I. Rationale
A. Most efficient and effective method of recording available
B. Excellent method of:
i. Obtaining materials for educational purposes
ii. Referral communications
iii. Self-improvement in area of pathology
iv. Case documentation for legal purposes
v. Demonstrating concern to the patient
II. Anterior Segment Photography
A. Most common camera type: 35mm Single Lens Reflex
i. Best format: 35mm (24 x 36 mm slide)
ii. Best film: Kodak Kodachrome 25 (ASA 25)
iii. Other, less common, cameras
a. 35mm Range Finder (24 x 36 mm)
b. Twin Lens Reflex (2 1/4" x 2 1/4")
c. Press and View (4" x 5")
B. Diaphragm and Apartures
i. F/Numbers: Ratio of camera lens focal length to aperture diameter
a. Common: F/1.4, F/2, F/2.8, F/4, F/5.6, F/8, F/11, F/16
b. Less common: F/22, F/32
c. For 50 mm focal length lens with constant shutter speed
1. F/No. = Diameter Aperture : Amount of light to Film
2. F/1.4 = 37.5 mm : X
3. F/2 = 25.0 mm : 1/2 X
4. F/16 = 3.1 mm : 1/128 X
5. F/32 = 1.6 mm : 1/512 X
ii. Depth of Field
a. Larger the diameter (Smaller F/No) <==> Less the Depth of Field
C. Magnification Terminology
i. Close-Up Photography (Large subjects at 1/10 X to 1X)
ii. Macro Photography (Small subjects at 1X to 50X)
iii. Micro Photography (Very small subjects at 25X to 1500X)
D. Types of Anterior Segment Photography
i. Monocular (1/2 X to 1X)
ii. Binocular (1/4 X to 1/3 X)
iii. Full Face or Profile (1/6 X to 1/5 X)
iv. Fluorescein (using filters)
E. Methods used to achieve magnification
i. Close-Up Lens
a. Plus lens that attaches to the front of the camera lens)
1. +3 D. (1/10 X to 3/10 X)
2. +6 D. (3/10 X to 1/2 X)
3. +10 D. (1/2 X to 7/10 X)
ii. Variable Close-Up Lens
a. Plus lens system that attaches to front of camera lens
b. Can be adjusted for different magnifications up to 6/10 X
iii. Extension Tubes
a. Non-optical sysstem that attaches between camera body and lens
b. Increases magnification by allowing closer focusing distance
c. Extension needed:
1. = (Focal length of camera lens) times (desired magnification)
2. Examples
a. 50mm x 1/5 = 10 mm extension needed
b. 50mm x 1/3 = 16 mm extension needed
c. 50mm x 1 = 50 mm extension needed
d. Extension tubes are in sets of 3 different lengths
1. Each tube can be used individually or in any combination
2. All three combined together has about 65 mm extension
3. Maximum magnification of about 1 1/3 X
iv. Bellows
a. Non-optical system that attaches between camera body and lens
b. Allows variable entension (same caluclations as tubes)
c. Infinite number of extensions between smallest & largest bellows
v. Teleconverters
a. Minus lens system that attaches between camera body and lens
b. Serves to double or triple the focal length of lens
1. Does not change the range of focus
c. Examples (with a 50mm focal length lens) : Magnification obtained
1. 2X Teleconverter creates 100mm focal length system : 3/10 X
2. 3X Teleconverter creates 150mm focal length system : 4/10 X
3. 2X + 3X converter will = 300mm focal length system : 9/10 X
vi. Lens Reversal Mount
a. Non-optical adapter ring that allows lens to be mounted reversed
b. Gives a fixed magnification of about 9/10 X
vii. Macro Lens
a. Specially designed camera lens
b. Focuses much closer than normal 50mm camera lens
c. Requires correction for curvature of field
d. Range of Magnifications up to 1X
F. Light Source
i. Electronic Flash with MANUAL setting
a. Typical guide number between 32 and 40 for film with ASA 25
ii. Attaching flash to camera
a. Holding to side, above or below: Cumbersome method
b. Sliding onto body: Fixed position only
c. Modified Straight Flash Bracket - see attached diagram
G. Anterior Segment Photography Procedure with Macro Lens
i. Mount flash to camera with the modified straight bracket
ii. Set the camera lens to the desired magnification
iii. Adjust flash so that it is at the end of the lens
a. May be placed to the left, right or below the camera lens
b. Depends upon the desired position of the corneal reflex
c. Full face and Binocular photos
Best to have flash above or below camera lens for even illumination
iv. Set flash direction to be aimed at the camera's focal plane center
v. Connect flash power cord to the camera (extension may be needed)
vi. Set camera shutter to proper speed for flash syncronization (1/60)
vii. Set camera aperture to proper F/No. for selected magnification
viii. Make sure flash is set to the manual mode
ix. Tell the patient to look at the center of the lens.
