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Sunday 20th 12.00 61/57F, thin high cloud softening the image. Interestingly, there is little of the usual thermal, image movement. It just keeps going lowly in and out of focus instead.
Following a suggestion on the Solar Chat forum I have added a 2" extension to the protective filters. [Baader 35Nm and KG3.] They are now well inside the back plate. Which should spread the thermal load more evenly over the filter surfaces.
Total distance from the filters to the PST etalon is now about 100mm. The D-ERF still transmits quite a lot of heat with a 6" aperture. Anything which reduces the thermal load on the PST etalon and following filters is helpful. I have more M48 spacers on the way. Note that these are not the usual 2" sliding fit, extenders.
Here are a couple of pictures of the entire H-alpha, etalon and filter train to show all the components. As I have labelled one image there is no point in repeating the list. I hope you can see how a reliable PST modification looks when applied to a 6" f/10 refractor.
It took some time to eliminate weak points in the chain. I found that the smaller diameter threaded adapters sagged. Particularly the T2 helical focuser when heavily loaded by cantilevered components. So I changed it from a T2 to 2" long throw. Now the whole stack is in 2" until the step down to the T2-1.25" camera adapter. *
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