Astronomik ProPlanet IR 742 1.25" or 2" ?

[astrorg]

Hi
It has been over a month doing no Deep Sky, Lunar or Solar imaging and need to get back - it is like I am drugged!

I was thinking to get a Astronomik ProPlanet IR 742 fro Lunar Imaging
QUESTION 1: but 1.25" or 2" ?

Also, I am guessing it would be of help using it for Deep Sky RGB images [especially with modified DSLR, to cut light pollution out more.
QUESTION 2: is it really useful for Deep Sky? I do have a modified DSLR + 178M/c cameras.

Thank you experts
Mauro
 

[wouterdhoye]

Hi,

The size of the filter will be dictated by the camera you use. For the typical planetary imaging camera's you're just fint with the 1.25" version. For larger chip camera's you might be better off witht he 2" version to prevent vignetting. Also depends on the chip to sensor distance. If money is no limiting factor you're always safe with the 2" version. 

The filter is totally useless for deep sky imaging as it only passes IR past 742nm. Waaaay too little light to be useful for deep sky imaging. For light pollution there are specific filters. i'd stick with those.

 

Wouter.