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Date: 07 Sep 2007 21:36:11
From:
Subject: Orion's Filter Wheel
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I've never been tempted to purchase a filter slide. The unprotected
filters in the slide seemed to be too susceptible to dew, frost,
various accidents, etc. On the other hand, I've been interested
enough in a filter wheel that I once devoted some time on designing my
own; but I could never seem to get beyond the rough design phase
(Obstacles came in the form of materials, fabrication, weight, the
necessary flexibility in focus travel, etc.)
Meanwhile, Orion has come out with a 5-filter wheel. I wasn't too
happy with the price; but I couldn't argue with the advantages of an
enclosed filter wheel. So, I decided to order one (after measuring
the surplus inward focusing range of my 13cm refractor).
I was impressed by both the design and craftsmanship of the (made in
Portugal) Orion filter wheel; but one minus mark against Orion is that
their literature suggests that the wheel requires 20mm of additional
focus travel. They don't specify that this is inward travel, but the
inward direction should be reasonably obvious to anyone who thinks
about it.
For visual use with my 13cm refractor the wheel requires an additional
inward focus travel of not 20mm, but 50mm. The difference (between 20
and 50mm) can be far from insignificant. As a matter of fact, one of
my eyepeices cannot achieve focus with the wheel when used in
conjunction with a standard 1.25" 90-degree mirror diagonal. (I can
substitute a 1.25" 90-degree, erect-image, prism diagonal and achieve
focus with that eyepiece, but even then there's very little (just
under 3mm) inward travel remaining. I could even dispense with a
diagonal altogether; but the discomfort of observing objects much
above the horizon would quickly become a very real pain in the neck.
Few Newtonians are likely to have sufficient inward focus travel for
the filter wheel; but I suspect that the wheel would work with a fair
number of refractors and catadioptrics. The only scope I really
wanted the wheel to work with was my 13cm refractor. It would have
been nice if it would have worked with my 30cm Newtonian; but I didn't
have any real hopes for that even prior to placing my order. I can
use the refractor to see which filters are best for which objects and
later use the right filters for the right objects when I observe with
other telescopes from my "arsenal".
I've yet to have an opportunity to use the wheel outside at night; but
inside it fits my 13cm telescope "perfectly" and functions superbly.
I pointed the telescope out a window at hill a few miles away to check
out the fit, etc.
If anyone is interested, after I've had an opportunity to use it in
the field I'll post additional details and comments later.
Bill Greer
To sketch is to see.
http://cejour.blogspot.com
http://www.rangeweb.net/~sketcher
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Date: 19 Sep 2007 18:41:13
From:
Subject: Re: Orion's Filter Wheel
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On Sep 19, 10:45 am, Tom Polakis <polakisgro...@cox.net > wrote:
>
> Hi Bill,
>
> I purchased the Orion filter wheel, and had a chance to try it out
> last night. Your review is spot on.
Thanks! I *try* to be impartial concerning such things.
> I have sets of Orion and Meade color filters. Without any thought, I
> installed the Meade filters. The sound of the metal filter cell
> scratching against the inside of the filter wheel housing was none too
> pleasant. I disassembled the wheel, and put an Orion filter side-by-
> side with a Meade filter. Sure enough, the Meade filter is too thick
> for the filter wheel. The good news is that I think the 'standard' is
> closer to Orion's thinner filters, as both a Lumicon UHC and Orion
> filters rotated in the filter wheel without any interference.
>
My first experience with that nasty, scraping sound came with my first
attempt loading the wheel. Upon inspection I noticed that one of my
filters was not screwed all the way into the wheel. After screwing in
that filter the rest of the way the scraping vanished.
Later I decided to try all 17of my 1.25" filters in the wheel. All
screwed into the wheel nicely; but one, an old filter that was
purchased from Criterion Mfg. sometime back in the late '70s, proved
to be thick enough to scrape. It appears that my other 16 1.25"
filters came from Orion at one time or another. It's worth knowing
that the Meade filters are too thick, and the Lumicon filters are thin
enough to work well. Thanks for the additional data!
I'll be using my wheel for checking out the effects of various filters
on different DSOs. In addition, I have plans on loading it for Mars
and the other planets. (I recently took a naked-eye peek at Mars and
Venus in the morning sky. Before sunrise Mars is quite high (and
bright) as seen from my location in the northwestern U.S.)
Bill Greer
To sketch is to see.
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Date: 19 Sep 2007 09:45:27
From: Tom Polakis
Subject: Re: Orion's Filter Wheel
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On Sep 7, 9:36 pm, AstroSketc...@gmail.com wrote:
> For visual use with my 13cm refractor the wheel requires an additional
> inward focus travel of not 20mm, but 50mm...
> Bill Greer
Hi Bill,
I purchased the Orion filter wheel, and had a chance to try it out
last night. Your review is spot on.
