Sky & Telescope - February 2020 - 31

p Depending on the subject you are shooting, the stars don't always
need to be in focus. In this case, these nightscape photographers are the
focus of the composition.

card or a piece of white paper in daylight with your intended
ﬁlter in place. Make sure the card or paper completely ﬁlls the
frame. Then simply change the color setting to Custom White
Balance and select this photo as the calibration image. Be
sure to keep this photo on your memory card when shooting
deepscapes, and to use the custom white balance setting.

Processing the Results
Once you've shot your images, a little post-processing is
necessary to achieve the best results. It's important that you
shoot in RAW mode to get the most out of your night's work.
I prefer to use Adobe Lightroom and Adobe Camera Raw (ACR),
though Nikon and Canon offer their own processing programs that can accomplish much of the same enhancements.

My ﬁrst step is to reduce noise in the image by opening it
in ACR and ﬁrst lowering the Texture slider by around 20. I
select the Detail tab in the right column. Rather than adjusting the Luminance slider in the Noise Reduction area, I prefer
to lower the Sharpening setting. Masks can also be applied
to target certain areas for additional noise reduction after
applying ACR, adding a layer mask over the areas you'd like to
target and repeating the ACR process. Next I change the color
proﬁle in the Basic tab to Adobe Standard, which slightly
increases contrast and saturation. If necessary, I'll increase
the Contrast and Vibrance sliders.
If I shot my deepscape at maximum aperture, I'll select the
Lens tab and ﬁnd the lens I used from the extensive pulldown
menu, which corrects for vignetting and chromatic aberration in many lens designs. Other settings that can improve
an image are the Shadow and Highlight sliders, which help to
bring out faint nebulosity or suppress bright areas in a picture
if necessary. The Dehaze slider is very powerful in increasing contrast in an image but requires restraint so as to not
"overcook" the result.
If you shot under light-polluted conditions, you can correct
the white balance in the Basic tab. Keep in mind that shifting the color slider to low temperatures in order to remove
the orangish cast of light pollution from the sky background
will also shift the colors of the stars, Milky Way, and other
celestial objects.
Using these tips, you too can shoot captivating deepscapes
that bring your favorite deep-sky objects down to Earth.

¢ Contributing Photographer BABAK A. TAFRESHI captures
the beauty of the Earth and sky from exotic locations worldwide. See more of his work at babaktafreshi.com.

q Left: Unilluminated foregrounds like the mountains seen here below nebulosity in Scorpius won't display much blurring in longer exposures, so you
can expose a deepscape for roughly four times as long. This image was captured with a Nikon D810a camera and a 105-mm lens, and tracked for 25
seconds at ISO 12800. Right: Slight illumination on the arc limited this exposure to 15 seconds at ISO 6400 with a 50-mm lens at f/2.8.

sk yandtelescope.com * FEBRUARY 2 02 0

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Sky & Telescope - February 2020

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