Astrophotography Complete Guide

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Hello My dear Friends,

Astrophotography is one of the most beautiful & enjoyable activities in Astronomy (most in Amateur astronomy) and there are many astronomers who like it & work on it.

In this topic, we put some good & useful points about this subject from good resources like Sky at night magazine, Cloudy nights & ...

So be with us & share your comments here

*With special thanks to all those who have contributed their knowledge, hardware tips and softwares in the internet

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How to take nightscapes
How to image the moon
How to image the planets
Imaging the Sun
Something about your camera
Introducing deep-sky photography

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How to take nightscapes
From: Sky at night

There’s a huge range of subjects up there in the night sky just waiting to be captured with simple-to-use, inexpensive equipment. A camera and a tripod is all you need to start taking photos of fantastic ‘nightscapes’ – big, wide-field views of the heavens encompassing things like bright stars and the Moon, and perhaps set against a horizon.

These types of shots are particularly good when that great sweep of stars that makes up our own Galaxy, the Milky Way, takes centre stage. Your pictures can also reveal the movement of the Earth by capturing star trails and tracking the changing positions of the planets over days, weeks and even months.

Closer to home there are meteor showers to watch out for, as well as ethereal noctilucent clouds and the shimmering greens and reds of the striking Aurora Borealis. All this and more can be captured with the most basic of equipment: a camera, a tripod and a remote shutter release.
Read on to find out how to do it.

.......to be continued

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Astrophotography is the photography of stars, planets, the Sun and Moon, and other celestial objects in the sky, such as galaxies, stars clusters and nebulae. It can be easy to get started shooting simple things but it will get progressively harder when you start to turn your attentions to the smaller, fainter objects.

“If you've never done this before try shooting the moon. You don;t have to do it in the middle of the night either you can get some beautiful shots at dusk,” said Jerry Lodriguss who's images of nebulae and galaxies have appeared in publications all over the world.

When it comes to equipment a simple camera and lens on a tripod will work or you can substitute the camera's lens for a telescope. A DSLR works best but you can use a compact with the cameras lens shooting through the eye piece of a telescope for shots of the moon or if you're feeling brave you can try a much more complex set-up: “Put a camera with a telescope substituting the camera lens on an equatorial mounting that is polar aligned with the Earth's rotational axis. Which is driven by a computer when using another telescope mounted piggyback on the prime telescope to track the stars with high accuracy.”
For those who live in towns and cities light pollution will stop you seeing the sky as it truly is so to get the best astrophotos you need to take a drive out into the country away from the city lights.

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EQUIPMENT

What you need to take your first quality astrophoto

Many of us have a compact camera we use to take everyday pictures, so why not turn it on the night sky? Today’s compacts can take reasonable images in low-light conditions, and some even include manual modes that let you take full control of the camera’s functions. The ability to adjust a camera’s settings for yourself will make for much improved images.

With the latest Canon PowerShot compact, you can keep the camera’s shutter open to the starlight for up to 15 seconds, and make its imaging chip very sensitive to light, with ISO values up to 3200. The Nikon Coolpix P500 also allows for manual shooting at these high and sensitive ISO values.

Settings like ISO allow you to capture a wide array of subjects, but there is a downside to compact cameras. Their lens sizes and zoom abilities often don’t let as much light reach the imaging chip as wider DSLR camera lenses do. And being fixed, they don’t have the flexibility of a DSLR’s interchangeable lenses.

DSLR (Digital Single Lens Reflex) cameras offer a much wider range of functions and most experienced astrophotographers will have one in their arsenal. They have the widest range of settings, providing full manual control.

They also have interchangeable lenses so you can swap to a more powerful lens to get close in on a bright star cluster like the Pleiades in Taurus, or a nebula like the Flame Nebula in Orion.

Many DSLRs also have an option to set the opening of the camera’s shutter – the exposure – in increments of seconds up to 30 seconds. After that, they’ll have a bulb or ‘B’ setting for even longer exposures – great for capturing star trails.

In our reviews, Canon and Nikon DSLRs have stood out for what they offer budding astrophotographers. The Canon 300D, 400D and 500D models are all good entry-level DSLRs for astrophotography, as is the Nikon D50 and D90. Fuji’s S3 Pro has also performed well in our tests.

to be continued...

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TECHNIQUE

DSLR camera settings for astrophotography

Bulb

The bulb setting allows you to precisely control the length of exposures. With it you can take shots lasting from one second up to several minutes and even longer, using a remote shutter release or the delayed timer. Such a wide range of exposures can be creatively exploited in your shots of the night sky. Stars can be made to look like pinpricks with a short exposure or trails with a longer one.

File format

Many cameras come with a range of file format settings that include RAW, JPEG, RAW+JPEG and even the JPEG settings can have a wide choice of compression levels. Get to know your camera’s file formats and ideally use the RAW setting. While this will produce the highest quality results, it will also save the least number of images on your memory card because of the large file size.

Noise reduction

This is an in-built facility in many digital cameras and it should be used carefully. When taking pictures with a lot of light across the image, for instance in twilight scenes, noise reduction can improve the shot by cutting out artefacts that are inherent in the camera’s sensor. However, when used on pictures of stars and constellations, noise reduction can remove fainter stars. In these circumstances, it’s best turned off.

Picture styles

This is another in-built facility that has to be used with caution. Many DSLRs allow you to alter settings like a picture’s contrast, sharpness and colour saturation and save the alterations as a user-defined setting. Subtle adjustments made here can enhance the final image, but it’s very easy to alter a picture too much by going over the top. The default settings are often the best to begin with.

to be continued ...

