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Old 15-12-2011, 08:46 AM
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SBIG STX What are your impressions?

Before I place an order for the Sbig STX with the 16803 chip, I would like to get some feedback from people who are using this camera or have an informed opinion.

Some of the reasons I chose this camera are as follows.

Dual chip inbuilt OAG
The filter wheel, 65mm filters
Fast down load
Mac compatible
Medium sized chip
Cooling rate
QE 60%

This will be the first CCD camera I have bought for Astro imaging. I wan't to get it right.
Its going to Cost around $15K but I am only getting 16 mega pixels for this amount of money is it worth it. Considering terrestrial medium format cameras can have up to 80 mega pixels or more.

Any feed back will be great.

Cheers
Phil
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Old 15-12-2011, 09:49 AM
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Is the guid chip in front or behind the filter in this camera ? Looking at pictures I assume behind filter wheel.

One heck of a first CCD camera Phil!
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Old 15-12-2011, 10:10 AM
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The guide chip is behind the filter wheel.

Quote:
One heck of a first CCD camera Phil!
Well I thought rather than spending a bunch of money on a cheaper camera. I might as well put in the extra and get something I will be happy with first time.
I come from a professional photographic background. I am very fussy when it comes to image quality.

cheers

phil
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Old 15-12-2011, 10:44 AM
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Megapixels arent everything. Arcsec/pixel vs local seeing springs to mind.

You can only fit so many 9micron pixels in a chip of "x" dimensions.

DT
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Old 15-12-2011, 10:46 AM
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Before you spend that kind of money on a first CCD camera just make sure you ask yourself what you intend to do with it and if it's the right one for your needs. Cheaper cameras are not necessarily bad cameras, they are just different. It very much depends on what you are going to use it for, how does it fit with your focal length, pixel size etc. You may discover that the chip doesn't fit your needs, unless you have of course checked all that.

Just mentioning it because none of these aspects (which are the most important) are included in the reasons you listed.
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Old 15-12-2011, 11:21 AM
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Quote:
Originally Posted by DavidTrap View Post
Megapixels arent everything. Arcsec/pixel vs local seeing springs to mind.

You can only fit so many 9micron pixels in a chip of "x" dimensions.

DT
Very true David.
I only have a 52mm flat field so 36mm x 36mm, 9micron pixels will have to do.

Quote:
Originally Posted by SkyViking View Post
Before you spend that kind of money on a first CCD camera just make sure you ask yourself what you intend to do with it and if it's the right one for your needs. Cheaper cameras are not necessarily bad cameras, they are just different. It very much depends on what you are going to use it for, how does it fit with your focal length, pixel size etc. You may discover that the chip doesn't fit your needs, unless you have of course checked all that.

Just mentioning it because none of these aspects (which are the most important) are included in the reasons you listed.
Thanks Rolf
Yes all of those aspects have been thought about.
I am trying to decide between other camera makes. The list was things that appealed to me that differ slightly between them.
IF you use a KAF 16803 chip in an SBIG, FLI, Apogee ect it still has 9 micron pixels it still has the same QE, well depth, ABG ect.

I want to know what other people think of the STX and the pros and cons that go with it.

Cheers
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Old 15-12-2011, 11:29 AM
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Pretty sure Martin Pugh uses one. Maybe he will chime in with his experience and views on the STX.
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Old 15-12-2011, 12:29 PM
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I did read Martin Pugh's review on the STX.
It would be nice to know what he thinks of the camera now.

Cheers
Phil
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Old 15-12-2011, 08:33 PM
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Just a small point on "megapixels"

If you count an Astro-mono camera in the same way as a "terrestrial" camera you need to look at a terrestrial bayer matrix (RGGB) and realise the likes of Canon Nikon Pentax et. al. interpolate data and place it in non-sensing pixel locations.

With "normal" daylight scenes this causes no problems, but with point or spectrally narrow sources (eg Astronomy) you will lose information.

eg. a 24Mp Canon camera only has 6M red pixels.

Using the same concept then, a 16MP mono camera doing a LRGB shot actually has 64Mp of data, but you can't get it with "one shot"...you need four....

This data not only 16 bit, but spatially more highly resolved (ie you are not interpolating colour data) than a "24Mp" one shot camera.

Plus with a luminance (ie unfiltered) domain, with all other aspects being equal, your S/N will be better as well.

P.S.
Mono cameras also perform significantly better in narrow band. eg. H-alpha , SII, OIII as they fully capturing the selected bands,
as opposed to single shot colour sensor than will render a red, pre-filtered version of say H-alpha, with 18 million green and blue pixels doing..well..not much

Last edited by Peter Ward; 15-12-2011 at 08:59 PM. Reason: clarification
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Old 15-12-2011, 09:04 PM
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I take it you have a CDK scope from your screen name.

