Barlows, CCD and lens problems.

[Specman]

Hi

I have been messing about with my NexImage CCD camera with a 2x Barlow and struggling the get the image focused. It then occured to me that the focal lengh was equivalent to a 5mm eyepiece which is beyond the useful power of the scope (Nexstar 4SE, 1300mm)

So, dont ask me why, but I thought it was a good idea to buy a 5x barlow . I know, I was having a senior moment! I would have been better buying 3x as it would have been more useful with my set of lenses (I could of course stack them if I ever needed 5x).

I found out that Celestron do a NexImage reducer lens that converts the camera to an equivalent of a 11mm lens, with a wider FOV so I have that on order.

My question is:

Is that 5x ever going to be of any use to me?

I have the revelation eye piece set containing 9, 12, 15, 20, 32mm lenses.

I also have two Celestron X-Cel lenses, 25mm and a new 8mm (I got the 8mm for the eye relief and FOV, as squinting through the 9mm Plossl was awkward wearing specs)

Any advice anybody has on using the NexImage would be appreciated.

Clear skies

Mark

[brianb]

I have been messing about with my NexImage CCD camera with a 2x Barlow and struggling the get the image focused. It then occured to me that the focal lengh was equivalent to a 5mm eyepiece which is beyond the useful power of the scope (Nexstar 4SE, 1300mm)

x2 Barlow is probably about optimum for high resolution imaging with your scope. Focusing isn't easy & will be next to impossible unless the seeing is good & the scope is properly cooled down to ambient temperature.

I suggest you sell on your 5x, such devices are pretty well useless except with scopes with a short focal ratio.

[TheThing]

You should be able to bring it to focus with a 5x, it will just be very easy to miss the 'sweet' spot of focus.

I have been using a 1.6x stacked with a 2x in my newt giving me, effectively, magnification of 450x. Way too much to use visually, but I managed to get the eade LPi focused on the moon thru it. It did take a lot of back and forth with the focuser t get it spot on. I've also got an extension tube to give me more back focus. You may find that you need to pull the Barlow et al out of the focuser if you cant back focus enough.