Greetings all,

I'm an amateur photographer who has a long-time interest in astronomy.
I'd like to try my hand at astrophotography, and hoped someone could tell
me a little more about some of the equipment I've come across.

Let me say at the outset that I have already done a little looking around
(FAQ's, etc.), and feel like I have an understanding of the basic issues
involved. I think I'll be happy to start out with some wide field imaging,
with the capability to image at least the planets a plus. If things go well,
I may become interested in imaging smaller/dimmer/farther objects. I won't
mind spending $2,000.00 (or even more) to get started, but would like for
what I buy to be workable.

With that said, here's what I've been considering:

- Meade ETX-125. Can be had from Telescopes.com for just over
$1K. Comes with the Autostar controller and the basic tripod can
be used in an equatorial mode. Besides what is a reasonable cost,
the apparent portability of this scope will be an advantage to me, as
I'll have to drive to my observing/photography site. I've also discovered
mounts for this scope that will allow "Piggyback" astrophotography.
*question: how difficult is polar alignment with this scope/tripod in
equatorial mode...? any special tricks...?

- Meade Lunar Planetray Imager (LPI) package. This seems to be a
pretty neat package for what I want to do. Only 640x480 resolution,
but will suffice. And coolest of all, it appears that I can use this
instrument/software to AUTOGUIDE the scope.
* is anyone here using this? does it work as simply as it seems, or
are there hidden snags? should I be looking at a more sophisticated
package, like the Deep-Sky Imager?

- Would it be better to start with a more substantial telescope, such as
a Meade 8" LX200-R? Would the drive system be better?

So my simple goal is to (maybe) buy the above items & take some decent
pics. I would be especially interested in hearing from anyone who has now
or previously used any of this equipment. If you don't want to post on-line,
please e-mail me directly as 'shadowdoc31' on yahoo.com.

Thanks for all your help!

Good ambitions. It suggests a scope in the f/5 to f/6 range assuming that you are using a CCD detector.


The Meade ETX-125 is an f/15 scope. With a typical CCD you get magnification/effective scale of close to 400 x! It definitely doesn't do wide field imaging. Even with a focal reducer it is good at small objects and planets only.

The Celestron Nexstar 5 or C6 on the same page are much better options (f/10 or lower)

Forget this, the Meade DSI is a CCD, the LPI is a CMOS. Effectively the LPI is only for use with the planets, the DSI will photo everything. You've saved on the telescope - splash out on the camera.

Don't forget to order a cheap focal reducer to increase the field

Ozark-- Thanks for your reply. A couple of points of
clarification:

1. Wide-field imaging. I admit I wasn't quite sure about
how "wide" the ETX-125's field is, but my plan in this
regard is to "piggyback" my Canon EOS-5D camera
on the scope and acquire images in that fashion. I
currently have an L-series lense that will zoom out to
24mm, and based on some non-guided results over the
past weekend, think that this will be sufficient. I am
considering, however, purchasing a 17mm lense if I
need to get even more of the sky.

2. I see the LX-200R has a focal ratio of f/10, although
it's a bit more expensive.

I've briefly looked at the Celestron C-5 that you
mention (about time to go to work), and it seems like
it would suit my purposes fine. My big question is
still to be sure that I can autoguide it via my laptop
using the LPI/DSI software.

3. I think you're probably right about getting the DSI
CCD device; there's even a DSI-2 version out now
which is pitched as being better. Would be very
interested in hearing from those with experience.

Thanks again!!

Piggy backing is good. You may find that light pollution limits long exposures to 5 - 10 minutes. Remember to set the telescope in polar mode not alt-az (this prevents field rotation)
The ETX-125 has a focal length 1905 mm, this is f/15 for a 5" scope. If you go to the 8" LX-200 you'll have a 2000 mm focal length (f/10) - this is equally difficult.

I've got an f/15 ETX-125 with 0.5 focal reducer (ie: f/7.5). Using the DSI with this I have a field of view just about big enough to frame M15. M13 is too big. The effective magnification is about 190 x.

Don't expect to guide the Meade either! The big problem with the DSI on the ETX is that the DSI USB goes straight through the finderscope! The usual compromise is to use the DSI upside down. The lack of guiding is not a problem though - mainly because the CCD technique is a stack of 15 - 30 s images rather than a long exposure. A stack of 24 x 15s was sufficient in urban skies to detect and image IC1296 - a small barred spiral next to the Ring Nebula - mag 17.3.

The DSI is the RGB Sony HAD chip. The DSI 2/Pro is the black and white version + RGB filters. This means that the DSI 2/Pro is effectively 1 magnitude better than the DSI.

Thanks again for your input...

After some more looking around, I'm now wondering if
the Celestron CG-5 Equatorial mounts aren't more what
I should be starting out with, given my main interest
in Astrophotography.

Is anyone out there autoguiding these mounts? I assume
one needs a special adapter to connect the USB port on
a computer to the autoguide port on a drive system.

I'd also be interested if anyone is using off-axis guiding
with something like the C8-S GT.

Hi shadow,
If you are planning on using the DSI (a Meade product), with a Celestron Scope, you will find that the two different Manufacturers did not use the same Scope driving systems.
You will need a Meade emulator device to interface with the Celestron Mounts, but only in order to use the Meade Envision telescope control software. check this link, http://www.skyinsight.net/wiki/index...tware_Emulator
You can however have control of your Celestron Mount with a software package called Nextstar Observer, http://www.nexstarsite.com/PCControl.htm
it is free and can be downloaded online, but you may also need a Celestron Cable and USB to RS 232 adapter, if your laptop doesn't have a Rs 232 port.

The Meade Emulator is only required if you plan on using the DSI camera's New Drizzle Feature, or if you wish to use the Meade Autostar telescope control or ACP.

For Auto guiding a Celestron Mount with the DSI you
will need a shoestring adapter, and from what I have heard there are several versions available online also.
The Nextstar Observer Scope control software has several versions for compatibility with the different Celestron mount Configurations, You can also download the virtual hand box controller which is useful for doing a search pattern to center your image on your CCD chip, if it doesn't appear in the field of view.
I Use the DSI on A CG5 ASGT Mount with a 6 inch f/8 refractor and a 0.5x focal reducer, along with the Nextstar Observer software, for telescope control, but since I typically only use 30 second maximum subs, and take many frames for stacking, I go unguided with with a good polar alignment, the trick is to use a focal reducer to minimize periodic error.
I am not familiar with the C8-S GT, but keep this in mind, the DSI is a small chip, and really requires a focal reducer, this requires plenty of back focus or inwards travel, on some scopes this can be a problem, if you then add a Radial offset Guider you may not be able to reach Focus. If the C8-S GT is a SCT scope then your focal length is rather long and even with a Focal reducer you may not get the image scale you would like.
An SCT usually has enough focus travel to use both a Radial offset guider and a focal reducer but check with the manufacturer first!. also keep in mind that without a EQ mount, or a wedge for a Fork Mounted ALT/AZ mount, your images will suffer from field rotation, and then another expensive piece of equipment is required a (Field De-Rotator), this also adds to you focal length.
Dennis

Shadow,
I forgot to mention that the DSI Pro Has A terrible fault, its in the RGB filter slide, its completely exposed to the elements and dewing and dust becomes a problem, not to mention it has a light leak due to the design of the filter slide.
I own both the DSI I one shot and the DSI I Pro with the Filters, You will have to refocus for each filter the IR filter should be installed in the nose piece of the camera and not in the slide! another engineering discrepancy. you would be better off with a set of Astrodon filters.
dennis