White light sun 23/05/2012

[RikM]

Shot this morning using an ST80 with Baader film over the small cap aperture. I used a QHY5 guide camera and QGvideo for capture. I used a dead barlow as an extension tube and added Meade ND0.96 and IR cut filters stacked. The whole lot sat on a camera tripod, so no tracking

Exposure 10ms and gain 10%, 60sec at 9 fps, stacked with AS!2 keeping the best 30%. Wavelets in Registax 6, final tweaks in CS3.

The streaks are dust bunnies but I haven't quite got flats sorted for white light

Anyway, I'm quite happy with this for a quick shot with stupid equipment. It would be handy to use Castrator to crop and centre the sun in the avi first, but it only allows up to 640x640 so the whole disc doesn't fit, so if anyone has any ideas how to solve that please let me know.

[Bizibilder]

The equipment may be a bit "unique" but the image is exellent. You certainly have all the basic detail there.

[spaceboy]

Hi Rik

I am considering getting an ST80 for several reasons and solar imaging/ observing is one of them. May I ask, have you tried the ST80 with a full aperture mask and did it improve the image or not ??

[RikM]

I do have a full aperture mask for it and for visual use with nice eyepeices at highish magnification 10mm or 7mm Pentax XW it is very nice indeed. With lower magnification you get a very noticable green ring round the edge of the disc and the image is almost too bright and low contrast.

For public outreach events I use the stock 25mm MA and 2x Barlow and the small aperture and this is really quite a nice sweet spot. Good contrast, sharp detail, no discernible colour fringing and it sits okay in a rucksack with a camera tripod. Not quite as nice a view as my masked down Newtonian but much less effort and more portable.

I haven't been able to try it for imaging with the full aperture because I can't use a short enough exposure or low enough gain with the QHY5. It just blooms / whites out, even with the ND filter. I suspect with a decent mono camera (DMK41 on the list for Santa this year) it will be really good.

[spaceboy]

Thanks for the info Rik. It is interesting that you say you get a ring around the disc as I was led to believe CA was not so much an issue when using solar filters on the sun??? Some thing to do with wavelengths and all that??