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back focus
Posted: Wed Oct 19, 2022 2:54 pm
by willow
I am currently set up with an f/6.3 reducer that provides a 105mm back focus to my ASImc183pro color camera. If I remove the focal reducer for planetary imaging will I be able to obtain proper focus or will I need to add an adapter to bring the system back to 105mm back focus?
Re: back focus
Posted: Thu Oct 20, 2022 1:22 pm
by admin
Hi,
I guess you are using an SCT of some sort to end up at f/6.3 with a reducer. Normally SCT scopes have a very wide range of focus, so it is unusual to run into issues with not having enough back focus (or not having enough 'inwards focus'). Remember that the focal reducer tends to bring the light to a focus in a more steeply inclined cone than without, so removing the focal reducer will most likely push the focal point away from the telescope, which you will need to compensate for using the focusing knob.
cheers,
Robin