Moon Photography - A How To Guide

Keith's Moon Photography
A few topics related to lunar photography...

Crescent Moon And Venus - Photo By Keith Cooley

Moon Photography
Although it is by far the biggest and brightest object in the night sky the moon is not an easy subject to photograph. Using a standard 50mm lens, an image projected onto a slide or negative is only about 1/50 of an inch. Also consider such issues as exposure times, film types, and lenses and you begin to understand what is needed to take photographs of the moon. With the recent introduction of inexpensive digital cameras a whole new area of lunar photography is now available to the amateur. I've included a few things to consider when trying to photograph the moon. Equipment, techniques and even a few formulas are presented.

The Moon As A Source Of Light
The moon appears full when it's in a position where the side of the moon facing earth is fully lit by the sun. Photographing a full moon isn't much different than photographing any other sun-lit object-except that it's pretty far away. Due to this fact it's recommended that you use either a SLR (single lens reflex) camera with a long lens or a semi-professional digital camera rather than a point-and-shoot or a single-use "disposable" camera. In fact, with a point-and-shoot you can get an image of the moon but it will be a tiny white point rather than anything that like the moon.

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Lunar Photography Using An SLR Camera

Determining Image Size on Film

The formula for determining the size of the lunar images on film is found by dividing the focal length (in millimeters) by 109 to arrive at the lunar diameter (in millimeters) on the film.

Examples

Lens Size Image Size

100mm 0.92mm

200mm 1.83mm

300mm 2.75mm

Photograph Results With Various Lens Sizes

50mm 135mm
300mm 800mm

Films
Color	B & W
Kodak Kodachrome 25	Kodak Tri-X Pan 400
Fuji Velvia-ISO 50	Kodak T-Max 100
Ektachrome 64,400	Kodak T-Max 400

Film
Since your subject is primarily black-and-white 400 speed black-and-white film would be a logical choice. Color negative ISO 400 or 800 film would also work. If you bracket a lot, you can use slide film, but there's a greater danger of losing detail because of overexposure if you do. If you follow these simple tips, you'll have no problem if you attempt to photograph the moon.

Bracketing Shots

When you bracket your exposure, it simply means that you make an photograph at the setting you think is correct, but you also photograph the same subject several more times, making slight changes in either the shutter speed setting or aperture. For most situations, we suggest that you make one or two images giving the film less exposure, and one or two that give the film more exposure.

You can't bracket fast-moving subjects-a breaking news photo or sports action shot won't wait long enough for you to make multiple exposures. But the moon (or a landscape or scenic) isn't moving so fast relative to your camera. Therefore, it's always a good idea to bracket your exposure. For our full moon shot, in addition to 1/250 and 1/500 @ f/16, you could give a little less exposure by making a photo at 1/1000 @ f/16, and a little more by shooting at 1/125 @ f/16. You can achieve the same bracket of exposure by keeping your shutter speed at 1/250 but using different aperture openings, such as one exposure each at f/16, f/22, f/11 and f/8.

Lunar Photography Exposure Guide (@f/16)
ISO Film Speed	Full Moon	Gibbous	1st Quarter	Thick Crescent	Thin Crescent	Earthshine
25	1/15	1/8	1/4	1/2	1
50	1/30	1/15	1/18	1/4	1/2
100	1/60	1/30	1/15	1/8	1/4
200	1/125	1/60	1/30	1/15	1/8	40 to 80 sec.
400	1/250	1/125	1/60	1/30	1/15	20 to 40 sec.
800	1/500	1/250	1/125	1/60	1/30	10 to 20 sec.
1600	1/1000	1/500	1/250	1/125	1/60	5 to 10 sec.
3200	1/2000	1/1000	1/300	1/250	1/125	2 to 5 sec.

Exposure Times vs. ISO Film Speeds

The speed (ISO) of the film being used for lunar photography determines the exposure times due to the varying brightness phases of the moon. The higher the speed (ISO) of the film, the shorter the exposure. The drawback of using super high speed films such as the ISO 3200 is that the finished pictures tend to be very grainy especially when enlarged. The following table gives the exposure times (in seconds) for various speed films at different phases of the moon. Due to atmospheric turbulence and light pollution, it is best to 'bracket' your exposures. Bracketing consists of taking exposures on both sides of the recommended shutter speed.

Exposure Times vs. Mount Types

It is recommended that the camera be used piggyback or as prime focus on a tracking telescope, however, depending on the size of lens being used, photos can be taken from a tripod. The limiting factor here is to limit the exposure (depending on the lens) to avoid star trails. Example: for a camera mounted on a tripod using a 50mm lens, the exposure can be approx. 12 seconds to avoid star trailing; mounted on a driven telescope, the exposure can be up to 4 minutes. The table shows the maximum exposure times using various lenses with fixed mounts and tracking mounts.

