The Pleiades or Seven Sisters, also known as M45, is one of the most iconic open star clusters in the night sky and a perfect target for photography.
The Pleiades star cluster is located northwest of the belt of Orion (top right when viewed from the UK) and looks like a bright smudge to the naked eye.
But photographing the Pleiades gives you the chance to capture its beautiful blue glow.
Consider the appearance of the Pleiades star cluster
The Pleiades is about 444 light-years away, about three times as far away as the more spread-out V-shaped Hyades open cluster.
The relative compactness of the Pleiades is a result of both the fact that it is a young star cluster and the fact that it is more distant than the Hyades.
As a young star cluster, the Pleiades is a hot, blue star, another factor that increases its visibility.
The main pattern appears as a box with handles.
The stars that form this pattern are all named, and the brightest star even has the Beyer designation Eta Taurus (η).
Photographing the Pleiades: Equipment and settings
To make a photo of the Pleiades cluster look “natural”, you need to include the entire pattern of the box handles, as well as leave enough space around the cluster so it doesn’t feel cramped.
If you use a wide-angle lens or a smartphone camera, you’ll be surprised at how clearly cluster shapes can be discerned at low image scales.
The lower image scale results in slightly less accurate tracking, with exposures up to 30 seconds not tracking any discernible stars at focal lengths less than 16 mm.
The longer the focal length, the closer you can photograph the cluster, giving it more visual impact.
However, as the image scale increases, so does the precision of the tracking mount.
The main star of the Pleiades cluster is quite bright, so it is not difficult to capture it.
Longer exposures allow you to “drill down” into star clusters to reveal more of the fainter clusters (the Pleiades cluster contains more than 1,000 stars).
capture the nebula
As the fainter stars of the Pleiades appear, it becomes clear that there is more to see. It’s a beautiful blue nebula.
This is a reflection nebula, a type that usually consists of microscopic particles of zinc and iron compounds and particles of carbon (diamond dust).
It is very effective at scattering blue starlight and is most noticeable around the Merope Nebula. The bright part of the nebula visible here is, unsurprisingly, known as Merope Nebula NGC 1435.
But there’s so much more you can bring out using long exposure astrophotography.
For a long time, the swirling nebula surrounding the Pleiades star cluster was thought to be residual material left after the cluster formed.
However, detailed analysis of this nebula reveals that it has a different proper motion than the stars in the cluster.
This star cluster was moving through a cloud of matter, resulting in the formation of the nebula we see today.
We also now know that it is not a single cloud, but two clouds moving in independent directions.
The step-by-step guide below will teach you how to take a single-shot photo of the Pleiades star cluster.
Once you master this, use deep sky imaging processes such as frame calibration and stacking multiple frames to create better results.
Device
- Digital SLR camera or equivalent
- tracking mount
- Wide-field telescope or lens with a focal length of 400mm or less
Step-by-step photography of the Pleiades star cluster
step 1
If you have a smartphone, check if it has a night photography mode.
It’s worth checking your phone’s capabilities online, as some even have a basic night mode that allows long exposures if you mount the phone securely.
It’s amazing how clearly you can see the shape of the star cluster without using a zoom lens.
Step 2
If you use a digital SLR camera or equivalent, a relatively wide-angle lens will still be able to capture the general shape of the cluster, similar to a smartphone camera.
When using long focal lengths without tracking, use the “500 Rule” to determine how long an exposure can be achieved without seeing significant star tracking effects.
The 500 rule is: Maximum exposure time = 500 ÷ Focal length (mm)
Step 3
Use a focal length that captures the main pattern and a good area around it.
If you zoom in too much, it’s obvious that the clusters are cropped. The image looks too constrained.
The ideal long-axis width of the image is 3°, which can be achieved using a 660mm lens on a full-frame sensor or a 400mm lens on an APS-C sensor.
Step 4
Star clusters make excellent focus targets for live view-enabled cameras.
Take your time and capture the stars clearly. For good sound quality and low noise, set the ISO to a low value (for example 400-1600).
Experiment with increasing the ISO and exposure time in increments until you get a detailed shot that you’re happy with.
Step 5
If you are using a tracking mount, consider increasing the exposure to 1-2 minutes depending on the accuracy of your mount.
Look for signs of reflection nebulae embedded in star clusters.
This typically makes the sky brighter, but this can be corrected through processing.
Step 6
Use the image editor to adjust the midpoint sliders for each color channel to remove light pollution and darken the sky.
However, avoid making it too dark. If you draw a gentle S-curve, the cluster may pop.
Pay attention to color balance. The nebula should appear light blue to cyan in color.
For smoother results, process multiple shots one on top of the other.
Were you able to capture an image of the Pleiades star cluster? Don’t forget to send us your image.
