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Old 10-03-2014, 05:00 AM
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skysurfer
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Weird small star points when using wideangle or normal with 6d ??

When I use wideangle and takes shots of the sky in CR2 format (or jpeg does not make sense) star images are rather tiny. Which makes them virtually invisible when displayed smaller than the original resolution.

Increasing contrast, reducing noise, etc.etc, whether Photoshop or darktable: the images, even of bright stars like Alpha Centauri or even Sirius remain tiny. It looks the difference between bright and faint stars is much less than in reality.

On the web I see several wide angle shots with nice bright stellar images, but for me it seems a no-go

These samples are exported from darktable into jpg format. Photoshop 6 gives the same result.
First one with Samyang 14 20 sec on ISO 6400 @f/2.8,
second one with Canon 24-105L @24 6 sec f/8 ISO 3200.

EDIT: Added two other samples with 24-105L @24 f/4 13 sec ISO 3200, same crappy small stars. Only converted to jpg by Canon DPP app, no further processing.
What am I doing wrong ?
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Last edited by skysurfer; 10-03-2014 at 05:24 AM. Reason: other samples
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Old 10-03-2014, 07:42 AM
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lazjen (Chris)
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I must be missing something here with your explanation, because to me, those single shot images look close to expected? Have you tried taking several images and stacking them?

Also, maybe you should check your camera settings? E.g. check the quality of the images being saved; turn off in camera noise reduction. etc.
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Old 10-03-2014, 09:03 AM
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Shiraz (Ray)
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"crappy" small stars?? - they are excellent small stars. I spend hours trying to get small stars - stars start out as unresoved points of light and only get bigger when the atmosphere/optics spreads them out - your optics are good and they are not getting blurred much - be happy . If you want a richer starfield, expose for longer - stacking is a good idea, as Chris suggests.

Last edited by Shiraz; 10-03-2014 at 11:32 AM.
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Old 10-03-2014, 05:09 PM
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I have a tracker and use it often and normally set lens fully open, but in this case my aim was just make a scenic picture in the twilight for which I squeezed the aperture and used only 6 seconds.

The other images are made in the dark with full aperture also intended as a scenic picture. However many scenic pictures show more difference between the faint and the bright stars.
Indeed small stars are better but because of the low bit depth of current displays (8 bits vs 12-14 bits of the human eye viewing the sky) brighter stars are displayed larger on many scenic sky images.
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