Coronado PST with Celestron NexImage camera

[Gerontius]

I am trying to use a NexImage camera with my PST; I've read that it is not possible to achieve focus with a camera directly coupled to the PST but a Barlow lens is required. So I have used my Meade 2x Barlow between the NexImage and the PST but still can't get focus.

Where am I going wrong please?

Has anyone used the NexImage with a PST?

Any advice would be appreciated.

[Photosbykev]

The focus plane on the PST is only 5mm above the top of the eyepiece tube so you either need to use a barlow to move the plane outwards or ensure that the sensor chip is inside the 5mm plane.

If the sensor on the NexImage is more than 5mm inside the camera body then the barlow is the main option.

It is also possible to completely tremove the eyepiece tube from the PST and it will split in half, this would allow you to only use the top half of the eyepiece tube and get everything much closer.

NOTE: while this is possible it will involve losing one of the rejection filters so it is unlikely the PST would be eye safe in this configuration.

With my PST I can achieve prime focus with a DMK41 if I remove the C/CS thread adaptor and position the front face of the camera body in contact with the eye piece OR use a 2.5x Powermate.

[Gerontius]

Kev

I am using a 2x Barlow but can't get focus - do I need to modify the Barlow?

[Peter Drew]

You could try unscrewing the Barlow lens and fit this to the camera nosepiece.