Lets Talk Lens Reciprocal

[connieg]

I had someone ask me if I used a tripod when I snapped this night shot. My response to them was I didn't need to, because I kept my shutter speed faster then the lens reciprocal. They had never heard of this before. First let me say you can use a tripod regardless of what your settings are, but if you ever wondered when you need one for sure, this is a good way to tell.

Here are my cameras settings:
Nikon D700
Manuel mode
50mm 1.4 lens
Aperature 2.8
Shutter Speed 1/80
ISO 800
Spot metering

If you look at my settings, you can see I was using a 50mm lens. The reciprocal of this lens is 50, so by keeping the shutter speed 1/50 or higher, I know I can hand-hold my camera and not expect to get camera shake regardless of the time of day. So what if I was using a zoom lens, 20-70mm, zoomed out to 70mm? The lens reciprocal would be 70, so I would want to keep my shutter speed no lower then 1/70.

Hope that helps.

Also, I don't shoot anything under 1/50 shutter speed without using a tripod.

[Loretta]

Connie, can you explain spot metering? I don't know anything about it. I appreciate any info about photography and settings as I try to improve my pictures.

[connieg]

We all know that our cameras uses reflective light to create a photographic image. Light areas reflect more light than darker areas. On most DSLR cameras, you have three types of light metering to choose from. Spot metering, Matrix and Centered weight. Each mode reads the light differently, from the smallest area in the frame to the whole frame.

Matrix mode uses the light from the entire frame to determine the correct exposure. I find using this mode for landscapes very helpful, specially if the light is even, without a lot of highlights and shadows. Spot metering measures the light at the focal point, ensuring the subject will be correctly exposed even if the background is much brighter or darker. It's a good choice if the light is uneven, with lots of contrast. Center weight meters the entire frame but assigns the greatest weight around the center focal point. It basically works the same as spot, only it's metering a larger area. It's a good choice if you have multiple subjects with backlights.

I don't have any examples to show you the difference, but if you want to experiment, you will definitely see the difference when you are shooting in low light or an area where the subject has a lot of backlight. Use the same subject and run through each mode setting your camera for a correct exposure.

[twistedbev2]

Thanks for the tips.

[Barb]

Thank you Connie! I googled lens reciprocal and no where did I find an explanation as clear as yours! awesome info!!

[Loretta]

I'll try this. Thanks for your explanation. It actually makes sense to me.