Last updated: 31 March 2001

Accessory Manufacturer Model Price
SAC-IVb CCD Imager Sonfest N/A $224
This is a continuation of a previous report on the Sonfest Promotions Inc. SAC-IVb lightweight and low-cost Astronomical Imaging Camera. Go to Part 1 if you have not read that report.

I decided to see if I could capture M42, the Great Orion Nebula, using the SAC IVb CCD attached to the ETX-125EC. At the suggestion of Sonfest I used a focal reducer (the Shutan Wide Field Adapter) to reduce the f/ ratio on the ETX-125EC. No eyepiece was used. Capturing was done using the ReelEyes version 1.1.1 on my Macintosh iBook. As focusing on faint objects is nearly impossible I used the bright star Rigel in Orion to achieve a good focus on the computer screen. I then had the Autostar GOTO M42; I did some minor slewing to get the image on the screen that I was happy with. I set the software to 100% gain (probably too much as it turned out) and the exposure to 1/4 second. I also set the white point adjustment to 100% red to bring out the nebulosity as much as possible. The following is a single frame from the captured movie and is unprocessed. It shows just what the CCD saw. If you look closely you can see a faint red area surrounding the four stars of the Trapezium.


I then used Photoshop 6.0 to combine ten frames from the movie into a single image. The result is shown below.


While more nebulosity becomes evident, you can also see the vertical scan lines from the CCD (which is why I think I set the gain too high). Also, I found that the nebula was more visible in the green so that was enhanced in Photoshop.

While this experiment demonstrates that the SAC IVb CCD can be used to image brighter nebula, it also shows that much more work is required to get really good results. I'll keep experimenting. I encourage other SAC CCD and ETX owners to send me their nebula imaging results for posting here.


From:	jpswann54@netscapeonline.co.uk (jpswann54)
After reading about it on your site, I purchased a SACIV b. Am very
impressed with it for the money. Am waiting to see how people get on
with a Wide Field Adapter before deciding whether to buy one. Your views
would be much appreciated.

Attached is a composite taken with an ETX 125 showing Saturn, Jupiter
and Io, Albireo and Mare Frigoris and Plato. Pictures were taken 6-8
October in Spain. We have not seen any stars here in England for

John Swann
Chichester, UK


From:	katetom@sd.znet.com (Kate / Tom)
Hooked up ETC-90EC, SAC-IVb, and Macintosh iBook. Once I got the
finderscope properly aligned (a prerequisite to maintain your sanity) I
easily grabbed images of the Moon, Saturn and Jupiter which I combined
in the attached picture. No post processing of the images except to
combine them in this one frame.

By far the coolest advantage of using this arrangement (scope, SAC-IV,
laptop) is the ability to share the telescope with several people
simultaneously. Also found that older folks, accustomed to watching
something on a screen, were a lot more comfortable than trying to bend
over the scope and squint into an eyepiece.

On another topic: I'd become hugely frustrated with the alignment
process and failure of scope to reasonably find and track objects. A few
weeks ago clouds were moving in and I wanted a quick peek at the moon,
so I just pointed it generally north, stood back and aligned the tube
with the horizon visually, and did a 2 star align. Didn't worry about
leveling the tripod, accurately aligning it with true north, etc.
Ta-rah. It worked just fine. Seems to be important that the stars used
in the alignment are dead center, but then everything else takes care of
itself. In fact, several night ago I used this alignment technique,
pointed the scope at the moon and pulled up the image on the laptop with
he SAC-IV, went in and ate dinner, and came back out to find the moon
still on the screen. The opposite limb, but hey....

Moon planets


Sent:	Sunday, March 4, 2001 03:39:07
From:	wgrainger@earthlink.net (Garrett)
Attached some first try moon shots with IVB I bought. It can produce
some pretty nice shots! Of course first time out, it's tough to be a
professional, but with some tweeking, it looks like a pretty good value.

As I play with it - I'll report improvements and sugestions...

By the way - good job with Clay, he's quite a great contributor....

Garrett Grainger


Sent:	Sunday, March 4, 2001 11:30:13
From:	cbfeldt@post1.tele.dk (Claus B. Petersen)
As many have said before me, thanks for a great site.

I have enclosed som pictures taken with the ETX125 and the SAC-IV CCD

Saturn: picture taken 22.02.01. Exposure1/8 sec. ETX125 + 2X barlow +
SAC-IV at primefocus. 77 pictures stacked with Astrostack.
Jupiter: picture taken 22.02.01. Exposure1/24 sek. ETX125 + 2x barlow + SAC-IV at primefous.70 pictures stacked with Astrostack
Venus: picture taken 22.02.01. Exposure1/53 sec. ETX125 + 2X barlow + SAC-IV at primefocus. 17 pictures stacked with Astrostack.
The area around Plato: Picture taken 03.01.01. ETX125 + SAC-IV at primefocus. 5 pictures stacked with Astrostack.
Sunspot AR9169: picture taken 21.09.00. ETX90EC + SAC-IV at primefocus.
More results can be seen at, home13.inet.tele.dk/etx/ Best regards Claus B. Petersen


Subject:	SACIV
Sent:	Saturday, March 10, 2001 05:53:26
From:	Gil.Sturgis@FLHOSP.ORG (Sturgis, Gil)

I recently purchased a SAC IVc from Scopetronix.  The attached is from
my first night out with the new toy.  At first I was not planning on
sending these in but after I pasted a few of them together, I was rather
happy with the result for a "first night".  These were taken with a SAC
IV at prime focus on an ETX 90ec with an Autostar on 3/2/2001.  Several
people have noted how critical finder scope alignment is with this
camera.  I agree and have had good results with a Rigel Quick Finder
that I also purchased from Scopetronix based on information on your

Gil Sturgis


Subject:	Saturn 23/3/01
Sent:	Friday, March 30, 2001 05:49:32
From:	ulric@cadence.com
From:	ulric@cadence.com (Ulric Jessop)
To:	etx@me.com
Here is a photograph of Saturn taken using the ETX90EC with a
2x barlow plus SACIV at prime focus. Exposure was 1/4 sec and
eight images were manually stacked using Corel Photo Paint.
Use of Jaggy Despeckle and Unsharp Mask. The photo was taken
in the street outside my Edinburgh flat just to test my newly
acquired camera.

Here is a photo of Jupiter taken at the same time
as the one of Saturn. Same procedure, except for
a shutter-speed of 1/10 sec.

Ulric Jessop, Edinburgh, Scotland

P.S. Your website is absolutely first-class.
Saturn Jupiter

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