Another usefull Photoshop Technique to try...

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Another usefull Photoshop Technique to try...

Post by Cschur »

Here is a halpha full disk shot I took yesterday in very poor seeing, with the Lunt LS100 and DKK51 camera. I have been struggling with getting the overall contrast of my disk shots up to a reasonable level without making the edges of the disk fade out to black because of limb darkening. for this new image, I tried a technique that I have used for years on deep sky images and it worked admirably. I took the raw stacked image, and applied a very small amount of the Shadows/Highlight filter to this disk, shadows set for maybe 1/8th strength and highlights set for 100 percent. Then processed normally. What I was now able to do was apply a deeper gamma curve to the image and bring out the surface mottling much better without loosing the edges. Try it - youll be surprised what the edges of the sun has in store for you!

Here is the image reduced to 1290 size to fit your screen. (Click on it darn it)




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Re: Another usefull Photoshop Technique to try...

Post by solarchat »

ya man, I use the shadow highlight tool on most of my my images. The double stack 90 shows such a 3 dimensional visual image that the camera rarely gets full brightness all the way to the limb. This is a useful tool but it is very easy to over do it.


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Re: Another usefull Photoshop Technique to try...

Post by Montana »

Thanks Chris! another top tip to try :)

Regards
Alexandra


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Re: Another usefull Photoshop Technique to try...

Post by Ken Crawford »

Nicely done Chris,

S&H is very powerful! When I presented in AU last summer with David Malin he showed me how S&H with the right settings works like his Photographic plate days Unsharp mask.

This is why I love the HDR Toning Tool in CS5. It puts several tools together working in concert! S&H plus a very high dynamic range toning curves tool - sharpening - Vibrancy - Gamma and Exposure - all at the same time and in 32bit! :woohoo:





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Re: Another usefull Photoshop Technique to try...

Post by Pedro »



http://re.apaaweb.com/sun_20120107_LUNT ... mosaic.jpg
SUN (20120107) PROMS. LUNT 152 F/6, BF3400, X2 Barlow, DMK41, four-panel mosaic (stack of 250 images each panel)

I also use shadows & Highlights in some of my solar images. Here's an example:

This way you can get the proms and disk details im a single avi. Works great form me.

best


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Re: Another useful Photoshop Technique to try...

Post by Cschur »

Ken, you make me want to sell my zeiss apo so I can afford the new photoshop! But wait, then I cant take photos. ;( But the good news is that we now have CS2 at work, and I can do some processing with it at lunch time. ;) Pedro, somehow I just knew you had allready tried this. You seem to have a great mastery of photoshop techniques. You must share you knowledge with us...


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Pedro,
I find with my double stack SM60/DMK41 I really do need different exposures for the surface and the proms (ie 1/120s for the surface and up to 1/11s for the proms)
Am I doing something wrong???


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Re: Another useful Photoshop Technique to try...

Post by marktownley »

Pedro,
I find with my double stack SM60/DMK41 I really do need different exposures for the surface and the proms (ie 1/120s for the surface and up to 1/11s for the proms)
Am I doing something wrong???

I only ever do 'one shots' with my DS40 - what gamma value are you using on the camera Ken?

I've used S&H for sometime now, it is pretty effective, also a high pass filter is very effective at teasing out limb details...


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

I used <300 gain camera setting.
Try to get between 1000-1500 frames...


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Re: Another useful Photoshop Technique to try...

Post by marktownley »

I used

What about the gamma setting?


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Don't touch the gamma...I always thought it was for display not for captur???


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Re: Another useful Photoshop Technique to try...

Post by marktownley »

definitely capture, I always leave mine on 100 (assuming your working in windows?)


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Re: Another useful Photoshop Technique to try...

Post by Pedro »

I usually use Gamma 75 for disk details and 200 to 250 for proms. If you want to get both on the same avi try a gamma value around 150 to 200 and overexpose slighthly (2/3 of the histogram). Then use S&H. I have to add that this technique (S&H) adds some noise, nevertheless it works very well in my images. The LUNT152 is great for getting prom details (aperture rules) ;)

Furtehremore I never touch gain (leave it at the lowest value)

best regards


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Hmmm
On the IC Capture, V2.2 running the DMK41 firewire version...
The range of Gamma settings are only 10-22
It also says in the IC Help file that gamma affects the display....

