Getting the best from your slit lamp photographs: settings, technique & some outstanding examples from our Slit Lamp Imaging Competitions

01.10.26

A great slit lamp photograph is about much more than simply pressing the shutter.

Photographic slit lamps, such as Haag-Streit’s BX 900, offer a remarkable range of options for controlling illumination, magnification, aperture, and contrast. Used thoughtfully, these controls can transform an image — revealing fine detail, separating different tissue layers, and help a clinical finding stand out.

This year's Slit Lamp Imaging Competition was a great reminder of that. Looking through the images, one thing became particularly clear: there isn't a single setting that produces the best image every time. The most effective images were those where the settings and the illumination technique had been chosen to suit the anatomy and the feature being photographed.

Haag-Streit Slit Lamp Product Manager and expert Ophthalmic Imager, Gemma Edwards shares her top tips for achieving an outstanding clinical image.

1. Where do I start?

Gemma says, “When photographing a new case, it is tempting to immediately start adjusting everything. A better approach is to begin with a known baseline and then make one change at a time.”

Haag-Streit's Slit Lamp Imaging Guide suggests a standard diffuse-illumination setup using:

  • ISO 500
  • Shutter speed of 1/125 seconds
  • High flash intensity
  • 100% background illumination, set at approximately 30 - 45°
  • A fully open, centred slit beam, with diffuser
  • Illumination at approximately 30 - 45°
  • 10× magnification
  • Aperture 4 (Step 1 = largest aperture, Step 5 = smallest aperture)


These settings are intended as a starting point, rather than a recipe that must be followed for every image.

2. Magnification: should I go higher?

The BX 900 offers 6.3×, 10×, 16×, 25× and 40× magnification. Other slit lamp magnification options will be different.

Gemma advises, “Higher magnification can be invaluable when the aim is to document a small feature, but it isn't necessary for an overview photograph. For example, 10× can be an excellent starting point when you want to show the overall appearance of the anterior segment. Moving to 16× or 25× can then help isolate a particular area of interest.”

As you increase the magnification, it becomes more challenging to capture a good image. At 40×, you are asking considerably more of your positioning, focusing, and illumination. Small movements become much more apparent, while the field of view becomes much smaller.

3. Aperture: where is the balance between brightness and depth of field?

The BX 900's imaging system provides five mechanical aperture settings. This is particularly useful when photographing at higher magnification. A larger aperture allows more light through, but provides less depth of field. A smaller aperture increases the depth of field, which can make it easier to keep the relevant structures sharp but reduces the brightness.

Gemma notes, “Aperture can be especially useful when the feature of interest isn't lying in a perfectly flat plane. The important point is not to think of aperture simply as a brightness control. It also changes how much of the subject appears acceptably sharp.”

Our photography cheat sheet can help you look at ISO, aperture, and shutter speed settings and help you understand these important photographic principles.

4. Slit width and height: how can I control the light?

The BX 900 allows continuous adjustment of slit width and length, with slit widths from 0 to 8 mm and slit lengths from 1 to 8 mm. The slit can also be rotated through ±90°.

A wide, open beam is useful for diffuse overview images. Narrowing the beam, however, can help emphasise particular structures and produce much greater definition.

For a broad overview: Wide beam + diffuse illumination = soft, even illumination.

For a more detailed examination: Narrower beam + carefully chosen angle = greater structural definition.

Gemma says, “The best Slit Lamp Imaging Competition photos often demonstrate this principle. The photographer hasn't simply made the image brighter; they've controlled where the light is coming from and what it is revealing through the use of different illumination techniques to best etherize the area of interest, through either direct or indirect illumination.”

5. Should I change the angle?

One of the easiest adjustments to overlook is the angle between the illumination system and microscope. Changing the illumination angle changes the way light interacts with the structures being photographed. It can alter reflections, shadows, and the visibility of subtle features. For diffuse illumination, we would suggest an illumination angle of approximately 30 to 45°.

Gemma advises, “If a feature isn't standing out, don't immediately reach for a different magnification or exposure. Try decentring the slit lamp and moving the illumination slightly and watch what happens to the reflections and shadows. Sometimes a few degrees is all it takes.”

6. Filters: use them to reveal information

The BX 900 provides blue, red-free (green), and grey (10%) filters, as well as diffuse illumination. An optional yellow filter can also be added. Each changes the appearance of the image in a different way.

For more information about slit lamp filters, read our blog post: "A practical guide to slit lamp filters".

7. Does the background illumination make a difference?

The pivoting background illumination is one of the features that makes the BX 900 particularly versatile for imaging.

The standard diffuse setup uses a wide slit beam combined with a diffuser to create a soft illumination; this is then set to approximately 30–45° of the optics. The pivoting background can then be placed on the opposite side of the optics and used to create an ambient ‘fill in’ light, further reducing the shadows in the final image. Changing the background illumination can substantially alter the contrast and appearance of the final photograph.

Gemma advises, “If you're trying to produce a clean overview image, background illumination can help create a more balanced presentation. For other techniques which require stronger contrast, reducing or removing it may allow a particular illuminated structure to dominate the image.”

8. Don't forget the optics!

One of the most frustrating experiences in slit lamp photography is getting a beautifully composed image that isn't sharp. Before changing the exposure, make sure the optical setup is correct.

Haag-Streit's Slit Lamp Imaging Guide specifically highlights the importance of correctly setting the slit lamp optics so that the operator and camera are focused on the same point. Haag-Streit recommends checking the focusing rod through the optics; if the slit lamp view is sharp but the captured image is blurred, the optical setup may be incorrect.

What did the 2026 Slit Lamp Imaging Competition images teach us?

The annual Haag-Streit Slit Lamp Imaging Competition celebrates outstanding slit lamp images and videos that combine clinical insight, technical excellence, and visual impact. The strongest images in this year’s competition demonstrated purposeful control.

Visit our 'meet the winners' page to see the top images and video. To download high-resolution images of all the top ten images, please visit our Wallpaper Collection page.

A simple workflow to try

When approaching your next image, try the following steps:

1. Check the focus carefully

Check that the optics are set correctly using the focusing rod. The optics and camera must work together.

2. Start with your standard setup

Use a consistent baseline rather than starting from random settings.

3. Compose at a low magnification

Use an overview image to show the full eye to help identify which eye you are documenting. Decide what you want the photograph to show.

4. Adjust magnification

Move higher if the clinical feature requires greater detail.

5. Adjust the slit

Consider whether a wider or narrower beam better demonstrates the structure.

6. Change the illumination angle

Look at how reflections and shadows change. Consider decentring the slit lamp to bounce light off either the iris or lens to better show subtle changes. 

7. Fine-tune the aperture

Think about both exposure and depth of field.

8. Check the composition

The camera is lined up to the right optic, try using both eyes to focus and line up the image, then close your left eye to get a better sense of how the captured image will look. 

The final photograph

Ultimately, the best slit lamp image isn't necessarily the most dramatic photograph, it is the photograph that communicates the clinical finding clearly.


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