Photographing The Moon With A Smartphone And A Telescope

Pushing The Boundaries Of Smartphone Photography

     Have you ever dreamed of taking great photos of the moon with your smartphone but when you try, the moon looks like this?​

The moon shot with a smart phone and no telescope.

     That tiny speck in the sky is probably not what you envisioned but if you try to get close with the smartphone's digital zoom, so much resolution is lost that the moon looks like an Atari game from the 80's with big square pixels and no detail. Clearly that's not going to work, so what to do then?

Telescope

     For this purpose, it is not necessary to spend thousands of dollars on a high end telescope (though I say get the best one you can afford)  Even the most basic of telescopes can get up close and personal with the moon. All of the detailed moon photos in this post were shot with a Cassini 80x800 telescope and a Motorola MotoX4 smartphone.

The Telescope Set Up

     The first step in this process is to get the moon lined up and in-focus in the telescope. If you're using a manual telescope, it will have to be readjusted several times throughout this process because the moon will rotate itself out of the frame every couple of minutes.
     The second step is to select the (telescope) eye piece that will render the best results. I recommend the eye piece with the least amount of magnification. On my Cassini 80x800 telescope, it's the 25mm eye piece. In my opinion, the 25mm is the easiest to use for a few reasons: #1, it has the most surface area making it easier to align the camera lens over it while still keeping the entire moon in the frame; #2, it brings the moon into sharp focus but with enough extra room that the telescope only has to be re-positioned every couple of minutes instead of every few seconds; #3, it creates the least amount of "camera shake". In this instance, it's not the camera that's shaking but actually the Earth. The higher the magnification of the telescope, the more noticeable the vibration. There are some complicated equations to determine the minimal shutter speed needed to eliminate camera shake based on the focal length of the lens but since we're shooting with a telescope and a smartphone, never mind all that and just use the 25mm eye piece.

The Camera Set Up

     This is the most challenging part and may require more than one attempt to get it right. Once the telescope is aligned with, and focused on the moon, you now have a brief window of time to get a few photos before starting the process over again. 
     #1. Align the back facing camera lens of the smart phone over the eye piece of the telescope. This sounds easier than it is but it gets better with practice.

     #2. Once you see the moon on the phone screen, the next step is to spot-meter and focus by tapping the moon with a finger or thumb. This tells the smart phone camera where to focus and what to meter the exposure on. 
     #3. When the moon is in focus and exposed correctly, shoot the photo! How do you know when the moon is exposed correctly? You should be able to see all the detail with no areas that are blown-out or so bright that no detail is visible. In short, the moon should look the same on the phone screen as it does to your eye when you look through the telescope. This part is especially important because if the image is over exposed, there is no way to recover this detail after the fact.

Composition

     Do not expect the moon to fill the entire image area of the phone, it will not. For best results, try to get the entire image area from the telescope to display on the phone. If the sky is not yet completely dark, you should be able to see a circle from the eye piece of the telescope. Don't try to zoom in with the camera, do your zooming by cropping the photo after the fact.

     Many telescopes come with a smart phone attachment that will supposedly hold the phone in the correct position over the eye piece. If you can get that to work, more power to ya, but I haven't found this to be a good method. I use the smart phone attachment but only as a guide to steady my hand. Because the positioning of the phone lens has to be so precise, it can be very difficult to keep it in the right spot while also tapping the screen to get focus and exposure and then hitting the "shutter" to take the photo. Once positioned correctly, the smart phone attachment makes an excellent guide to assist in aligning the camera lens with the eye piece of the telescope.

Don't Push!

     The other reason the smart phone attachment is only useful as a guide is because the camera lens needs to not be touching the eye piece of the telescope. To determine the exact distance for optimal image quality requires experimentation but should be within an inch. What you don't want to do is to rest the phone directly on the eye piece. This will usually be too close but the other problem is that (while trying to do everything else at the same time) it's easy to start pushing down on the phone which in turn can push down on the eye piece thus throwing the telescope out of focus. It is not possible to achieve a focused image with the camera unless the telescope is in sharp focus.

Trial And Error

     Not gonna lie, photographing the moon with a smartphone and a telescope is not the easiest thing to do but with practice and experimentation, excellent results can be achieved. I've been working at it for about eight months now and, while at first I found the whole process to be time consuming and frustrating, I can now usually set up the telescope and get my images in about 10 - 15 minutes. The secret is patience and practice.

Post Processing

     The foundation of creating great images is always to shoot a great image in the first place. By that I mean, the basics should be in order. The image should be in focus and exposed correctly with relatively good composition. Post processing is not a crutch or magic wand to turn bad photos into good photos, rather it is a tool to make (already) good photos better.
     I try to keep the entire process in the phone so the app I like to use for editing photos is called Snapseed and is available for both iPhone and Android. Make your rotation, cropping, and exposure tweaks with this app.

Rotation?

     Be advised that a reflector telescope turns everything upside down so the moon will be upside down in your photos and will need to be rotated during the post process.

Happy Shooting And Good Luck!

     The most important thing is to keep trying. Please feel free to ask questions by posting them in the comments section at the end of this post.
     All detailed moon photos shot with Motorola MotoX4 and Cassini 80x800 telescope, edited in-phone with Snapseed.