Andrea B. Posted June 30, 2018 Share Posted June 30, 2018 Here's the Visible Rainbow.D610 + UV-Nikkor + Baader UV/IR-Cutf/8 for 1/80" @ ISO-100Southwest Harbor, Maine, USA Observation: The actual rainbow was very much more vibrant looking than the photographic version. And the skies were really more dense with moisture and cloud/fog layers than is shown here. I have no explanation for this difference between actual rainbow/sky and photo rainbow/sky. What gives? :) Here's the UV Rainbow attempt.D610 + UV-Nikkor + Baader UV/IR-Cutf/8 for 1/2" @ ISO-200 First is the UV photo as shot.No rainbow can be seen. And the sky looks flat. Here is the raw composite (from Raw Digger). The histogram endpoints were move in to restore the usual contrast to the raw comp.No rainbow can be seen. Note the usual effects of "UV haze" (scattering of short wavelengths) in the distance. Here is my first harsh contrast treatment which does bring out a lighter streak in the sky where the UV rainbow might be if there is such a thing as a UV portion of the rainbow? Must be, else I would not have found this lighter streak. Note that this lighter streak is very much to the left of the visible rainbow shown above. And in this harsh version the density of the moisture in the sky is obvious. The harsh contrast treatment also brings out a circular reflection(?) artifact seen to the right of the light streak. This artifact is probably from the shiny BaaderU but I did not test further to confirm this. I suspect there are a lot more of this kind of circular reflection artifact in our typical BaaderU photos than we might want to look for. But it really took a lot to bring this one out, so I'm not too worried. Here is a second harsh contrast edit for the UV shot. Again the light streak and circular artifact become visible (light streak just barely). This time there are some interesting diagonal light streaks cutting across the sky. None of these lighter areas show up in the photo as shot (not shown).f/8 for 1" @ ISO-200Full disclosure: I cloned out some sensor condensation artifacts in the form of small round blobs. Very humid this day. I don't know what has caused the blobiness above the treeline on the right. I think that was something atmospheric. Link to comment
dabateman Posted July 1, 2018 Share Posted July 1, 2018 Great analysis.I don't think that circle is back reflections from the Baader (probably is), but rather you actually found the pot of gold at the end of the rainbow. Too bad you can only spend it in the uv world. Link to comment
Andrea B. Posted July 2, 2018 Author Share Posted July 2, 2018 Thanks, David. I think you're the only one who looked at this! Link to comment
otoien Posted July 2, 2018 Share Posted July 2, 2018 Here's the Visible Rainbow.D610 + UV-Nikkor + Baader UV/IR-Cutf/8 for 1/80" @ ISO-100Southwest Harbor, Maine, USAObservation: The actual rainbow was very much more vibrant looking than the photographic version. And the skies were really more dense with moisture and cloud/fog layers than is shown here. I have no explanation for this difference between actual rainbow/sky and photo rainbow/sky. What gives? :)While I do not have any explanation, I typically find that visible rainbows need some underexpose to saturate colors better together with some contrast enhancement. It is easy to overexpose and wash out colors. It is surprising that there is not more showing in UV. Perhaps try some IR next time. Regarding that UV-only pot of gold, it seems to be easy enough to spend it up in the UV world. :D Link to comment
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