Use Your Smartphone for Astrophotography

Since getting my old PowerSeeker 127EQ and snapping some quick shots of Jupiter through it, many people have asked me how to do the same. They most often assume it to be a relatively complex thing to do, but it’s not. It’s actually pretty simple and not actually that expensive to get started.

First, you need a telescope. I started with the 127EQ, but I now almost exclusively use my Orion SkyQuest XT8. Both are reflector-type scopes in that they use a mirror to focus the light they receive. Bang for your buck, it’s hard to beat the 127EQ. It’s cheap, has a 6-inch mirror, comes with a sturdy-enough mount, and provides a nice, entry-level viewing experience. Collimating it, however, is a bit of a nightmare. But you can benefit from my experience with doing so.

Saturn, taken on 6-30-19 at 240x magnification with Samsung Galaxy S9. 100 ISO. 1/30s exposure. F1.5 Aperture.

If you can spend three to four hundred dollars, the Orion XT8 is a great scope. It’s a bit bulky, but it’s powerful, offers some surprising optics, and is easy to use and maintain. It benefits from mounting a right-angle view finder and having a strong back to lift it. It’s about 40 lbs.

Be warned. Neither scope will allow you to perform complex astrophotography with a DSLR camera that requires auto-tracking mounts for long exposures. The 127EQ theoretically supports a motor to turn its equatorial mount, but I was never able to get mine to work.

But that’s fine, because this is about doing astrophotgraphy without a headache or spending too much money. You can purchase a much less expensive scope, but those scopes tend to be smaller and less stable. You can’t take pictures if your camera/phone keeps tipping your telescope over or the weight of it bends the eyepiece focuser, which I’ve had happen to a $50 scope I bought for fun that I won’t name.

Once you have a scope you’re going to want your smartphone to have a decent camera. Almost all the modern flagship models from recent years have pretty solid cameras. Most importantly, the cameras have modes that let you manually adjust their capture settings. I started with a Samsung Galaxy S7 and migrated to an S9, which is what I use now. But the new iPhones and Pixel phones are supposed to have even better cameras now.

With your phone in hand, make sure the back camera lenses are clean. Next, open your camera app and look for your image capturing settings. On my Samsung phone, I access these through the “Pro” mode.

Jupiter, taken on 6-9-19 at 240x magnification with Samsung Galaxy S9. 100 ISO. 1/45s exposure. F2.4 Aperture.

The important settings you’re looking to adjust are the ISO, the shutter speed, the focus (manual/auto), and the aperture (if your phone supports more than one aperture). You will also want to set your phone to take as high a resolution picture as it can. The more pixels the better!

The ISO affects your camera’s sensitivity to light. The higher the ISO, the more sensitive it becomes but also the more “noise” you get. The shutter speed controls how long your camera’s sensor is exposed to incoming light. The longer you leave it open, the brighter your image will be. Leave it open too long and your image will blur if it’s moving. When trying to take pictures of planets and other bright objects, you’re going to want to use less ISO and a shorter shutter speed. That generally gets you more color and detail in your image.

The focus is important, too. You can almost always set your camera to manual focus and set the focus distance out to “infinite,” as if you’re focusing on mountains in the far distance. But, sometimes if you have a bright enough and big enough planet or moon, you can play with your camera’s autofocus to see if it’ll work. When it does, the results can be much better than the manual “infinite” focus.

If you can change your phone’s aperture, you should know that the larger the aperture, the more light the sensors receives. The focusing issues with the smaller depth of field from the larger aperture aren’t usually a problem with astrophotography, but sometimes too much light can be a bad thing, especially with brighter objects like the moon and some planets. Trying take pictures with each aperture setting to see what’s returning the best image.

Lastly, learn how to set your camera’s delay timer. Unless you want to invest in a remote for your phone’s camera, the next best thing is setting a 2-5 second delay on taking pictures after you click the button. Even sturdy mounts can momentarily vibrate and wobble after you manipulate your phone and these movements are dramatically amplified at higher viewing magnifications. The timer delay lets these things settle down and stop before the camera goes off, protecting your shot.

