guide to astrophotography

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  • How To Guide: Astrophotography with a DSLR Photography Gear, Photography Gear Tips & Tricks Add comments

    Jul112012

    Getting started in Astrophotography is easier than you think but mastering it will take a life time. This is a guide for beginners or people with a small amount of experience. Ill be focusing on taking pictures with nothing but DSLR cameras and regular lenses. No telescope required! The only other piece of equipment you will need is a tripod. If you have another type of digital camera with a manual setting you can still follow along though some of the options I talk about may not be available to you. Later on I will go into some other pieces of gear you can buy that will further enhance your ability to take pictures. Finally we will talk about how to process your images in Photoshop as most of the time the image straight from the camera is a bit underwhelming. All the pictures featured in the article were taken by me with a DSLR (either Nikon D300 or Nikon D700).

  • Milky Way Nikon D700, 105mm f/3.5, 8x2min,

    ISO 3200

    Choosing A Camera Any Digital SLR camera should be enough to get you started. If you are looking for a specific camera to buy for this purpose, Canons are the most popular for astrophotography but Nikons also do fine. The most important reasons for using a DSLR are the large sensor (for better signal to noise ratio), the ability to keep the shutter open as long as you want and the ability to shoot RAW files. This makes full-frame DSLRs even better because their sensor is larger than regular DSLR cameras. The last basic piece of equipment you need is a tripod.

    Did you know? Some DSLRs can be modified specifically for Astrophotography use. While DSLRs are fine for photographing stars, galaxies, and reflection nebula their weak point is emission nebula because they have an built-in filter to block out certain wavelengths of light. By removing this filter or replacing it with clear glass you can improve the sensitivity for hydrogen-alpha light. One company that will do this to your camera, or sell you a pre-modded one is Hutech. Canon has even released a DSLR specifically for this purpose known as the Canon EOS 60Da. The benefit of that is you still get a full manufacturers warranty. The downside? This mucks up the color balance of regular daytime shots, so it is not the best option unless you want to use that DSLR solely for Astrophotography.

  • Other helpful equipment Shutter release cable isnt absolutely necessary but highly recommended.

    You can by cheap third-party ones on ebay instead of paying for a genuine one.

    Anti-fog cloth can help with condensation that builds up on your lens under certain atmospheric conditions at night time. If your lens keeps fogging up this might help.

    Red flashlight to see what you are doing out in the dark. Using a regular flash light will harm your night vision but red light wont.

    A sky tracking mount to take exposures longer than 30 seconds or so. This requires an extra investment so I recommend trying other methods first. I will talk about trackers later.

    A comfortable chair (you will be waiting a lot) and extra warm clothes if its winter time.

    Binoculars to enjoy the view while pictures are being taken or to maybe pick out your next target.

    Nikon D700, 24mm f/3.5, 120 seconds, ISO 1600 single exposure

    Choosing A Location Some types of Astrophotography are doable in the middle of the city but that tends to be limited to lunar or planetary photography. Planetary photography requires a telescope but if you have a telephoto lens of at least 300mm or so

  • you can get some nice shots of the moon. Photographing deep sky objects or getting a lot of stars in your image is not very doable in the middle of a city. The good news is just driving for 15 minutes outside of city limits can really improve the sky quality.

    I want to shoot Location

    The Moon All you need is a clear sky! This can be done right in the middle of a city.

    Night-time landscapes (Starscapes)

    Starscapes are shots where the landscape is mostly lit by the moon (or stars at exceptionally dark locations) and you will need moderately dark skies for this. Think Suburbs or darker.

    Wide-field shots or Constellations

    You can get away with doing some of the brighter constellations inside a medium size city as long as you are sheltered from city lights by trees or buildings but outside the city will be best.

    Star Trails

    About the same as Constellations, but as with any Astrophoto the darker the sky the better. If you want to do very long single exposures you need a true dark sky site, but if you plan on stacking many shorter exposures you have a lot more flexibility.

    The Milky Way

    For this it is ideal to be at least 30 miles/50km away from any city or town. You can get away with being closer to the city if the milky way is in the sky opposite the nearest city. For the absolute best milky way images you need to be many hours away from any cities.

