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Question about image quality

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#1 ourobouros2k2

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Posted 25 March 2012 - 07:59 PM

I have the basic Lunt 60 tilt tune, single etalon. I like the images that I get, but have yet to hit the detail in the dark regions that looks like hairs. I get dark "orange peel" effects, but not the dark, almost black "hairs" around the active regions. I usually image with a 2x barlow.

is the detail I am looking for eluding me due to:

1. needing more magnification
2. better imager
3. needing double stack
4. all above?

I just want those crisp hair-like details, but I don't know what will get me there.

thanks,
Andy

#2 Naturlich

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Posted 25 March 2012 - 09:14 PM

are you using a colour cam (that mallincam?)? Thats seriously not a good idea and will drop quality dramatically.

Don't need more mag.

don't need DS

30 second to 1 min captures, keeping about the best 100 frames, then picking the frames with the least deviation (if you're using AviStack2) will probably drop you to about 50ish (or less) frames total to be stacked. the longer your captures the more motion blur you could induce. I've found that stacking 50 frames (or less) is perfectly adequate.

Nat

#3 Naturlich

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Posted 25 March 2012 - 09:20 PM

This is one from today with my little 35mm & DMK41, less than 50 stacked frames from approx 900 (1 min capture at 15fps):

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#4 ourobouros2k2

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Posted 25 March 2012 - 09:28 PM

Awesome shot! Gotta get a mono imager. That's what I am talking about right there! Will work for DMK41 being painted on a sign right now, lol. BTW, love the Gayatri mantra in your sig :)

#5 stets

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Posted 25 March 2012 - 09:32 PM

I like your full-disk image.

#6 Naturlich

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Posted 25 March 2012 - 09:42 PM

Thanks guys, glad you like the image (makes a nice change having some clear skies!)

Yeah Andrew, mono is the only way to fly when it comes to solar imaging. The DMK41 on the LS35 gives very good full disk images, but at the cost of high mag images (I can push it to 3x barlow max on my scope really) but I can get pretty reasonable proms at prime, 2x and 3x, your LS60 should perform quiet well with a DMK41.

Glad you like the mantra :) I'm not a religious person at all, but the mantra has a number of translations, the one I prefer is something along the lines of:

"Almighty Supreme Sun impel us with your divine brilliance so we may attain a noble understanding of reality."

So say we all!

#7 old_frankland

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Posted 26 March 2012 - 02:47 PM

Awesome shot! Gotta get a mono imager. That's what I am talking about right there! Will work for DMK41 being painted on a sign right now, lol. BTW, love the Gayatri mantra in your sig :)


If you just gotta shoot full disk stuff, then the DMK41 is killer, but if you want to push magnification to the limit the DMK21 is a far better way to go. This stuff is shot with a 50mm aperture filter and DMK21. Seeing conditions pose the biggest challenge.

http://www.lafterhal...halpha_sun.html

#8 Chris Schur

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Posted 26 March 2012 - 03:25 PM

You also have not mentioned how you post process the images. I think you have all the data you will need to get those fine "hairs", but if you are using too large a radius for example, they will not show. I do see your disk has a strong gradient and is not uniform with a gentle limb darkening. A synthetic flat field will correct this condition.

#9 ion

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Posted 27 March 2012 - 06:29 AM

Full disk requires a field of view around 32 arc minutes and proms need a couple more on either side. According to my calculations with CCDCalc (see caveat below) the LS60 + DMK41 only provides 30.8 arc minutes. Fortunately an 0.8x reducer on the LS60 + DMK41 has the same field of view as the LS35 + DMK41 image posted earlier.


LS35 + DMK41 = 38.4 x 51.2 (Naturlich)

LS60 + DMK41 = 30.8 x 41 (Not wide enough)

LS60 + DMK41 + 0.8x = 38.5 x 51.3 (Same as LS35 + DMK41)

LS60 + DMK21 + 0.5x = 37.1 x 49.4 (Another popular combination)

LS60 + DMK51 = 36.4 x 48.5 (Perfection?)

By the way a reducer is desirable anyway for the next time something like this happens.

Caveat: To use CCDCalc one has to enter specs from various online documents for the scopes and cameras. I have triple checked my entries so sensible purchases can be made but a typo anywhere including the program code could induce errors. Any necessary corrections are welcome...






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