RC300 - Piggyback ED80 or ED 120?

[bloodhound31]

Originally Posted by DavidTrap

Ok Baz,

The 8300 chip is too small. You'll do better with an 11 or 16mp camera - larger and deeper pixels. But at a much higher cost...

DT

For instance?

[gregbradley]

Originally Posted by bloodhound31

Thanks Greg. I take it with self guiding you don't need the separate guide-camera like a Lodestar or something because there's a chip in the main camera that does the job?

What about the MOAG or MMOAG? Do you still need that? I wouldn't think so if the camera is self-guiding.... Trying to make sense of it having never seen one set up and had a play with it.

I just sent an email away to Peter looking for a total package to go on the back of the RC300. Let's see where that goes.

Hey you guys I much appreciate all this. Once it all comes together I am sure I will be far better armed to pull the trigger because of all of your advice/experience.

Cheers!

Baz.

The only cameras that are self guiding are SBIG cameras as its an SBIG invention that is patented. Self guiding cameras are typically the ST series and STL.

The ST8300 does not have any guiding at all. I think its the STF and the STT that do. The STF has the OAG built in. The STT has the updated electronics and I think is compatible with the new filter wheels - Peter would know and you can also check the SBIG website.

MMOAG or MOAG are mega monster off axis guider and mega off axis guider respectively. They have a little prism that sticks down into the light path and reflects a guide star up into a guide camera like a Lodestar. This is what I use except I use an SBIG STi guide camera (same shape as Lodestar).

You would only need that if you had an ST8300 (the cheapest in the 8300 range of SBIG cameras) as it has no guide capability without it.

With an STF you could install your Lodestar guide camera in the built in off axis guider and have a guide cable going from the Lodestar to the mount.

The STT has better electronics and is compatible with the filter wheel with the guide chip in it. These are better solutions than self guiding inside the camera as that means the guider guides through the filters. Guiding through the filters is a problem imaging with narrowband filters are they require long guide exposures to capture the guide star like 30 seconds or more. That is too long for autoguiding. Hence the models above either have a built in offaxis guider (requires a Lodestar or SBIG STi guide camera) or the filter wheel has the guide chip in it and does not require a separate guide camera (nice and neat, one less USB cable and power lead).

If you price an ST8300 + MOAG plus filter wheel and 36mm filters as one option. Then STF8300 with OAG and filter wheel plus 36mm filters then STT8300 plus the guiding filter wheel plus 36mm filters you can compare costs.

Alternative would be FLI Microline 8300 + filter wheel and 36mm filters and MOAG. Or QSI583 or 683 WSG +25mm filters which has built in filter wheel and off axis guider.

There are other 8300 cameras on the market, Apogee Alta, Apogee Ascent, Atik, QHY, Starlight Express.

Just as a thought the FLI Microline 8300 is upgradeable to another KAF series chip later if you want. I was quoted $3750 by FLI to swap out my KAF8300 for a KAF6303E if I wanted. Not bad if you check the prices for KAF6303 cameras.

Greg.

[bloodhound31]

Originally Posted by gregbradley

The only cameras that are self guiding are SBIG cameras as its an SBIG invention that is patented. Self guiding cameras are typically the ST series and STL.

The ST8300 does not have any guiding at all. I think its the STF and the STT that do. The STF has the OAG built in. The STT has the updated electronics and I think is compatible with the new filter wheels - Peter would know and you can also check the SBIG website.

MMOAG or MOAG are mega monster off axis guider and mega off axis guider respectively. They have a little prism that sticks down into the light path and reflects a guide star up into a guide camera like a Lodestar. This is what I use except I use an SBIG STi guide camera (same shape as Lodestar).

You would only need that if you had an ST8300 (the cheapest in the 8300 range of SBIG cameras) as it has no guide capability without it.

With an STF you could install your Lodestar guide camera in the built in off axis guider and have a guide cable going from the Lodestar to the mount.

The STT has better electronics and is compatible with the filter wheel with the guide chip in it. These are better solutions than self guiding inside the camera as that means the guider guides through the filters. Guiding through the filters is a problem imaging with narrowband filters are they require long guide exposures to capture the guide star like 30 seconds or more. That is too long for autoguiding. Hence the models above either have a built in offaxis guider (requires a Lodestar or SBIG STi guide camera) or the filter wheel has the guide chip in it and does not require a separate guide camera (nice and neat, one less USB cable and power lead).

