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Old 24-05-2020, 04:02 PM
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graham.hobart (Graham stevens)
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4 hours on Rho

Long time no post- have been busy with work and other stuff but last week I managed two nights in a row (rho!) with Canon 6D unmodded, Samyang 135mm at f2.2, 300exp at iso 400- from around 90 frames culled to 50 ish with flats and darks.
it feels good to get back on the horse again.
Graz in Taz
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Old 24-05-2020, 08:16 PM
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gregbradley
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Very nice. These Samyang 135mm lens images are very impressive.

Dust facing up eh? I am more of a dust facing down person but it looks good that way as well!

I would love to have the Sigma Art 105 F1.4 lens. Perhaps next Milky Way season.

Greg.
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Old 24-05-2020, 10:05 PM
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graham.hobart (Graham stevens)
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rho

thanks Greg!!
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Old 24-05-2020, 10:20 PM
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strongmanmike (Michael)
Highest Observatory in Oz

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Hey Graham, its a good shot for sure but on my brightness/contrast calibrated monitor it is very bright and washed out, do you perhaps use a very high contrast screen for processing..?

Try using this grid to calibrate your screen.

Mike
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Old 26-05-2020, 06:54 PM
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graham.hobart (Graham stevens)
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rho

Hey Mike thanks will try that out- I processed during the day with the blinds down in my lounge but there was a fair bit of sunlight leaking through- maybe I over compensated ??
I will have another go as I might actually get more data later tonight
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Old 26-05-2020, 10:23 PM
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astronobob (Bob)
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Real nice Graham, and a grouse target for lenses, well done, I must try Rho again, I see your exposures are 5mins, quite long for F2, would have had high right end signal on the histogram.
How did you find the noise levels on the 6D at iso 400 ?
She's a nice bright image all the same..
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  #7  
Old 27-05-2020, 07:00 AM
Placidus (Mike and Trish)
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A very fine acquisition.


If you look very closely at the left hand end of your histograms, you'll see that the foothill for each channel (that is to say the place where the numbers first kick up from the horizontal axis) is well to the right of the vertical axis. That makes the image look like it is taken through fog. Slide the black point for each channel until the histogram kicks up from the origin. That will make the dust lanes look much more prominent with absolutely no loss of meaningful data.




[Edit: I just read Mike Sidonio's comment. I think he's saying approximately the same thing. He's saying that if the contrast on your monitor is too high, and you're adjusting your image by eye, your greys will look black, and you'll think all is fine. You probably need to calibrate your monitor, as he suggests, but the technique I'm describing works even with an uncalibrated monitor: it looks at the underlying data, and therefore how the blacks will look on someone else's properly calibrated monitor, not how it will be displayed on your screen. We do both: we calibrate the monitor AND look at the histogram.).



Best,
MnT
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