Basics of Astrophography
Clicking pictures of planets, Deep sky objects, star trail photography is something everyone would like to do. But frankly speaking before doing astrophotography, one should have the basic idea of what all accessories you require and how to do it .This blog discuss about the basics of astrophotography and it will help you to do backyard astrophotography with equipments almost every photographer has on hand, so here we go!!
Let me tell you all in brief about different types of astrophotography and the main accessories required for good astrophotography!
Types of Astrophotography
Fixed-Position Astrophotography/Simple Night Sky Astrophotography
This is the simplest method in which a DSLR camera with exposures of about 30 seconds, moderately high ISO capability, and “blub” setting can take photographs of the night sky. This type of astrophotography is called Fixed-Position Astrophotography .star trails, constellations, aurora, the Zodiacal Light, satellite passes, and even Milky Way pictures can be clicked.
Prime Focus Astrophotography
Prime focus is a simple technique in which you need to remove the camera lens and the telescope eyepiece and mechanically attach your camera to the telescope eyepiece. Usually a “T” ring and “T” ring adapter is used to attach the camera to the telescope focuser.
http://www.weasner.com/etx/astrophotography/2011/weasner/D7000_OAG.jpg
The telescope must have an equatorial mount and a very accurate drive/motorized system. Now when you attach a camera in eye piece how much magnification do you get with a telescope? This basically depends on your telescope’s focal length .Just divide the telescope focal length in millimeters by 50mm the result you get is your telescope’s magnification.Just consider an example if I have a 600mm focal length refractor telescope the magnification at prime focus with a camera will 600mm /50mm =12 ,that means I will get 12 X magnification.
You can watch video to understand more about this technique
Afocal Astrophotography
Afocal projection is a method that uses both the camera lens and the telescope eyepiece here the difference is that the camera is focused on infinity and merely held up to the eyepiece. This can be a wonderful way to take pictures of the moon and sun. Again reminding you all!! If you are taking pictures of the sun you MUST use a solar filter or you could ruin your camera, your telescope or YOUR EYES!!!This method is very easy and is especially applicable to those of you who have a Dobsonian mount telescope. The exposures of the moon and sun are short so no tracking is necessary in that case using a motorized mount.
https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTB7ZYKNlejXcgxAL2EVM-Rd87DVkmEyMdqNDSST8MYl21K6-9V
You can watch this YouTube channel to learn how to do Afocal Astrophotography in details
Eyepiece Projection Astrophotography
Taking prime focus pictures of the planets can be somewhat disappointing. The images that you get are VERY tiny and have poor resolution due to their image scale. To make the image scale larger a special “T” adapter is acquired that allows you to insert an eyepiece into the optical path between the camera and the telescope. This “projects” a larger image onto the camera thus effectively increasing the focal length of the system
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.Image courtesy
http://www.celestronimages.com/data/media/9/2a-VB-Eyepiece-Teleextender-Tring-CanonEOS.jpg
Piggyback Photography
Image courtesy
http://www.astronomyhints.com/piggyback_wcamera.jpg
In piggyback photography, you use a telescope’s mount to track the sky but the camera shoots through its own lens, not through the telescope. For this you need a camera with a (“bulb”) setting on the shutter to permit long exposures and a telescope capable of tracking stars as they move from east to west.
You can watch this YouTube channel to learn how to do Piggyback Photography
Astrophotography is definitely expensive a hobby! Some people literally spend huge a amount of money .You don’t have to spend million dollars worth of fun in the hobby of astrophotography. Modestly-priced equipment can take images that will give you immense satisfaction and enjoyment.
Equipments required for astrophotography
There are three main items necessary for good astrophotography: 1) A good, solid motor-driven tracking mount , 2) a telescope, and 3) a camera. There are also a handful of astrophotography accessories that will make imaging easier, but are not necessarily “required.”
TELESCOPES
Refractors and reflectors both work well for astrophotography, to know about different types of telescopes you can read our Blog
Choosing the best telescope for astrophotography will vary greatly depending on the type of imaging you want to do
- For faint galaxies and planetary nebulae:a big aperture, long focal length telescope would be your choice.
- For wide field images: a fast telescope would be more preferable.
- Planetary imaging has its own focal length requirements that are even longer than is needed for galaxies.
Tips on Buying a Telescope.
- Please stay away from any telescope that you can easily buy in any departmental store.
- There is no substitute for optical quality. The optical quality of a telescope is one of the most important factors for a telescope. The biggest and fastest telescope won’t work very well if its optical quality is not very good.
