Equipment

I have a 70mm diameter Baader Planetarium CERF mounted in a cell made by Ambermile Astro (Arthur Edwards) and two adapters.

Using the PST etalon removed from the PST with the Boa constrictor tool (after removing the rubber cover and the locking screw so the adjusting ring is removable), I have a telescope that can be setup three ways.

A 40mm aperture Hydrogen alpha scope without the PST etalon (as it was before)

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A double stacked 40mm aperture Hydrogen alpha scope

A 67mm aperture Hydrogen alpha scope

The assembly is done with adapters made by Ambermile threaded onto the PST etalon as in the photo below. The left hand one is the 2" focusser adapter that has been made before and the right hand one fits the etalon, is 54mm long and has a 1 1/4" fitting to take the Coronado BF10 diagonal.

I have recently added a DMK 31AF03 camera to my equipment which has increased the frame rate from 5fps (Toucam SC3 and Pro b/w) to 30fps (less in practice, probably 10), and the resolution from 640x480 to 1024x768. The IC Capture software also allows more control of the exposure and dynamic range.

 

Results to date 24/11/06

I have been able to confirm that the ED80 will reach focus easily with the PST etalon, with and without a Barlow lens.

The etalon does give H alpha images in both arrangements and is easy to optimise. I have not been able to make comparitive images to test the resolution, mainly because of rain, cloud and gales, but I will post results as soon as I can.

Using the PST etalon and 67mm CERF seems to give quite a bright image at the eyepiece. I don't think I will be looking longer than I need to set up for imaging. The sun is so low at the moment it is difficult to get comparison shots but I am planning to do this as I am able.

The contrast was not so good as the SM40 but there was a small improvement in resolution.

I felt that the ED80 and 67mm aperture was very promising so I decided to try a longer focal length low quality scope. The quality was not important as the application is monochromatic.

The first image is using the ED80 and SM40/BF10 with a x2 Barlow lens (1200mm focal length), the one below it is using the 67mm C ERF and the 1000mm Helios and PST etalon/BF10. I prefer the 1000mm image.

 

Results to date 10/07

I have been pleased with results of the 70mm C ERF (67mm aperture mounted) and the secondhand 120mm Helios f 1000mm achromat, particularly with prominences. I started doing animations of these. Then I decided to try improving the resolution with a larger aperture filter on this low quality scope. I am now using a 110mm C ERF that mounted gives an aperture of 105mm. There is a marked improvement in resolution. It all needs more testing and improving. It will help to have some more solar activity to focus on.

In 2008 after some discussions on the UKAI solar equipment forum I cut 50mm off the tube to get the etalon into the best postion in relation to the focal point of the objective. That is to match the position of the etalon in the PST. This has improved the contrast and made better images of the solar surface. It still has a sweet spot problem but by fiddling about this can be minimised.