Astrophotography with a digital SLR camera


Images taken with Nikon D7500


The image on the right is a star
field showing a quasar (the
nucleus of a very remote galaxy).

The bottom-left inset shows my
camera and telephoto lens on a
star tracker (the white box).

The top-left inset shows where
I pointed the camera in the
constellation of Draco.

The top-right inset shows a
blow-up of the centre region
of the image. The quasar is
the tiny grey dot identified by
the two tick marks.

Quasar at a distance of 25 billion light-years
256 x 30s


The light from the quasar
travelled for over 12 billion years
on its way to the camera.

During that time the Universe has
expanded and so the quasar is
now about 25 billion light-years away.

The image was taken with a
Nikon D7500 DSLR and a
300mm f/4 lens mounted on
an iOptron SkyTracker.




The montage on the right
comprises three images
taken during the BASoc
Star Party of 2019.

All the images were taken with
a Nikon D7500 DSLR and
a 300mm f/4 lens mounted
on an iOptron SkyTracker.

Montage of images taken during BASoc Star Party





M45 Pleiades Cluster
14 x 60s

C33 + C34 Veil Nebula
33 x 60s

M31 Andromeda Galaxy
32 x 60s




The image on the right is the
centre of the Milky Way from
Aquila (top left) to Scorpius (right).

Jupiter is the bright 'star' above right of centre.
Saturn is near the left edge.

It was taken with a Nikon
D7500 DSLR and a 35mm lens
set at f/4 and mounted
on an iOptron SkyTracker.

Milky Way from Aquila to Scorpius
6 x 10 x 120s



The image is a mosaic of
6 images, where each
image was created by
stacking (adding together)
10 individual exposures,
each of which was 120s long.





The image on the right is the
centre of the Milky Way from
Sagittarius (left) to Scorpius (right).

Jupiter is the bright 'star' above right of centre.
Saturn is near the left edge.

It was taken with a Nikon
D7500 DSLR and a 35mm lens
set at f/4 and mounted
on an iOptron SkyTracker.

Milky Way from Sagittarius to Scorpius
4 x 10 x 120s



The image is a mosaic of
4 images, where each
image was created by
stacking (adding together)
10 individual exposures,
each of which was 120s long.





The image on the right shows Antares
(the brightest star in the constellation
of Scorpius) and the Rho Ophiuchi
molecular cloud complex.

This star-forming region is one of
the closest to us at a distance of
about 400 light-years.

It was taken with a Nikon
D7500 DSLR and a 135mm f/2 lens
mounted on an iOptron SkyTracker.

Antares and Rho Ophiuchi
60 x 120s



The image is the result of
stacking (adding together)
60 individual exposures
each of which was 120s long.

Click here for a labelled image.


Images taken with Nikon D7100




The image on the right is the
centre of the Milky Way from
Scutum (top) to Sagittarius (bottom).

It was taken with a Nikon
D7100 DSLR and a 85mm lens
set at f/2 and mounted
on an iOptron SkyTracker.

Milky Way through Scutum and Sagittarius
4 x 10 x 120s



The image is a mosaic of
4 images, where each
image was created by
stacking (adding together)
10 individual exposures,
each of which was 120s long.

Click here for a labelled image.




The image on the right is the
Milky Way from Cygnus (top left)
to Scorpius (bottom right).

It was taken with a Nikon
D7100 DSLR and a 10-20mm lens
set at 10mm and f/5.6 and
mounted on an iOptron SkyTracker.

Milky Way from Cygnus to Scorpius
6 x 240s



The image was created by
stacking (adding together)
6 individual exposures,
each of which was 240s long.

Click here for a labelled image.


Images taken with Nikon D200 + 35 mm f/1.8 wide-angle lens




The image on the right was taken
with the K2 star tracker that I
designed and built to allow long
exposure images to be taken
without the stars trailing due
to the rotation of the Earth.

Milky Way through Scutum and Scorpius
20 x 60s



The image was created by
stacking (adding together)
20 individual exposures,
each of which was 60s long.

Stacking reduces the noise levels
in the images and so allows
fainter detail to be captured.


Images taken with Nikon D70/D200 + Sigma 100-300 mm f/4 telephoto lens

M31 Andromeda Galaxy
2 x 600s

M45 Pleiades star cluster
3 x 300s
M8 Lagoon + M20 Trifid Nebulae
300s

C63 Helix Nebula
20 x 120s
NGC7000 North America Nebula
20 x 120s

Total Eclipse of the Sun
5 images of various exposures
( more images here )

Comparison of Raw/Stacked/Processed images


Images taken with Nikon D200 + Sigma 100-300 mm f/4 telephoto lens

Markarian's Chain and other galaxies
Virgo and Coma Berenices
10 x 120s

Markarian's Chain and other galaxies
Negative image makes it easier to differentiate
galaxies (fuzzy edges) from stars (sharper)

Markarian's Chain and other galaxies
Negative image with galaxies labelled
with Messier (M) numbers or NGC numbers


Images taken with Nikon D70 through Meade LX200 telescope

M42 Orion Nebula
LX200 prime focus mosaic of 4 x 300s

Moon (11 day)
LX200 prime focus mosaic 1/250s

Five moons of Saturn
LX200 prime focus 8s
( click here for labelled image )

Other images taken through Meade LX200 telescope

M1 Crab Nebula
LX200 with DSI imager
45 x 15s
M51 Whirlpool Galaxy
LX200 with DSI imager
60 x 15s
C23 Spiral Galaxy
LX200 with DSI imager
66 x 30s
Saturn
LX200 with 26mm eyepiece
Canon XM2 camcorder
Subset of 8075 x 1/25s exposures f/38



Specification of Meade LX200 telescope
  • Mirror diameter = 250 mm
  • Focal length = 2500 mm
  • Focal ratio = f/10
See www.meadeuk.com for more details

Specification of Nikon D70 digital camera
  • CCD chip resolution = 3000 x 2000
  • Pixel size = 8 x 8 microns
  • Chip size = 24 x 16 mm
See imaging.nikon.com for more details


Image processing

The images were processed using the freeware Macintosh image analysis software Image SXM, a program that I wrote for use with scanning microscopy images (but which can also be used with astrophotography images).

If a caption indicates '6 x 120s' this means that 6 images (each of 120 seconds exposure) were added together in software. The object(s) of interest will add up but random noise that is inherent in all images will tend to cancel out, giving a 'cleaner' resultant image compared to the original images.

Mosaic images were created using Image SXM which automatically overlaps images and then removes any visible artefacts at the joins.



Click here for my first attempts at astrophotography with a Meade LX50 telescope


Steve Barrett      August 2020

S.D.Barrett@liv.ac.uk

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