For the main OTA rings I'm
using Orion rings and for the guide scope I am now using ADM rings from
ADM Accessories.
Initially I was using guide scope rings from Orion as well. These rings
though are not adequate for long exposure times. With them I was not
able to take exposures any longer than two minutes due to differential
flexing. After upgrading to ADM rings I'm now able to take five and ten
minute exposures.
Differential flexing is a
problem any time you have a guide scope piggybacked to your main
telescope. I honestly was not expecting to have as much trouble with
flexing as I have had. Currently flexing is the limiting factor keeping
me from taking longer exposures. Unless you use a camera which uses a
second imager to make guiding corrections using the same imaging
telescope your setup will have some degree of flexing. One simply has to
minimize it as much as possible.
I have purchased a few
filters that I feel are very important for astrophotography. Because
CCD imagers are sensitive in the IR range as well as the visible range, if
not filtered, the images captured tend to not be of very good quality.
After all, you normally just want to capture the visible light not the IR light. This is not always the case, but
normally you want to cut out the IR range and UV range, and just leave
the visible light range. The filter in the bottom right of the picture
is my Baader Planetarium UV/IR-Cut-Filter. I can screw this filter
directly onto the camera.
Another very important yet rather
expensive filter is the H-alpha filter. This filter, top center, blocks all light
wavelength except for the 656nm H-alpha emission line. In other words
this filter effectively filters out all light pollution found around
most backyard observatories. This filter is mostly used for H-alpha
emitting nebulae and tends to lower the amount of light which reaches
the CCD.
A good focal length reducer
(FLR) is a great addition to any telescope setup, and a must for
astrophotography in my opinion. An FLR screwed onto an eyepiece or CCD
camera effectively increases your field of view and amount of light
reaching your eye or CCD chip. The trade off is less
magnification and potential aberration issues. I use an Atik x.5 FLR pictured bottom left.
Dew is always a problem when imaging with telescopes. The simplest
and most effective solution to this problem is to use dew heaters. I
built my own dew heaters for both the main imaging scope and guide
scope. On the above photo the dew heaters are the two yellow straps seen
on the telescopes. I use a temperature controller board which I built as
a kit to control the heaters. You can get these on line for less than
twenty dollars.
Dew heaters can also be purchased of course. I found
them to be rather expensive though and this is a project that most
hobbyists can do themselves. I followed the
instructions on this post at iceinspace.com to build the heaters.
The weight of my complete telescope setup is over one hundred pounds.
This is not the type of setup that you want to be taking outside for an
imaging session and then bring back inside every time if you can help
it. I had no intentions of doing this so from the start I planned for a
semi permanent installation.
To this end I poured a cement slab for the Atlas mount to sit on. I
added a cable which secures the mount to the cement slab to keep the
mount from ever tipping in high winds. On the image to the right the
cable is just visible in the center of the tripod legs.
I then purchased a large 365 cover from
Telegizmos.
These covers are excellent and they will not leak, guaranteed. The only
thing to worry about is humidity inside the cover. A simple solution is
to add a heating rod inside the cover to keep the temperature above the
dew point. I purchased mine from
ScopeStuff.
Still rust on bolts is an issue so I keep a close eye on this and
regularly cover all needy parts with a thin film of grease.
My imaging cameras consist of a
Meade DSI Color and Meade DSI Pro monochrome CCD camera. These are good
camera and work well, but they are older models and the imagers are small. I
use the DSI Color as the main imaging camera because it is easier to create
full color images with it. The DSI Pro requires the use of color filters to
create color images and this can be time consuming so I use it as my guide
camera. One added benefit of using the DSI Pro for the guiding camera is
that it is more sensitive than the DSI Color and this is beneficial when you
are running 1 second exposures in the guiding software!
Well, this is my primary astrophotography setup. Rather simple yet quite
effective.
