All you need is a DSLR, a tripod and a remote release timer. You may want to add a lens hood and a right-angle viewfinder. DSLR Astrophotography Untracked. digital cameras. • Currently I use a Nikon D Digital Single Lens. Reflex ( DSLR) camera and an Apple iPhone 6s Plus for my astrophotography. for this purpose, Canon's are the most popular for astrophotography but Nikon's also do fine. The most important reasons for using a DSLR are the large sensor.
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Using a Modified Camera. DSLR CCD chips are very sensitive to infrared light. This requires installing an IR filter over the chip. Unfortunately this also filters out . The three most common forms of wide-angle astrophotography with DSLR cameras Wide-field, or landscape, astrophotography - photographs of the night sky. Types of Astrophotography. • Telescope not always required! • Through the telescope eyepiece. • Camera with lens on tripod. • Camera with lens on motorised.
This DSLR Astrophotography for Beginners Tutorial will help you get started figuring out what you need to download and what you need to learn. There are two basic types of DSLR astrophotography; short exposure and long exposure. Short exposure is typically reserved for the moon and sun, but can also be used to do large areas of the sky and star trails. Long exposure is normally considered exposures longer than thirty seconds at a very far away and dim object such as a nebula brightly colored gas cloud in space. All those really cool Hubble telescope images are all in this category. DSLR astrophotography and other forms of photography have much in common. Asking lots of questions and reading lots of books is a great start, but eventually you need to get out there and test things to see how they work for you.
Calculating the Guiding Tolerance Method 1 The size of this box must be measured first. To do this, find a star on the celestial equator and meridian, and put it on one crosshair of the box with the guiding eyepiece in the guidescope.
Turn the telescopes drive off, and time how long it takes for the star to drift across the box to the other crosshair. Repeat this procedure several times and average the results to get a more accurate reading.
A star will drift approximately 15 arc seconds per second. If it takes 2 seconds for the star to drift across the box, then the box is 30 arc seconds wide. I use a barlow with my guiding eyepiece and my cross hair box is about 17 arc seconds wide.
A guiding tolerance of 7. Examine the images made at this tolerance and see if they are acceptable. For higher quality work, stricter tolerances must be used. Calculating the Guiding Tolerance Method 2 Another way to look at it is that the 80mm guidescope can resolve about 1.
That means that the star can drift no more than about 2. If the astrophotographer is more critical, and desires stars with an elongation of less than 1. To try to keep the star without any elongation, the 1. These are critical guiding tolerances indeed for a scope of mm aperture and one meter of focal length.
Calculating the Guiding Tolerance Method 3 Another method of calculating the guiding tolerance in reference to the crosshair box is to use a value of. Most are this size, but this should be checked with the manufacturer of the guiding eyepiece.
Guiding Tolerances for Shorter Focal Length Lenses By plugging in different values for lenses of different focal lengths, it is easy to see that the guiding tolerances go down for lenses of shorter focal length.
For a lens of mm focal length, the guiding tolerance doubles to about 5 to 6 arc seconds. For a lens of mm focal length, the guiding tolerance goes up to about 25 arc seconds, which is bigger than the diameter of the box, so as long as the star is kept inside the box, an easy task, no trailing should be evident.
For lenses of focal length shorter than mm, the tolerances are usually greater than the periodic error of the mount and should not need to be guided at all. Manual Guiding Procedure When using an off-axis guider, the object is acquired and framed and focused. The off-axis guider is then rotated until a suitable guidestar is found and the guiding eyepiece is focused on the guide star.
For a separate guidescope, the deep-sky object is acquired in the photographic instrument and it is framed and focused. A guidestar is then acquired in the guidescope, preferably as close as possible to the deep-sky object to minimize differential atmospheric refraction. The crosshairs of the guiding eyepiece are then oriented so that they parallel the cardinal directions east-west and north-south, which correspond to the right ascension and declination of the equatorial mounting. The buttons on the hand controller of the drive of the telescope mounting are then oriented in the same manner so that when the star moves in one direction, the correct button can easily be pressed to correct.
