Offaxis guiders opinions?

[gregbradley]

I do use my large format camera with the reducer as well. F4.45 and 17 inches gives faster images. I want the scope to be versatile. An OAG or a self guided camera is a necessity these days at the minimum for best images.

Cropping does not seem to emulate the above.

Greg.

[ericwbenson (Eric)]

Originally Posted by gregbradley

I do use my large format camera with the reducer as well. F4.45 and 17 inches gives faster images. I want the scope to be versatile. An OAG or a self guided camera is a necessity these days at the minimum for best images.

Cropping does not seem to emulate the above.

Greg.

Perhaps Paul meant binning. Cropping would be used to get rid of off-axis aberrations, for the CDK they are low and the reducer would most likely make them worse (but further out in an absolute FOV way). Binning or resizing the image accomplishes the same as the reducer EXCEPT for the smaller FOV. You get the same shorter subs out of the reducer and binning, and of course in both case you don't get more signal per unit time. So again, what is the reducer for...FOV, is this what you are after?
EB

[Paul Haese]

Originally Posted by gregbradley

I do use my large format camera with the reducer as well. F4.45 and 17 inches gives faster images. I want the scope to be versatile. An OAG or a self guided camera is a necessity these days at the minimum for best images.

Cropping does not seem to emulate the above.

Greg.

I was thinking that if you crop you could produce a similar field of view. That being with the larger format at native f ratio and the smaller format with reducer. Surely an AO with the larger format camera would produce exceptional results, instead of having to go down this path with the smaller format camera????

What are the sampling rates for both systems?

I had not considered binning either, just cropping.

[gregbradley]

You bring up interesting points. Perhaps it is indeed better to AO the larger camera and crop the result if I want that. I certainly intend to do more imaging with the larger chip. I also intend to take my CDK to my dark site at some point to get access to better skies/seeing for it.

I intend to do both. An AO unit is on my wishlist.

The Trius though works quite well in that its 77% QE and 66% QE in Ha and about 60% in O111 with half the read noise of the Kodak chips.

The reducer gives it a wider FOV otherwise I found in some images it was too close up and that is not always a good look.

Binning the Trius also works well as they are half the size pixels of the 9 micron Kodaks and binning gives a similar look to the Kodaks but at several times the signal to noise ratio. So its a fast road to China.

As far as the CDK goes I don't see any aberrations out wide, its perfectly corrected. So no problem there with the large camera. The smaller camera is less susceptible to gradients, in fact I haven't had any trouble with gradients. Gradients are an issue with the large camera and I have to process them.

The Trius seems to be an excellent narrowband camera with the option of binning available for even a faster boost to data acquisition.
Its not without its faults but I see now FLI and QSI offer models using this chip. Also Wolfgang Promper is now displaying some Namibia images using a FLI MIcroline 694 camera that are quite nice.

I find the camera a bit hit and miss on my large refractor. Perhaps the small one it may be better. I get some bad haloing on bright stars on the TEC180. I don't with other cameras. I am wondering if it needs a bit more UV/IR block on that scope as it may be more sensitive to UV/IR than the other cameras.

Greg.

[SpaceNoob (Chris)]

If only these sony sensors were just a bit bigger....

[gregbradley]

Originally Posted by SpaceNoob

If only these sony sensors were just a bit bigger....

Yes that is true. They are a bit small.

A full frame one would be amazing.

Greg.