Once you have a grasp of these settings. It’s time to purchase a Cell Phone Adapter Mount. This little device connects your cellphone to whichever eyepiece you’re using in your telescope. They range in price from around $10 to $40. The things to consider are the quality of the material, the weight of the mount, how well your phone will fit, and the depth/height of your eyepieces after they’ve been completely slotted into the focuser. If your favorite eyepiece is shallow, pay careful attention to how the adapter you want to use will attach to it. And you want to get the best combination of sturdy material and low weight. I linked the one I use above.

Whichever one you purchase, it will take a little practice and/or some careful marking to be able to slot your phone into the mount in such a way that its camera (note: some phones have multiple cameras on the rear) is center positioned over the lens you mount it on.

In my experience, the easiest way to do this (and redo this because the adapter will probably need periodic readjustment) is to slot your phone and slot a wide angle eyepiece. Meaning, connect an eyepiece with a wide diameter lens. Then open your phones camera and point the combo at a lamp across the room. You should be able to see the lamp on your phone through the eyepiece. If you don’t make some adjustments and try again.

Once you have the wide angle lens good to go, it’s time to refine your adjustments with a narrow angle lens. These lenses tend to be tiny in diameter but offer the most magnification when viewing. Replacing the wide angle eyepiece with the narrow angle eyepiece and check for the same lamp. If the camera is centered properly, you should just get a circle of light in the middle of your screen. If not, make some careful adjustments.

As always, take care not to drop or dirty your eyepieces. Take reasonable precautions before you start.

So now, you have a telescope, you have experience adjusting your phone’s camera settings, and you have an aligned mount. Go find yourself something to take a picture of. It’s easiest to start with a big bright planet like Jupiter, but it’s also pretty easy to shoot the moon. Whatever you choose, direct your scope toward it and focus it for the eyepiece you intend to use for the photo. If you have the ability to tighten up or lock your focuser in place after doing this, then do so. You don’t want it to move for the next step.

Uranus, taken on 10-19-19 at 240x magnification with Samsung Galaxy S9. 200 ISO. 1/10s exposure. F1.5 Aperture.

Now, slot your phone into the mount if it isn’t already slotted. Make sure it’s snug and not going to slip out. Then carefully attach it to the eyepiece with the object in view and in focus. You need to make sure the eyepiece is secure in the focuser and that the mount is secured to the eyepiece, all while not moving your scope. This can get tricky, especially at high magnifications.

For bright objects, you should easily see them appear on your phone’s screen, even with an automatic camera setting. If not, switch to your advanced settings and increase the ISO and/or reduce the shutter speed. The latter usually works better in my experience. Once you can see the object through your phone’s camera, you can begin to make the adjustments to bring out the objects color and detail.

For high magnifications and even lower ones, you’re going to have to readjust your scope to keep the object centered. Whether it’s a star, a planet, or the moon, it’s going to be moving. And the higher the magnification you use the faster it will travel through your field of view. This, too, takes some practice. If you over adjust, you’re probably going to have to detach the mount and find the object all over again unless your view finder is perfectly aligned with your scope.

Note: If you decide to shoot the moon, especially when it’s near full; it’s going to be really bright. Don’t be afraid to increase the shutter speed to hundredths of a second.

Once you have a mix of settings that look good, take a picture using the timer. But keep in mind, what you’re shooting will be moving, so you may want to slightly offset the objects position in your camera before taking the picture to correct for this movement. This can also get a little tricky, but you’re not trying to be perfect. You can always crop the image later. It’s more crucial for “large” celestial objects like the moon or nebula. As parts of them can move out of frame.

Keep readjusting and trying a mix of settings. While I suggested the “Pro” mode, there are new and specialized modes you can also try like the “Night” mode. I don’t suggest taking pictures with the digital zoom. Feel free to use the zoom to adjust settings to bring out color and detail, but zoom back out when you’re done. You can always enlarge the photo later without losing the initial data.

You can be methodical about all of this or correct it on the fly. The photo metadata usually captures most of the settings you’re using. You can even experiment with video, which can be used to get many frames of images for image stacking. Image stacking is a more advanced concept I’m currently learning about it, but it really produces some fine images.

Neptune, taken on 9-7-19 at 240x magnification with Samsung Galaxy S9. 400 ISO. 1/3s exposure. F2.4 Aperture.

