So I have a Nikon D5500 and want to take an image of the moon, I also have an 8inch telescope too. My issue is when the camera is coupled to the telescope the moon takes up more than the frame, so its impossible to get an image of the full moon.

Can anyone recommend a tutorial, or is it possible to take a few images of the moon and then stitch them together on a computer afterwards? Or will it always look fake since the lighting wont be uniform?

  • 2
    Do you have sharp images? If yes, you are past the hardest part. Stitching is easy compared to getting sharp images at very high magnification. Stitching will be easier if you shoot on manual with the same settings for each shot.
    – Mattman944
    Jun 3, 2020 at 1:05
  • 1
    What software do you plan on using to stitch?
    – Mattman944
    Jun 3, 2020 at 1:07
  • 1
    Why wouldn't the lighting not look uniform? The sun is shining directly on the moon, and is a fairly stable source of light in terms of variability.
    – Michael C
    Jun 3, 2020 at 4:30

3 Answers 3


Your biggest challenge will be to aim at the different spots on the Moon accurately. This is because the Moon moves its own width roughly every two minutes. You'll need to use stitching software that can handle irregular intervals between each shot.

There should be no issue with different brightness levels, assuming a cloud free sky. If you take all of your shots within a few minutes when the Moon is more than about 20° above the horizon and use the same ISO,exposure time, and aperture for all of the shots there should be no noticeable difference in brightness from one shot to the next. After all, the Sun that is shining directly on the Moon is very stable in its luminance output.


Moon Angular Size

The Moon is roughly 1/2° (in angular width) from edge-to-edge. The Moon doesn't have a perfectly circular orbit ... it's a little closer or farther depending on where it is in the orbit. When the moon is at it's closest point (perigee) it appears to be a little bigger (it can be just fractionally larger than 34 arc-minutes wide).

Ideal Focal Length

Given a camera with an APS-C size sensor (1.5x crop factor), you might be able to fit the Moon into the frame with a focal length of 1800mm ... but that's a pretty tight fit and doesn't leave much margin for error. Around 1500mm would be a more comfortable fit.

Telescope Focal Length

You mentioned having an 8" telescope but you didn't mention which model. I'll take a guess that this is a Schmidt-Cassegrain Telescope (SCT) and not a Newtonian reflector since there are other issues using a DLSR with a Newtonian reflector (most are not well-suited to astrophotography with a DSLR -- but there are exceptions).

If true (telescope is an 8" SCT) then you probably have an f/10 telescope which would mean your focal length is about 2000mm ... that's a bit too much to fit the entire disk of the Moon.

Using a Focal Reducer

You can obtain a focal-reducer (depending on the specific telescope model it may or may not be a combination focal-reducer/field-flattener). Most of these will give you a reduction factor of around .7x (sometimes it's .65 or .68, etc. but it's probably at least .7 ... convenient because a .7x reduction also reduces the focal ratio of the scope by 1 full stop meaning it also doubles the collection of light. So your 2000mm f/10 scope becomes a 1400mm f/7 scope.

At that focal length (1400mm) you should easily be able to fit the entire disk of the moon in your camera's field of view.

Adjust the Exposure for use with Focal Reducer

Avoid over-exposing the Moon (don't trust the camera's metering). Your shutter should speed should be roughly half of your camera's ISO setting. e.g. if using ISO 100 then use a shutter speed of 1/200th sec. At ISO 200 set the shutter to 1/400th sec. etc. Evaluate the images and tweak as needed (you might need to shoot slightly faster to ensure nothing is over-exposed and you have good detail across the surface of the Moon.)


There are magnification reducing lenses (like a Barlow, only opposite) that can be used to widen the field of view. You would put these lenses between the camera adapter and the telescope's focusing tube.

Assuming you're somewhat close to a full disk image, one of these (usually around 0.65x) will get you the full disk in a single exposure.

They're generally sold by telescope suppliers, rather than camera stores; I see them most commonly mentioned in connection with Schmidt-Cassegrain types like Celestron, because these telescopes are optically limited to relatively long effective focal lengths.

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