A bit of practice before the exposure is started is always a good idea here. The star is then moved until it is exactly at the intersection of two of the crosshairs. The exposure is then started, preferably with the self-timer in the camera so that the star can be monitored as the shutter opens. The astrophotographer then uses the slow motion electronic controls of the mount and attempts to concentrate during the entire exposure and keep the star on the crosshairs, or as close as possible within the guiding tolerances calculated for the focal length of the photographic instrument.
All mounts that use worm gears will have some periodic error that cannot be eliminated. This error usually is evident as a gentle movement of the star first in one direction, and then back to the starting point over the time period it takes the worm to make one revolution. This gentle periodic error is easy to guide out and correct for.
Some mounts and gear systems however can produce erratic error, or a large part of the periodic error that comes during a small time interval.
For these types of error, the star must be vigilantly monitored or it can easily exceed the guiding tolerance for long focal length photographic instruments. The location and height of the guiding eyepiece should be considered both at the start of the exposure and for where it will be at the end of the exposure.
A comfortable position at the start can deteriorate into a very uncomfortable one at the end of a long exposure. Double check to make sure that the camera is, in fact, set to Bulb for long time exposures. This was vastly different than today's digital astrophotography where a series of short exposures can be added or averaged together to produce the same results as a single longer exposure.
For really serious long exposure manual guiding, a zen-like concentration had to be maintained that blocked out the excruciating physical pain of sitting motionless for long periods of time in the freezing cold and staring at one faint star while the beauty of the rest of the universe went by overhead, unobserved. A visit to the bathroom was also strongly recommended before the start of a manually guided long exposure in the cold.
Astrophotography How-To Books by Jerry Lodriguss If you like the information you have read here, I have several books that you may find of interest. If you think there is a lot of information here on these web pages, just wait until you see how much more there is in these books! You will see how easy it is to take great pictures with very modest equipment and basic methods that are within everyone's ability.
With this book you will learn how to take amazing images of the night sky with your DSLR camera. It is for beginning astrophotographers and explains in step-by-step detail how to stack your images in DeepSkyStacker and then process them in Photoshop.
You will learn how to improve the brightness, contrast and color of your deep-sky images to produce beautiful results.
For reflectors you need to make sure they are designed for astrophotography. The reasoning is that some reflectors such as Newtonians including Dobsonian mounted Newtonians can not focus with a camera attached and need to have the primary mirror moved forward. Moving the mirror forward is not at all an easy task and should not be attempted except by a professional or very advanced amateur. Astrographs are a type of reflector telescope specifically made to be able to focus with a camera attached.
This is important because the lower the f-ratio, the shorter exposures you can use, and this is called a faster scope. So, a f5 scope is faster than a f7 scope which is faster than a f12 scope which is slower than a f10 scope.
This also means a faster scope has a shorter focal length and less magnification actually larger field of view than a slower scope given the same aperture. One other important consideration with your choice of scopes is the focuser size. Many starter scopes come with a 1. This is a problem because if you hook up a camera such as a DSLR to this you are likely to get some vignetting of the image. Vignetting is where the center is nice and bright but the outside edges are darker, especially the corners.
Many scopes designed just for astrophotography have 2. Larger focusers also provide more stability to the image train with lots of things like cameras, field flatteners, filters, etc attached. Your choice of scope will also determine your mount. You need a mount that can easily hold your scope. Mounts have maximum load specifications such as 30lbs.
This means that the scope can accurately drive up to 30lbs of payload not including the counterweights. I disagree with such a broad statement and get a little more technical with it. Be warned, do not go by the maximum load rating alone as these are sometimes incorrect and you also should consider the software you will use to drive the mount if you will be using a computer. I have had experience with an Orion Sirius mount rated at 30lbs and a Celestron CG-5 rated at 35lbs and in my experience would take the Sirius mount every time.
It is more stable at any load, quieter, interfaces with my software much better, and is far easier to align and use out of the box. If you get the chance to use both before you download one it will greatly help you decide on what works best for you.
The plywood is huge, turns into a kite in the slightest breeze, and because of its size makes it very hard to control quickly and accurately. Even though the dog food is heavier, it is much easier to control and wind does not affect it.
This means with a payload including scope, camera, adapters, guidescope, etc of 20lbs you can use a HEQ-5 rated at 30lbs for a refractor, or if you want to use a reflector you need to use an EQ-6 rated at 40lbs. One note is that these weight ratings do NOT include the counterweights.