I have sets of Orion and Meade color filters. Without any thought, I
installed the Meade filters. The sound of the metal filter cell
scratching against the inside of the filter wheel housing was none too
pleasant. I disassembled the wheel, and put an Orion filter side-by-
side with a Meade filter. Sure enough, the Meade filter is too thick
for the filter wheel. The good news is that I think the 'standard' is
closer to Orion's thinner filters, as both a Lumicon UHC and Orion
filters rotated in the filter wheel without any interference.
I would have never anticipated that filter cell thickness had any
import.
Tom
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Date: 10 Sep 2007 16:22:55
From:
Subject: Re: Orion's Filter Wheel
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On Sep 10, 1:40 pm, Tom Polakis <polakisgro...@cox.net > wrote:
>
> Is the additional back focus measurable on the filter wheel? It
> should be the distance between the front of the unit that interfaces
> with the focuser and the back end where the eyepiece seats. If this
> is 50mm, then yep, it's an additional 50mm of back focus, and I'm back
> to square one. If so, then I wonder how Orion (and Adirondack) make
> the claim of 20mm?
Hi Tom,
The filter wheel comes with three screw-on adapters -- a camera (T-
thread) adapter, a 1.25" nosepiece (to fit into a 1.25" focuser), and
a 1.25" eyepiece adapter (for use with 1.25" diagonals and/or
eyepieces).
The wheel w/o any of the adapters measures about 20mm in overall
thickness. As a visual-only observer I'll be using the wheel with the
two 1.25" adapters which, together with the wheel's thickness,
requires about 50mm of additional in-travel of the telescope's focuser
(from the point at which the wheel seats against the scope's focuser
to the outside end of the 1.25" eyepiece adapter is about 50mm).
Actual measurements were taken. The above numbers are not off by more
than 1 millimeter. As a matter of fact the total in-travel was
determined by two different methods, one by making measurements on the
scope's focuser with and without the filter wheel, the other by
measuring the overall thickness of the components that were added to
the scope. Both measurements resulted in the same 50mm value.
It looks like the camera adapter (which I'm not likely to be using;-)
along with the wheel would extend from the back of the scope's focuser
a total distance of about 27mm (ignoring the T-threads onto which the
camera attaches). This measurement may not be as accurate as the
others. It's based on other measurements (which I had already made)
and some minor computations.
The only way in which I could envision the unit requiring only 20mm of
additional focuser travel would be if the telescope's 1.25" eyepiece
holder could be unscrewed from the telescope and screwed onto the
filter wheel while the filter wheel is screwed onto the threads that
remain on the scope's focuser; but this arrangement makes some pretty
big assumptions. I don't know if there exists a telescope (though
some of Orion's scopes *might* work) in which this hypothetical
situation can become a reality.
My first posting wasn't intended to be a review. I may put together a
"real" review later, after using the unit under a dark sky.
Bill Greer
To sketch is to see.
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Date: 10 Sep 2007 12:40:13
From: Tom Polakis
Subject: Re: Orion's Filter Wheel
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On Sep 7, 9:36 pm, AstroSketc...@gmail.com wrote:\ > For visual use
with my 13cm refractor the wheel requires an additional
> inward focus travel of not 20mm, but 50mm. The difference (between 20
> and 50mm) can be far from insignificant...
>
> Few Newtonians are likely to have sufficient inward focus travel for
> the filter wheel...
Bill,
Thanks for the review. Yikes, that would certainly include my
Newtonian! This filter wheel -- originally sold by Adirondack under
the name Atik and now branded by Orion -- was going to be my next
purchase. I have a 10" Newtonian, and need a filter wheel to do tri-
color Webcam imaging with a monochrome Webcam. I also planned to use
it visually for rotating a UHC and OIII filter into view.
Is the additional back focus measurable on the filter wheel? It
should be the distance between the front of the unit that interfaces
with the focuser and the back end where the eyepiece seats. If this
is 50mm, then yep, it's an additional 50mm of back focus, and I'm back
to square one. If so, then I wonder how Orion (and Adirondack) make
the claim of 20mm?
Tom
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Date: 10 Sep 2007 20:24:28
From: William Hamblen
Subject: Re: Orion's Filter Wheel
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On Mon, 10 Sep 2007 12:40:13 -0700, Tom Polakis
<polakisgroups@cox.net > wrote:
>If so, then I wonder how Orion (and Adirondack) make
>the claim of 20mm?
Here is a link to a PDF of the instructions for the Orion filter
wheel. The 20 mm thickness looks good for photographic applications
using a t-mount to connect the camera. The visual use the eyepiece
adapter adds quite a bit more thickness.
http://www.telescope.com/text/content/pdf/IN_313_Mult_File_RevA.pdf
Bud
--
The night is just the shadow of the Earth.
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