If you price an ST8300 + MOAG plus filter wheel and 36mm filters as one option. Then STF8300 with OAG and filter wheel plus 36mm filters then STT8300 plus the guiding filter wheel plus 36mm filters you can compare costs.

Alternative would be FLI Microline 8300 + filter wheel and 36mm filters and MOAG. Or QSI583 or 683 WSG +25mm filters which has built in filter wheel and off axis guider.

There are other 8300 cameras on the market, Apogee Alta, Apogee Ascent, Atik, QHY, Starlight Express.

Just as a thought the FLI Microline 8300 is upgradeable to another KAF series chip later if you want. I was quoted $3750 by FLI to swap out my KAF8300 for a KAF6303E if I wanted. Not bad if you check the prices for KAF6303 cameras.

Greg.

Thanks Greg, that is excellent information mate. The more I read back through all these posts the more it is all making sense.

Different folks do have different opinions and suggestions though. What are your thoughts on the 8300 chip being too small for the RC300, as David has mentioned?

Baz.

[renormalised (Carl)]

Originally Posted by bloodhound31

For instance?

http://www.bintel.com.au/Astrophotog...oductview.aspx

http://www.bintel.com.au/Astrophotog...oductview.aspx

both with one of these...

http://www.bintel.com.au/Astrophotog...oductview.aspx

[gregbradley]

Originally Posted by bloodhound31

Thanks Greg, that is excellent information mate. The more I read back through all these posts the more it is all making sense.

Different folks do have different opinions and suggestions though. What are your thoughts on the 8300 chip being too small for the RC300, as David has mentioned?

Baz.

Yes KAF8300 would not be an ideal match. They all work, its a matter of which works best. KAF8300 has 5.4 micron pixels.

Theory is sampling theory where you want around 3X to get a good sample of sound or light. Too small a sample and it means you are getting too small a slice of the available light to fall on each pixel. Then if that slice is below the seeing level then it will be more blurred as well.

So the target is 1/3 of your typical seeing. So if your seeing is around 2-3 arc seconds you get .66 to 1 arc seconds per pixel for ideal sampling. My CDK17 and Proline 16803 for example is at .66 arc seconds. That seems to work well. The 8300 though is more like .4 and I know from trying it that it loses sensitivity (due to too small a slice of the light falling on each pixel not because its less sensitive - its not).

If seeing is good then the 8300 would work. But you'd have to get seeing around 1.5 arc secs which is not many places in Australia.

Ron Wodaskis free ccd calculator shows all this. For 2.5 metres focal length you are going to want 9 micron pixels and this will give you about .77 arc seconds/pixel which is in the sweet spot. 5.4micron pixels will give you .45 which is too low.

I am about to try a Trius 694 camera with 4.54 micron pixels and high QE on my CDK17. I'll have results after the first clear night.
I'll probably end up using it on my refractors but who knows.

9 micron pixel sensors are the KAF6303E, the KAI 110002 and the KAF16803.

There's a reason the KAI11002 is still popular after all these years.
Its a 35mm sized sensor so you'll need a corrected circle that will illuminate a chip this large. From memory its around a 44mm diagonal of corrected imaging circle from your scope for it to work without vignetting and coma.

Greg.

[bloodhound31]

Looking at the MMOAG. It looks like you can't rotate the prism around the FOV as you can with say - the Orion Deluxe OAG.

What is the method then, for finding a guide star? Do you have to rotate the whole unit on the back of the focus tube?

Baz.

[Paul Haese]

Originally Posted by bloodhound31

Looking at the MMOAG. It looks like you can't rotate the prism around the FOV as you can with say - the Orion Deluxe OAG.

What is the method then, for finding a guide star? Do you have to rotate the whole unit on the back of the focus tube?

Baz.

You use a rotator Barry. Either motorized or manual.

[bloodhound31]

Originally Posted by Paul Haese

You use a rotator Barry. Either motorized or manual.

Right. Ta.

[gregbradley]

I have only occassionally had trouble getting a guide star using a MMOAG at 3 metre focal length. Sometimes it has meant moving the object from centre of the image off to one side. I don't rotate anything, simply use the joystick to move the scope a bit to one side or the other too look for a guide star. You can also increase the guide exposure length to bring up dim stars if your mount can handle it.

Greg.