Sunspot in AR2734 Continues | + FD, Proms, Plages | March 7th 2019

[MalVeauX]

Heya,

Woke up to some clouds, but they went away... imagine that, around 9am or so there were some low stratus clouds, but then it cleared up by 0930 which was nice. Seeing was ok for a while, but deteriorated as it got closer to 11am, at which point, large scale became unusable. Following AR2734, the poles have elongated from each other since yesterday, but the visible umbra have diminished some. Another region near by is also churning with some interesting plages and fibrils. A couple of prominences are notable on the limb today compared to yesterday, a few larger but very feint ones. I managed to capture the largest one that was very feint lifting off as it broke into two pieces and the top of its large arch released it. Happened pretty quickly. Couldn't get anything usable in white light at large scale due to the poor seeing and the short wavelength I attempted (395nm). I realize I need to go longer on the wavelength to attempt anything right now at large scale, so I may have to get a loose 656nm filter for convection cells for now. My hopes were to add a 430nm G-band filter, but, with the seeing as it is like this, I don't think I'll be able to utilize it at large scale with my system under these seeing conditions and that's the only place G-band really shows off is under high resolution and large scale. So, maybe another day. Maybe it's time to add a Baader HA 35nm filter for my "white light." Anyhow, today's subject matter presented in B&W native, inverted and false color options. A few Earth scales provided for perspective.

AR2734









Plage & Fibrils









Lifting Prominence





Full Discs









Earth Scales





Equipment

C8 Edge HD SCT with Aires 200mm Tri-Band D-ERF
ST80 (masked to 60mm) Refractor
Baader UV/IR Block filter
Quark Chromosphere
ASi174MM + 0.5x Focal Reducer

SolarSetup_03072019.jpg (117.86 KiB) Viewed 2090 times

Binoviewing visually just to see

BinoViewing_HA_C8Edge.jpg (114.73 KiB) Viewed 2090 times

FOV of the Quark at F42 then with the 0.5x focal reducer (you can note the minor vignetting). I pushed gamma down to make it easier to see and focus which required more gain. Otherwise, I can image at 0 gain which is nice.

SolarSetup_FIreCapture_Screenshot_03072019.jpg (168.58 KiB) Viewed 2090 times

Very best,

[Carbon60]

Nice set of images, Marty.

Stu.

[MAURITS]

TOP images Marty.

[marktownley]

Good images Marty!

[bart1805]

You are having fun with the new equipment Marty! Nice to see.
Do you set Gamma at 100 just to focus and set it at neutral again when imaging?
Nice lifting prominence! Double lines indicate for me it is a bit over processed. I use the adaptive mode in IMPPG, then you can define which bit of the image is less processed than others. It is also very useful to create less noise in the black areas of the image.

[MalVeauX]

Do you set Gamma at 100 just to focus and set it at neutral again when imaging?
Nice lifting prominence! Double lines indicate for me it is a bit over processed. I use the adaptive mode in IMPPG, then you can define which bit of the image is less processed than others. It is also very useful to create less noise in the black areas of the image.

Hi Bart,

Yes, I set gamma to 100 and increased exposure values for the purpose of focus and for the screen shot. Otherwise, I shoot gamma neutral and require no gain.

I will look into adaptive mode in IMPPG, I may not be fully utilizing it! Thanks!

Very best,

[bart1805]

Hi Marty, check 4.3:
https://github.com/GreatAttractor/imppg ... /README.md

[MalVeauX]

Hi Marty, check 4.3:
https://github.com/GreatAttractor/imppg ... /README.md

Thanks!

Very best,

[Christopher]

Nice set Marty. Interesting prom.

[eroel]

Marty:
A very good session.
Regards,
Eric.

[Astrophil]

Good looking images Marty. Seems like the new system is working well.

Phil

[Valery]

Yes, I set gamma to 100 and increased exposure values for the purpose of focus and for the screen shot. Otherwise, I shoot gamma neutral and require no gain.

Sad! This is a very common mistake - to set gamma at a neutral value. One always will loose delicate shades in the final images.
Gamma should be set at the value when a histogram is nearly full - intensities from zero to about 250 in 8 bits.
In this case you have all 8 bits to represent the brightness range (dynamic range) you have recorded.

The gamma should be set at the value when you see maximum shades of the sun surface at the screen.


Valery

[Montana]

These are cracking shots Marty

Alexandra

[MalVeauX]

Yes, I set gamma to 100 and increased exposure values for the purpose of focus and for the screen shot. Otherwise, I shoot gamma neutral and require no gain.

Sad! This is a very common mistake - to set gamma at a neutral value. One always will loose delicate shades in the final images.
Gamma should be set at the value when a histogram is nearly full - intensities from zero to about 250 in 8 bits.
In this case you have all 8 bits to represent the brightness range (dynamic range) you have recorded.

The gamma should be set at the value when you see maximum shades of the sun surface at the screen.


Valery

My understanding of gamma in Firecapture is that it is simply software manipulation, so it's not doing anything that I cannot do in post-processing, correct? Gamma has been removed as a hardware control feature in the SDK for ZWO cameras if I recall. I merely uncheck gamma for most captures, since it's just software here.

If not, could you show examples of a full histogram and how to change the gamma appropriate to it?

I note that a lot of people will not fill the histogram, and instead, fill it only into the 40%~50% range, and stack and then raise what they wish in post from dynamic range of the strong signal to noise ratio. But how does gamma play into this?

Very best,

[rsfoto]

Hi Marty,

Great images. Congratulations

regards Rainer

[Valery]

My understanding of gamma in Firecapture is that it is simply software manipulation, so it's not doing anything that I cannot do in post-processing, correct?

Incorrect. You can see this easily - compare the view of the screen when you playback already recorded movies of the same area (for example AR) with a neutral gamma and gamma set for higher contrast.
Let assume we imaging an AR at large scale. 8-bits. When you recording at neutrat gamma you recording brightness levels from 110 to 142 (mostly grey image - no black, no bright white). Dynamic range is 32 brightness levels or 5 bits. When you set gamma so that you strech histogram from 0 (back) to bright white 255 the dynamic range is full 8 bits 256 brightness levels. So in the first case you have DR of only 5 bits and in the second case you have DR of 8bits. Better to have 8 bits than 5bits.


Valery

[marktownley]

I have been doing some experimentation with my PGR cameras lately, and are able to image in their native 10, 12 or 14bit output (depends on camera), i'm finding I can expose way up to >90% of the histogram with no issues in post processing or stacking. If I do this in 8 bit mode I find I have to keep the histogram down at 70% - same experience as you Marty!

I do totally get your logic and reasoning Valery and 'gamma exploration' is on my list of things to try on those long summer days!

[MAURITS]

Do you set Gamma at 100 just to focus and set it at neutral again when imaging?
Nice lifting prominence! Double lines indicate for me it is a bit over processed. I use the adaptive mode in IMPPG, then you can define which bit of the image is less processed than others. It is also very useful to create less noise in the black areas of the image.

Hi Bart,

Yes, I set gamma to 100 and increased exposure values for the purpose of focus and for the screen shot. Otherwise, I shoot gamma neutral and require no gain.

I will look into adaptive mode in IMPPG, I may not be fully utilizing it! Thanks!

Very best,

Marty when you mean "gamma neutral" is it than the 50% as startpoint in FireCapture?

One other thing, I find the histogram reading a lot more difficult in FireCapture than in SharpCap ....