Astrophotography is a goal for almost every telescope owner. It was the same with me. You usually come across this topic when you own the telescope. Then, when you start searching for the equipment you might need, it will knock you down. Typically, the price tag for professional astrophotography is starting at $3000 which is for most people unacceptable. And this includes only the telescope and the mount; I’m not even counting the DSLR camera and other accessories. You don’t want to spend so much money when you are just starting a hobby. It is ridiculous.
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Here is a short video I made to show you what can you expect from budget astrophotography:
I wrote two articles where I address this issue, and I recommend the entry point telescope and mount for astrophotography, and it is around $1000. At this price, it is starting to be more attractive and realistic. Today, however, I will show you how to do basic astrophotography under $600! And that price includes not only the telescope with the mount but also the DSLR camera, accessories, and software.
What are we going to need for that:
- fast telescope on GoTo motorized mount
- DSLR camera
- Ultra Thin T-Ring to connect the camera to a telescope
- capturing software
- stacking software
- processing software
- dedication and a little bit of DIY skill
Cheap Telescope For Astrophotography
By cheap I mean adequate piece of equipment for least money possible for this purpose. This is the most expensive part of our budget astrophotography setup.
First, we need the GoTo mount, not a manual one. GoTo system will find every target automatically, and it will track the object during the shoot. Manual mounts can be upgraded with a step motor that tracks the object, and it is even cheaper, but you will have a hard time to find deep space objects on the sky with it. So, for our purpose, the GoTo is a must.
The cheapest GoTo mounts are altazimuth. For astrophotography, it’s recommended to use equatorial mount because you can take long exposures with it. But it can be done with an altazimuth mount too. You are going to be limited to a 30 to 60s exposures depending on the position of the object on the sky. The 30s exposure is good enough to take some nice pictures even in medium-polluted skies. The exposure limit is caused by the field rotation. The altazimuth mount is not compensating for each sky movement, so if you track the object long enough, you will see that the object rotates. In some cases, you can take more than 30s exposures. The rule of thumb is that if you photograph something close to the meridian, the rotation of the field is higher.
The easy way to find out how much and when is the object rotating is to use Stellarium. Just find the object in the Stellarium and use the camera frame simulation. You have to pick the telescope and the camera you want to use. It will create a red rectangle on the map so just zoom in to see it on the full screen and fast forward the time. You will get the sense when is the object rotating less and you can do longer exposures. Trial and error is the best practice here.
Another good reason to get an altazimuth mount is that many times people want to do astrophotography from the backyard or balcony of the apartment and not travel somewhere for the dark skies. It is also my case because I’m doing astrophotography mostly from my apartment balcony. The advantage of the altazimuth mount is that you don’t need to see the Polaris for the star alignment. It is a major factor because you can’t properly align EQ mount without the Polaris. I don’t see the Polaris from here because the view is obstructed, so AZ GoTo mount was the only option for me. AZ mounts can be aligned without the Polaris. I also go out with the telescope, but I spent most of the time on the balcony. Moreover, altazimuth mounts are very easy to set up compared to EQ mounts.
Telescope(OTA) For Budget Astrophotography
The most common telescopes used for professional astrophotography are very expensive Apochromatic refractors. These telescopes cost thousands of dollars. So, it’s obvious this is not the way we want to go. On the other hand, the reflectors are also used for astrophotography, and they are quite cheap, but they have to be specially made for it. Dedicated reflector for astrophotography has a specific design and shorter focal length to reach focus with DSLR. Therefore because they are cheap, we are going to use a reflector.
Next reason to use reflector is that essentially, it is a light bucket. Newtonian reflectors have bigger aperture than refractors so they can collect more light. Because of this, you can do shorter exposures what is essential for us because we are going to use altazimuth mount with limited exposure time. So, how big aperture is suitable for astrophotography? The answer is the bigger, the better. However, if we want to stay in the budget, we will be happy with 130mm aperture. This aperture will collect enough light to get good results with a 30s exposure.
The focal length of the telescope is also important. And the shorter focal ratio is the way to go. With high focal ratio, you will end up with too much magnification and smaller field of view. The short focal ratio will allow you to photograph wider objects like M31 Andromeda galaxy or beloved M42 Orion nebula. The shorter focal ratio also means that the telescope will be fast. It will allow us to collect more light during the 30s exposure than with a slow telescope. So, let’s say we can use a telescope with common specifications. These are 130/650. 130mm aperture and 650mm focal length will give us f/5 scope which is a great light collector. You can further look for the telescope with the parabolic primary mirror to avoid problems with spherical aberration. The last important thing to have on the telescope is 2-inch focuser which I will explain later why we need it.
The SkyWatcher Explorer 130P or Celestron NexStar 130SLT fulfills all requirements for the mount and OTA. They are basically the same scope under different brands. Plus, both of them have a small handy feature which is the focus locking. I personally own the SkyWatcher.
