elpajare
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Post by elpajare on Aug 31, 2017 9:51:07 GMT
On moon nights I usually use the Bresser refractor to photograph cumulus and stars. Taking advantage of the fantastic invention of color in the current chips I like to compare the color of the stars they give and compare it with the type of star (O, B, A, F, G, K, M). Sometimes there are curious differences especially in the brightest stars, but as my telescope is not pure apochromatic I am never sure if it is the fault of the telescope. It would be interesting to be able to compare the same objects that I have photographed with the Bresser with some photographs made with apochromatic refractors (..the expensive ones) It's just an idea of collaboration and entertainment just in case someone is interested. This is my first photo, IC 1848 in the very center of the soul nebula in Cassiopeia with a IR Astronomik filter on. There are stars of type O, B and A
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Post by Deleted on Sept 1, 2017 6:50:49 GMT
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elpajare
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Post by elpajare on Sept 1, 2017 16:39:23 GMT
I like this link, maybe in the future i will go there.
Now, is only to share the different color which we capture with our telescopes and cameras.
A practical entertainment to see what colors better captures each chip than we normally use.
For example, it seems that the IMX224 captures blue light very well with my Bresser acro 102 mm
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elpajare
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Post by elpajare on Sept 5, 2017 10:02:12 GMT
This is Al Fakbhir, its a yellow giant Class B like our Sun. I used a Contrast-Boost filter from Baader and a UV/IR filter from ZWO together. Only adjust Levels and Brightness/Contrast. I think that color is very close to the real and this combination of filters maybe is doing a good job. We will continue testing... Thanks for the idea Robert, I have bought a Paton Hawlesky filter and I'll soon bother you with photos of spectrograms
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elpajare
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Post by elpajare on Sept 5, 2017 13:20:06 GMT
And this Algol, a blue-white star class B. The Contrast-Boost filter cut almost all the nice blue color of this class of stars. Investigating the properties of this "recommended filter" to avoid the chromatic aberration of the refractors, we see that it only lets pass a part of the spectrum between 460 and 700 nm. Disguise a bit the chromatic aberration but it destroys the real color of the stars. In my opinion, not suitable for photographing and is completely destroying color balance. This one example:
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Post by Dragon Man on Sept 6, 2017 10:39:28 GMT
Yes Carlos, the Contrast Booster filter works similar to a yellow filter used to reduce Chromatic Aberrations and Violet Fringing. It does this by cutting most of the blue light and enhancing yellow light. That why the blue has gone and there is a slight yellow cast.
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Post by Deleted on Sept 7, 2017 10:30:58 GMT
The Fringe Killer is the mildest of the minus violet filters that Baader produce.
It takes out UV, violet, and the shorter end of blue, as well as IR beyond H-alpha.
Not saying it will give you true colours, but I find it useful for cutting back CA on bright objects, and still allowing some blue to come through.
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Post by Deleted on Sept 7, 2017 10:44:05 GMT
This is Al Fakbhir, its a yellow giant Class B like our Sun. I used a Contrast-Boost filter from Baader and a UV/IR filter from ZWO together. Only adjust Levels and Brightness/Contrast. I think that color is very close to the real and this combination of filters maybe is doing a good job. We will continue testing... Thanks for the idea Robert, I have bought a Paton Hawlesky filter and I'll soon bother you with photos of spectrograms You bought a Star Analyser - excellent! I have one too but I haven't used it much. Now I we can work together maybe. Robert
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elpajare
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Post by elpajare on Sept 8, 2017 8:58:52 GMT
Yes, we wil do if you want.
Its a new and exciting way to learn more about light and stars. Im expecting the Star Analyser soon by mail fro the UK.
Maybe we will need a new section in the Forum....haha
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Post by davy on Sept 9, 2017 22:18:30 GMT
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Post by davy on Sept 9, 2017 22:25:04 GMT
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elpajare
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Post by elpajare on Sept 10, 2017 6:41:01 GMT
Very interesting links, thanks Davy.
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elpajare
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Post by elpajare on Sept 10, 2017 15:03:59 GMT
This is a picture taken last night. Color of some stars they look pretty good. This shot was taken at max. gain and 10" expo. Each cumulus has different expo time, it depends on the quality of the sky and contaminating lights. The lower the better but but always maintaining the visibility of the main object. The thing is usually between 2 and 10 seconds. People do not usually take into account the color of the stars when photographing, I like to do it. My refractor has limitations due to the chromatic aberration but a little work with Gimp solves many problems.
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Post by Deleted on Sept 11, 2017 6:45:10 GMT
I can definitely see some consistent colour differences there.
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elpajare
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Post by elpajare on Sept 11, 2017 6:55:38 GMT
Thanks Robert. Can you do some shots of this object to compare telescopes?
With my reflector is very difficult to have any color, stars are almost all overexposed and I like to see how APO/ACHRO refractors performs.
if you do not mind and you have time
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elpajare
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Post by elpajare on Sept 15, 2017 14:24:13 GMT
Another picture about a known cluster ( Perseus double) taken with the skywatcher and a little overexposed. The IMX178 has been able to capture color in some bright stars, I never can do it with the Infinity or IMX224. I love it. 10x15" stack + gain max + Skywatcher 200/800
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elpajare
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Post by elpajare on Sept 16, 2017 9:37:14 GMT
This is a picture taken WITHOUT ANY FILTER with the IMX178 Im surprise completely because there is almost no annoying halo here. One thing that all ignore when speaking of chips is his specific sensibility to the specific color. IMX224 does not respond the same then IMX178 neither. With the IMX244 i have a lot of halo and I must to use UV/IR filter always. This is a shot of 10x4" with the Bresser+IMX178. Only correct Levels and Contrast with GIMP.
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Post by Deleted on Sept 17, 2017 5:56:18 GMT
Binned or unbinned?
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elpajare
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Post by elpajare on Sept 17, 2017 7:48:49 GMT
Always unbinned.
I have not managed to find any advantage using the binning, it is likely that I don't know how to use it.
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elpajare
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Post by elpajare on Sept 17, 2017 11:12:42 GMT
More interesting things about stars color. I always had trouble finding different colors with the SKW, I thought it was because the stars were overexposed but it is not. The IMX178 chip manages to find colors where others can not 10x15" with IMX178 . A lot of different color in the stars 87x1,5" with INFINITY
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