Lunt CaK B1200 + PST #1 yellow

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george9
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Lunt CaK B1200 + PST #1 yellow

Post by george9 » Mon Oct 01, 2018 12:02 am

I was experimenting with a PST #1 yellow filter with my Lunt B1200 CaK. I was testing on a 70mm F/6.8 doublet. I only have an R2 Revolution imager, so no reasonable photos to show. I will try to attach iPhone shots of the R2 monitor.

Lunt with the yellow filter vs. Lunt without:

1. Gain had to be increased from 6dB to 18dB, so it was dimmer.

2. It seemed a little higher contrast between the active region and the rest of the disk, within the limits of the R2.

3. I think is could see more subtle variation within the active region itself.

4. I could not see the H-alpha filament in either one.

5. I could see subtle linear details in both, but perhaps better with the yellow filter but not sure.

6. There was a faint reflection with the yellow filter that I could tilt off axis. It only showed up at higher (e.g., 42 dB gain).

7. Prominences were visible only in the solo Lunt (at about 42 dB).

Some of the difference in contrast, perhaps, could be the change in brightness and the fact that the R2 has discrete gain settings. Maybe the dimmer version just lined up better with the R2's thresholds.

So I probably will not be able to tell much more unless I move up to a real camera and computer.

I may just sell the PST CaK, stick with the Lunt Cak and R2, and put my investment mostly into H-alpha because I am mostly visual.

George
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TheSkyBurner
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Re: Lunt CaK B1200 + PST #1 yellow

Post by TheSkyBurner » Mon Oct 01, 2018 1:39 am

do not sell it for too cheap, these things are worth no less than your b1200 filter; and the demand for them is insane.

keep in mind it is much larger than the b1200, and supposedly has narrower bandpass. I ask no less than $700 for mine. That is more than fair for how rare these are.

people are saying they are dual or triple cavity filters. That places them in the thousand dollar range by manufacturing standards.

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Re: Lunt CaK B1200 + PST #1 yellow

Post by marktownley » Mon Oct 01, 2018 6:14 pm

This using the filter that is in the end of the gold tube / entrance to the black box George?
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george9
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Re: Lunt CaK B1200 + PST #1 yellow

Post by george9 » Mon Oct 01, 2018 9:19 pm

Yes, the first filter after the objective lens. It is thin and yellow and 25mm in diameter. The one after it is mirror-like. Then the black box.

(In case it's not obvious, the image with the 18 above is the one with the yellow filter. And thanks for the advice, Apollo.)

George

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