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
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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