So if a mount can hold a maximum of 20lbs of load, that is in addition to any counterweights needed to balance that 20lbs. In order to take long exposures, even with a great mount, you need to align it correctly. EQ scopes need to be polar aligned, or aligned with the north celestial pole. This is just about pointed to the star Polaris in the northern sky. In fact, if you are doing visual you can just point the mount towards Polaris and be done, unfortunately with AP you need to be a little more accurate.
See figures 9 and 10 for examples of incorrect alignments. Note that since it is an alignment problem figure 9 which is the top left corner of the image, and figure 10 which is the lower left, show the exact same problem.
Results of bad alignment Your nicer EQ mounts have what is called a polar scope built into them, this is a small scope actually in the mount itself. Looking through the polar scope you may see something similar to figure Figure View through a polar scope.
The little circle next to the word Polaris is where you want to adjust the scope so that the star Polaris is visible in the center of that circle.
Use the images of the constellations Big Dipper and Cassiopeia to align it correctly with those constellations in the sky at the time you are setting up. Note that the images and the circle to put Polaris in rotates as the scope rotates, line up the constellations and center Polaris. The other thing you need to check before you start imaging is the balance of the scope.
There are three axes you need to balance on an EQ mount, the first is shown here in figure 12 : Figure I can then loosen the declination release and pivot one end of the scope up and down to see if it is balanced. To balance it, I loosen the scope ring knobs and slide the scope towards the lighter end and recheck.
Once finished, I tighten the scope ring knobs back down and move to the front of the scope. Balancing the scope tube. Now we need to balance the second axis just like we did to the first one. This time, loosen the right ascension lock and pivot the scope and weight up and down.
You can slide the weight left and right as it appears in figure 13 above until it balances the scope. The third axes is just pointing the nose of the scope straight up in the air and making sure that the nose does not tip one direction or the other.
This is primarily to see if you have too much weight strapped to one side or the other such as on an astrograph with the camera hanging off one side. While this DSLR Astrophotography for Beginners Tutorial only covers the basics of adjusting and setting up your equatorial telescope mount you can read everything you ever wanted to know about setting up and using your mount in Getting Started: Using an Equatorial Telescope Mount by Allan Hall.
Next up is the guiding. Long exposure work requires that the telescope follow the stars exactly. If it does not, you get odd shapes for the stars instead of round, or you get streaks, or some other weird things.
For this we use an autoguider which watches a star and send minute corrections to the scope computer to make sure it is dead on accurate. One thing to note is that the larger the field of view a telescope has smaller f-ratio, less magnification the easier and more forgiving the guiding is. Now that we have the guider, you have to have some kind of scope to put the guider into so it too can see the stars.
I prefer the second method which mounts a second telescope onto the main scope for the guider, look back at figure 4 to see what this setup looks like. This allows me to have a wider field of view for the guider so I have more guide stars, and also allows me to do whatever I want to the optical path without having to worry about the guiding. Orion sells the guider in two packages like the ones I recommend, the mini autoguider package and the awesome autoguider package.
The difference is the scope size. I run the awesome package so I get the larger 80mm guide scope which has a longer focal length and is therefore more accurate.
Once you have an autoguider you may need to tweak it, using guiding software such as PHD Guiding you can get a graph that shows you exactly how the mount is moving see figure 14 , then tweak the settings to get smoother guiding. As a general rule you want the two numbers on the far lower left, Osc-Index and RMS to be as low as possible and the graph to be as smooth as possible.
A graph showing the guiding characteristics of my mount using PHD Guiding. Canon has probably the widest array of software available to control the camera which you will need of any brand. You can however use pretty much any of them, I for example use a Nikon D and it does a fantastic job. Why weather sealing? One word, dew. Now some people will scream and say you can get a much cheaper body that will do just fine, and it will, right up until the dew forms on it, the scope rotates, and the runoff seeps into the camera shorting it out.
One thing you notice I did not mention with cameras is their maximum ISO. Having higher ISO performance is good, but not because you want to use it.
ISO is usable in a pinch. The problem is, you will be stretching the image so you need the dynamic range offered by the lower ISOs which is why the vast majority of my imaging is at ISO If I need more light I just extend the exposure time.
