Causeway Coast Sun Apr 23 - CaK closeups

[brianb11213]

See "white light" thread for preamble. Equipment used, William Optics FLT 110, Lunt B1200 CaK diagonal, 2.5x Powermate, Imaging Source DMK21AU618.

AR 11459, 1611 UT:


AR 11460, 1615 UT:


AR 11462, 1610 UT. Note that the bridge in the spot nearest the limb is differently orientated to the white light shot taken a few minutes earlier:


AR 11465, 1614 UT:


AR 11466, 1616 UT:

[marktownley]

Nice closeups there Brian!

[Cschur]

Those are some of the sharpest calciums I have ever seen. Your seeing in UV must have been phenomenal!

[brianb11213]

Your seeing in UV must have been phenomenal!
You'd be surprised. AT least I didn't have the usual jet stream smearing to put up with, but there was continuous changes in focus and a fair bit of image movement - except that just occasionally (usually after a gentle gust of wind) the image would settle down and be sharp & reasonably steady for a half a second or so. I work on the basis that I'm going to shoot at least five times as many frames as I stack; usually it works out that if I shoot 2500 frames (which takes about 45 seconds) I can get a reasonable image. If the seeing is wobblier then I shoot more frames & still end up stacking the best 500.

The real key to getting sharp images in CaK, I've found, is to be very very careful getting the focus as accurate as you can. It usually takes me 5 to 10 minutes before I'm happy. Keeping the focal length reasonable is a good idea, too, if you go too long then it becomes much more difficult to focus & the longer exposures mean that the seeing gets more of a chance to wreck things. Either that or you shove up the gain & need to shoot more frames to keep the noise down.

Just here we've had some pretty good seeing this month, well unusually good for this part of the world, quite surprising really with towering shower clouds all around. I don't know where the jet stream has gone to but at least it isn't parked overhead, which it often is in this part of the world.

I was in a bit of a rush yesterday as I was unable for reasons of bad weather in the morning & unavoidable commitments in the afternoon to start shooting until the sun was starting to get low. If I'd have had more time I would probably have tried some shots with the 4x Powermate.

[Bill E.]

wow they are great....k2u

[edobosz]

Excellent images there with fine details.
Ted

[GaborKiss]

I love them, great work!

[swisswalter]

Hi Brian

excellent CaK close ups

[Derek Klepp]

Brian third pic seems you've caught a jet in CaK.

[Montana]

These are all incredible Brian, I think pic 3 tops them all, that certainly is a very fine feature!

Alexandra

[GaborKiss]

Great images Did u use full aperture the scope or reduced tó 100mm which is recommended for the CaK by Lunt?

[brianb11213]

Did u use full aperture the scope or reduced tó 100mm which is recommended for the CaK by Lunt?
I got lazy & stopped bothering with the aperture reduction. In any case the solar radiation here at 55 deg North & sea level is a lot less intense than it will be for those nearer the equator & at higher altitudes ... I've given up putting my eye to a CaK filtered scope since I know I'm going to see nothing, so what risk there is falls on the camera alone.

I certainly would reccomend stopping down or using an objective end energy reducing filter of some sort or other if using the Lunt CaK modules with an aperture considerably larger than 100mm. 120mm, ummm. 140mm, no thanks, just too risky.

[florencior]

Impressive detail! I liked them all.