Exposure Times & Mount Types
Lens (in mm)	Image Size on Film (in mm)	Fixed (tripod)	Driven (At Sidereal Rate)
50	0.45	12 sec.	4 min.
100	0.9	6 sec.	2 min.
200	1.8	3 sec.	1 min.
500	4.5	1 sec.	20 sec.
1000	9	1/2 sec.	10 sec.
1500	13.5	1/4 sec.	7 sec.
2000	18	1/8 sec.	5 sec.
2500	23	1/15 sec.	3 sec.

Examples Of Lunar Photography Using An SLR Camera

Here are a few examples of moon photography using a SLR camera. Two of the photos were taken the same evening a few minutes a part. A slightly shorter exposure time combined with waning twilight produced pictures with differing tones and hues. The center photo was taken during hazy conditions and shows the moon fuzzy with little detail. I suggest using foreground objects such as trees or buildings in your photos to give them a more personal touch. Click on any photo for an expanded view.

Lunar Photography Through A Telescope

PRIME FOCUS METHOD

This is the simplest method for lunar photography. If you have a catadioptic telescope, such as a Schmidt,Cassegrain or Maksutov, remove the camera lens, and using a simple adapter (T-ring, available at camera stores and astronomical supply houses), attach the camera directly to the telescope (without its eyepiece). The telescope becomes the camera lens, in effect, a very long telephoto lens. For example, a 5-inch Celestron or Meade Schmidt,Cassegrain telescope becomes a 1250mm, f/10 telephoto.

AFOCAL METHOD

This method requires two tripods, one for the camera, and one for the telescope. The camera (with lens) is set up as close to the telescope eyepiece as possible, and focused on the image seen through the cam- era. The exposure time is calculated by determining the focal length (F) and the f/ratio of the telescope system. F = focal length of camera lens x magnification of telescope f/ratio = F/diameter of the telescope objective Magnification of the telescope = focal length of telescope focal length of eyepiece

PROJECTION METHOD

This method requires the use of a special adapter which is much more expensive than the simple T-ring used in the prime focus method. The adapter connects the camera without its lens to the eyepiece of the telescope. This is an advanced method used in most amateur astrophotographers,

Digital Lunar Photography
In the 1990s digital cameras and image processing began to make an impact on the world of photography. Digital imaging will continue to attract more fans as equipment drops and processing power increases. The Internet gives you the ability to publish and exchange information, in the future digital images will be the format of choice.
			A few examples of digital lunar photography. Pictures taken with a Sony MVC-CD1000 digital camera with maximum zoom. Thanks to Gary Braden for the digital lunar photographs.
Although existing photographs can be turned into digital files, most amateur astronomers are more excited about capturing images of the moon directly in a digital format. Cameras that can record digital images are referred to as CCD instruments. Each graphic format used to capture images translates the image's distinctive elements into individual bits, creating a bitmapped version of the original. CCD stands for charge- coupled device; a CCD camera projects an image onto a specialized computer chip (referred to as a CCD chip), which records variations in light intensity as a set of digital measurements. While several digital formats are available most cameras use a compressed format know as JPEG (Joint Photo Expert Group) This format will reduce file size and allow you to store more images for a given amount of camera memory. Although, the more you compress an image, the greater the loss of picture quality. If your particular camera has this option, try taken lunar photographs using the black and white mode. CCD images captured in black and white can actually turn out sharper than those taken while in the color mode. Advantages of Digital Photography You get instance results and immediate feedback on your work. Keep what you like and discard the rest. Depending on the camera's memory, more images possible than a roll of film. No lab processing or developing cost. Disadvantages of Digital Photography Color and resolution not as good as film. Due to electronic noise exposure times limited to a few seconds. Post imaging work needed on most shots. Technology still in the process of evolving.

A Few Ideas And Suggestions

For more general information on photographing the night sky visit my Tripod Astrophotography site. Here you'll find lots of information about equipment (Cameras, tripods and cable releases), accessories, films, image processing, etc. All the things needed to get you started in the hobby of wide-field astrophotography.

RULES FOR PHOTOGRAPHING THE MOON
Always use a tripod and cable release (SLR).
Use the camera's highest resolution setting (Digital).
Photos of the full moon are flat and featureless. For more interesting pictures, photograph the Moon at crescent or quarter phases when the mountains and craters are illuminated from the side and cast shadows.
Always bracket exposures since exposure times given by formulas are approximate, varying according to the exact phase of the Moon, atmospheric conditions, etc. To be safe, bracket at one and preferably two stops on both sides of the exposure suggested by the formula.