    Galaxies and Deep-Sky objects

    The requirements are the similar to Milky Way shots; rural skies or better. Some objects will photography decently even in suburban skies. Some of the bigger objects like Andromeda Galaxy and Orion Nebula can be done with a telephoto lens but you will still need a tracker of some kind to move your camera with the motion of the sky.

    Light Pollution

  • Light pollution is caused by stray man-made light that is aimed at the sky. The main problem for astronomers is it washes out the sky and reduces the amount of stars and deep-sky objects you can see and/or photograph. Aside from the aesthetic problem of the nasty orange haze in the sky instead of stars, light pollution is an incredible waste of energy. Why do we need to light up the sky? If all the light from street lights and outdoor lights was aimed at the ground with proper shades above them to reflect ALL of the light to the ground, you would be able to use lower power lights. Lighting up the sky is akin to leaving all your windows and doors open while you leave your furnace on in the winter. A complete and utter waste of energy. You can find more information at the International Dark Sky Association. If you live in the USA or parts of Canada you can see how the light pollution is where you live by going to the Dark Sky Finder site. You can also get a good idea of where you would have to go to get dark skies. For other countries if you Google your country name along with light pollution map you should hopefully have some luck in finding one.

    Beginner Shots

  • In this part we are going to cover all types of shots that can be taken with your DSLR without a tracking mount moon shots, starscapes & widefield shots, star trails and milky way wide shots.

    Guide Navigation Introduction & The Basics | Beginner Shots | Advanced Shots | Photoshop Processing

    Lunar Eclipse & Saturn Nikon D300, 240mm, f/6.3, 0.3 seconds, ISO 1600 single exposure

    Moon Shots The above shot of the February 20th, 2008 lunar eclipse was taken just with a 70-300mm lens and a tripod nothing fancy. That brightest point of light on the left side is actually Saturn. A view like this wouldnt have been possible with a telescope. While close ups of the moon are great you can get interesting shots like this with just a telephoto lens.

    Focusing can be tough in Astrophotography but moon shots are the exception. My suggestion is to use your camera to autofocus on the moon and then set it to manual focus and be careful not to adjust the focus. Even though the moon is bright and you can use a fast shutter speed you still need to minimize camera vibrations. If you dont have a remote shutter cable to trip you should use the self timer mode on your camera to take shots. Something like 3 or 5 seconds is enough for vibrations to dissipate. You will want to use manual

  • exposure mode for the moon as auto exposure will overexpose it usually. Here are some recommended settings to try:

    Full moon: f/8, 1/640, ISO 200 Half-moon: f/8, 1/500, ISO 400 The above are only starting points. Exposure time will change with the moons position in the sky and other factors. You want it to be bright but be careful not to overexpose the brightest edge. Below are some ideas for other types of shots you can take of the moon (click to enlarge). The first one is showing off the earthshine on the moons surface. The overexposed part is what you are normally seeing the the dim part is normally cloaked in shadow but with a long exposure you can see the shadowed section of the moon dimly lit by the earths reflected light. The other one is a stylized picture of the moon in some clouds.

    Starscapes and Wide-field shots

  • Starscape over a camp fire Nikon D700, 24mm, f/4, 60 seconds, ISO 1600 single exposure

    Starscapes are probably my favorite type of shot to take. In the above shot I was looking forward to taking some milky way shots but the clouds rolled in as you can see. While they would have ruined the shots I planned on taking they arguably enhanced this one. What I just said is tantamount to blasphemy though. Clouds are the arch-nemesis of any astronomer!

    Focus: The first thing you need to do is focus on the stars. There are many ways to do this but you may struggle your first few times dont get discouraged. If you have an older style lens (the ones that usually have an f-stop ring right on the lens) those lenses typically have a hard infinity focus stop so they are the easiest; focus to infinity and you are done. This is probably why my 2 favorite astrophotography lenses are my 24mm f2.8 Nikon prime and 50mm f1.8 Nikon prime. More modern DSLR lenses usually dont have a hard infinity

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