GAMMA CONTROL
All monitors show a non-linear display trait. This means that the differences between similar dark gray values can not be displayed. This effect can be neutralized by so-called gamma correction. With this property gamma correction can be switched on and off. There are cameras that provide more than one type of gamma correction (i.e. a special correction for taking images from the human skin - used in the medical field).


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Re: Another useful Photoshop Technique to try...

Post by Pedro »

My DMK41 is the USB model and I use the latest version of the soft 2.2 (64bit). I only change exposures and gamma settings to obtain my avis. I nerver touch gain.

best


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Hmmm
Is this a USB/Firewire difference?

Pedro, what gamma range is available to you?
What's the lowest Gain setting on your system?


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Re: Another useful Photoshop Technique to try...

Post by Pedro »

I do no have the DMK41 here with me so I can not check the whole functions of the soft. Gamms starts at 0 and I guess it goes up to 500 if I am not mistaken. I always use 50 to 75 for disk details and 150 to 300 for proms.

best regards


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Pedro,
That's OK I'm sure someone will comment.

The rest of my available settings are:
Codec Y800
Exposure: 1/10000 to 36000s
fps: 3.75/7.5/15
gain: 180 - 1023


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Re: Another useful Photoshop Technique to try...

Post by Montana »

Hi Merlin,
Unfortunately I have the USB version too.

I use the default gain of 260 but I do push it up for CaK and proms because I struggle for exposure and I would get nothing if I didn't but I never go beyond 400. For gamma the default is 100, I use 70-85 for the disc, and around 120-200 for the prominences. Hopefully this will give you some indication of at least the scale. I am sure your gamma isn't just on screen, what you see on screen is what you get, I can't see this being different just because of the data exchange method.

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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

Alexandra,
If I ever see the sun again (!) I'll check out the differences with gamma setings....


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Re: Another useful Photoshop Technique to try...

Post by swisswalter »

Gruezi all

I'm totally puzzled. I learned here not to touch gain if possible (gain is pain!). I work with the exposure time and the gamma. Gamma gives me on the screen more contrast and also in the avis. I feel the more gamma I choose, the narrower gets the line between under exposure and over exposure.

I have the feeling that all this gamma thing depends on the CCD cam you use, the absolute number is different from CCD to CCD and recording software to recording software.

I'm I totally wrong :?


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

gamma is a contrast enhancement. According to IS, in windows 1 gamma =100, (for firewire 1= 10)
I see many reference where gamma should be set to 1 and not changed.....


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Re: Another useful Photoshop Technique to try...

Post by earl »

I have recently started playing around with gamma settings on my DMK41. Usually I leave gain at 260 and gamma at 100. Adjusting exposure using the histogram allows to maximize exposure providing me both disk and prom details. The trade off is less time processing with decent prom details. Recently on my time-lapse I started adjusting gamma to around 150 then adjusting the exposure to get more prom details without over saturating the limb, however, this usually blows out the disk.

I would agree that each CCD is different and settings will never be the same from one unit to another even if the CCDs were produced at the same time. The electronics of the camera will introduce variables resulting in minor differences in settings. My wife and I see this all the time with her professional cameras. While they are very close in detail and tonal ranges one camera does perform better than the other even though they are the same type and purchased together.


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Re: Another useful Photoshop Technique to try...

Post by Merlin66 »

I think the aspect of this thread I find surprising is the fact of using gamma to record the surface detail and the proms in the same exposure. The DMK is only an 8 bit camera, and since I started solar imaging, I've always had to use different exposures for the surface and the proms. I took it for granted, that it was necessary.....


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Re: Another useful Photoshop Technique to try...

Post by Montana »

Not necessarily, as soon as I put the double stack on the PST I can suddenly get surface and prom on the same exposure, why is that then?

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Re: Another usefull Photoshop Technique to try...

Post by marktownley »

Intersting the way the thread has developed...

Completely agree with Alexandra - in double stack mode with the SM40 I can easily capture surface and proms in one go; yes, I know the proms aren't as 'bright' as doing a seperate prom shot, but with post processing I can do a pretty decent job of pulling out the prom detail. It's only when the sun is low and seeing is bad that I struggle to do this.

