 222
On Apr 27, 2010, at 6:05 AM, Ray Byrne wrote:
Hi Alan,
Oddly I never received this message directly just added to one from Milton. I took your advice and ran my movies through QT Pro7 and it was obvious that not only was the transparency pretty poor but so was the seeing. The image of the Sun was continuously seething and writhing so it would also account for the poor result. I did try out the technique with PS and single frames and they were marginally better but as they say "you can't polish a turd"
Thanks for your help Alan I do mean to press on with this as the Sun has always been of particular interest to me. Where I live I'm surrounded by houses with tiled roofs, tarmac paths and roads etc. so I wonder if I'm just unlucky and have permanent poor seeing (I've never been able to get past a certain level of image quality). I notice that you image fr! om your backyard are you similarly surrounded by possible sources of turbulence (mind you houses in the US are wooden I believe rather than brick).
Cheers for now
ATB
Ray
Hi Ray,
In my experience, it can be very difficult to get accurate alignment and stacking using chromospheric details on a spotless sun... especially so if transparency is poor and the details even lower in contrast than under a cloudless sky. To my eye, these two pictures look very soft and somewhat overprocessed while trying to bring greater contrast to the detail.
I would suggest scanning through the movie to locate a sharp frame. I usually do this with a copy of Quicktime Pro v.7. You can select and copy a single frame and paste it into a new document in Photoshop. Apply a gaussian blur (1.0 pixel radius should work well) a! nd then unsharp mask. The result might be a bit grainy depending on yo ur capture settings, but it will show you the potential of your data. If it looks a lot sharper than your stacked image, the stacking process is not working out well. I often use single frames to create solar images. My blue sun was made from two individual frames - also a day of very low activity and high turbulence. The sun provides enough light that the individual frames should have a nice signal to them - stacking may not be needed at all.
I've seen a lot of very fine images from PSTs with this modification - keep at it!
Apologies to Milton and Alberto for not commenting on your recent posts and the new version of Astro IIDC. I've been very busy with travels and work... hope to have time to get back to my night job soon!
best wishes,
Alan
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