STX would be good in several ways. SBIG seems to have closed the gap whilst retaining the self guiding as well as adding several guiding options. SBIG is ahead of the other camera makers in this regard.

One issue though with a CDK as I was thinking of an STX6303 is that the chip is lower down in the STX body than Apogee or FLI. It is 40mm plus the faceplate plus the filter wheel is thicker at around 30mm.

Normally that would not be an issue but if you plan to use the CDK reducer it has very limited backfocus and ideally is setup around 45mm from memory. It still works further out but spot sizes get larger and F ratio increases.

But it would be cool be able to self guide and not rely on a guide scope with the reducer. STL or QSI would work there. But they don't do the 16803. You can't add an off axis guider to the reducer. I use a guide scope and usually get round stars but perhaps 25% are not.
I plan on adding a 2nd autoguider to reduce the effects of flexure.

One point about megapixels. 2 cameras of similar performance with same pixel size - one is 3 times the size of the other. The larger one you can always crop if you want to zoom in and highlight your target. You can't add to the smaller chip's view.

I am not sure if there is an advantage to the 65mm filters. I think that is needed so the guide chip gets light but I wonder if it reduces vignetting.
Not sure.

I get vignetting on most scopes with the 16803 but not a lot on the TEC180. I get a lot on the CDK.

Greg.
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Old 15-12-2011, 10:11 PM
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Quote:
Originally Posted by Peter Ward View Post
Just a small point on "megapixels"

If you count an Astro-mono camera in the same way as a "terrestrial" camera you need to look at a terrestrial bayer matrix (RGGB) and realise the likes of Canon Nikon Pentax et. al. interpolate data and place it in non-sensing pixel locations.

With "normal" daylight scenes this causes no problems, but with point or spectrally narrow sources (eg Astronomy) you will lose information.

eg. a 24Mp Canon camera only has 6M red pixels.

Using the same concept then, a 16MP mono camera doing a LRGB shot actually has 64Mp of data, but you can't get it with "one shot"...you need four....

This data not only 16 bit, but spatially more highly resolved (ie you are not interpolating colour data) than a "24Mp" one shot camera.

Plus with a luminance (ie unfiltered) domain, with all other aspects being equal, your S/N will be better as well.
Good point Peter

Quote:
Originally Posted by gregbradley View Post
I take it you have a CDK scope from your screen name.

STX would be good in several ways. SBIG seems to have closed the gap whilst retaining the self guiding as well as adding several guiding options. SBIG is ahead of the other camera makers in this regard.

One issue though with a CDK as I was thinking of an STX6303 is that the chip is lower down in the STX body than Apogee or FLI. It is 40mm plus the faceplate plus the filter wheel is thicker at around 30mm.

Normally that would not be an issue but if you plan to use the CDK reducer it has very limited backfocus and ideally is setup around 45mm from memory. It still works further out but spot sizes get larger and F ratio increases.

I am not sure if there is an advantage to the 65mm filters. I think that is needed so the guide chip gets light but I wonder if it reduces vignetting.
Not sure.

I get vignetting on most scopes with the 16803 but not a lot on the TEC180. I get a lot on the CDK.

Greg.
I want to use the focal reducer on the CDK and yes you are right the optimum back focus is 47mm this does not give me much to play with.
The filter wheel is 32mm add this to the STX of 40mm and this is way over optimum.

I was looking at the FLI specs today the Proline has a back focus of only 30.23mm and the filter wheel that carries the 65mm filters is only 15.24mm thick, this would fit nicely. But as you said no room for a OAG.
Also I heard today that FLI are going to do a MAC driver to run with the SKY X. It is only in the beta stage but it's better than nothing.

So it might come down to filter wheels and thickness.

Maybe I should get a different scope for wider field imaging and not bother with the focal reducer. I am very unsure which way to go at the moment. All of these cameras seem very good.

Greg what do you think is causing the vignetting? with a flat field of 52mm the 16803 chip should fit nicely into this.


Cheers
Phil
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Old 16-12-2011, 11:03 AM
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I just heard from Planewave that I will not be able to use the STX filter wheel in the image train with the focal reducer. ( I thought that this might be the case). So it looks to me that the STX is off the Cards.


Thank you to all who posted their comments.

Cheers
Phil

Last edited by CDKPhil; 16-12-2011 at 01:09 PM.
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Old 16-12-2011, 01:16 PM
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Hi Phil,

I use a PL16803 and CFW4/5 on the reducer and it is at the optimum spot.

The PL is 30.23mm and the CFW4/5 is 19.8mm or so.

