ST10 versus ST8300

[gregbradley]

I am wondering whether a 3200ME chip would be more suitable for my setup than the 8300 chip.

I am planning to use it on my CDK17 at 1950mm and 2959 focal length
as well as my TE180 which is 1260mm focal length and F7.

The 8300 works quite well with the TEC and only change I would make is using shorter subexposures to prevent bloated bright stars.

The 8300 isn't a great match at 2959 focal length with the smaller pixels (5.4 microns) unless the seeing is really good. I haven't used it at 1950mm yet but I imagine it will perform better.

The 3200ME is much more sensitive and I think is a very good chip for galaxy images which is what I would mainly use it for on the TEC or CDK.
It has slightly larger pixels at 6.6 microns.

But it is also only 3.2 megapixels. Perhaps that is less important but it also has a narrow FOV.

Opinions?

Greg.

[Terry B]

Things to consider.
The ST10 has better well depth and is NABG.
Are you mostly imaging galaxies?
If so think how many are big enough to need the bigger chip. I can only think of 3 in the southern sky.
How often will NABG be a problem?
How many potential targets have bright stars in the same field?
Will you also want to use the camera for science images? Ie photometry.
The NABG is better for this as it has a more linear response.

[gregbradley]

Are all ST10's NABG? I thought that was just the 10XE and the 10XME was ABG?

The 8300 is ABG and that is a big plus for imaging as you don't lose that much sensitivity (or at least I don't think so) but blooms on bright stars are I hear a pain to correct.

In physical size the chips are similar dimensions with the 3200ME a bit smaller than the 8300 but its not a major difference.

Greg.

[Paul Haese]

Originally Posted by gregbradley

I am wondering whether a 3200ME chip would be more suitable for my setup than the 8300 chip.

I am planning to use it on my CDK17 at 1950mm and 2959 focal length
as well as my TE180 which is 1260mm focal length and F7.

The 8300 works quite well with the TEC and only change I would make is using shorter subexposures to prevent bloated bright stars.

The 8300 isn't a great match at 2959 focal length with the smaller pixels (5.4 microns) unless the seeing is really good. I haven't used it at 1950mm yet but I imagine it will perform better.

The 3200ME is much more sensitive and I think is a very good chip for galaxy images which is what I would mainly use it for on the TEC or CDK.
It has slightly larger pixels at 6.6 microns.

But it is also only 3.2 megapixels. Perhaps that is less important but it also has a narrow FOV.

Opinions?

Greg.

Well depth for Galaxies Greg. The 8300 is too short on that and the stars always seem huge despite the advantage of being able to sharpen endlessly when over sampled. I got a STL11K for my narrow length stuff because larger pixels will be easier on stars and the stars don't appear to be monsterous.

For the TEC though mate I am going 20 minutes in a few colours and only found a couple of times that the stars are a pain with the 8300. I know you have a bit more diameter but go longer on your subs. You can process out bloated stars a little by using masks and the minimum funtion.

Field of view is really an issue if you want that wide expanse with a numbr of detailed galaxies. Why not use your 16803 on the CDK? Surely that will work on that scope. Is it image circle? Good well depth, big field that you can crop to suit. I know you have the field correction now, so what is the issue?

[Terry B]

Originally Posted by gregbradley

Are all ST10's NABG? I thought that was just the 10XE and the 10XME was ABG?

The 8300 is ABG and that is a big plus for imaging as you don't lose that much sensitivity (or at least I don't think so) but blooms on bright stars are I hear a pain to correct.

In physical size the chips are similar dimensions with the 3200ME a bit smaller than the 8300 but its not a major difference.

Greg.

My ST10XME is certainly NABG. I think all of them are.

[gregbradley]

Is blooming much of a problem then? I haven't noticed it as being an issue in ST10XME images.

Greg.

[Terry B]

Originally Posted by gregbradley

Is blooming much of a problem then? I haven't noticed it as being an issue in ST10XME images.

Greg.