When you feel like you’ve taken enough pictures (the more the better), go through them. Zoom in, examine them closely. Try some basic cleanup with a photo auto-adjuster or import them into a more complex application like Adobe Photoshop or some photo editing app.

To summarize, all you need to get into astrophotography is a telescope, which can run as little as $100 or as much as you like; a $10 phone mount; a smart phone, which you probably already have; and some patience and practice.

And to be fair, you don’t technically need a telescope. Venture out to a dark enough place with clear skies and you can manipulate all the same camera settings on your phone or DSLR/non-DSLR camera to take some incredible pictures of the Milky Way or other deep sky objects (DSO).

Collimation, My Nemesis

Collimation has become my nemesis in recent weeks. The seemingly simple task of making the center of one mirror reflect another is deceptively difficult. When I first got the PowerSeeker 127EQ, I hoped this would not become a problem. It was something other people had to deal with not me.

That changed when some debris blew into my scope and got stuck to the primary mirror. I tried tilting the scope and blowing it out with an air can, but it didn’t work. So, I needed to remove the mirror. I consulted the manual and some YouTube clips to see how to best do it. I undid the correct screws and carefully placed the mirror aside on a table where I could remove the debris with a lens cloth and a more direct application of canned air.

I was a little excited to have a reason to clean the mirror, believing getting the shipping dust off of it would give me a clearer image than I’ve had before. While I’m sure it did help, my first look at the moon and the bright February crescent of Venus was more like viewing them through a telescopic prism. The images were terribly skewed by the “coma,” which is the technical term for the telescope reflecting a smeared and stretched image, giving it a reddish and bluish light tail. Even the moon, which is the first and easiest thing to see, was blurry and I couldn’t focus the image to make it sharp.

I knew what the problem was and also knew what I read about the difficulty of collimating the 127EQ, but I believed I was better than others. I believed I could just follow the directions in the manual and do it by eyeballing things without even using a collimating eye piece. I was wrong.

Peering into the open (no lens) eyepiece, I could see the reflection of the primary mirror was well off center. I made some adjustments to the secondary mirror with a screw driver. The secondary mirror is held to the scope with a single, long middle screw and angled with a triangle of shorter screws. You turn those three screws one at a time to try to center the view of the primary mirror in the eyepiece. I did that, as best as I could, but I was just making my best estimation that the image of the primary mirror was centered in the circular darkness of the eyepiece.
The next step was to center the reflection of the secondary mirror inside the reflection of the primary mirror by adjusting the primary mirror.

On the 127EQ, the primary mirror has six identical screws spaced out in pairs in a triangular pattern. The most clockwise of the pair is the locking screw and the other screw is the adjustment and mounting screw. Yup, the adjustment screws are what hold the mirror into the bottom of the telescope.

Furthermore, the screws can really only pull the mirror tighter against the scope mounting. The pushback comes from three rubber sleeves or plugs the screws pass through. So as you tighten the screws you compress the rubber. As you loosen them, the rubber ideally expands to push the mirror out.

In practice, this is really problematic. Unless the mirror is horizontal to the ground, it’s weight tends to tilt the screws and the metal disc its mounted on against the edge and mounting brackets inside the tube, meaning the rubber plugs or plugs aren’t “strong” enough to push the mirror out as you loosen the screw or screws. There’s an entire video on the web about how to replace all six of these screws with finger-adjustable wings and how to replace the rubber plugs with springs.

I devised a simpler solution than replacing the plugs with springs. I know you’re supposed to be able to purchase some at the hardware store, but I didn’t figure it was worth the effort of trying to find some that might fit. Nope, I used gravity instead.

I learned that the best way to adjust the mirror was to keep it horizontal to the ground so gravity would do the job the rubber plugs couldn’t do and more evenly. There is some risk of the mirror falling out of the bottom of the tube by doing this, but it’s a really small risk since you would need to unscrew all three adjustment screws completely. By the time you popped the second screw out, you should be able to recognize the peril.

I found this gravity method also worked for adjusting the secondary mirror, at the risk of dropping a screw driver into the tube and cracking the mirror.

Figuring I mastered the mirror adjustments and after hours of tinkering, my eyeball results improved the image, but were still inadequate. I realized I needed a tool. Despite seeing all the reviews that suggested using a laser collimator, I opted to purchase the collimation eyepiece listed in the Celestron manual. I thought it would be cheaper than a laser collimator and almost as effective.