Let me first dispel a myth about DSLRs. Some people say that they are completely insensitive to high wavelength red such as Hydrogen Alpha Ha for short , this is absolutely not true, see figure Ha is at about nm in the visible spectrum and a standard DSLR will capture it just as well as anything else in the visible spectrum. The problem comes because there are some very dim Ha nebulas which are just too dim to do easily with a standard DSLR. Keep in mind that when you do this, it massively increases the red in your images making everything very very red including things that should not be red and totally useless for normal photography without additional filters or heavily tweaking the custom white balance feature of your camera.
Both Nikon and Canon cameras can be modded. I am currently still using an unmodded camera. You could also consider a dedicated CCD imaging camera built just for astrophotography. The advantages are that they are usually internally cooled which can dramatically reduce noise, they are more sensitive to the full spectrum of light, they can have filter wheels built in, and they can have guiders built in.
They can also get very expensive in a big hurry.
Unfortunately there is no such thing as generic DSLR astrophotography settings for your camera because that depends too much on the target and your telescope. This astrophotography for beginners tutorial suggests starting at seconds at ISO and go from there. DSLR Astrophotography for Beginners Tutorial Section 5: Other important equipment Depending on where you live you might be like me down here in Texas where you have a real problem with dew.
I have come home from the dark site and literally used five or six towels to wipe off my equipment before taking it inside. When I lift the lid to one of my equipment cases at the dark site, water runs off and splashes on the ground not drips, not trickles, literally splashes. So unless you just want to image for an hour or two and then pack it up, you need dew control. I use a four port, dual channel dew controller with four dew strips heated strips with velcro that warm the air around my optics to keep them dry.
Without these it would be more trouble to set up and tear down than it would be worth imaging for an hour or two. Now you may think, scope, mount, guiding, camera and dew, that should do it! Not even close. Next we need at least one computer to run the shutter and guide the scope the autoguider plugs into a computer to run software that does the actual guiding. Most imagers use a laptop or netbook for this. I actually use two, one netbook for shutter and guiding, and one laptop for image transfers images show up complete with histograms on the screen immediately after taking each frame , remote control of the scope and session planning.
To preserve your night vision you can get neutral density sheets and cover the laptop screens. Neutral density called ND from now on sheets basically dim the screen much dimmer than just turning down your brightness.
The advantage to ND over something like Rubylith red plastic sheets is that if your screen is covered in red then it becomes very difficult to make out faint nebulae in your images. ND solves this problem by dimming the screen and not changing the color. I recommend using ND. The actual amount you need will depend on how bright your screen is when on the minimum brightness setting.
I also highly recommend Rosco brand as these have been the best I have found by far, and they are really inexpensive. To see a selection of Rosco neutral density filters for your computer screen, click the following link: Find Rosco Neutral Density Filters Now we need to be able to focus accurately.
I start by pointing the scope at a bright star, something like Vega or Rigel. Then using the live view on the camera zoomed all the way in I make the star as small as possible using my focusing knobs and then lock the focus. Once that is done I place a Bahtinov focusing mask over the front of the scope and shoot a four second exposure at ISO to make sure my focus is perfect, adjusting the focuser forward and backward in small increments until the central line is centered in the cross as in figure If I am using a narrowband filter such as Ha, I double the exposure time to eight seconds.
Focusing with a Bahtinov mask Figure A typical Bahtinov Focusing Mask that fits over then end of the telescope. To see a selection of Bahtinov focusing maks and find one for your telescope click the following link: Find The Right Bahtinov Mask As long as we are talking about round stars, the spacing of the camera, type of telescope and options used can really cause some strange problems. For example, a refractor typically needs what is called a field flattener to make sure the stars at the outer edges are just as round as in the center.
When you do not have one, you can get images with the corners looking like figures 19 and Note that the stars elongate in different directions between the two figures, that is because figure 19 is the top left and figure 20 is the bottom left, they elongate towards the center of the image.
Field flatteners typically need to be designed for a specific F-ratio scope and will note something like it is for a F5-F7 scope. Even if your scope is in this range, the field flattener may require a T-thread spacer between the field flattener and the camera. This spacing is critical to the performance of the device. Elongated stars caused by not having a field flattener on a refracting telescope, upper left and lower left corners of the same image.