Let me start by stating that I'm fairly new to astrophotography. I have a Canon 6D Mark II with an EF 24-105 F4L IS USM lens and a Rokinon 14mm F2.8 lens, a Manfrotta tripod and an iOptron star tracker. I've done a ton of research and tried to plan thoroughly for a recent Milky Way shoot in the Anza-Borrego desert last weekend. I took about 20 shots with the Rokinon lens at ISO 1000, f2.8, 120 second exposures. I had to toss 8 of them because of planes flying through, but that still left me with 12 decent images. I shot 7 dark frames and 10 offset frames. I tried to capture flat frames using the white T-shirt method but I could clearly see uneven lighting through the material so I figured they were going to do more harm than good and skipped that.
The star tracker was aligned very well - reviewing the raw images in Lightroom 6 and PaintShop Pro showed no visible migration of stars from one image to another, even when zoomed way in at the corners.
I used DSS to stack the photos and made sure that the “embed changes but do not apply them” box was checked before saving the final image. When I imported that into Lightroom 6, the image was very dark. The stars and Milky Way appeared only after boosting the exposure - a lot. But the final image was nearly colorless, save for a strong yellow tint. I tried everything I could in Lightroom to draw out the colors, but the results never came close to the original images in terms of color accuracy.
Making matters worse, while I had no problem applying the Rokinon lens corrections to the original raw images in Lightroom (it appears in the list under the "Custom" setup option), it would not offer me the Rokinon profile when editing the TIFF file - the list only includes the default lenses. So I cannot eliminate the slight fish eye effect or the blurring of stars in the corners. That would seem to be a non-starter for me.
So I decided to try it another way. I edited all 12 of the raw images in Lightroom first, exported them to TIFF files, and then let DSS do the stacking (no dark or offset frames used). The results were much better. The colors were intact and the air glow was substantially reduced.
This leads me to my questions:
1) Does anyone know how to apply lens corrections to TIFF files using Lightroom 6 if they aren't in the Default list?
2) Every work flow I've read on line has the stacking done first and then the final editing in Lightroom or PhotoShop. But in my case, that just didn't work very well so I'm wondering if I'm doing something wrong or if reversing the order is more commonly done than it would seem?
I've attached some files to show you what I'm seeing:
IMG_0499.JPG: This is a sample of an original, unedited Light frame.
IMG_0499.-1JPG: This is the same shot, editing in Lightroom with the lens corrections, tone curve adjustments, and a little sharpening (nothing else).
DSS Output.JPG: This is what the DSS stacked output looks like once imported into Lightroom (screen shot)
DSS Output (exp+3).JPG: This is what the DSS stacked output looks like once I crank up the exposure by +3 (screen shot). Notice the absence of all color except for a strong yellow tint.
DSS Output (TC and WB).JPG: This is what the DSS stacked output looks like once I make soem slight adjustments to the tone curve and dial down the temperature (-18). The yellows are weakened but not completely gone, and half of the stars are now blue in color, which is clearly unrealistic.
Milky Way (PSP).JPG: This is what the final image looks like if I edit the raw files in Lightroom first, then stack using DSS. Although some stars are still too blue in this image than I would like, the colors of the Milky Way are more accurately reproduced than when I stack first.
But there isn't that much difference between the 2nd image (single edited RAW sample) and the final image (stack of edited samples. So I'm not sure I'm even achieving the desired result here.
I've read countless posts by other people who are losing color in the DSS tacking process. I've tried many of the suggestions for adjusting various settings, but nothing seems to work.