Telescopes we recommend:
For Beginners
- SkyWatcher Esprit 80mm ED Triplet APO
- Astro-Tech AT65EDQcost $549 ;65mm aperture, 420mm focal length, f/6.5 four-lens/two-group dual ED element refractor
- Explore Scientific 80mm f/6 Triplet ED Apochromatic Refractor,cost$799 – 80mm aperture, 480mm focal length, f/6 air-spaced triplet ED apochromatic refractor
Intermediate
- Celestron EdgeHD 8
- Orion 190mm f/5.3 Mak-Newt Astrograph,cost $1,400 : 190mm aperture, 1,000mm focal length, f/5.3 Maksutov – Newtonian
- Takahashi FSQ-106ED cost $4,395 – 106mm aperture 530mm focal length, f/5 triplet apochromatic refractor
Advanced
- Celestron EdgeHD
- Explore Scientific 127 $1,999 – 127mm aperture, 952mm focal length, f/7.5 air-spaced triplet apochromatic refractor
- Takahashi Epsilon 180ED Hyperbolic Astrograph$4,495 – 180mm aperture, 500mm focal length, f/2.8 Hyperbolic Astrograph
You can visit this online website, if you want to buy a telescope http://www.buytelescopes.com/search?q=
MOUNTS
Mount is an important factor! Astrophotography is near impossible without a good mount. A German Equatorial mount is preferred, as it will eliminate field rotation as it tracks your object through the night sky.
Mounts we generally recommend for astrophotography other than this:
- SkyWatcherStarAdventurerAstroPackage(designed for beginner DSLR and camera lens astrophotography)
- Celestron AVX Mount(beginner/intermediate)
- SkyWatcher EQ6 Mount(intermediate use/medium loads)
- Celestron CGEM DX Mount (intermediate /Advance)
- Celestron CGE Pro(Advance)
DSLR CAMERA FOR ASTROPHOTOGRAPHY
First of all If you are having a DSLR camera than its fine!!You can use that,but If you don’t have one and you are planning to have one then before you buy it , ask yourself these simple questions:
- What kind of pictures do you want to take?
- What is the best kind of camera to take them with?
- How much do you want to spend?
- How deep do you want to get into it?
The best camera you need depends on the answers to these questions! Not on the Cost, never think that a costly DSLR camera is MUST for your astrophotography. First of all you need to understand the basic DSLR camera features for which you can refer our blog. Never rush to buy a camera on online!! before buying it is always good to do some research work for that you can join any astronomy club, meet the members, and go to Night sky observation and use their telescopes. See what kinds of cameras they are using and what kinds of results they are getting. Find out which kind of astronomical objects you are most interested in photographing, and then research which cameras and telescopes are best. If you don’t live near a club, then get on the internet and see what people use for shooting.
DSLR camera we recommend
Beginner
- Canon EOS 1000D (Digital Rebel XS)
- Nikon D3100
Intermediate
- Canon EOS 550D
- Nikon D300S
Advance
- Canon EOS 5D Mark II
- Nikon D3S
Recommended Cameras for Long-Exposure, Deep-Sky Astrophotography
Top-Rated Cameras
- Canon 5D Mark II – Best high-end DSLR
- Canon 1000D (Digital Rebel XS) – Best entry-level DSLR
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| 5D Mark II | 1000D (Digital Rebel XS) |
Image courtesy http://www.bhphotovideo.com/c/product/583953-REG/Canon_2764B003_EOS_5D_Mark_II.html/BI/1445/KBID/1937
Camera lenses for Astrophotography
If you are a beginner the best lens to get is a simple 50mm f/1.8. It is small, lightweight,fast and most important factor ITS CHEAP! If your DSLR camera has a zoom lens, then you can certainly try it out for astrophotography. But if you think you need a additional lens then decide what type of astrophotography you would like to do.
Remember one thing as the focal length of the lens increases, things become more critical and the degree of difficulty increases!
Wide angles are great for scenic shots on a fixed tripod for constellation shots.
Telephotos are great for large nebulae like the North America nebula and the Milky Way star clouds in Sagittarius.
