TEC140 + 20D 사진 (야후 digital_astro group에서)

by 김상욱 posted Oct 01, 2004
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크게 작게 위로 아래로 댓글로 가기 인쇄
20D로 찍은 사진이 있어 링크 걸어봅니다.
찍사의 실력 탓인지 사진이 약간 삐리리해보입니다.
(아래 본문의 링크는 깨져 있습니다. 바로 아래 링크를 누르면 사진을 보실수 있습니다.)

http://tinyurl.com/6828k
http://tinyurl.com/5dnzh
http://tinyurl.com/464zc
http://tinyurl.com/4eqdj

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All,

Over the last couple of weeks, I received both a Canon EOS20D and a TEC-140
(#112). By last Thursday, I had managed to collect the necessary
adapters/remotes to allow me to use all of this for the first time. It was a
nice night from the point of view of observing (clear, temperatures around 15C,
etc.) but the moon was probably about 3/4 full (with the attendant bright sky
background) and that limited me with respect to the DSO's.

When used visually, the views of the moon fomr the TEC were fantastic.
Details were super sharp. The moon's brightness was such that it almost hurt to
look (think I'll need some ND filters) but it almost seemed that I was walking
along the rilles and between the craters. I also tried looking at some double
stars. I could clearly split the double double (e Lyrae) at 122x (using my
Televue 8-24 zoom at 8mm). I also looked at some globulars (m13) and galaxies
(M31/M33). The views here were probably impacted by the brightness of the sky.
It would be really nice to try this scope (visually) at a dark sky site. I also
can't wait (and didn't stay up) for views of the planets. The TEC will be a
keeper.

In the middle of viewing things, I set up the 20D for prime focus and did a
fair amount of imaging (my first DSLR images and first Prime Focus images). I
started with the moon and used same for focusing with the camera's viewfinder
only. This worked quite well. One (very) nice feature of the TEC is that it
has a micrometer on the focuser. Open loop focusing in the future (temperature
calibrated??) uisng this micrometer to set the focus position may be sufficient
till I get the (ordered) Angle Finder C or upgraded IP. I also did not realize
that I left the "autorotate" sensor "on". This meant that my dark frames were
(sometimes) rotated from my "light" frames (and, just rotating them back didn't
work for some tbd reason). So, I didn't apply dark frames to any of the images
(the camera had very little). I also was using the Canon RS-80N3 remote and
counting down the exposure times. When I looked at the images, the exposure
times were not as uniform as I would have liked. However, I just ignored this
and stacked the images (using IP2.0) as though they were all the same exposure
time. When I get my TC-80N3 (also backordered), I'll be able to improve on this
as well.

Now for the images, all taken with ISO 1600 (remember, I couldn't use darks,
the moon was very bright, exposure times were uneven, and some objects --
especially M45 -- were pretty low on the horizon when I imaged them): (These
also are all conversions from ~3504 x 2236pixels x 16bits RGB TIFF images to
~640x480 x 8bit RGB GIF's) [Hope I got all the tiny URL's right too.]

a.. M13 at prime focus (a stack of three 1 minute images -- all approximate
exposure times): http://tinyurl.com/6828k. This turned out to be an excellent
image far superior to any that I had gotten with my CP5700. Stars are distinct
to the core of the cluster and, for a bonus, I even imaged a small dim galaxy
(NGC6207) at the same time (if I were trying for the galaxy, I would have used a
longer exposure). The GIF image, while still nice, doesn't do justice to the
original.
b.. M31 (a stack of 5 -2 min images): http://tinyurl.com/5dnzh. This image
also shows the companion galaxies M110 and M32. The dust lanes in M31 are also
very clear. Note, this image does not have any background (or dark current)
removed -- its just a digital development "stretch" of the stack of 5. I
suspect that I'm also getting some falloff (a form of vignetting) at the edges
of the image. a focal length of 980 mm is a bit too much for M31. A very nice
image for only 10 minutes of exposure with little compensation.
c.. M33, the Pinwheel Galaxy (a stack of 7-2.5 min images):
http://tinyurl.com/464zc. Again, lots of arm structure (and an emission nebula
in M33--NGC604) is visible). I had tried this with the 5700 and had only gotten
hints of arm structure. Here it is in its glory (and, I know it would be better
with darks applied, taken in a dark sky, more images, etc.)
d.. M52, another open cluster (3-1 min images): http://tinyurl.com/4eqdj.
Here again, nice round stars across the field of view. Again, a serendipitous
capture of NGC7635, the Bubble nebula. I wasn't trying for this and, again, if
I were trying to image just this, I would have used a longer exposure.
In all of these images, I know I haven't captured the depth of the
capabilities of either the TEC or the 20D. And I know that there were some
things I did wrong and can improve on. Still, I do think these start to show
what these instruments are capable of. Enjoy. And, given that these are (for
me): first light for telescope, first light for 20D, first DSLR shots, and
first Prime Focus shots (four firsts for me in one night), I am very happy.

Teri Smoot