Philosophy:
Taking astrophotos has been a lifetime of adventure. I started taking
astrophotos in 1978 using the very basic still-camera method. A lot
of film has come and gone, most of which was wasted or just not worth
sharing with others. On the
Astrophoto & CCD Image page you will see a selection of the
latest "best" I have to offer. As the techniques improve, so will the
images. I believe that improvement is the ultimate goal. I do not see
"perfection" as a possibility! There are just so many factors. In time, I have
found that just selecting an object to image has become a lot of the fun. I spend
99% of my imaging time actually doing photometry of variable stars. If I find
myself with an extra clear night, then I will take pretty pictures.
Why share these images? I hope that others get the chance to
measure their image quality against mine, for better or worse.
I show mine not because they are the best on the web...they are far from
it! I want people to know about the many details and intricacies of
astro-imaging. There is a lot to it. Any details I can share that
might help others is a good thing. Any details that you, the reader,
can share with me will be appreciated, and tried. I have to thank those
on the Astrophotography Mailing List (APML) and the SBIG and Starlight
Xpress mailing lists for all of their kind patience and shared knowledge.
Instrumentation:
The primary equipment I use for imaging includes the following:
- My dome! The Northwood Ridge Observatory has been the best thing for my imaging
projects. Without the dome, equipment setup and takedown would be just too much to allow me to
really focus on the work involved.
- Celestron 8 SCT optical tube assembly.
I use an old 1979 vintage C-8 that has extraordinary optics. I have done some repolishing
work on the primary and had it recoated. The focussing mechanism has been slightly modified
to reduce image shift and to lengthen the back focus. I also have enabled a mirror
lock down system to completely remedy image shift, but I find that this is rarely needed
with CCD imaging as I don't often need to image longer than 15 to 30 minutes.
- Takahashi FSQ-106n optical tube assembly. This is serial number 57 of a fine, wide field
refractor. It is really a true astrograph and not as well suited for visual use as it is
for imaging and photography. With its 4" focuser, any imaging device can be attached and
still achieve a full, unvignetted view. I love it.
- Takahashi CN-212 optical tube assembly. This is a 212mm muti-purpose telescope that can operate
either in Newtonian focus or as a Cassegrain instrument. The short focal length of the Newtonian
mode allows for excellent wide field, deep sky views as well as superb CCD imaging. The longer
Cassegrain focus yields magnificent planetary views.
- Losmandy G-11 German Equatorial Mount with Digital Setting Circles.
The original Celestron 8 fork mount and tripod were just not up to the task of
astrophoto and CCD imaging work. I replaced it with the G-11 and have not been
sorry since! It is a perfect mount for imaging with the C-8. It has very predictable
periodic error and is rock steady. It is an older G-11 that lacks the second latitude
lock down bolt, but this has not been too much of a problem.
- Celestron f/6.3 focal reducer lens.
CCD imaging and astrophotography both benefit from using the focal reducer.
The imaging focal plane is flatter and pinpoint across the surface. The only
problem is that this lens requires significant back focus, which some C-8's can not
reach. If you add on more equipment behind this lens (off-axis guiders, filter holders),
then you will require even more back focus. Some vignetting also is present on 35mm
film. Still, the advantages outweigh the negatives.
- Sivo Scientific Nu-View II Spectrometer.
This is a high resolution, fiber-fed spectroscopic instrument which I use to collect
data on variable stars and other objects of interest. It can be used
visually for brighter objects, but its real powers are when a CCD imager
is attached. The ST-237 is the imager I have attached currently.
- SBIG ST-7XME CCD Imager.
This is a self guiding CCD imager utilizing two chips. It also is better
suited towards photometric studies with its temperature regulation and
non-antiblooming. An antiblooming version is available, but I decided to
not go that route. There is a sacrifice in light sensitivity when
antiblooming chips are used and a loss in scientific ability. Thus, when I
want to study star brightnesses or image those really faint fuzzies, I use
the ST-7XME.
- SBIG ST-8E CCD Imager.
This is also a self guiding CCD imager utilizing two chips. This imager has
been upgraded to USB and has the larger TC-237 guider chip. I like to use this
imager with the FSQ-106n for wide field views.
- SBIG ST-237A Imager.
I use this instrument for high resolution spectroscopy. It is attached permanently
to the Nu-View II fiber-fed spectrometer from Sivo Scientific.
- IBM ThinkPad laptop computer.
This is the brain that controls the CCD imager. I also use it to snap autoguider
images and to run theSky and MAXIM DL/CCD software. The screen can be too bright, but some
red cellophane takes care of that.
- Tea or coffee, down coat, gloves, flashlight, mosquito repellent....
Methodology:
I have placed a brief desciption of my basic techniques here.
Please keep in mind that techniques and instruments are constantly changing.
Last Modified: 3/08/08 5:41p
This page: © Copyright 1997-2008 by John A. Blackwell
