How to convert an XT-8 OTA for photography....

Ok, now that I've upgraded from the XT-8 to the XT-12 IntelliScope w/
OL, I would like to start looking into options for using the XT-8
Classic Dob's OTA for photography. I guess I can just remove the
bearings, buy some rings for an 8" reflector, a motorized goto
equatorial mount, a CCD camera, and start shooting huh?

Can I use the 8" OTA from the XT-8 classic Dob for photography? It's
an f/6 scope. I read somewhere a while ago that scopes used for
photography should be f/5 or less. Is that really true.

If I can proceed as planned, what type (make and mod if you please) of
mount would you recommended?

I'm not going to be doing this conversion in the immediate future, just
trying to size up the cost of the conversion.

Errol

Well, yes and no. typically, you'll need to move the newt's mirror up
the tube a bit in order to be able to obtain focus with a camera. Plan
on a good, hefty mount...that long newt tube demands that. Think "EQ-6"
minimum.

Uncle Rod

Starboard wrote:
Ok, now that I've upgraded from the XT-8 to the XT-12 IntelliScope w/
OL, I would like to start looking into options for using the XT-8
Classic Dob's OTA for photography. I guess I can just remove the
bearings, buy some rings for an 8" reflector, a motorized goto
equatorial mount, a CCD camera, and start shooting huh?

Can I use the 8" OTA from the XT-8 classic Dob for photography? It's
an f/6 scope. I read somewhere a while ago that scopes used for
photography should be f/5 or less. Is that really true.

If I can proceed as planned, what type (make and mod if you please) of
mount would you recommended?

I'm not going to be doing this conversion in the immediate future, just
trying to size up the cost of the conversion.

Errol

Starboard wrote:
Ok, now that I've upgraded from the XT-8 to the XT-12 IntelliScope w/
OL, I would like to start looking into options for using the XT-8
Classic Dob's OTA for photography. I guess I can just remove the
bearings, buy some rings for an 8" reflector, a motorized goto
equatorial mount, a CCD camera, and start shooting huh?

Can I use the 8" OTA from the XT-8 classic Dob for photography? It's
an f/6 scope. I read somewhere a while ago that scopes used for
photography should be f/5 or less. Is that really true.

If I can proceed as planned, what type (make and mod if you please) of
mount would you recommended?

I'm not going to be doing this conversion in the immediate future, just
trying to size up the cost of the conversion.

Errol




Hi.

You can use your OTA, and it can work well.
It all depends on what you want to take pic's of.
Personally, I would leave the scope as is, and
buy an SCT with mount. (like a Celestron CGE
series) The SCT is a more versatile instrument
for photography/imaging than the newt is.
Both have their drawbacks, and good points.


But if you want to continue onwards...
Something like an EQ 6, Atlas, or better a G 11,
or best, a Titan or AP 900 (and above)
IMHO, nothing less will do.




--

AM

http://sctuser.home.comcast.net

"Starboard" wrote:

Ok, now that I've upgraded from the XT-8 to the XT-12 IntelliScope w/
OL, I would like to start looking into options for using the XT-8
Classic Dob's OTA for photography. I guess I can just remove the
bearings, buy some rings for an 8" reflector, a motorized goto
equatorial mount, a CCD camera, and start shooting huh?

I recommend: "A Manual of Advanced Celestial Photography" by Wallis &
Provin. It's an older (1988) book; but it contains some information
that's likely to prove quite useful to your new project.

Chapter two is "Instrumentation". Subheadings in this nearly 50 page
chapter include: "Optical systems", "Mountings and drives",
"Mechanical and design considerations", and "Telescope accessories".

The "Mechanical and design considerations" section contains
information on (among other things): "Flexure" and "Newtonian
diagonal: size, placement and illumination".

Sure, some of the book is outdated; but you'll still find much of it
relevant -- covering issues you may not have considered.

Despite my preference for sketching at the telescope, I have a copy of
the above mentioned book. I have read it; and I'm keeping it!! Who
knows, someday I may change my ways ;-)

Of course, you could also 'just start shooting' ;-)
--
Bill
Celestial Journeys
http://cejour.blogspot.com

On 5 Jan 2007 15:41:15 -0800, "Starboard" wrote:

Ok, now that I've upgraded from the XT-8 to the XT-12 IntelliScope w/
OL, I would like to start looking into options for using the XT-8
Classic Dob's OTA for photography. I guess I can just remove the
bearings, buy some rings for an 8" reflector, a motorized goto
equatorial mount, a CCD camera, and start shooting huh?

While I'd definitely recommend a nice beefy goto equatorial mount for a
Newt intended for imaging, another option is a good tracking platform
for your Dob. People do successfully use them for imaging.


Can I use the 8" OTA from the XT-8 classic Dob for photography? It's
an f/6 scope. I read somewhere a while ago that scopes used for
photography should be f/5 or less. Is that really true.

The focal ratio is largely irrelevant to imaging. What you want to do is
match your focal length to your pixel size. Given your scope's FL of
1200mm, and a typical CCD pixel size of 9um, that gives you an image
scale of 1.5"/pixel, which is pretty optimal. If you want to image wider
fields, you could consider a 0.5x focal reducer.

As long as this OTA has a nice rigid structure, it will be good for
imaging. If you use a large chip sensor, however, you'll need a Paracorr
or other coma correction device.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com