Friday, February 15, 2008
Second light for Canon FD 200mm f2,8 lens
Rosette nebula is located very low in the horizont at my location.
The maximum elevation is about 29 degree.
Last night I shooted one hour of exposures to RGB channels, with UHC-s
filter 6x600s.
Hevay light pollution coused strong gradient and very weak signal/noise.
Then I shooted 9x1200s for H-alpha channel, but thin upper clouds ruined 5 exposures.
Final image is composed from 6x600s RGB and 4x1200s H-alpha.
This lens is fast enough to capture a nice amount of photons in that time,
not very deeb image but tolerable.
Here is pure H-alpha version:
Thursday, February 14, 2008
First light, Canon FD 200mm f2.8 lens
Last nigh was very windy, almoust a storm. Normaly I do not shoot under that kind of
conditions. How ever, this time I wanted to test my 200mm f2.8 Canon lens under the stars.
"HARTH & SOUL"
IC 1805 & IC 1848 in H-alpha light.
Only 6x1200s, this is a fast lens. Flats and Bias, guided with LX200 and PHD-guiding.
Camera QHY8 + QHY5 guider.
I added some color, but there was problem with camera orientation, so image is clipped.
Color data: only 3x600s with UHC-s filter
I shoot California nebula as well. Elevation was very low at the end of the exposures,
only about 28 degrees.
H-alpha 4x900s, same setup.
Color version:
3x600s trough UHC-filter added.
Over all, I'm veryhappy with this lens. This is very first time to me use camera lens
for astro photography.
I was expecting severe distortion in the image edges, there is none!
I was expecting severe color aberration, there is none!!!
This lens was unexpencive, doe the old FD model, about 120€.
Here is the link for moreinformation:
http://www.mir.com.my/rb/photography/companies/canon/fdresources/fdlenses/200mm.htm
All the images are shooted with full f2.8 aperature.
The front lens aperature is 72mm.
FOCUSING Fast lenses are very difficult to focus manually, it's pure luck to reach sharp focus. 200mm f2.8 lens has about 20 microns sharp focus area! I build a simple autofocuser to my lens by using TCF-s temperature compensating focuser. I'll send real pictures about that later. Here is a picture about principle.
This system solves allso problems with focus temperature shift!
TCF-s focuser is easy to move back to the main telescope at anytime.
I was able to use FocusMax with the lens and reach sharp focus in 30 seconds.
Thursday, January 31, 2008
Monday, January 28, 2008
IC 1848, start of the project
Last night I started a new project with IC 1848.
Here is first Ha exposures, 5x1800s and 7x900s.
I'll shoot more lights for H-alpha and color in near future, if weather allows.
This is a very dimm target for my focal lenght, LX200 GPS 12" @ f6.3
It will need an other five hours of exposures, I think.
Camera: QHY8 cooled 6mb color cam.
Guiding: SXV-AO active optics system
Thursday, January 24, 2008
IC 1805 core, color added
The core of IC 1805 4h of H-a
LX200 GPS 12" f6.3 + SXV-AO (Active Optics system) and famous QHY8
Added 2h of RGB data trough UHC-s filter
WORK FLOW
H-alpha RGB combination method under PS:
Both, H-a and RGB, processed first separetly by usual manner.
H-a converted to RGB format + Blue&Green channels filled with black.
(Reult is a Red image)
Red image is pasted top of the RGB as "lighten"
Red images gamma set to litle bit lighter, about 1,25
Flatten image.
This image is then copyed to top of the original grayscale image in "lighten" mode.
Flatten image.
This image is pasted to top of the RGB Ha combination image and used
as luminance with about 50% opacity.
Color balance + other small tweaking.
Sunday, January 20, 2008
Horsehead nebula
I just found this data from my hard drive.
I shoot this one 25.12.2007, only 1,5 hours of H-aplha light 900s subs.
Very bad seeing, stormy and target was only about 15-20 degree
from horizont.
Lx200 f6.3 + QHY8 + Baader 7nm H-a filter.
Guiding SXV-AO (helpped somehow with extremy bad seeing)
Friday, January 18, 2008
Elephant trunk Nebula, reprocessed
I did this object again from the scratch.
H-alpha blending to the RGB-data was not too good in ealier version.
This time the method was:
R-channel = Ha80% +R
G-Channel = as it
B-channel = Ha15% +B
+
Ha luminance 49%
After this I added some saturation and use the Ha luminance again with 40% opacity+Color balancing. This method is similar to LLRGB method, where luminance data is used twise.
From the Ha data i used only the first 4h and skip the last 2,5 hours, becouse the later data
was effected by strong wind and bad seeing. Partly for that the stars are much tighter.
Active optics was used for both, Ha and RGB, datas.
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