I don't really know how to do this but I opened all images in photoshop and then stacked in order from 8.30 until 2.30 at half hour intervals. For each new level I did luminosity and moved the top sun so its edges lined up rather than sunspots as I figured they would have moved during the transit. Once on top I made the top image darken so Venus became black. Any advice would be welcome as we have been linked with another school in Honk Kong so I want to try to align them as well as possible.
I was thinking about doing something similar but by taking the pics, converting them to an avi in Vdub and aligning using castrator and then try a stack although it sounds as if I might be over-complicating things.
I'd be stoked with a result like that.
edit:
Actually my method doesn't work well, the compression doesn't like the bright disc of the sun.
Nice work Mark For my composite transit image http://www.iceinspace.com.au/forum/s...ad.php?t=92098 I selected one set of images near the middle of the transit when the seeing was better as the background sun image. I then copied and pasted the other twelve image sets on top of that background image as individual layers in normal overlay mode. Then working through each layer individually by having only it and the background turned on (the eye symbol), I set the opacity to about 50 percent and lined them up based on the solar disc. Once they where all lined up, I then went through each individual layer again this time at 100% opacity, and using a layer mask on each layer I painted out everything bar a small area around Venus. Once this was done for each layer it leaves just the background image with it's single crisp sunspot regions (and any other features) with Venus "time lapsing" across the disc.
Cheers
Greg
I used GIMP to stack my images taking only the quarter of Sun that contained Venus but not the sunspots and pasted as new layer. I lined up the two edges of the Sun (from the quarter) with 100% opacity but then used a "Darken Only" mode rather than "Normal". I'm not sure what the equivalent is in PS but it only kept Venus and nothing else from the quarter. If the image was darker than my base image I brightened it slowly until the base image came through.
For my composite transit image 
