|Year : 1984 | Volume
| Issue : 5 | Page : 317-319
"Photoadaptor for ocular photography" a new design
N Amrut Patel
M.&.J. Institute of Ophthalmology, Ahmedabad, India
N Amrut Patel
M.&J. Institute of Ophthalmology, Ahmedabad
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Patel N A. "Photoadaptor for ocular photography" a new design. Indian J Ophthalmol 1984;32:317-9
Photography has become, in a rather quiet and unassuming way, a major influence on ophthalmology, since last decade. Its role in documentation and education is irreplaceable. It has also become one of our most popular means of recording and presenting our most memorable experiences. In the service of ophthalmologist who can not afford costly photographic attachments, we have developed a Photoadaptor which is very simple and very cheap and at the same time it can take photographs of a very good quality which one can compare with photographs of all other kindly of costly equipments available in the world today.
As shown in the [Figure - 1], this Photoadaptor is a simple hollow metal tube one side of which there is a hole, the inner diameter of which is equal to the outer diameter of the eye piece of the slit lamp or operating microscope so that this eye piece snugly fits into this hole. To keep this eyepiece study and tightly at its position a locking ring is introduced after introducing this eye piece in to the photoadaptor tube.
The eye piece is so adjusted at a definite distance by means of the collar of Photoadaptor so that the true image formed by secondary objective, falls just inside the centre of curvature of the eye piece, which forms final image on the other side near outer centre of curvature of the same eye piece. To capture this image, formed on the other side of the eye piece the camera is fitted on the other side of phtoadaptor in the slots, which lies on outer diameter on that end.
2) Camera Body
You can attach any camera body to this photoadaptor after detaching its lens system. After this specialized photography, you can detach camera from the Photoadaptor and use it for routine photography. If you do not have a camera and if you are planning to buy one then it is recommended that you buy a camera with SLR system and electronic automatic exposure time control which gives the best results on this photoadaptor, as well as avoids the calculations of exposure time and speed.
Optics of the system:
Normally in the operating microscope or slit lamp as shown in [Figure - 2], there are two magnifying elements. The first magnification is accomplished by the primary and secondary objectives whereas the second magnification is carried out by the eye piece. The eye piece is acting as a simple magnifier as the image is formed just within the focal length of the eye piece and so final virtual image is formed towards the patient side.
Now if we just pull the eye piece outside, the image will form somewhere between the focal length and the centre of curvature of the eye piece and in such a case this eye piece acts as a tertiary objective, instead of simple magnifier and therefore the final image will form on the side of the observer [Figure - 3]. This is what we have done in our photoadaptor. We have displaced the eye piece outwards to a required distance by means of collar of photoadaptor and final image is taken over the camera where the film roll is facing.
With the help of this photoadaptor you can photograph any thing that you see in a slit lamp or operating microscope. The procedure is as follow:
1. Take out one eye piece from the microscope.
2. Now pass this eye piece into the photoadaptor and take it out through the collar.
3. Lock this eye piece into the photoadaptor by introducing the locking ring.
4. Now attach your camera to your photo adaptor.
5. After this put the front part of the eye piece which is projecting through the collar of the photoadaptor, back into the microscope.
6. Now with the other eye piece focus the tissue which you want to photograph.
7. On focusing in the other eye piece the camera is automatically focused for sharp photograph so you can press the button and photograph is taken.
General Suggestions for Better Photography:
1. Camera: Camera body with electronic automatic exposure time control gives best results but where this facilities are not available, short exposure time for wide field photography and long exposure for slit and goniophotography is advisable.
2. Film: Colour photographs gives better contrast and details compare to black and white. For colour photography slides Ektachrome 400 (day light, 400 ASA) film of Kodak is recommended.
3. Illumination: 'It should be brightest possible and positioned in such a way that reflections from the cornea or area of interest are reduced to a minimum.
4. Magnification: For more details higher magnification and to cover big field lower magnification is preferred.
5. Slit Photography: 2 width and height are adjusted in such a way that only area of interest is illuminated.
Advantages of This System are being very simple, very cheap, easily available and avoids use of flashgun.
A low cost photoadaptor to photograph ocular lesions through slit lamp or microscope is presented.
[Figure - 1], [Figure - 2], [Figure - 3]