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Date: 09 Aug 2006 07:50:43
From: Dave Mitsky
Subject: The Vixen Sphinx Mount
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Since the price reduction, I've been considering the purchase of a
Vixen Sphinx equatorial mount and would like a bit of feedback from
owners. I have read a number of positive reviews but have some concerns
and questions regarding the brightness of the display screen, software
issues, the stability of the tripod for astrophotographic use with a
101mm Tele Vue refractor, any matters that I should be aware of in
general, and so on.
Thanks in advance for your opinions.
Dave Mitsky
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Date: 09 Aug 2006 15:38:38
From: Michael McCulloch
Subject: Re: The Vixen Sphinx Mount
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On 9 Aug 2006 07:50:43 -0700, "Dave Mitsky" <djm28@psu.edu > wrote:
>Since the price reduction, I've been considering the purchase of a
>Vixen Sphinx equatorial mount and would like a bit of feedback from
>owners. I have read a number of positive reviews but have some concerns
>and questions regarding the brightness of the display screen, software
>issues, the stability of the tripod for astrophotographic use with a
>101mm Tele Vue refractor, any matters that I should be aware of in
>general, and so on.
>
>Thanks in advance for your opinions.
One of the better resources is the Vixen Sphinx Yahoo group. You might
read some past posts there.
I have owned a Sphinx since its first release. I find the mount has
excellent tracking if you polar align, acceptable goto for the size
instruments it can handle, and is only average for serious
astrophotography -- but with great potential with a couple of
fixes/upgrades.
I use an SV105 with my Sphinx and the mount is an excellent match for
any 4" apo weight-wise. The advertised max load is 22 lbs, but I
wouldn't push it beyond 20 lbs for astrophotography. I find the Vixen
HAL-110 tripod and half pillar adequate except in a strong breeze,
although there is some sag when a scope is mounted. Be sure to polar
align after the tripod is loaded.
The backlight on the StarBook is bright, but with the included neutral
density filters and the timed "backlight off" feature it is tolerable
in my opinion and I frequent mag 6 observing sites. I still wish Vixen
would offer a shades of red or grey option for the interface which
would work with a red filter. There are some screens which contain a
lot of blue which absolutely doesn't work with a red filter.
If you are working in the northern hemisphere, get the Vixen polar
scope (the backlight is too bright for the southern pole). The Vixen
polar scope is quite accurate for nothern pole aligns. I find I can
take 3 to 5 minute unguided exposures with about 60% success with
focal lengths of 650mm or less. The goto and tracking is also much
improved with a good polar align. With practice I can now easily do
this in the field.
Autoguiding input is now active out of the box instead of requiring
the silly $20 activation fee. However, you may have difficulty with
DEC corrections. The DEC backlash is reported as variable and is quite
sensitive to "tuning" by Vixen repairmen according to some reports.
Mine has very sluggish DEC response at guiding speeds.
One of the nicest features of the Sphinx is the fact that you can
autoguide via the Ethernet port and ASCOM PulseGuide commands.
Therefore, there is no reason to fart around with complex cables or
relay boxes for guiding -- although there is a separate autoguide port
for SBIG and Vixen guiders.
PEC is not included which is a shame. There have been recent rumors
that it will be added, but no official verification or announcements
from Vixen and I wouldn't bet on it. With PEC and a good polar align,
5 minute exposures with a 4" apo would be a snap with the mount.
Some people will complain about the lack of other convenience
features, but I don't really miss them. Tours and double star lists
are nice but I've never relied on those even with mounts that have
them. I am quite satisfied with the StarBook interface and often have
just connected my Stellacam II to my 4" apo and toured various
constellations using RA/DEC coords straight from the NSOG books. I did
Scorpius about three weeks ago this way. The Chart mode of the
StarBook allows quick slewing to any arbitrary RA/DEC position in my
experience -- I don't need direct entry of coords.
I've taken a few photos with Canon 10D -- nothing spectacular. If you
are interested, I'll post some links.
The best features of the Sphinx are excellent tracking with a polar
align and unrivaled portability. If I was setting up an observatory I
wouldn't choose the Sphinx, but if you have to travel to dark sites
you will quickly learn to love the portability.
---
Michael McCulloch
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Date: 10 Aug 2006 05:25:02
From: Dave Mitsky
Subject: Re: The Vixen Sphinx Mount
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Michael McCulloch wrote:
> On 9 Aug 2006 07:50:43 -0700, "Dave Mitsky" <djm28@psu.edu> wrote:
Edit
> The best features of the Sphinx are excellent tracking with a polar
> align and unrivaled portability. If I was setting up an observatory I
> wouldn't choose the Sphinx, but if you have to travel to dark sites
> you will quickly learn to love the portability.
>
> ---
> Michael McCulloch
Michael,
Thanks for that information. I joined the Vixen Sphinx Yahoo!Group
yesterday, before seeing your reply, but haven't received any responses
as of yet.
I'm definitely interested in a portable mount and the lighter the
better, within reason.
Are you saying that you can't directly enter coordinates into the
StarBook?
I'd certainly like to see your images.
Dave Mitsky
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Date: 10 Aug 2006 11:13:04
From: Michael McCulloch
Subject: Re: The Vixen Sphinx Mount
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On 10 Aug 2006 05:25:02 -0700, "Dave Mitsky" <djm28@psu.edu > wrote:
>Thanks for that information. I joined the Vixen Sphinx Yahoo!Group
>yesterday, before seeing your reply, but haven't received any responses
>as of yet.
Not sure what group you went to, but I see no post at:
http://groups.yahoo.com/group/Vixen_Sphinx/
For best response, you need to ask more specific questions than "how
is the Sphinx for astrophotography?"
