The photographer is looking for generalized feedback about the aesthetic and technical qualities of their image.
Description
At 6:14 this morning, 17 min after it rose just off the left edge of the frame – it’s moving pretty fast now. (Sunrise was at 7:05.) This is at 400mm (full frame sensor). I could have gone to 500mm but wanted to frame both some horizon and a few stars near the top to check focus. It’s close to the sun so it rises in the morning twilight – not ideal for the dim tail. I enhanced contrast a lot here to make it show up as much as possible. It was not visible to me, but it was visible in the viewfinder with live view. At this focal length it took 1/8 sec SS to avoid star streaks. The lens is f/5.6 at 400mm and I needed ISO 2500 to get a decent exposure.
It will be visible to the east before sunrise for a few more days, with a very low horizon.
Specific Feedback
All comments welcome.
Technical Details
Mostly described above. There was a lot of noise as I increased contrast, and LR Enhance at the 50% default did a better job than Topaz with any of its options. I would have tried DXO Pure Raw again but my trial has expired and I’ve tried it on many difficult files and I’m totally done with it – LR Enhance has been just as good in every case and much more convenient. Topaz is still very good in most cases but Enhance is better in a few where I need a lot of contrast enhancement like this one. Enhance gives me a DNG raw file that lets me fine-tune settings. If I use Topaz I’m in PS with a rasterized file and don’t have the tonal overhead needed to use the LR Develop settings further. (Yes, I can use them, but far better to do it in the raw converter before going to PS. Once a file has been saved in PS I will do all further adjustments in PS.)
Critique Template
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@Diane_Miller I’m curious how you got the 1/8 of a second? I put my FF camera (Nikon Z8) into the Spot Stars App in photopills. I put in the 400mm and f/5.6 (I assume aperture does not matter) and I got 0.49 seconds using the more conservative NPF rule. So I would have thought you could have gone close to 1/2 a second? I attached my screenshot. Might be a difference in the sensors too - I’m sure pixel pitch factors in there.
I’m one of those irritating pixel-peepers! (Don’t invite me to your cocktail parties…) I’ve actually never shot an un-tracked astro shot at such a long focal length, so I aimed at some stars and shot a test and zoomed in on the playback and kept increasing SS until I got minimal star streaking, as that would also streak any detail in the comet. (Of course, as small as diffuse as the comet is right now, there really isn’t any, but I’d like to get what I can.) So I was happy with 1/8 sec.
BIG caveat: Any sort of camera shake will be deadly at this level of detail. I turned off IS and shot with a remote release and let the camera settle down after touching it. Used a very sturdy tripod (RRS carbon fiber, legs fully spread and “stretched” and heavy-duty head (Gitzo fluid-damped gimbal) locked tight. That leaves atmospheric thermal turbulence, which I can’t control, but it is usually a little less of a factor in early morning with cool air. Proper astro processing using a tracker and telescope deals with it by shooting many, many exposures (hundreds if you can) and averaging them out in special software with maddening steps, but it’s mostly automated just in the last few years.
You’re right, pixel pitch does factor in, as does lens quality and sharpness. Aperture shouldn’t be a factor except in edge/corner sharpness.
Another big caveat – don’t rely on focus peaking to focus. Use manual focus and zoom in on a star – or the moon.
Congratulations on at least getting an image of the comet. I had a perfectly clear morning on Friday, and I stood out there for over an hour and did not see the comet, even though Stellarium Mobile said it was above the horizon. I guess I might have been looking right at it but it was just to dim. If I have clear skies tomorrow morning, I will try again.
the 1/8 second SS sound about right to me at 400 mm focal length and pointing almost directly east, where the sky moves the most. Overall the image looks good from a noise perspective.
Thanks, @Youssef_Ismail – hope you got it!! I couldn’t see it, even with averted vision, even knowing exactly where to look from a small tree on the horizon. The first morning I didn’t see it in the viewfinder or looking at the shots in the field – only spotted it dimly in one in the computer. The second night, knowing exactly where to look, I saw it in the viewfinder, but barely. The sky looked clearer that night, too. Bringing contrast way up showed a low pall of smoke/haze the first night that wasn’t there the second.
Can you arrange for clear skies the 13th through at least the 15th? And for the predictions of its brightness increase to hold up? Thanks!
And I just saw this morning on SpaceWeather that another one has been found – should be visible around the end of October, and maybe quite large/bright.
I wish I had that kind of power!