Or in any desired direction to emphasize certain portion of eye
x. Move toward the object to be photographed
xi. Press the shutter release button when sharp focus is obtained
H. Procedure with Extension Tubes,
Close-Up Lens or Reverse Rings attached
i. Same as with Macro Lens except:
a. Flash positioned at side of camera instead of at the end of lens
b. Camera aperture is set at the smallest diameter (usually F/16)
I. Procedure with Teleconverter
i. Same as with Macro Lens except: Aperture set to smallest (F/16)
J. Procedure for Fluorscein Photography with Macro Lens and ASA 25 film
i. Prepare camera the same as for 1X mag shots
ii. Set aperture at F/8 for 50mm lens or F/5.6 for 100mm lens
iii. Cover flash with a 47A Wratten Gelatin Filter using rubber bands
iv. Place a filter over the camera lens
a. Either a medium yellow filter (Y48, K-2)
b. Or a green filter (X1, X13)
v. Move toward eye and press shutter release when focus is obtained
K. Shooting a test roll
i. Prepare camera for 1X magnification
ii. Select subject that will be available after test roll processed
iii. Shoot several test shots changing only F/No.
a. Keep a good record of each setting so that slide can be matched
iv. Prepare the camera for 1/3 X, 1/6 X and fluorescein photography
a. Shoot several shots using various F/No. around values suggested
v. Have slided processed and select F/No. that provides
a. Brightness and color closes to the subject's eye and skin
b. Use these F/Nos. in future photography sessions
vi. Variables
a. For Ext.Tubes, Close-up lenses and Reversal Rings
1. Variable will be distance of flash from eye or object at 1X
a. Camera aperture will remain at F/16 for all test shots
b. Change flash position in a systematic manner
c. Keep an accurate record of all flash positions
b. For 1/3 to 1/6 X and Fluorescein shots
1. Variable will be the F/No. with F/16 probably smallest available
L. What to do if all test roll shots are not acceptable
i. If all exposures are too dark (underexposed) try
a. Use a stronger flash (higher guide number)
b. Use a closer flash position if possible
c. Use a faster film (Higher ASA number)
1. Kodachrome 64 or Ektachrome 64 ( +1 1/3 F/No.)
2. Fujichrome 100 ( +2 F/No.)
3. Ektachrome 200 ( +3 F/No.)
ii. If all exposures are too light (overexposed) try
a. Use a weaker flash (lower guide number)
b. Move flash further from the eye
c. Use a neutral density filter over the flash
0.3 ND ( -1 F/No.) 0.6 ND ( -2 F/No.) 0.9 ND ( -3 F/No.)
M. Miscellaneous hints
i. If the patient has dark irises, you might have trouble with detail
a. Open up aperture by 1 or 2 F/No. to slightly overexpose
ii. If you need extra length to move flash further away
a. Attach two or more straight flash brackets together
iii. Take an extra shot or two
It is less expensive and time consuming than getting duplicates
iv. Get a flash that operates on both batteries and an AC cord
v. Use the rechargeable type of batteries for convience and expense
vi. For Fluorescein shots
a. Consider using Ektachrome 200 film
b. Higher ASA allows you to shoot at a higher F/No.
c. Increases the depth of field with smaller aperture
vii. To steady shot
a. Use your thumb on the bottom of camera lens
b. And your fingers on the patient's cheek for 1X shots
N. Record Keeping
i. As you take slides write down
a. Patient's name, the date and diagnosis (+ eye if monocular shot)
b. Include magnification and the number of slides that you take
ii. When the roll is exposed, you will get best results
a. If you have Kodak process it for you
b. Kodak will only process their own brand
iii. When the processed slides are returned, write onto the slide
a. Patient's name, the date and diagnosis
b. The magnification and eye (if monocular)
O. Slide storage
i. Store in a manner that makes them readily available
ii. Keeping slides in patient's folder is one method
iii. Indicate on patient's folder that pictures are available on file
a. Store actual slides in a seperate index card file
iv. Good idea to create a seperate list of slides you have available
a. Store by diagnosis so they may be handy for presentations
v. Plastic slide holder are good for protecting the slides
a. Can be cut apart to accommodate the number of slides for patient
P. Release Form
i. Necessary if you plan to show slides to others
ii. Or if slide will be published and the patient can be identified
Q. Conclusions
i. Easy method noting patient anomalies
ii. Practice building benefits
iii. Excellent system for general photography
iv. Tax benefits
v. Self improvement
Modified from C.E. lecture by Dr. David Perrigin - University of
Houston - College of Optometry
This page last revised on August 26, 1997.