24.02.2020 Undoing the harm?

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Monday too. My old 6" f/8 PST H-alpha telescope had an internal D-ERF. This made converting it to white light use, at a whim, rather difficult. 

My new H-alpha telescope has an external D-ERF. So it could be quickly converted for white light imaging with the Herschel Prism. The internal filters could be removed or simply left in place. The monochrome camera doesn't care [much] what colour it sees.

The reason for this latest rethink? The change in the mounting's behaviour with the addition of the 7" f/12 refractor. It is so long and heavy that it rather dominates the mounting. The 6" F/10 on its own was crisp and completely effortless. It required only one 5kg weight to balance and that was marginally too heavy. So that I added four brass weights to the saddle to achieve perfect balance.

The external D-ERF would need a secure location when not in use. It's removal is simple and foolproof. Three, large, nylon thumbscrews. A slight complication is the dew heater but that is hardly a major problem to solve. 

The tail end would need the PST stack removed. It would be replaced by an empty 2" extension. I could add the helical focuser to obtain extra length without effort and have focusing included. 

Another option would be to have a full aperture Solar foil filter for the 6" to replace the D-ERF. 

Food for overnight thought? I think so.

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