Monochrome H-Alpha Venus Transit Timelapse Image

[CapturingTheNight (Greg)]

Hi all,
Just adding to all the other transit images.

I was absolutely blessed with beautiful weather for this event. I was fully prepared to pack up my gear and head off to chase clear skies but two days out from the transit all the weather forecasts pointed to a fine and clear day for my home area. I decided to trust it and I invited family and friends around to witness it with me. Despite many casting doubts over my weather forecast due to the persistent rain in the days leading up to the event, I never backed down and the day dawned with not a cloud in sight. It remained that way until about one hour after the transit had finished when the clouds started to roll back through. In addition to the Coronado solar scope I also had an 8" F/6 Dobsonian Telescope setup with a white light solar filter so that family, friends and I could visually observe the transit at the same time as my camera was doing it's thing on the other scope.



This sequence spans a 6 hour period from second contact (left) at 8:30am (Australian EST) through to third contact (right) at 2:30pm. The shots in between were taken at half hour intervals.

Canon 60D
Baader Hyperion 8-24mm Zoom EP
H-alpha Coronado PST (Personal Solar Telescope)
NEQ6 Pro Goto Telescope Mount
50 images stacked together in Registax 6 for the faint prominences around the solar limb.
5 images stacked together for the surface detail of the sun and one of the Venus images.
Additional 12 images of Venus processed individually and then layer masked on top of the background image.

By far and away the longest time I have spent on a single astro image. 2 hours or so of setting up and packing away gear. 6 hours or so of imaging. A couple of hours of downloading, converting and backing up the 1500 odd images that I took on the day. 9 hours of image editing, and it STILL isn't finished! I'll add colour tomorrow.

I think I'll stick to my landscape astrophotography. It's much easier.

Cheers

Greg

[Adelastro1 (Wayne England)]

Great shot Greg. I love the detail in your image.

I very hurriedly set up a work PST with my D7000 DSLR (finished getting the right adaptors for focus at 10pm the night before!) so didn't get to try it out first unfortunately. I'm also inexperienced at processing the images afterwards. I see that you used a DSLR as well so I was wondering what else, if anything, that you did to get such a fantastic image. It's a mono image that you have uploaded so did you use another filter at all? My images are red/orange and appear a bit out of focus I presume because I was capturing it as a colour image and the colours were in different focus. Is there a way to fix that? Here's a couple of examples.

Thanks,
Wayne

[CapturingTheNight (Greg)]

Originally Posted by Adelastro1

Great shot Greg. I love the detail in your image.

I very hurriedly set up a work PST with my D7000 DSLR (finished getting the right adaptors for focus at 10pm the night before!) so didn't get to try it out first unfortunately. I'm also inexperienced at processing the images afterwards. I see that you used a DSLR as well so I was wondering what else, if anything, that you did to get such a fantastic image. It's a mono image that you have uploaded so did you use another filter at all? My images are red/orange and appear a bit out of focus I presume because I was capturing it as a colour image and the colours were in different focus. Is there a way to fix that? Here's a couple of examples.

Thanks,
Wayne

Thank you Wayne As i understand it. A DSLR isn't the best thing to use to image through a H-alpha scope because of the Red Green and Blue colour profile. H-alpha is more registered on the R channel and the G and B channels only add noise to the image. What I do is I set the camera to monochrome mode. This does not solve the noise issue but I personally find it much easier to focus the image (through magnified live view) if I am not distracted by all that red. I then process the images still in monochrome and only add a false colour representation at the end. Stacking multiple shots in something like Registax helps bring out more detail but only if the detail is there in the first place. Looking at your images, focus might be slightly out but I think the biggest issue with them is that they are overexposed and you have lost the surface detail. Either that or you had the tuning ring thingy (sorry I don't know the proper name for it- t's at the back end of the gold tube before the black box) not set to capture the prominences. Turn it one way and the image gets brighter and all you can see are sunspots (and Venus) or turn it the other way and the image gets darker and the faint filaments and prominences appear. I have it wound all the way in that last direction. When taking an image you need to look at the histogram closely and ideally look at the individual RBG histograms. There will be two peaks in them. You want the right hand peak of the red histogram to be fully within the range of the histogram. That's all your data. If you have overexposed then this peak can be completely off histogram scale to the right hand side and all the data for the sun detail is lost. For surface detail I use an ISO of 100 and a shutter speed of 1/30th of a second. For the faint prominences I use a shutter speed of 0.6" of a second. Particularly for the surface shots when the image comes up on the LCD it should be very hard to even see anything at all (unless you have the camera and your head in a very dark box) but all the data is there. I typically have two sets of images. One for the prominences and the other for the surface detail. I then paste the surface shot on top of the other one so that only the prominences are sticking out around the edge.
What were your camera settings for these shots?
Cheers
Greg

[iceman (Mike)]

Looks really nice Greg, would love to see a larger image!

[CapturingTheNight (Greg)]

Originally Posted by iceman

Looks really nice Greg, would love to see a larger image!

Thank you very much Mike It's coming. Once I am completely happy with it (within the limitations of the equipment used) I'll get some full size views up somewhere.