Diana Lens for Canon EOS
April 8, 2011 | Filed Under Diana, Teaching | Leave a Comment
I just received my new Diana plastic lens with a Canon EF adapter in the mail today. I unboxed it, and popped it on my Canon 5D II. With my camera in manual mode, I started to make some exposures to see what the lens looked like. With a lens like this there are no electronics to connect to your camera system, therefore no lens information is displayed on your camera or recorded when you take a picture. This particular Diana lens has a single aperture, and like any obsessive compulsive photographer, I wanted to know what it was. I figured a quick Google search would give me my answer, but what I got instead were links to websites with people questioning what the aperture of the lens was and/or how to use the lens. I hope this helps.
How to determine your lens aperture of your plastic lens.
Items needed:
- Camera with working light meter
- Standard camera lens
- Toy camera lens (the one you’re trying to figure out the aperture of)
- An 18% grey card
- Tripod (not totally necessary)
- Beer (for advanced users only)
**NOTE – Make sure that the lighting is as even as possible and that it will not change for the duration of this test. I’m using window light on a cloudy day.
Before we begin, it’s important to know how the camera’s light meter works. The light meter in your camera is calibrated to 18% grey. That means that whatever the camera sees, the light meter gives its reading relative to 18% grey. In essence, if you’re in any sort of automatic mode, the camera tries to make whatever is in front of it 18% grey. Let me show you.
I’ve put my camera into Aperture Priority Mode and set my Metering Mode to SPOT. I’ve chosen spot metering so that the area being metered is very specific. It is indicated by the red circle in the photos. Now I’m going to take a picture with the 18% grey card in the metered area and see how it looks.
BAM! That my friends is a technically perfect exposure! My camera is trying to make an 18% grey card 18% grey so it is technically a perfect representation of that tone. Let’s see what happens if I put something white in the metered area.
Boooooo. The camera is trying to make that white card 18% grey. It is an under exposed photograph. Can you guess what will happen if we put black paper in the metered area?
You got it! Over exposed. The camera is trying to make the black card 18% grey which is lighter than it is in real life.
So now that we’ve got the nerdy science stuff out of the way, let’s see how this knowledge helps us figure out the aperture of our Diana lens. I am going to start by putting the Diana lens on my camera and leaving the settings in Aperture Priority Mode with Spot Metering. I’m going to make sure that the area being metered is filled solely with my grey card. Let’s go ahead and take that shot and see what we get.
Notice that the aperture reading is 0.0 – that’s the variable we’re trying to figure out. My shutter speed is 1/5 – WRITE DOWN WHATEVER YOUR SHUTTER SPEED WAS! What we do know in this scenario is that our camera is trying to make 18% grey 18% grey which is technically a good exposure.
Now for the moment we’ve all been waiting for! Next we’ll swap out the Diana lens for our Canon lens. If you’re using a zoom lens, make sure to best match your focal length to that of the Diana lens so that the metered area is in the same spot as it was with the Diana lens. In Aperture Priority Mode, adjust your aperture until the shutter speed matches that of the exposure with the Diana lens. Let’s see what we get.
My exposure came out to f 13 @ 1/5. That means that the aperture of my Diana lens is f 13. There you have it!
Now that I know the aperture of the lens, it will allow me to better control my exposures in manual mode, and make shooting with strobes much easier. I’ll post some pictures after I get a chance to do some more shooting with the lens.