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Filaprom just


Davey-T

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Only managed one vid before the clouds invaded, lots of big blue patches but not where the Sun was  :sad:

Didn't capture much of the filament bit but that may be my rubbish processing skills.

Quark Chromo, PG BFly .5X f/r,100mm refractor.

Dave

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Viewing the filaprom today I thought it seemed rather tenuous other than when light cloud passed over it giving the usual "double stacking" effect. Superb images on Solarchat give the filaprom a definite "see through" appearance.  :smiley:

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I had a quick play, but could not do much better yet,it is not easy data to process. Contrast in the filament is a lot lower than in my captures from today. On the one hand that made me wonder whether the etalon was perfectly on band, but the surface detail looks pretty good. I will give it another go tomorrow

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The guy on Solar Chat used an "inverted filter" to bring out detail.

Anyone know where I can find a tutorial on that ?

Dave

Inverted filter might simply mean inverting the grey scale (like my part inverted shots that often reveal more detail in he spicules and prominences), or they may mean an inverse filter. This is a form of deconvolution prone to letting noise explode, so I would say LR deconvolution may be better.

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Thanks Daz, looks a bit more filament on the disc on yours, it was only 50 frames of 1000 of a poor video, looking on Gong it's still there so am going out for another try if the clouds stay away.

Dave

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I had a quick go too, I found it tricky Dave and dazzaa's done a cracking job there I think.

I am not sure but my feeling was that your tuning was a slight touch off. So I would suggest try taking some images with your current tuning and a few different tunings either side of it (try two or three notches apart if possible), recording a movie or two at each tuning, then see which one comes out best.

Probably my tuning is not spot on either, must play with it properly some time. I just don't seem to be getting nice long sunny days at the weekend.

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I tuned my Solar Spectrum filter from 43-49 ℃ and found the response quite consistent over large range. Between 44℃ and 48℃ it was hard to call a difference. There is quite a wide range of values that give good results, so I stuck with upper 45℃ as a sort of optimum. I would expect quarks to have a similar wide range of settings that work well (although the wider bandpass of the Quark might require finer tuning, I don't know).

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I think you are right, Michael, I accidentally recorded three clicks clockwise of my default one session, and they look okay (phew!) One click I think is a fairly minimal difference, so I would try two or three clicks apart. I may be wrong but I have imaged with about four different Quark's and Dave's image feels a touch off and a bit like when my tuning has been slightly off. Still looks nice, but I think it might get a touch better and then easier to process.

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I never seem to get a long enough session to be able to experiment, just been out and done a few vid's, not so much cloud today ATM but a gusty wind, I've had to cut down to 1000 frames and try to anticipate the wind and hope the vid finishes before the next big gust.

But I've managed more today than yesterday so far  :smiley:

What's the theory behind the tuning, I thought it was something to do with the centre of the Sun being closer than the proms so you could tune it accordingly, which way do you tune it for  closer / further ? or am I talking XXX as usual  :grin:

Dave

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Nothing to do with distance, just to do with matching the wavelength passband of the etalon to the centre of the H-alpha line. You can get slight changes as you tune near centre from material moving at different speeds. A bandpass of 0.7Å is equivalent to about 31.5 km/s resolution in radial velocity. The 0.3Å bandpass I use to 13.5. With the Lunt LS35 I have once or twice tweaked tuning and actually seen certain areas of proms brightening and fading as I tuned.

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