Bob’s Knob’s and my artificial star (long)

I have had my Celestron Deluxe for more than three years now and not
once during this time have I ever collimated the optics. I knew it was
something that at some point I would have to do, but wasn't really sure
when they would be requiring some attention. I vividly remember first
light through the scope, which occurred during a cool October evening,
and the views of the Moon, Saturn, and Jupiter were quite spectacular.
As the first telescope purchased since my teens, I was really overtaken
by the sights and consequently became accustomed to its performance.
Not having anything to compare it to, I never realized that the
performance could be improved.

Last year I purchased a Stellarvue AT1010 primarily as a quick grab-n-go
scope for those nights when I didn't really feel like dragging
everything outside. The views through the Nighthawk are really quite
good and the chromatic aberration, though present, is not that
objectionable. Vic Maris really makes a great product for the price!
Eventually I ended up mounting the Nighthawk on my 8” SCT as a
complementary scope – looks good and can be detached quickly.

Beside looking at the planets and other DSO’s, I also enjoy watching the
star closest to us and, in fact, often spend more time doing this just
because of the grind of commuting to and from work. In this
configuration I use a Thousand Oaks Type 2+ glass solar filter on the
SCT and a Kendricks Baader film filter on the AT1010. For the past
couple years now, I have volunteered (coerced by the wife actually) to
set up my rig for her class, grade level and ultimately, the entire
school in support of science day activities at her elementary school.
The kids really enjoy looking through the scopes and, having both types
of filters (orange and white) as well as apertures (203mm and 80mm),
gives them a different perspective from each. During a solar observing
session this past June, I noticed that the image in that little ‘ol
Nighthawk seemed to be much better than that in my trusty C8. Yeah I
know the 80mm cuts through a thinner slice of air, but still, it didn't
seem right. Since then I have taken both out at night for further
evaluation and found that on the image seemed to be sharper on the
little AT1010. This shouldn't be – aperture is supposed to rule! The
more I looked through the C8, the more I was convinced it had to be the
collimation.

Weather being as it has been lately, I looked for ways to produce an
artificial star indoors so that I could beat the rain and avoid the
humidity. What I ended up using was a piece of fiber optic cable of
about six foot in length that had ST type (bayonet) connectors on both
ends, a light source, and a piece of mat black foam board from Walmart.
A small hole was made in the foam board with a nail and using a black
permanent sharpie, was blackened to blend with the black background.
One end of the fiber optic cable was inserted from the back (white side)
of the board until it just cleared the front. I again blackened any
visible white spots (from white cable tip). You can barely see the
glass fiber up close! Using a night light and an extension cord, I
replaced the 4w bulb with a 60w chandelier bulb and placed the
contraption inside a coffee can for a light source. Might have to look
for one of them really bright white LED's. I then poked a small hole in
the plastic lid with the nail and inserted the other end of the fiber
optic cable into this. I positioned the ST connector over the light and
taped it down. Plug it in and -- voila’ – an instant tiny, bright star!

I positioned the foam board about 30 feet away from the scope and placed
the light source (coffee can) behind the board on an 8” square piece of
plywood to prevent any heat damage to the carpet. The can serves as a
brace for the propped up board. After several failed attempts to focus
on that damn star with a 10mm for (200x), I finally got it centered in
the eyepiece. I had to illuminate the location of the fiber tip with a
flashlight to help guide the optics into position and once centered,
turned the flashlight off. Laser pointer might help here. There it was
– a nice small, bright star (estimated mag 2 maybe 3), indoors, no rain
and air conditioned no less. Too bad all observation sessions weren't
like this! I was able to produce in-focus concentric rings but the
out-focus rings were not readily apparent. Also, the symmetry of
in-focus were not fully centered and the star (pinpoint of light) was
not properly centered. Drat, out of collimation!

I didn't like the Phillips screws used on the C8 for collimation, so I
replaced them with a set of Bob’s Knob’s. Following the instructions
provided, I tilted the scope downward so gravity would pull on the
secondary and, one-by-one, carefully removed the screws and replaced
them with a knob. A really easy, non complicated drill, though you can
feel the secondary go loose when a screw is removed. When all three
screws had been replaced, I then double checked them to insure they were
all finger tight before turning the OTA horizontal. Gad’s that all I
needed – drop the secondary – but thankfully all was well.

Using the flashlight to illuminate the fiber tip, I re-acquired my
artificial star. Folks, we got a problem here – those are not
circles!!! I never saw light patterns with spikes in them like that! I
took me awhile to get the feel of which knobs to adjust – always
tightening – and loosening the appropriate opposites to finally get the
pattern back on track. Let me say that collimating a scope with these
knobs is a breeze and would highly recommend them to anyone considering
using them. It really makes the task an easy one.

I popped in a TeleVue 2x Barlow, effectively raising the power to 400x,
and continued to refine the pattern until everything appeared centered.
After about an hour of total effort (minus building the star), I now
have what appears to be a reasonably well collimated SCT. I was able to
see several concentric circles both in and out of focus. These circles
really looked sharp and more important, they were centered! Now to get
some decent skies and check the results outside.

I apologize for being a little long-winded, but I thought I’d share my
idea for creating an artificial star indoors using a piece of fiber
optic cable and a cheap light source as well as to say that, if you're
not using Bob’s Knob’s on your SCT – get them! They really are easy to
install and use. Come on Mars …

Clear skies to all ...

Harry

Harry,
I also find a good refractor can beat an SCT on the sun, as does my
Newtonian. I think it's a contrast issue; the SCT's folded optical path has
no place to hide the stray light when viewing a large (1/2 degree) and very
bright object.

The refractor has no folds; contrast is it's specialty. My Newt is full of
flocking paper and the filter that acts as a baffle, preventing light from
hitting the tube near the eyepiece. It'll be interesting to see how your C8
does after collimation.