I use my camera almost exclusively for photometry so it doesn't worry me.
It occurs when there is a bright star (mag 6 or brighter) in the field and the exposure time is longer than about 1 min. An example would be imaging eta carina where there a lots of bright stars. For imaging galaxies it would almost never be a problem. Exposures of up to 10 mins may allow a mag 11 star (depending on the filter) to saturate but this will also occur with a ABG camera. It has to massively over saturate before blooming occurs. The result is you lose the colour data for that star but the dimmer parts of the image will have better S/N.

[loc46south (Geoffrey)]

Hi Greg - I have just finished rebuilding my Observatory and have upgraded my primary imaging camera from a ST8 to a ST10 - My telescopes are Mewlon 250 and a 120mm Refractor. My secondary camera is a ST8300.

The primary advantage of the ST10 is that it has 3 times the well depth and from 400nm to 900nm it has nearly twice the QE of the ST8300. It is a NABG chip but the well depth is that great (75,000), that used sensibly it is not a problem plus there are a number of software applications that handle the problem easily.

The high QE% of the camera gives it sorter exposure times with the refractor - especially in the HAlpha range and intelligent use of binning lets it really capture the detail of the smaller galaxies.

On the negative side it does not have the acreage that the newer ABG chips have. I originally bought the ST8300 with intentions of using it on the M250 at f10 by binning it at 3x3 but the ST10 binned 2x2 stomps all over it in results.

Cheers
Geof Wingham

[strongmanmike (Michael)]

Originally Posted by gregbradley

The 8300 works quite well with the TEC and only change I would make is using shorter subexposures to prevent bloated bright stars.

Greg.

This bloat you refer to and have spoken about before..?..are you confusing this with saturation..? How can shallow wells cause star bloat..? Bloat is caused by sensitivity to IR that is not being focused by the optics..? small wells saturate more easily and small pixels can cause over sampling but not bloat...?

As for the choice of cameras...get both use the 8300 for the stars (no blooms) and the 3200 for the rest ...FLI can put a 3200 in a MicroLine can't they..?

Mike

[gregbradley]

Originally Posted by Terry B

I use my camera almost exclusively for photometry so it doesn't worry me.
It occurs when there is a bright star (mag 6 or brighter) in the field and the exposure time is longer than about 1 min. An example would be imaging eta carina where there a lots of bright stars. For imaging galaxies it would almost never be a problem. Exposures of up to 10 mins may allow a mag 11 star (depending on the filter) to saturate but this will also occur with a ABG camera. It has to massively over saturate before blooming occurs. The result is you lose the colour data for that star but the dimmer parts of the image will have better S/N.

So galaxies are ok then. Sounds good.

Originally Posted by loc46south

Hi Greg - I have just finished rebuilding my Observatory and have upgraded my primary imaging camera from a ST8 to a ST10 - My telescopes are Mewlon 250 and a 120mm Refractor. My secondary camera is a ST8300.

The primary advantage of the ST10 is that it has 3 times the well depth and from 400nm to 900nm it has nearly twice the QE of the ST8300. It is a NABG chip but the well depth is that great (75,000), that used sensibly it is not a problem plus there are a number of software applications that handle the problem easily.

The high QE% of the camera gives it sorter exposure times with the refractor - especially in the HAlpha range and intelligent use of binning lets it really capture the detail of the smaller galaxies.

On the negative side it does not have the acreage that the newer ABG chips have. I originally bought the ST8300 with intentions of using it on the M250 at f10 by binning it at 3x3 but the ST10 binned 2x2 stomps all over it in results.

Cheers
Geof Wingham

Thanks Geoff.
I would mainly want it for galaxy imaging so that's good to know the blooming isn't an issue there.

Originally Posted by strongmanmike

This bloat you refer to and have spoken about before..?..are you confusing this with saturation..? How can shallow wells cause star bloat..? Bloat is caused by sensitivity to IR that is not being focused by the optics..? small wells saturate more easily and small pixels can cause over sampling but not bloat...?

As for the choice of cameras...get both use the 8300 for the stars (no blooms) and the 3200 for the rest ...FLI can put a 3200 in a MicroLine can't they..?

