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SBIG ST200XM vs Starlight SXV H9

 

Since I bought my ST2000XM I've had many mails asking why I switched and what I thought of the camera relative to the SXV. As a result I pulled together the following pages which I hope will be of use to those facing a similar decision. At the end of the day both of these cameras are excellent performers as the many users testify, for example: ST2K  Matt Thomas, Dean Jacobsen; SXV Wolfgang Promper and Rick Krejci. So you can't really go wrong whichever one you choose. Ultimately camera choice will be governed by your personal imaging preferences/circumstances but I hope this page will set the differences in context.

 

 

Background

 

 

A few months ago I finally gave in to chip fever and sold my trusty MX716 and bought myself an SXV H9. As I expected I was delighted with the camera from the moment I took it out the box. It looked the part and I had few problems getting good results with my Borg 76ED. Unfortunately the wheels came off when I tried to use the SXV with my longer focal length scope and I found that the weight of my main scope, guide scope two cameras and all their paraphernalia was just too much for my EM10 when imaging at ~1.5 arc seconds per pixel. It was fine with the MX716 at 2 arc seconds per pixel  but the smaller pixels of the SXV just tipped the balance. Using my MX716 with a Barlow  in self guide mode I proved the set up could guide at the 1.5 arc second image scale without the extra weight of the guiding system. I was then left with two options: upgrade the mount or, shift to a self guide camera and sell the SXV and ST4 etc (I can't use an OAG with my MakNewt). Portability is essential to me as I set up fresh every night so the self guide camera was the only real route route and I picked up a used ST2000XM and CFW8 on Astromart.

 

 

First Impressions

 

 

The table below gives a rough overview of how the cameras compare in the box.

 

ST2000XM

SXV H9

Chip Size

11.8 x 8.9 mm

9 x 6.7 mm

Pixel Size

7.4 microns

6.45 microns

Weight

900g

400g

Software

CCOps/CCSoft/Sky

SX Software

UK/Ireland Cost ($)

(1 ~ 180c)

5030

3330

(3825 with guide head)

US Cost ($)

3499

2899

 (3170 with guide head)

Self Guide

Yes

No

(Optional Guide Head)

Power Supply

110/240v

110/240/12v

Cooling

Yes with user set point

Yes

Carry Case

Yes

No

 

 

QE is also a point for comparison for the cameras. In short there's not a lot of difference between them at the blue/green end but the SXV has around twice the QE at the red end. Peak QE for ST2000XM is around 55% at the blue end while the SXV is around 65% at the red end. You can go to the manufacturers web pages to see the actual curves or try www.astrovid.com for all the info in one place (BTW the comparison curve on the SXV page is out of date).

 

 

Getting Started

 

 

Both cameras are easy enough to set up and use. I guess I spent two nights with each one before the bugs were ironed out. Little things like software versions, USB drivers, length of USB cables and power supplies but nothing too serious. In both cases I had excellent customer support from the manufacturers. Once installed the  USB links work really well and gave fast and reliable downloads.

 

The ST2K has user controllable cooling , as well as the option to add a supplemental cooling water circuit. Where I live I'm lucky to get above 15 oC  during the day never mind at night so the standard cooling fan is all I use. 

 

A big difference between the cameras is the software. When used with the CCDSoft package that comes with the camera the ST2K is easy to use with full support for focusing, guiding, calibration and imaging. Food and drink to a science guy which made the imaging experience all the more enjoyable.  The software that comes with the SXV is not up to the job and in my opinion and you will need to upgrade to do any serious imaging, I used AstroArt and it works fine.

 

One major issue for me was the speed of set up with the ST2K. As my SXV system had become more complicated I was taking longer and longer to set up and get ready for imaging. Moving from the self guide MX716 to the SXV, ST4 and guide scope had added another 30 minutes to my set up time and the cable spaghetti had begun to frustrate me. With the ST2K I was back to my old set up times. Controlling my Temma mount via the copy of The Sky that came with the camera I could center targets locate guide stars etc all from the house. As I set up fresh every night and often have to take things down in a hurry (never leave home in Ireland without an umbrella) this is a big plus. Obviously if you have a permanent set up or plan on unguided imaging this isn't an issue.

 

 

Image Comparisons

 

 

To compare the camera performance I took a range of exposures with both cameras on my Borg 76ED at 500 mm f6.6 through an Astronomic Ha filter. This was a key test for me as I wanted to see how the ST2K would do as I do a lot of Ha imaging. I took 10 minute sub exposures and exported the files from Astroart after an auto stretch.  The SXV image looked like this (no darks):

 

(click on image for high res. view)

 

The SBIG raw frame looked like this:

 

(click on image for high res. view)

 

I nearly fell of my chair being used to the SXV but a quick dark frame soon restored normality:

 

(click on image for high res. view)

 

Resultant image

 

(click on image for high res. view)

(note the trailed stars on the ST2K image are my fault not the cameras I had the optics  tilted)

 

So overall the differences are as expected and plain to see the ST2K has a bigger field of view but has less red signal and needed a dark frame. Both images looked pretty good to me but the ST2K will need longer exposures on Ha objects.  I thought it would also be interesting to look at stacked exposures with both cameras and the images below are the sum of 3 ten minute exposures with the same set up for the SXV (again no darks):

 

(click on image for high res. view)

 

and the ST2K (dark corrected)

 

(click on image for high res. view)

 

Again the results were pretty much as expected  more signal for the SXV but you'd get there with the ST2K with a bit more time.

 

An important point to note about the ST2K is that you can, if you're lazy like me, take your dark frames the next day and as the camera has set point cooling, temperature matching is not a problem. So yes dark frames are a bit of hassle but its not as bad as some might suggest.

 

 

Conclusions

 

 

Camera for camera I think its probably a tie the higher noise and lower red QE of the ST2K are probably offset by the smaller chip of the SXV. The real difference is in the overall package and there the ST2K is a winner for me. I have grown tired of hunting for guide stars, focusing the ST4 and fixing flexure. I get very few clear nights and since switching from self guide with my MX7 I've wasted half of them messing around with widgets in the dark.  The ST2K represents a user friendly well supported camera with a lot of potential especially when you factor in AO7 and the CFW8.

 

Of course all this leaves out one key issue, cost. As can be seen from the table above the cameras are a wash in the US which lets the technology do the talking but the European price differential has to be a serious issue for potential buyers.  I went the used route and, factoring in VAT on the import, I sold my SXV, ST4 and a few other bits and pieces for the cost of a VGC ST2K and CFW8. That is one way round the problem but it is not to everyone's taste.

 

At the end of the day I had a particular problem which was nicely solved by the ST2K, I'm sure others will have different stories to tell. I'm still a fan of both cameras.

 

 

Foot Note

 

For the QE junkies out there I borrowed an ST10XME image (left) from Paul Kanevsky taken with his TEC 140 and Astronomik Ha filter (25 minute exposure) and compiled a side by side with comparison with the ST2K (Astronomik Ha 160mm f5.5 MakNewt 25 minutes). Clearly the XME would leave both the SXV and ST2K standing for QE but then its twice the price .