help with Saturn

[red dwalf]

here is my second image of Saturn, still not very sharp and not much detail, but not certain what i`m doing wrong, should i be using a IR filter and can anyone recommend one ? have been looking at a Astronomik Pro-Planet 742 Filter, not certain if this is the right one for me as it`s recommend for 6" and over scopes and mine is 5.1" but i`m hoping to go bigger in the future, also i was only using a 2x barlow taking my f5 scope upto f10 so do i need a higher f rating, trouble is when i use a 3x barlow i can`t find the planet in the field of view.

any help gratefully recieved.

[Brinders]

I use an Atik IR block filter using my Neximage for imaging the planets and moon (the CCD is the same as the Philips SPC900NC web cam) available from Modern Astronomy.

I think though, that you may be expecting a little too much of your scope. With the brighter planets it is focal length that is required as much as aperture, and while using a barlow will increase the image size on the chip through your scope it will not make it as big as I think you are probably hoping for and barlows present their own problems with degradation of the image. You must also consider atmospheric conditions that will affect the final image. Good seeing is essential for Saturn and Mars.

As to getting the image on the chip, with high magnification this can be a problem. I advise using an out of focus image to get the subject on the chip then focusing and moving the scope in altitude and azimuth with the controller as you focus. If you are using hand controls it will be more difficult.

Finally, newtonians are diffcult to get focus on a CCD chip as there is quite often insufficient inward focus without having to move the primary further up the tube, although a barlow may negate this.

Brinders