I've got a new filter holder, I made myself. And now it's safer and I can focus with both hands, the solar image.
I was wondering, even though the shutter speed is 1/4000 sec, that since it's at the ecliptic and it's magnified, if that's what is causing the spots to look blurry of if it's mostly a focusing problem.
On that subject I remember a book called: the FX system of exposure determination, where they give an equation that expresses the length of time in seconds at an object of declination using a certain focal length lens will make a trail of so many mm on the film/sensor. That could be useful too.
Nice job. I had a quick play with your photo in Lightroom - it looks pretty good with some adjustments to white balance, contrast, clarity, and sharpness (some granularity is visible).
Without knowing more about your set up, the blurriness may be due to a combination of factors:
* mis-focusing - I find that zooming in using LiveView mode with manual focus to be the easiest option,
* optical distortions from your filter welding filter,
* lack of sharpness and/or diffraction from your lens - most lenses are sharper with the aperture set to 1-2+ stops smaller than wide open, and the latest Canon crop cameras tend to blur from diffraction at f/8 or smaller.
Might be worth practising/test without the solar filter on terrestrial scenes or the moon to see how sharp a photo you can get with/without the filter.
Taking all those solar pics, I didn't track any of them (yet). It was just on a tripod. Waited until the shaking settled down (the lens is a bit heavy).
It is a Canon Rebel T2i camera ISO 100, 1/4000.
The lens was a Kenko (35mm type) lens. This one was zoomed in at 800mm, F16
So I'm wondering (remembering the FX book, but I loaned someone, it isn't back yet) but that book had this equation that described the length of trail in mm on the film/sensor, given the time of exposure in seconds, the focal length of lens, and the declination of the star (given that the mount doesn't track).
So it looks like the fuzzy look of the Spots despite the in focus look in the viewfinder could be due to 2 things against it: the Sun being at ecliptic (like it always is), and also the zoom of the lens. But then against these 2 things is the 1/4000 sec. So the equation should help, I just need to find it on the net. Or need help.
Thank you.
The softness is almost certainly a limitation of the lens, i.e. it's not sharp at 800 mm. High quality super telephoto lenses are very, very expensive... e.g. Canon's 800 mm f/5.6L lens is *double* the price of a Tak FSQ-106!
At 1/4000 sec, it's very unlikely to be blur from sidereal rotation. It doesn't look like rotation blur because the spots are round (not elongated in one direction), and the edges don't show any trailing blur.
By the way, approximate calculations for trailing just need a bit of arithmetic. The sky appears to rotate at around 15 degrees per hour (15 arc seconds per second), so in your 1/4000 second exposure it will rotate 15/4000 = 0.00375 arc seconds. The sun is around 30 arc minutes in diameter, and in your image it is approximately 800 pixels high, which gives a scale of 30*60 / 800 = 2.25 arc seconds per pixel. Thus, during one exposure the sun will have moved 0.17% of one pixel - i.e. there is definitely no trailing occurring here.
One last thing... 1/4000 sec ISO 100 f/16 is still *VERY* bright - so please be careful and protect your eyes. Using a Thousand Oaks 99.999% blocking solar filter, I get exposures of 1/250 sec ISO 100 f/4 - i.e. your solar filter lets in 256 *times* more light than a typical safe-for-visual-use filter.
I hope you don't mind, but I did a few quick tweaks of your original image (size reduction, white balance adjustment, contrast, clarity, and sharpness).
There's actually a fair amount of detail there - with the processing, it's easier to see the granulation and sun spots.