HAve fun,
Frank

"Harry Bogucki" wrote in message
...
. . . During a solar observing
session this past June, I noticed that the image in that little ‘ol
Nighthawk seemed to be much better than that in my trusty C8.

I don't have a SCT, but I enjoyed reading your review anyway!
Cleardarkskies!
Orion

"Harry Bogucki" wrote in message
...
I have had my Celestron Deluxe for more than three years now and not
once during this time have I ever collimated the optics. I knew it was
something that at some point I would have to do, but wasn't really sure
when they would be requiring some attention. I vividly remember first
light through the scope, which occurred during a cool October evening,
and the views of the Moon, Saturn, and Jupiter were quite spectacular.
As the first telescope purchased since my teens, I was really overtaken
by the sights and consequently became accustomed to its performance.
Not having anything to compare it to, I never realized that the
performance could be improved.

Last year I purchased a Stellarvue AT1010 primarily as a quick grab-n-go
scope for those nights when I didn't really feel like dragging
everything outside. The views through the Nighthawk are really quite
good and the chromatic aberration, though present, is not that
objectionable. Vic Maris really makes a great product for the price!
Eventually I ended up mounting the Nighthawk on my 8” SCT as a
complementary scope – looks good and can be detached quickly.

Beside looking at the planets and other DSO’s, I also enjoy watching the
star closest to us and, in fact, often spend more time doing this just
because of the grind of commuting to and from work. In this
configuration I use a Thousand Oaks Type 2+ glass solar filter on the
SCT and a Kendricks Baader film filter on the AT1010. For the past
couple years now, I have volunteered (coerced by the wife actually) to
set up my rig for her class, grade level and ultimately, the entire
school in support of science day activities at her elementary school.
The kids really enjoy looking through the scopes and, having both types
of filters (orange and white) as well as apertures (203mm and 80mm),
gives them a different perspective from each. During a solar observing
session this past June, I noticed that the image in that little ‘ol
Nighthawk seemed to be much better than that in my trusty C8. Yeah I
know the 80mm cuts through a thinner slice of air, but still, it didn't
seem right. Since then I have taken both out at night for further
evaluation and found that on the image seemed to be sharper on the
little AT1010. This shouldn't be – aperture is supposed to rule! The
more I looked through the C8, the more I was convinced it had to be the
collimation.

Weather being as it has been lately, I looked for ways to produce an
artificial star indoors so that I could beat the rain and avoid the
humidity. What I ended up using was a piece of fiber optic cable of
about six foot in length that had ST type (bayonet) connectors on both
ends, a light source, and a piece of mat black foam board from Walmart.
A small hole was made in the foam board with a nail and using a black
permanent sharpie, was blackened to blend with the black background.
One end of the fiber optic cable was inserted from the back (white side)
of the board until it just cleared the front. I again blackened any
visible white spots (from white cable tip). You can barely see the
glass fiber up close! Using a night light and an extension cord, I
replaced the 4w bulb with a 60w chandelier bulb and placed the
contraption inside a coffee can for a light source. Might have to look
for one of them really bright white LED's. I then poked a small hole in
the plastic lid with the nail and inserted the other end of the fiber
optic cable into this. I positioned the ST connector over the light and
taped it down. Plug it in and -- voila’ – an instant tiny, bright star!

I positioned the foam board about 30 feet away from the scope and placed
the light source (coffee can) behind the board on an 8” square piece of
plywood to prevent any heat damage to the carpet. The can serves as a
brace for the propped up board. After several failed attempts to focus
on that damn star with a 10mm for (200x), I finally got it centered in
the eyepiece. I had to illuminate the location of the fiber tip with a
flashlight to help guide the optics into position and once centered,
turned the flashlight off. Laser pointer might help here. There it was
– a nice small, bright star (estimated mag 2 maybe 3), indoors, no rain
and air conditioned no less. Too bad all observation sessions weren't
like this! I was able to produce in-focus concentric rings but the
out-focus rings were not readily apparent. Also, the symmetry of
in-focus were not fully centered and the star (pinpoint of light) was
not properly centered. Drat, out of collimation!

I didn't like the Phillips screws used on the C8 for collimation, so I
replaced them with a set of Bob’s Knob’s. Following the instructions
provided, I tilted the scope downward so gravity would pull on the
secondary and, one-by-one, carefully removed the screws and replaced
them with a knob. A really easy, non complicated drill, though you can
feel the secondary go loose when a screw is removed. When all three
screws had been replaced, I then double checked them to insure they were
all finger tight before turning the OTA horizontal. Gad’s that all I
needed – drop the secondary – but thankfully all was well.

Using the flashlight to illuminate the fiber tip, I re-acquired my
artificial star. Folks, we got a problem here – those are not
circles!!! I never saw light patterns with spikes in them like that! I
took me awhile to get the feel of which knobs to adjust – always
tightening – and loosening the appropriate opposites to finally get the
pattern back on track. Let me say that collimating a scope with these
knobs is a breeze and would highly recommend them to anyone considering
using them. It really makes the task an easy one.

I popped in a TeleVue 2x Barlow, effectively raising the power to 400x,
and continued to refine the pattern until everything appeared centered.
After about an hour of total effort (minus building the star), I now
have what appears to be a reasonably well collimated SCT. I was able to
see several concentric circles both in and out of focus. These circles
really looked sharp and more important, they were centered! Now to get
some decent skies and check the results outside.

I apologize for being a little long-winded, but I thought I’d share my
idea for creating an artificial star indoors using a piece of fiber
optic cable and a cheap light source as well as to say that, if you're
not using Bob’s Knob’s on your SCT – get them! They really are easy to
install and use. Come on Mars …

Clear skies to all ...

Harry



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