And now, the tricky part. I said above that reflectors have to be made for the astrophotography. You won’t be able to do prime focus astrophotography with DSLR and standard Newtonian reflector. So, you have a few options with standard Newtonian reflector:
- Buy a dedicated reflector for astrophotography. (expensive)
- Use Barlow lens to reach focus. (this option is not ideal because of added optics and high magnification with Barlow lens)
- Do eyepiece projection astrophotography with eyepiece adapter. (also not ideal same as with Barlow lens because this is not prime focus astrophotography)
- Replace your focuser with low profile focuser to reach prime focus with DSLR. (can be pricey and can involve drilling to your tube to fit the new focuser)
- Move the primary mirror deeper inside the tube of the telescope to move the focal point up in the focuser. Easy and cheap DIY project. Now, I will explain this method in the details.
How To Modify Newtonian Reflector For Astrophotography
I have to warn you at the beginning because by doing this you will lose the warranty of the telescope and you can also break or damage the primary mirror. But it is not so hard to do it right, so don’t worry. Let me explain how I did it.
The story began when I decided to use my SkyWatcher 130P on AZ GoTo mount for astrophotography with DSLR. I’m using this telescope mostly for Video Astronomy(EAA) and visual astronomy. I have no problem to reach the focus with my Samsung SCB-2000 and SCB-4000 because their sensors are not as deep in the body like on digital cameras. So, I bought Canon EOS 1000D and tried to put it on the empty focuser and tried to focus. I wasn’t able to reach focus even on the terrestrial level, but I knew that it wouldn’t be possible because this telescope is not dedicated to astrophotography. But I tried, you never know 😀 I calculated that I need maybe 2-3cm to reach the focus with the DSLR.
Every telescope has collimation knobs at the back of the telescope. And you can actually push the mirror with these knobs deeper in the tube. The default position of my primary mirror was not too much in the tube, so I was able to move it with collimation screws good chunk of distance deeper in the telescope. I tried again to put the DSLR to the focuser and focus. It was still not enough. However, I was able to focus on terrestrial objects now.
I decided, after close inspection of the mirror mounting, that I will be able to replace the screws or extend them and push the primary mirror deeper. There was no obstruction to it so no limit. After removing the primary mirror mount by unscrewing 4 screws and removing the mirror from the mounting, I realized that 3 adjusting screws are permanently mounted. I was planning to replace all the screws with longer versions and if you can do it, go for it. In my case, because three screws were permanently mounted I decided to only extend them by connecting them with other screws. I went to the hardware store and bought 6 long screws. I didn’t find the long hex nut screw coupling to connect the screws, but I bought something similar – dropping anchor fastener.
Locking screws were not a problem because they can be replaced with longer screws. To connect and extend the screws on the mirror, I used dropping anchor fastener. First, I had to cut off a little bit with a metal saw to allow the connection. Then screw it halfway on the mirror screws and put the extension screw and tighten it up from the other side. I was not able to find longer springs in the hardware store, so it is without the springs now. A bit harder to collimate but come on, it ain’t stupid if it works :). Now, the mirror was deep enough to reach the focus with the camera. I forgot to take pictures for every step, and I don’t want to disassemble it again. But I will be replacing the screws with shorter ones soon because now it looks horrible. Then I will update the article with photos of each step. But it is an easy procedure, and you get an idea how to do it if you are handy.
Connecting DSLR To The Focuser
The only thing you need to connect the camera to a telescope is a T-Ring. I already ordered one, and after doing that, I realized that I don’t want to push the mirror too far in the tube because I will lose some light and it can create some distortions. If you move it too far, you are cutting portion of it by secondary mirror because the secondary is not designed for it. The next thing is that if you move it only enough to reach the focus with focuser entirely on the bottom, the focuser tube will extend too much inside the telescope tube. I wanted to spare every millimeter on each end.
When I was trying the DSLR on the focuser, I was putting it on the empty tube, and I forgot that between two, I have to use that thick T-Ring. Looking at the standard T-Ring, it seemed very thick. I was loosing almost a centimeter with this. I saved some millimeters by removing the 1.25″ adapter and screwing the T-Ring directly on the 2″ to 1.25″ reducer.
Later on, I found a solution for the thick T-Ring. Wondering on the First Flight Optics website where I bought my telescope, I found special Ultra Thin Canon EOS T-Ring which was exactly what I needed. I ordered one right away, and now it is an essential part of the setup.
DSLR Camera For Astrophotography
Basically, every digital camera can be used for astrophotography. Most people already own one. In this case, I was looking for cheap used ones, and I came across two models: Canon EOS 450D(Rebel XSi) and Canon EOS 1000D(Rebel XS).
The difference between them is that 450D is more expensive, it is 14bit and has a 12-megapixel sensor. The 1000D is 12bit with a 10-megapixel sensor, and it is cheaper one. 1000D is also much lighter than 450D. I bought used Canon EOS 1000D with two lenses and only 8000 pictures taken for $90. Looks like new with no scratches.
You can also modify any camera by removing one or both filters. If you perform full modification by removing both filters, you need IR cut filter to use with the camera. The modification is a pretty delicate technical task, but you can do it by yourself if you’re handy or some companies can do the modification for you if you are not up for it. For now, I’m using the unmodified version, but I plan to modify it soon. I was working for 5 years as an Apple Certified Technician so it will be easy for me. By modifying the camera, you allow more H-alpha wavelengths to reach the camera sensor which is important for photographing most nebulas. It is a good idea to buy spare batteries or dummy battery with DC adapter because there is nothing more annoying than to run out of the battery in the middle of the night.
