Re: What would you buy with $10-12,000?
- Here's my stab:
You can easily spend most of your time polar aligning and focusing,
so you want to buy equipment to minimize that.
Some deep sky objects can be difficult to find, a goto scope will
save you time.
Having licked those problems, you can get on with imaging.
What works for me:
Takahashi EM-200 Temma PC Jr. mount (save money by getting the Jr, if
you don't care about 700x slewing). $4,100 new (you may need
dovetail plate hardware for the OTA)
EM-200 Tripod $600.00 new
SBIG ST-2000XM with CFW-8a. $4,500 new
If you can buy the above used, you can save some for the OTA &
Depending on the OTA, you will want a motorized focuser to use with
FocusMax (freeware). For refractors you can probably just get a
RoboFocus. For SCTs you may want a Crayford add-on.
The OTA comes down to preference, get the largest aperture you can
afford with the remaining money, but leave some money for
accesories. But if you get a refractor, make sure it is an APO.
Celestron has a deal: 5 eyepieces & filters for $99 with the purchase
of one of their scopes (OTA's count).
Make sure the OTA isn't too much for the EM-200 to handle (ask the
group). I think most OTAs in your remaining budget should be OK. I
like the EM-200 because it is easy to polar align, itsets up quickly
and is portable (the counter-weight shaft retracts into the mount
The FS-102 sale is continued until June, but that scope will probably
push you over budget with all the accessories.
Kendrick Heaters and / or dew shields
Optional finder scopes.
Powermates (instead of barlows)
If you have existing 35mm lenses, you could consider buying one of
the lens adapters for the ST-2000XM (one of the 3rd party ones that
supports the CFW-8a). That can give you the wide-field views, then
you can use a longer focal length for your OTA.
Hopefully you find some or all of this useful,
- Hi Richard,
Thanks a lot for the comparisons. I liked the way you used the filters on the Crab. It seems that I would be better of starting with a 9nm or 10nm filter.
Regards and Happy New Year!
----- Original Message -----
Sent: Thursday, January 01, 2004 11:41 PM
Subject: [ccd-newastro] A DIFFERENT CONCLUSION ABOUT 4" refractorRe: What would you buy with $10-12,000?
--- In firstname.lastname@example.org, "Bill Bradford"
> Great example of images. What is your opinion as to the Ha filter
that would enable you to image the greater number of targets. I saw
that you used the 3nm a lot in your photos.
I have two different Ha filters: a 3nm Custom Scientific and a 9nm
Schuler. The Schuler really is an Ha + [NII] filter though: the two
[NII] lines are just either side of the Ha line and are only about
2nm separated. So the Schuler picks them all up. The Cust Sci doesn't
The Cust Sci also doesn't let as much light through so it will not
expose the detector as fast as the Schuler.
I ended up putting my Schuler in my LRGB filter wheel as my 5th
filter. My Cust Sci is in my Emission Line Filter wheel along with my
other Cust Sci filters: [SII], [NII], [OIII] and Hbeta.
I have obtained good results with both filters. For the ST10XME, it
is nice to have a bit of a speedup so the Schuler is a good choice
and particularly so if you want to self-guide because the Ha really
socks the stars.
I mostly use the Cust Sci with my FLI Dream Machine. With the higher
quantum efficiency in the TK1024 back-illuminated detector and the
huge 24 x 24 micron pixels, the camera is very very fast compared to
my ST10XME. Just the geometry alone accounts for about a 9:1 speedup.
So the greater attenuation going through the Cust Sci doesn't seem
too bad with the DM. Some folks have been using the newer 4.5nm Cust
Sci filters with good success, but I cannot speak to any first hand
experiences with them.
I did a comparsion shot of the Schuler versus Cust Sci filters back
in mid 2002. I shot the Pelican: 6 x 10 minutes with each filter.
Here's the comparision result:
Because I was concerned about whether or not the 3nm Cust Sci filters
really would separate [NII] from Ha, I shot a "tricolor" image of the
Crab using Ha for Red and [NII] for both Green and Blue. If the data
were the same in both filters, the color image would be greyscale
basically. But it is not:
Happy New Year!
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