Thinking I had the problem licked, again, I slotted the eyepiece, which was recommended in the manual, and found it had two problems. First, it was too long. Unlike other reflector telescopes, the 127EQ is of the variety that needs a corrector lens in the base of the eyepiece to fix and focus the image bouncing off the secondary mirror. It’s kind of an inexpensive way of increasing the focal length of the scope without increasing the actual length of the scope or the size of the mirror. The collimation eyepiece wouldn’t slot fully into the eyepiece mount because the bottom of it would hit the corrector lens.

The other problem was the eyepiece tube was just a little too slender and the bottom of it was just loose enough when slotted in the eyepiece mount to move around. Meaning, I was eyeballing centering the eyepiece so I could center the image of the primary mirror so I could center the image of the secondary mirror in the middle of the eyepiece crosshairs. After many more hours, I got improved results but not enough to warrant the $30+ I paid for the eyepiece.

View down the eyepiece mount of my 127EQ not very well collimated with the eyepiece tool.

So, I returned it and bit the bullet. I purchased an inexpensive laser collimator, the SVBONY Red Laser Collimator, for about $25. Many reviews claimed the laser needed collimation itself because it didn’t come out of the projector completely centered. But there was an easy way to test this by rolling the pointer in place and seeing if the laser dot on the wall turned a circle of stayed mostly in place.

The one I got stayed mostly in place, but because of the corrector lens in the 127EQ I couldn’t just slot it and go. Nope, I had to take apart the eyepiece mounts, remove the corrector lens, and put it back together without the lens and without forgetting the proper orientation of the lens. That done, I slotted the laser collimator and tried not to blind myself as the beam lit out of the telescope. The collimation was well off.

I followed the directions as best as I could. The primary mirror of the 127EQ doesn’t have anything marking the center of it, so you’re doing your best to reflect the laser from the secondary mirror onto the middle of the primary mirror. More eyeballing. And yes, there are plenty of sites and videos about how to mark the center of the mirror with a sticky 3-ring reinforcement ring. I wasn’t even going to bother at this point. I ended up loosening the secondary mirror and adjusting it by hand before locking in the adjustment screws and then doing the same to the primary and then going back to the secondary and then back to the primary. For whatever reason, I wasn’t able to get the laser to strike the perceived middle of the primary mirror, reflect back into the eyepiece off the secondary mirror and hit the target in the laser collimator.

View down the eyepiece mount of a laser collimated 127EQ. The black bump in the bottom is actually the edge of the clip on the secondary mirror. The next time I collimate the scope, I’ll fix this.

But I got much, much better results. I stayed up way, way too late on a clear and very cold night to get these. The lighting conditions were not ideal thanks to a lit parking lot and neither planet was especially close at the time, but I’m still proud of what I was able to do and my view of things with my eye was inspiring and far clearer and more vivid than my Galaxy S7 can capture.

Jupiter was closer than the last time I viewed it, so I was able to capture the striping with my Galaxy S7 by playing with the Pro Mode settings.

The most powerful lens I used was the extra 9mm lens I purchased as part of a kit separate from the scope. Those kit lenses are by far my favorite to use. They manage decent magnifications with a great viewing area for my eye and pictures. I have the 4mm lens that came with the scope that can push it to its maximum, practical magnification of 250x, but that’s really kind of pointless if you’re getting a little more than twice the magnification at a quarter of the viewing area.

Saturn isn’t especially close right now, but I managed a crisp enough image at roughly 111x magnification with my Galaxy S7. I also stayed up way, way too late waiting for Saturn to rise.

So, I picked up another after market lens I’m desperate to try when the sky clears. It has the 4mm focal length for maximum magnification, but with a 10mm lens to see it through. Check the pictures below to see the comparison. It’s also worth mentioning the lens is a lot clearer than the one that came with my scope.

Both lenses have a 4mm focal length. Which one do you think would be easier to peer through?

My scope is collimated for the time being, but I’m not looking forward to doing it again. I spent hours figuring it out and researching it. When it comes to astronomy and this telescope in particular, collimation will remain my nemesis.

And thanks to theskylive.com for providing so much useful info about the planets.

@DivergentZen