16.3.2020 Lunt B1200 S2 straight through blocking filter.

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 Monday 16th. Overcast but clearing to large plates of cloud with very little blue coming from the west to SW.

12.00 51/48F [In/Out] Reset date and time in AWR. Then mostly thick cloud.

12:30 Still waiting for enough sun to center image, Sync in CduC and focus the telescope. Overcast! If it wasn't so still and mild I'd give up.

14.26 53/49F.  Overcast after lunch too!



The Lunt B1200S2 blocking filter has arrived from Bresser.De. via DHL. Excellent and very quick service from both.

This Lunt BF has male T2 threads at both ends. 1.25" receptacle with bronze clamping ring and two thumbscrews at one end. 2" OD body at the other end. The internal components are locked in place with what appears to be blobs of clear silicone. This is to stop the ignorant from removing vital components which protect the yes.

A 2" barrel extension tube with internal thread is supplied. The views through the filter are deep red.

I have screwed my ASI174MM camera to the T2 thread at the "thin" [eyepiece] end. Though I could have used the 1.25" adapter. I also used an adapter at the telescope end to have its thread match the 2" helical focuser. Thank goodness for having a broad selection of adapters.

14:40 I am still waiting for some sunshine. To see if I can achieve focus. Or whether to try different adapters.

14:50  Brief sunshine allowed me NOT to achieve inward focus. So I dispensed with the 1.25" receptacle and screwed the camera directly to the main BF 2" body, T2 thread, at the tail end.

The field of view seems much larger than the PST 5mm BF but the constant cloud is making etalon tuning progress very slow. The images right are 800x600 with the new BF. The surface structure after iMPPG is very 3D without looking too artificial.

There are large areas of brighter and darker at 1936 x1216. Not what I'm used to with the PST BF. Though I do have very clear surface structure.

The well focused BF filter stack layout is shown at image right.The 2" body of the Lunt BF is now completely hidden inside a 2" x T2, threaded, 2" barrel adapter.There is hardly a full second of clear sun to capture any videos. The image brightness across the image is highly dependent on an absence of cloud.

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