What types of objects do you wish to capture? What type of scope and
camera do you want to use at what image scale? What exposure times are
you interested in pursuing?
>I'm definitely interested in a portable mount and the lighter the
>better, within reason.
The Sphinx is a clear winner in functionality/weight ratio.
>Are you saying that you can't directly enter coordinates into the
>StarBook?
No, not directly. You use the Chart mode and quickly scroll the
crosshairs to the desired coordinates by using the zoom/scroll
buttons. Frankly I like it and it works fine for me. Others like to
complain about it.
>I'd certainly like to see your images.
Again, nothing spectacular, but here are some. I use an unmodified
Canon 10D, so I get a heavy dose of blue channel in my images:
http://www.gamesforone.com/stars/images/b33.jpg
http://www.gamesforone.com/stars/images/m11.jpg
http://www.gamesforone.com/stars/images/m24.jpg
http://www.gamesforone.com/stars/images/ngc6603.jpg
http://www.gamesforone.com/stars/images/m45.jpg
http://www.gamesforone.com/stars/images/m46and47.jpg
http://www.gamesforone.com/stars/images/m8.jpg
http://www.gamesforone.com/stars/images/markarian.jpg
These are all created from unguided exposures (some are several
stacked) about 3 to 5 minutes in duration.
Here is an image that is 66% of the full resolution of the original
RAW from the 10D:
http://www.gamesforone.com/stars/images/ngc6603-2.jpg
That shows reasonably round stars even when unguided. Imagine what the
mount could do with PEC.
I'd love to try a larger pixel count CCD camera (such as an SBIG2k or
11k series) on it sometime for some guided wide-field shots, but I
don't have access or the $5k minimum to buy one. Most people with
those kind of cameras have already bought AP or Tak mounts.
----
Michael McCulloch
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Date: 11 Aug 2006 13:04:37
From: Dave Mitsky
Subject: Re: The Vixen Sphinx Mount
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Michael McCulloch wrote:
Edit
> Not sure what group you went to, but I see no post at:
>
> http://groups.yahoo.com/group/Vixen_Sphinx/
My second post now appears on the Vixen Sphinx group. I've received
one reply which included a link to a very informative site on the mount
and the StarBook.
http://enzerink.net/peter/astronomy/pages/sphinx.htm
>
> For best response, you need to ask more specific questions than "how
> is the Sphinx for astrophotography?"
>
> What types of objects do you wish to capture? What type of scope and
> camera do you want to use at what image scale? What exposure times are
> you interested in pursuing?
As I said originally, I plan on mounting a 101mm f/5.4 Tele Vue
refractor on the mount. Its weight is approximately 10 pounds. I'm
interested primarily in Canon 300D prime focus shots of the typical
showcase deep-sky objects and the occasional comet, nothing fancy.
> >I'm definitely interested in a portable mount and the lighter the
> >better, within reason.
>
> The Sphinx is a clear winner in functionality/weight ratio.
>
> >Are you saying that you can't directly enter coordinates into the
> >StarBook?
>
> No, not directly. You use the Chart mode and quickly scroll the
> crosshairs to the desired coordinates by using the zoom/scroll
> buttons. Frankly I like it and it works fine for me. Others like to
> complain about it.
>
> >I'd certainly like to see your images.
>
> Again, nothing spectacular, but here are some. I use an unmodified
> Canon 10D, so I get a heavy dose of blue channel in my images:
>
> http://www.gamesforone.com/stars/images/b33.jpg
> http://www.gamesforone.com/stars/images/m11.jpg
> http://www.gamesforone.com/stars/images/m24.jpg
> http://www.gamesforone.com/stars/images/ngc6603.jpg
> http://www.gamesforone.com/stars/images/m45.jpg
> http://www.gamesforone.com/stars/images/m46and47.jpg
> http://www.gamesforone.com/stars/images/m8.jpg
> http://www.gamesforone.com/stars/images/markarian.jpg
>
> These are all created from unguided exposures (some are several
> stacked) about 3 to 5 minutes in duration.
>
> Here is an image that is 66% of the full resolution of the original
> RAW from the 10D:
>
> http://www.gamesforone.com/stars/images/ngc6603-2.jpg
>
> That shows reasonably round stars even when unguided. Imagine what the
> mount could do with PEC.
>
> I'd love to try a larger pixel count CCD camera (such as an SBIG2k or
> 11k series) on it sometime for some guided wide-field shots, but I
> don't have access or the $5k minimum to buy one. Most people with
> those kind of cameras have already bought AP or Tak mounts.
>
> ----
> Michael McCulloch
Michael,
Thanks for the additional information.
Dave Mitsky
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Date: 11 Aug 2006 17:42:17
From: Michael McCulloch
Subject: Re: The Vixen Sphinx Mount
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On 11 Aug 2006 13:04:37 -0700, "Dave Mitsky" <djm28@psu.edu > wrote:
>As I said originally, I plan on mounting a 101mm f/5.4 Tele Vue
>refractor on the mount. Its weight is approximately 10 pounds. I'm
>interested primarily in Canon 300D prime focus shots of the typical
>showcase deep-sky objects and the occasional comet, nothing fancy.
The Sphinx is an ok match for that application as is (judge my results
for yourself), however it would be absolutely >fantastic< if PEC was
available to reduce the periodic RA error to less than 2 (or at worst
3) pixels on the Canon at that image scale.
I usually have to throw away ~40% of my 3 to 5 minute exposures due to
stars trails during the time when the RA periodic error curve displays
maximum excursion.
You won't find a mount that is more easily transported or quicker to
setup and accurately polar align in the field than the Sphinx.
---
Michael McCulloch
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