Mike

It happens with any scope I have used Mike. Perhaps you are right there. Perhaps bloat is the wrong word. I'll dig up an image and highlight what I am talking about. Looking over my images I see it doesn't happen as often as I thought. Sometimes brighter stars will not so much bloat as spill over more than the 16803 camera will show it. I think that is the small wells? At least I thought it was.

Greg.

[Bassnut (Fred)]

I dont think you can really compare the 2 Greg, as Geoff says, theres a huge difference in QE, well depth, chip size and NABG/ABG (arnt the filter sizes different too?).

The ST10XME really would stomp on the 8300 for NB especially, and with SBIG anyway you get internal or external guide with a cooled guide cam option.

Blooming stars is a pain with bright stuff with RGB, but I dont have a problem at all with blooming in NB.

[Paul Haese]

Not going to respond to my post Greg?

[Terry B]

Originally Posted by strongmanmike

This bloat you refer to and have spoken about before..?..are you confusing this with saturation..? How can shallow wells cause star bloat..? Bloat is caused by sensitivity to IR that is not being focused by the optics..? small wells saturate more easily and small pixels can cause over sampling but not bloat...?

As for the choice of cameras...get both use the 8300 for the stars (no blooms) and the 3200 for the rest ...FLI can put a 3200 in a MicroLine can't they..?

Mike

There are other causes for bloat as well. Each star image should be a gausian shape that extends out to infinity even with a perfectly focussed star. For very bright stars that massively saturate the receptor you are able to detect the outer part of the star image as it is bright enough to be detected. Fainter stars will not show this as it will be below the detection threshold for the camera. A shallow well depth will exacerbate this as it is easier to saturate the image.

[gregbradley]

Originally Posted by Paul Haese

Well depth for Galaxies Greg. The 8300 is too short on that and the stars always seem huge despite the advantage of being able to sharpen endlessly when over sampled. I got a STL11K for my narrow length stuff because larger pixels will be easier on stars and the stars don't appear to be monsterous.

For the TEC though mate I am going 20 minutes in a few colours and only found a couple of times that the stars are a pain with the 8300. I know you have a bit more diameter but go longer on your subs. You can process out bloated stars a little by using masks and the minimum funtion.

Field of view is really an issue if you want that wide expanse with a numbr of detailed galaxies. Why not use your 16803 on the CDK? Surely that will work on that scope. Is it image circle? Good well depth, big field that you can crop to suit. I know you have the field correction now, so what is the issue?

Sorry Paul. I missed this one.
I do use the 16803 on the CDK. I am comparing the 8300 to a possible 3200 chipped camera. Minimum filter does not work that well and you can tighten stars a tad but easily overdone before it wrecks them. It really isn't a very good tool Deconvolution is better but still you need good data to start rather than trying to repair a problem.

The STL11 stars will appear smaller but that is only because your image scale is larger with the larger chip (ie less magnified). They probably aren't smaller. I think its only an issue sometimes and I can simply shorten the exposure time if there are bright stars in the field.

The 3200 chip though is appealling in that the extra QE, slightly larger pixels (not that large though) could be good for galaxy imaging.

Some of the best galaxy images are by Daniel Verschase and he used an ST10XME for a lot of them with a 14.5 inch RCOS.

Originally Posted by Bassnut

I dont think you can really compare the 2 Greg, as Geoff says, theres a huge difference in QE, well depth, chip size and NABG/ABG (arnt the filter sizes different too?).

The ST10XME really would stomp on the 8300 for NB especially, and with SBIG anyway you get internal or external guide with a cooled guide cam option.

Blooming stars is a pain with bright stuff with RGB, but I dont have a problem at all with blooming in NB.

Internal guide chip would be handy sometimes. Although guiding is not that much of an issue with the MMOAG. I am looking more at a FLI Microline 3200. But then it costs a lot more than the SBIG equivalent. I am not sure if the better cooling and cleaner electronics, frame buffer is worth it compared to the self guiding and AO accessories of the SBIG.
But then I can use my FLI filter wheel and I have all the adapters so a ML3200 would simply plug in. An AO unit would be handy.

Greg.