Guide to Lens Filters for Solar Photography

Solar eclipses are awesome spectacles of nature that are irresistible to photographers. Besides eclipses, the star at the center of our solar system is an amazing photographic subject—even when it is not being partially or totally blocked by the moon. If you want to photograph a solar eclipse, or just photograph the source of our fragile planet’s warmth and light, you need a solar filter for your lens. Let’s look at the different options available to photographers.

Photographs © Todd Vorenkamp

Safety

Before we begin…

WARNING!

Do NOT look through the OPTICAL VIEWFINDER of a camera when the lens is NOT protected by a filter that is specifically designed for SOLAR VIEWING.

Do NOT wear solar observing glasses and look through the OPTICAL VIEWFINDER of a camera when the lens is NOT protected by a SOLAR VIEWING filter.

These warnings are for OPTICAL VIEWFINDERS and do not apply if you are using a mirrorless camera’s electronic viewfinder, digital camera LCD screen, or Live View on the LCD screen on a DSLR.

All solar filtration, with the exception of H-Alpha filters and drop-in solar filters, should be mounted at the front of the camera’s optical system. If using an H-Alpha or drop-in filter, an IR/UV Cut filter at the front of the lens is recommended.

For more solar viewing and solar eclipse safety tips, please click here.

Types of Solar Lens Filters

We will discuss several types of solar filters in this article:

• Mylar® film white light solar viewing filters

• Heavy Neutral Density (ND) filters (minimum 16-stop)

• Hydrogen Alpha / H-Alpha / Ha solar filters

We will also discuss UV/IR Cut filters but, these are NOT, on their own, solar photography filters.

Mylar® Film Solar Viewing Filters

Mylar® is a brand name for a polyester film that has dozens of uses, from wrapping Pop-Tarts to insulating spacecrafts to party and large balloons to… solar photography filters and solar glasses. Mylar® film solar filters are perfect for solar photography and solar viewing.

If you are using the optical viewfinder on a DSLR or another type of optic, you may look at the sun through a Mylar® filter mounted on the front of the lens. (Do NOT look through an unfiltered camera lens while wearing Mylar® solar glasses.)

When shopping (or owning) a Mylar® solar filter, you will see that the surface of the filter may be wrinkled. To a photographer, photographing through a non-uniform surface seems like a horrible idea, but these Mylar wrinkles will NOT affect image clarity and they are intentionally engineered into the film to reduce distortion.

Characteristics of a Mylar® solar lens filter:

• Less expensive than other types.

• Some filters render a whiteish or pale-yellow sun in photographs. Others may give a yellower color. The sun’s color can be changed in post processing.

• Not as durable as other types. The material is fairly fragile and, if a hole develops in the film, the filter must not be used.

• Avoid touching the film with your fingers. They may be cleaned with the same tools and methods you use for proper lens cleaning, but you must be careful not to puncture the Mylar.

White light solar viewing filters made from optical glass are not currently available at B&H. These glass filters are more durable than Mylar® and may show a more natural yellow-ish sun. The big catch: images with glass filters are not as sharp as with the Mylar® filters—a huge win for Mylar® filters!

Neutral Density Filters

ND filters simply darken an image. The advent of digital cameras and electronic viewfinders has made the ND filter a viable tool for solar photography—but NOT for solar viewing or using optical viewfinders.

For solar photography, you should use, at the minimum, a 16-stop ND filter.

Characteristics of an ND filter:

• CANNOT be used with optical viewfinders or to view the sun.

• More expensive than Mylar® filters.

• More durable than Mylar® filters.

• Easier to clean than Mylar® filters.

• Generally, the sun may be rendered more yellow with an ND filter than a Mylar® filter, but the color rendering is dependent on the specific ND filter. The sun’s color may appear very similar to what you get with Mylar® filters.

Photographers often ask if they can stack multiple less-than-16-stop ND filters to create a single 16-stop+ setup. The answer is, “Yes.” But, for every piece of glass you place between the sun and your lens, image quality gets degraded. We recommend using a single 16-stop+ ND filter for NON-OPTICAL VIEWFINDER solar photography.

Hydrogen Alpha / H-Alpha / Ha Filters

H-Alpha filters capture a very narrow band of sunlight and allow you to view details on the solar surface beyond sunspots. These electronic filters are often tuned to allow viewing of either solar prominences or chromosphere details.

H-Alpha filters require an electrical power source and can be mounted on telescopes between the scope and eyepiece, or on camera rigs between the camera and lens. Be sure to verify compatibility with your camera/lens mount or scopes. Additionally, H-Alpha filter manufactures often recommend the use of UV/IR Cut filters when doing extended observations.

UV/IR Cut Filters

UV/IR Cut filters are sometimes added to solar viewing setups to help reduce the amount of UV or IR radiation that reaches the H-Alpha filter and/or camera sensor. They also assist in accurate focusing when using H-Alpha filters.

WARNING: These filters are NOT stand-alone solar filters for photography and viewing. These filters can be combined with different solar filters for an added level of specific protection.

UV/IR Cut filters are not required add-ons for Mylar® or ND filter setups, but they may improve sharpness or detail.

Styles of Solar Photographic Filters

Solar photography filters generally come in four types: threaded, slip-on covers, square, and drop-in filters.

Threaded filters are like standard photographic filters and screw onto your lens’s threaded front opening. The advantage of these is that they are very secure once in place and their operation is familiar to most photographers.

Slip-on cover "universal" filters are more universal in nature and cover the entire front of your lens. They are available in sizes that cover large lenses and telescopes and are very easy to don and doff. That ease of operation can be beneficial during a total solar eclipse because you can go from photographing the “diamond ring effect” to removing the filter and photographing totality within seconds. A threaded filter will require more time to remove. If they are not secured properly, they can be knocked off easily. Again, do not fret over the fact that the Mylar® material on these filters is not super smooth—the wrinkles do not affect image quality. For very large telephoto lenses, you might find that a telescope slip-on solar filter works for the large objective lens.

Square solar filters, like their mainstream square photo filter compeers, require a special filter holder to secure them in front of the lens. If you already have a square filter system, adding square solar filters to your quiver might make good sense.

For large telephoto lenses, drop-in ND-style solar filters are available. If you have a lens that accepts drop-in filters, you may want to use these drop-in solar filters in conjunction with an IR/UV Cut filter at the front of the optic as you would with an H-Alpha filter. Since the drop-in solar filters are ND-style, do NOT use them with optical viewfinders.

Do you have questions about solar filters for photography? What filters have you tried? Which ones do you love? Let us know in the Comments section, below!