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MASTERCLASS

Capturing star trails reveals the dynamic night sky

In the northern hemisphere the stars appear to rotate anticlockwise around one particular star – Polaris, the Pole Star. This star is almost exactly on the celestial pole. It’s not quite, but is certainly close enough for all intents and purposes.

Over the course of 24 hours the stars complete a full circle around Polaris. If you take a 10-minute, wide-field exposure that includes the Pole Star, you’ll see in the result that the stars further from Polaris have longer trails.

The arcs get longer as you move from the pole towards the celestial equator until, at the celestial equator, they are at their longest. South of this the arcs begin to decrease in length again towards the south celestial pole, which for us here in the northern hemisphere lies below the horizon.

Star trail pictures in four steps

Equipment

Select your lens and fix your camera to a tripod. Adjust the tripod legs so that they provide a solid base. Attach the remote shutter release so you don’t vibrate the camera when taking the shot.

Camera settings

Select the ISO, switch the camera to ‘bulb’ mode so there’s no limit to the length of the exposure, and focus. Make sure your flash is disabled and switch on the long exposure noise reduction.

Subject

Decide whether to shoot short star trails near Polaris, or longer trails by aiming at a constellation near the celestial equator. Ursa Minor is good for the former while Orion is good for the latter.

Capture and review

Take several exposures ranging from five minutes up to half an hour and review them on the preview screen. If the sky is too bright, reduce the ISO and set the aperture to a larger f-number.

to be continued...

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SOFTWARE

Take your shots from camera to the finished product

One of the best thing about digital images is that you can make them even better before you proudly show them off, by tweaking them with photo-editing software like Photoshop or with freeware like GIMP.

With photo-editing software there’s so much that can be done that it can seem a little daunting at first, so we’ve singled out a few key adjustments to make, like adjusting the ‘levels’, the range of light and dark pixels in the image, to change the tone of the image and reduce the effects of light pollution. Watch our software walkthrough below to see what effect this can make.

Key image-editing adjustments

Histogram

The histogram tool allows you to adjust the contrast and brightness range of the pixels in your image.It’s a very useful aid in making stars stand out and reduces the effects of light pollution. By adjusting the histogram you can bring out detail that may be lost in the background.

Levels

Like the histogram tool, the levels tool can help reduce the effects of light pollution by giving you control over the amount of red, green and blue in an image. Making subtle changes to the red, green and blue levels can dramatically reduce the orange hue created by light pollution.

Colour balance

This tool has three sliders, each controlling two colours: yellow and blue, magenta and green, and cyan and red. By moving the sliders you can change the balance of colour between the two colours. Watch the changes to decide how far to go with each slider for the best effect.

Sharpening and softening

One way to improve an image is to slightly soften or blur the pixels with the softening filter. This reduces the effect of any noise in the image. Use carefully, as it can soften the stars as well. The sharpening filter can also be used to make the image and stars look crisper.

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How to image the Moon
From: Sky at night

You too can take lunar images like this. Here's where we show you how

Capture our nearest celestial neighbour in all its glory with the second part of our astro imaging masterclass

With its ever-changing face and myriad of interesting features, the Moon is a truly wonderful target for astrophotographers of all abilities. But for all its obviousness and brightness, it takes considerable attention to detail to capture top-quality images of our natural satellite. Here, we show you how to do it.

EQUIPMENT

The kit that you’ll need to begin snapping the Moon

Anyone with a telescope and a basic camera can take a good image of the Moon. But it’s best to use a webcam or CCD camera to take lunar images. These cameras are capable of taking short videos, consisting of many frames per second, which is why specialised lunar and planetary CCD cameras are often referred to as ‘high frame-rate’ cameras.

You can use any kind of scope with these cameras; however, large-aperture Schmidt-Cassegrain and Maksutov-Cassegrain telescopes are popular choices with top lunar astrophotographers. This is because their longer focal lengths are well suited to ‘close-up’ imaging of the Moon, and compared to a high-quality refractor, you get a much larger aperture for your money.

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Accessories for lunar imaging

Nosepiece

To attach a webcam to the eyepiece holder on your scope you’ll need a ‘nosepiece’ adaptor. They can be bought from all good astronomy shops for between £12 and £25. You’ll probably need to remove the webcam’s lens first though, before screwing the nosepiece in place.

Filter

If you are using a monochromatic planetary camera you might find it useful to use a red filter when capturing lunar images. Using one can help produce a crisper final image. A red filter typically costs between £20 and £70.

Barlow lens

For detailed webcam close-ups of the lunar surface and its craters, a Barlow lens is a must. It increases the focal length and the magnification of your telescope system by typically two or three times. A Barlow will cost you between £40 and £120.

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TECHNIQUE
Dramatic lunar features to capture

Crater Clavius

This grand lunar crater is a great target if you’re trying to push your equipment to its limit. See how many of the small craterlets you can capture on the crater floor.

Crater Copernicus

One of the most stunning craters on the Moon, Copernicus makes for a wonderful imaging target. See if you can capture its magnificent terraced walls.

Montes Apenninus

This impressive chain of peaks is one of the great lunar mountain ranges and a good target for afocal photography. It stretches 600km across the Moon’s surface.

Rupes Recta

Also known as the ‘Straight Wall’, Rupes Recta is an enormous fault on the lunar surface. The trick is to catch it under the right illumination to see it clearly.

Vallis Alpes

This dramatic valley cuts straight through the lunar Alps. The challenge with this object is to see if you can capture the elusive rille that runs right the way through it.

Tycho

Crater Tycho is famously surrounded by bright ejecta rays – brighter material that was flung out by the asteroid impact that formed the crater itself. It has a huge central peak.

to be continued ...