DSLR Settings For Astrophotography
These are the setting I’m using on Canon 1000D, but it will be similar to every camera. You can play with them if you know what you are doing, and you can get better results.
1. The camera is in the manual mode
2. Auto cleaning: enable
3. viewfinder cap installed while making exposures
4. Shutter speed set to Bulb (I use an interval timer to control my camera)
5. ISO set at 1600
6. Quality: RAW images
7. red-eye: Off
8. review time: off
9. auto power off: off
10. Auto rotate: off
11. LCD off/on between: Shutter Display
12. screen color:1
13. Live View: on
14. Live View Grid Display: on
15. Live view metering timer: 1 minute
a. exposure level increments: 1/3 rd stop
b. Flash synchronous speed in Av mode: auto
c. Long exposure noise reduction: off
d. High ISO speed noise reduction: off
e. Auto lighting optimizer: disabled
f. AF assist beam firing: disabled
g. AF during Live View shooting: disabled
h. Mirror lockup: disabled
i. shutter/AE lock button: AE/AF no AE lock
j. Set button when shooting: Menu Display
k. LCD display when power on: display
l. Add original decision data: off
Software For Astrophotography
You can use software which is completely free or pay some fee to get one with more functions. You will need three types of software. Capturing software that is transferring the image to your computer. Stacking software to stack RAW images. Processing software to fine tune the images and reveal the details after stacking.
Canon EOS Utility vs. BackyardEOS – Capturing
These programs not only capture the image from your camera but they are also controlling the camera which is very important.
Canon EOS Utility
Canon Utility is a free application that you can download and use with your camera. You can control exposure and everything you need to take the photo. But, it is very basic, and it is not made for astrophotography specifically. If you need to take many exposures, you’ll have to do it manually. This can be uncomfortable because you have to sit behind the computer all the time. The positive thing is that it’s free and you can do astrophotography with it if you are patient and have nothing to do during the shooting session.
BackyardEOS is software dedicated for astrophotography use with Canon cameras. There is also a version for the Nikon if you have one. This software is essential if you are taking the astrophotography seriously. It has a lot of options with exposure plans, controlling the camera, focusing, telescope controlling and many more. I love this software, so I highly recommend it if you plan to do astrophotography with DSLR. It has a 30-day trial version, and they are happy to extend it to another 30 days if you encounter cloudy nights after download. Then you can choose from two licenses: Classic Edition and Premium Edition. The Classic Edition is $30, and it is great to start the astrophotography. You can upgrade later to Premium for $50 with many more options. It’s not free, but it’s cheap for what it can do.
DeepSkyStacker – Stacking
After you take a lot of exposures, you have to stack them to create one file. The DeepSkyStacker is the software to do that. It is completely free. When you open it for the first time, it can look complicated. Don’t get scared. It is easy to use, and there are many tutorials on the internet to help you with it.
Processing Software For Astrophotography
When you stack all the exposures, you will end up with a single file. Don’t be surprised if you don’t see anything on the image. You have to process it and bring up all the hidden details in the file. Here again, you have a free and paid option to choose from. The free option is GIMP, and the paid option is well known Abobe Photoshop. It’s up to your preference what you want to use. Maybe you already have Photoshop, but the GIMP is also an amazing piece of software for free. Image processing in astrophotography can be frustrating and many times has a steep learning curve. There are fast and easy methods of how to process the image and then the complicated advanced methods to get the “Hubble like” image.
What You Need For Budget Astrophotography
Telescope: SkyWatcher Explorer 130P AZ GoTo – $416
Celestron NexStar 130SLT Computerized Telescope – Click here to check the price on Amazon.
Camera: Canon EOS 1000D – $90
Accessories: Baader Ultra Short Canon EOS T-Ring – $38
Software: BackyardEOS – $30
TOTAL = $574
As you can see, astrophotography can be done for less than $600. You don’t have to spend thousands of dollars. You can do it even cheaper than that with only the camera, stock lens and tripod to shoot milky way but for deep sky astrophotography, you need the telescope. You don’t have to use reflector either. Refractor on AZ GoTo mount will work fine you just have to take more exposures and do more image processing to remove chromatic aberration. One advantage of a refractor is that you don’t have to perform any modification to the telescope. Refractors have focuser with a long focusing range, and it is no problem to reach the focal point with the DSLR.
Here are my first pictures with this setup. The results can be much better than this but I wanted to photograph as many objects as possible the first night, so I was taking only 30 exposures. It was the only clear night in a while, and I finally received the T-Ring adapter that day. I was eager to try it. All pictures were taken from my balcony in the city. I live on the edge of the city in the yellow zone of polluted skies. It was a bit misty as well so it was hard to get a good result by shooting the objects near the horizon(M51). So, enjoy the photos and don’t be scared to start with the astrophotography. It is a fantastic feeling to get any picture of deep sky objects. More pictures are available in my Reddit post.