Sunday, October 28, 2012

Close Up Filters

I keep a wish list on Amazon. Some of it is big stuff, including my next L lens. Others are small items. I had a gift card burning a hole in my virtual pocket, so I bit the bullet this week and picked up a set of close-up lens filters for my 77mm lens collection.

Quoting Wikipedia (I Love That Place):
Close-up lenses typically mount on the filter thread of the primary lens, and are manufactured and sold by suppliers of photographic filters. Some manufacturers refer to their close-up lenses as diopters, after the unit of measurement of their optical power.
While some single-element close-up lenses produce images with severe aberrations, there are also high-quality close-up lenses composed as achromatic doublets which are capable of producing excellent images, with fairly low loss of sharpness.
Close-up lenses are usually specified by their optical power, the reciprocal of the focal length in meters. Several close-up lenses may be used in combination; the optical power of the combination is the sum of the optical powers of the component lenses; a set of lenses of +1, +2, and +4 diopters can be combined to provide a range from +1 to +7 in steps of 1. A split diopter has just a semicircular half of a close-up lens in a normal filter holder. It can be used to photograph a close object and a much more distant background, with everything in sharp focus; with any non-split lens the depth of field would be far too shallow.

This "Polaroid Optics 77mm 4 Piece Close Up Filter Set (+1, +2, +4, +10)" collection in a nice black storage pouch. Basically, they let you get closer to your subject than the lens' normal minimum focus distance. For my 70-200mm Canon f/2.8L lens, that's about 1 meter. Here's the original shot at max zoom (200mm) and minimum focus distance, taken indoors, handheld with IS enabled:
Incidentally, these are at ISO800, f/2.8, 1/50th on a Canon 5D Mark 3. Next, I show the +1 adapter:
So you can see the subject fills the frame more completely, but since I am closer, the DOF is considerably shallower. I could have adjusted that by reducing the f-stop to say f/8, and using a tripod to stabilize the camera, but I was lazy and wanted to hand-hold the camera.

Here's the +2, where you can see the DOF getting even shallower:
You can see some sharpness along certain parts of the focus plane - the word "Since" on the left, and the letters "'S ORI" on the right of the lid. It's nice having an IS telephoto that lets you shoot at 1/50 at 200mm!

Here's the +4. It was getting a bit sketchy at this point hand-held, trying to get a reasonable focus point:
It's still pretty amazing that I can get that close - literally inches away, with a 70-200mm lens. I see a log of white, foggy diffusion on the image, which was really bad with the +10. I won't bother showing you those shots. Handheld they were unusable.

Next I switched to my Sigma 85mm f/1.4 lens. Here's the original shot:
That's inside the range of the 70-200mm. I tipped the subject to get a good plane of focus. Next, +1:

Nice clarity, a little color shift owing to 60Hz flourescent lighting. I did no correction at all on these images. Here's +2:
Nice and sharp. This was ISO800, f/1.4, 1/400 sec. The can almost looks like it's floating in a DOF soup. And the +4 at 1/8 sec f/5 (to reduce DOF a bit):
This is an 85mm portrait lens on a full frame camera. Pretty impressive!

This was a $50 close-up filter set. I'll do a more detailed macro study in my studio with a tripod and some tasty small items, so we can revisit them. Until then, it's another great tool for my camera bag. They will come in handy for photos of wedding rings.

Oh, the subject, Bag Balm? It's a great ointment, originally developed for cow udders. I grew up on a farm and we used this on many animals. It's great for dry skin, and chafing from sitting on an indoor rower for hours!

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