Wide Angle
Canon EF-S 18mm-55mm f/3.5-5.6 AF Zoom ($175)
Normal
Canon EF 50mm f/1.8 II Canon ($115)
Nikon AF Nikkor 50mm f/1.8 D ($125)
Telephoto
Canon EF 200mm f/2.8 L II USM ($775)
Nikkor AF 180mm f/2.8 D ED-IF ($900)
Image courtesy
http://www.lonelyspeck.com/wp-content/uploads/2014/08/beginner-astrophotography-kit.jpg
The items above are all you need to start making astrophotography, but there are a couple extra things that can help you out:
HEAD LAMP
Best of the Best: Petzl Tikka RXP
Affordable Luminosity: Petzl Tikka XP
Beginner on a Budget: Petzl Tikka +
Intervalometer
Cheap and Reliable: Neewer Intervalometer
Star Chart App
iOS: Sky Guide, PhotoPills, Stellarium
Android: Stellarium
You can watch this video to understand astrophotography
https://www.youtube.com/watch?v=COlvv21gRXQ&list=PLkwzpKJzj4SydUamq5V8uGZfzr8H0HZ0F&index=2
Polar Alignment
One thing you need to keep in mind when doing astrophotography is that the earth rotates on its axis once per day, but you’re never trying to capture a “still” object .The earth rotates, and so do observers who are standing on it. This gives the appearance as if stars circle in the sky. If observed with bare eyes, stars move very slowly (one revolution in 24h), but the telescope magnification increases this speed proportionally. A telescope with a power of 100, let stars “move” 100 times faster. If an observer uses for example an eyepiece with apparent FOV of 50 deg, and a telescope with magnification of 100, it takes only about 2 minutes for a star to wander from one side of the eyepiece to the opposite site. What might be slightly annoying for stargazing is completely unacceptable for astrophotography
Image courtesy: http://www.astronomysource.com/wp-content/uploads/2011/12/Polar-axis_3_640-475×316.jpg
Many (not all) equatorial mounts have a hole bored straight through the mount along the polar axis. Examples of mounts that I know have such a hole include the Celestron CG-5, Stellarvue M4, Orion Skyview Deluxe, Losmandy G8 and G11, Skywatcher EQ3 and up, etc.
http://www.themcdonalds.net/richard/astro/writings/images/cg5-polar-hole1.jpg
Step 1: On some mounts the hole is obstructed when the mount is in a certain position and unobstructed in some other position when the Declination is rotated 90 degrees, the obstruction moves aside and you can see through the hole
http://www.themcdonalds.net/richard/astro/writings/images/cg5-polar-blocked.jpg
Step 2 Set the polar axis of the mount roughly to the North (Polaris)
http://www.themcdonalds.net/richard/astro/writings/images/cg5-latitude.jpg
Step 3 Roughly level the head of the mount and rotate it so the polar axis is pointing as close toward North ,you can use magnetic compass to find it.
http://www.themcdonalds.net/richard/astro/writings/images/cg5-level.jpg
Step 4: find it Pole star /Polaris with your naked eye, not through the telescope in the night sky
http://www.themcdonalds.net/richard/astro/writings/images/Polaris-found.jpg
Step 5: Kneel down and try to look upward through the hole in the polar axis.
http://www.themcdonalds.net/richard/astro/writings/images/cg5-polaris-in-hold.jpg
Step 6: adjust the up/down and left/right position of the mount until Polaris is centred in the hole through the polar axis
http://www.themcdonalds.net/richard/astro/writings/images/cg5-polaris-in-hold.jpg
http://www.themcdonalds.net/richard/astro/writings/images/cg5-az-adjust.jpg
Step 7:use the polar alignment adjustment controls to do this adjustment.
Finally If Polaris is centered in the hole through the polar axis then it means you are done with polar alignment !! your mount is ready!!
Motion of telescope using motors with regard to Earth’s Rotation
Now , computerized GoTo mounts are available these mounts have coordinates of thousands of celestial objects stored in their memory they do have electronic versions of setting circles built in they are called rotary sensors. A computer calculates the position, counts the necessary sensor impulses and drives the motors to the right point. Before the computer can find any object, it needs calibration on reference points, which are usually three known stars (three-star-alignment). After a successful three-star-alignment, the computer can point the telescope automatically at any wanted celestial object.
You can watch this video to learn how to do astrophotography
https://www.youtube.com/watch?v=COlvv21gRXQ&list=PLkwzpKJzj4SydUamq5V8uGZfzr8H0HZ0F&index=2
Astronomical Software For the PC
- DSLR Camera Control
- Software-Assisted Focusing
- Focus Max $Free – Focusing software that automates focusing if you have a motorized focuser that works with Maxim DL or CCD Soft
- Image Acquisition Automation
- DSLR Shutter $Free – image acquisition automation
- Image Calibration, Aligning and Stacking
- Deepsky Stacker $Free – Image calibration, alignment, stacking
- Regim $Free – Image calibration, alignment, stacking
- IRIS $Free – DSLR control, image acquisition automation
- Image Correction and Enhancement
- Photo Utilities
- StarTrails – $Free – Stack individual frames to create a star-trail image
- StarStax $Free – Stack individual frames to creat a star-trail image
- Planetarium Programs and Atlases
- Stellarium $Free
- Cartes du Ciel $Free
- Virtual Moon Atlas $Free
Image Courtesy:matt Pollock a Nikon D800 with Nikon 14-24mm lens was used and the sky was shot at F/2.8, ISO 3200 for 20 seconds at 14mm. The foreground was captured at F/2.8, ISO 4000 for 30 seconds. no pixel manipulations were performed other than blending the trees and treeline with the sky and adjusting white balance, contrast, clarity and other sliders in Adobe Camera Raw and Photoshop CC 2015