I'm running a USB DMK31 and on 260 gain (minimum) and 100 gamma (default) and with my DS40 @ f21 I operate at 1/37s when the sun is low in the sky, 1/45s when the sun is high. I find with the contrast i'm getting from my DS 100 gamma works for me for one shots...

What f-ratio are you working at Ken? I know the DMK41 is slightly less sensitive than the 31, but 1/11s for proms seems really low to me (compared to what I run at) - especially seeing as you are working at 60mm aperture compared to my 40mm.


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Re: Another usefull Photoshop Technique to try...

Post by Merlin66 »

Seriously, I need separate exposures....
I usually run at around f25 with the double stack.
This was the case when I started with a DMK21 as well...


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Re: Another usefull Photoshop Technique to try...

Post by marktownley »

Lose an ERF on the inner etalon, I reckon you'll get your prom exposures upto more like 1/27s ;)


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Re: Another usefull Photoshop Technique to try...

Post by Photosbykev »

with the DMK41 on my LOHA 4" f/11 scope I normally shoot two exposures. The proms are typically 1/15second and the surface detail 1/150sec with gain at 260 and gamma 100.

I have played with the gamma to get a single image containing proms and surface detail but found I had to really push the post processing to get the best out of them which introduced a lot of noise as the proms tended to be under exposed.


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Re: Another usefull Photoshop Technique to try...

Post by Merlin66 »

Kev,
That seems to match my experience.
Mark, at this stage I'm not prepared to dismantle one of the SM60...
I was wondering though...could it be my exposures are so affected by the tuning I apply between the double stack filters? I really do spend a lot of time setting each filter and then working them together to get the "best" narrowband performance.
Typically the intensity, from a single stack, or when both filters are tuned together for Ha is reduced by 50% when they are set for 0.4A bandwidth. This would mean x2 exposure durations for the same settings.....
(Has anyone else measured this?)
Any comments?


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Re: Another usefull Photoshop Technique to try...

Post by Montana »

Hi Merlin,
I typically have an exposure of around (can't remember exactly) 1/60-70 for SS and when I double stack the PST I go down to 1/25 or 1/19 or thereabouts for surface detail.

Regards
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Re: Another usefull Photoshop Technique to try...

Post by marktownley »

Mark, at this stage I'm not prepared to dismantle one of the SM60...
I was wondering though...could it be my exposures are so affected by the tuning I apply between the double stack filters? I really do spend a lot of time setting each filter and then working them together to get the "best" narrowband performance.
Typically the intensity, from a single stack, or when both filters are tuned together for Ha is reduced by 50% when they are set for 0.4A bandwidth. This would mean x2 exposure durations for the same settings.....
(Has anyone else measured this?)
Any comments?

Fair play Ken if you don't want to take one apart, however it is only all screwed together so is easily reversible (I will stop going on about it though!).

Regards my tuning the outside etalon (furthest from objective) I never adjust the position of - it is set up so that the reflection is thrown wide of the actual solar image. I've adjusted the hinge plate to do this and the t-max tuner remains locked closed permanently - not adjustment ever since needed. The inner etalon (closest to objective) is a similar setup - again hinge plate adjusted accordingly, t-max tuner locked shut for best position. To adjust for optimum tuning from one observing session to the next I simply rotate the dew shield the etalons are mounted on; this has the slightest sag in it due to weight of etalons and provides just enough variation in tilt required to tune - even in winter in cold temperatures and high atmospheric pressure.

There are a couple of things you can check for Ken if you haven't done so already; are the 2 t-max tuner units diametrically opposite each other? This gives the best contrast... Also have you checked the alignment of the hinge plates? - they offer some adjustment and if not true can affect resultant contrast...


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Re: Another usefull Photoshop Technique to try...

Post by marktownley »

Hi Merlin,
I typically have an exposure of around (can't remember exactly) 1/60-70 for SS and when I double stack the PST I go down to 1/25 or 1/19 or thereabouts for surface detail.

Regards
Alexandra

What f-ratio is this at Alexandra?


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Re: Another usefull Photoshop Technique to try...

Post by Montana »

Oh yes, that's when I have the 2x Barlow in as this is when I use the DStack most, sorry!

Regards
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Re: Another usefull Photoshop Technique to try...

Post by Merlin66 »

Mark, et al,
I've gone back to the double stack SM60 thread and added my comments on tuning a DS, rather than this thread.


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