Solar Features, High Res & FD | Sept 23rd 2019

[MalVeauX]

Heya,

Woke up to a pleasantly clear sky and some ok seeing. Was able to get a little data at a few different scales.

I namely wanted to look at angular resolution differences between two wavelengths, in this case, 610nm and 430nm. 430nm has 41% higher angular resolution than 610nm. The difference is pretty close to comparing apertures of 150mm to 200mm in terms of resolving power, but also balancing angular resolution of the wavelength of light with it, so that they're similar.

Convection cells (150mm F16 at 430nm with 2.9um pixels):



Convection cells (200mm F10 at 610nm with 2.9um pixels):



High Res Spicules at the Limb (200mm aperture)





Prominences and chromosphere features (120mm aperture)







Full disc (52mm aperture)



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Colored:

















Earth Scale:

EarthScale_Spicules_200mmF10_PST_BF10_101frames_Colored_09232019.jpg (150.42 KiB) Viewed 1567 times

Equipment:

C8 Edge + Aires D-ERF + PST Etalon & 10mm BF + ASI290MM
120mm F10 Achromat + PST Etalon & 10mm BF + ASI290MM
52mm F11 ED + PST Etalon & 10mm BF + ASI174MM

EarthScale_Spicules_200mmF10_PST_BF10_101frames_Colored_09232019.jpg (150.42 KiB) Viewed 1567 times

Very best,

[MAURITS]

Excellent Marty.

[marktownley]

You had a really excellent bounty there Marty, very impressed with the 6"/430nm/290m combo...

[MapleRidge]

A superb series of images Marty...excellent results

Brian

[ffellah]

All great, Marty, but the granulation shots are my favorite. Very sharp and detailed.

Franco

[Carbon60]

Great set of images, Marty. Interesting comparisons.

Stu.

[DeepSolar64]

Incredible resolution!

[marktownley]

What is the exposure time like marty with the 430/152/290 combo?

[Montana]

A really super set Marty, very interesting to see the difference in the granulation between 430 and 610nm

Alexandra

[MalVeauX]

Thanks all

What is the exposure time like marty with the 430/152/290 combo?

Mark, the exposure is nuts. It's a very very high transmission system. The 150mm F8 refractor is stock. Inside the focuser I have a Baader blue CCD-IR block imaging filter as the primary ERF and it handles the 6" heat no problem. The scope is F8 and the critical sampling of 430nm and 2.9um pixels is around F16, so thankfully I was able to just use a standard 2x barlow to get there. But the transmission is so high that it's fully saturated at the camera side. Even with the Edmund Optics 430nm +/-10nm 45% (?) transmission filter. I have it mounted inside of a UV/IR block filter which is in front of it that does not cut out 430nm (its a standard ZWO UV/IR block filter). I had to grind transmission down with a 10 stop ND3.0 Baader ND filter. Without it, I was saturating at 0.032ms exposure times. A 6 stop ND filter wasn't enough either. I had to go to a 10 stop. This let me get back to something reasonable so I had room to work without touching gain. So with gamma far right in Firecapture (100), zero gain, I was at 3.5ms exposure time after all that. Without the 10 stop, I was stuck at 0.032 saturated, and near saturating in the 0.08ms, etc area, requiring gain just to get the histogram I wanted, because shortening exposure time oversaturated too much, all at zero gain, so I had to really grind down transmission to have wiggle room.

The same happens with my SCT in white light. My D-ERF -> Red IR block CCD imaging filter (ERF2) -> Baader 610nm imaging train for convection cells requires a 6 stop ND filter just to not oversaturate at 0.032ms too. I had to get a 10 stop just to be able to have room to expose without messing with gain.

I have a couple of skybenders so they make nice housings to hold multiple filters in an imaging train, so I have incorporated that to make it a "module" that I can just insert for Gband imaging (though this 430nm filter is not tight enough on bandpass to truly show Gband and my apertures are limited on top of that to show off Gband features, so if nothing, this is just a nicer high contrast approach with a smaller aperture). Using a 6" refractor is much easier to have an ERF for than a SCT or reflector without great cost or destroying coatings/aluminum and achieves high resolution with the shorter wavelength.

Very best,

[bart1805]

Why do you use a Gamma setting of 100?

[MalVeauX]

Why do you use a Gamma setting of 100?

Just to make it easier to see a high contrast to focus. Then turn gamma off and adjust as needed for histogram wanted.

Very best,

[bart1805]

Why do you use a Gamma setting of 100?

Just to make it easier to see a high contrast to focus. Then turn gamma off and adjust as needed for histogram wanted.

Very best,

Interesting. I decrease Gamma to see more contrast, up the exposure a bit and focus. But if it works for you, don't change.

[MalVeauX]

Why do you use a Gamma setting of 100?

Just to make it easier to see a high contrast to focus. Then turn gamma off and adjust as needed for histogram wanted.

Very best,

Interesting. I decrease Gamma to see more contrast, up the exposure a bit and focus. But if it works for you, don't change.

I might have the terminology backwards. When I set gamma to 100, it gets very dark and the contrast is very high. When I set gamma to a lower value, say 37, the shadows and mid-tones are so spread and similar that the whole image is virtually grey without contrast. Maybe when I set gamma to 100 it's contrast to minimum? How would you describe gamma in FireCapture and this observation?

Very best,