It works fine but I do get the occassional elongated star subexposure whereas when I use the MMOAG on the scope without the reducer round stars are routine.

I plan to mount a 2nd autoguider - perhaps an STi with the lens kit or mount my ST402ME with an efinder and a Losmandy D block to the dovetail and run it on 60 second guide corrections using a 2nd CCDsoft running alongside the CCDsoft that runs the Proline and guide camera.

I am using a Vixen VMC95 for a guidescope. I think I get a small amount of flexure at times. Probably when the scope is at more of an angle.

STL is another choice as its got the filter wheel, the self guiding and fits the backfoucs requirement. An STL6303E does bloom but its also quite sensitive plus you could use an AOL when not using the reducer. 9 micron pixels as well are a good size.

Proline 09000 is another one that could be good but it would really have to be the Proline as you need a good ghost imaging solution and FLI seems to be ahead of the others on that point. I don't really see ghost imaging with the 16803 or 8300 for that matter. I have seen it once in an image and once in some darks. Its easy enough to avoid. Don't take an image of the moon or Jupiter or something like that before you do an imaging run. If a just goes through your image and leaves bright trails either turn off the camera and start up again (it only takes a few minutes to cool anyway) or simply press on. Mean combine in CCDstack gets rid of the quite faint ghost image it will leave. Otherwise I haven't noticed any RBI. If its there it must be awefully subtle and therefore no gain in handling it for pretty pictures.

I don't think I do get vignetting from the filterwheel. All my scopes vignette to some degree. Some a lot with reducers but they flat field out. The CDK design has a smaller than usual secondary but the cost of that is higher vignetting. None virtually with an 8300 chip and the outer 1/3rd drops off on the 16803. Good flats are essential as I found it can be a bit tricky to correct unless everything is just right.

I think you've made the best choice with the 16803 chip. Its the best out there at the moment. Given Kodak's financial woes and selling off of its chip business I wonder what that will mean. More chips or less?

You'd think the new owners would be keen to expand and develop the business and give it needed capital.

Greg.




Quote:
Originally Posted by CDKPhil View Post
Good point Peter



I want to use the focal reducer on the CDK and yes you are right the optimum back focus is 47mm this does not give me much to play with.
The filter wheel is 32mm add this to the STX of 40mm and this is way over optimum.

I was looking at the FLI specs today the Proline has a back focus of only 30.23mm and the filter wheel that carries the 65mm filters is only 15.24mm thick, this would fit nicely. But as you said no room for a OAG.
Also I heard today that FLI are going to do a MAC driver to run with the SKY X. It is only in the beta stage but it's better than nothing.

So it might come down to filter wheels and thickness.

Maybe I should get a different scope for wider field imaging and not bother with the focal reducer. I am very unsure which way to go at the moment. All of these cameras seem very good.

Greg what do you think is causing the vignetting? with a flat field of 52mm the 16803 chip should fit nicely into this.


Cheers
Phil
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Old 16-12-2011, 03:32 PM
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Thanks Greg, Some really good advice.

I think the Proline will be the best solution for my needs. Cost is not much different to the STX, but a big advantage being able to use it with the reducer.

I really like the STi as a guide solution a very neat piece of kit. The mounting for this camera looks very solid, and because it is so small flexure should be minimal. This will be on my shopping list along with the MonsterMOAG.

I will be very keen to hear how you go with the two guide camera setup.

I read the article on the other thread about the demise of Kodak, what a sad story. I hope for photography's sake in general, that the new company that has bought the imaging solutions division will continue to produce and develop new chips. We will have to wait and see.


Cheers
Phil
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Old 17-12-2011, 04:37 PM
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Quote:
Originally Posted by CDKPhil View Post
Thanks Greg, Some really good advice.

I think the Proline will be the best solution for my needs. Cost is not much different to the STX, but a big advantage being able to use it with the reducer.

I really like the STi as a guide solution a very neat piece of kit. The mounting for this camera looks very solid, and because it is so small flexure should be minimal. This will be on my shopping list along with the MonsterMOAG.

I will be very keen to hear how you go with the two guide camera setup.

I read the article on the other thread about the demise of Kodak, what a sad story. I hope for photography's sake in general, that the new company that has bought the imaging solutions division will continue to produce and develop new chips. We will have to wait and see.


Cheers
Phil
I am interested in the STi as well but I believe work is being done on the shutter and it is delaying deliveries. I am hoping it will be similar to the Lodestar but better and autodark actually works plus it should be CCDsoft friendly.

STX is a cool machine and all those guiding options look very handy in a guidescope situation unless they have ways of incorporating it with OAGs. Plus its currently cheaper than a Proline. But in this particular case the extra dimensions don't work well.

Greg.
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