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Wollensak 8mm Cine Lens for Macro
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PostPosted: Tue Oct 20, 2009 11:15 pm    Post subject: Wollensak 8mm Cine Lens for Macro Reply with quote

In another thread here, I mentioned that cine lenses can be easily configured for macro use -- on virtually any camera. I had picked up this tidbit years ago, and never really acted on it until today. So I decided it was time to put up or shut up.

I have an old Wollensak 1/2" f/2.5 Cine-Raptar lens in 8mm cine (D-mount) that I probably pulled off a dead camera some 20 years ago. Today I put it to work.

To use this lens for macro work, all you need is an extra lens cap for the lens you intend to use, a means to drill a 1/2" hole, and some glue. In my case, the lens I've selected to use is a Tamron 90mm f/2.5 macro. I had an extra cap that fit the lens, so I drilled a 1/2" hole dead-center in the middle of it, then set the Wollensak lens atop the cap, reversed, and ran a bead of medium Super Glue (cyanoacrylate) around the edge. This particular lens's barrel is wider than 1/2" so I just had to make sure as best I could that it was accurately centered.

I got the idea to do this from a John Shaw book I bought back in the 1980s -- in his The Nature Photographer's Complete Guide to Professional Field Techniques he explains how. He was showing how, if one reversed a normal lens in front of a tele, it would increase magnification by a factor found by this formula: (focal length of "prime" lens)/(focal length of reversed lens) -- the "prime" lens being the one actually mounted to the camera.

So it occurred to me I could do the same thing with a cine lens and a lens cap. In this case, I have: 90mm/0.5" (about 13mm) = 7x.

The flash always accentuates dust, and it doesn't look very special, but it works. This lens cap had a metal cover on the front, which popped off when I drilled the hole, exposing its inner workings.




The drawback to using a lens like this is the distance from the subject to the front edge of the lens is about 1 cm. I had to position the camera/lens about that distance from the subject, then I was able to fine-tune the focus using the Tamron. I tried to take pictures of a couple of flowers, but finally gave up because the wind kept blowing them in and out of focus. So I decided on a box with some small print instead. It was an easier subject: stationary and flat.

Here's the box, from an old Lexmark printer. Its outer dimensions are probably about 25 cm x 40 cm or so. Note the Wollensak lens sitting on top of the box. I used the Tamron 90 @ f/5.6 for this shot.



And a 100% crop of the above image, showing the general area where I was focusing with the Wollensak. Note the "XP" text.



And here's the image taken with the Wollensak. I didn't do any PP to the image other than resize it for here:



Here's the same image with some contrast and a bit of high-pass sharpening done to it.



I was also surprised to get a full frame of view on my APS-C-sized camera from this tiny lens. It's inner diameter is only maybe 4mm.

The above Wollensak image was taken with the Wollensak wide open at f/2.5 and the Tamron also wide open at f/2.5. You can see that there's quite a bit of sharpness fall off toward the edges. I suspect that, if I were to stop both lenses down to at least f/8, this softness would be substantially reduced. John Shaw recommends leaving the reversed lens wide open, however, and just controlling aperture and hence exposure with the prime lens.

John Shaw mentions in his book that his favorite lens pair is a 105mm reverse mounted onto a 200mm, which yields him 2x magnifications. The working distance isn't much better, though -- only 3, maybe 4 cm from the edge of the front lens to the subject.

So anyway, you don't necessarily need bellows or special macro lenses to do high-magnification work. You can use a cheap cine lens like I've done, or buy a reversing ring for not much money to reverse mount a wide angle lens, which Shaw doesn't mention, but which I know from experience also works well. Or you can get a special reverse mounting ring, with filter threads on both sides, for mounting lenses nose-to-nose.

One other accessory that becomes handy when working at these magnification levels is a macro stage. It allows one to precisely position ones camera, getting the setup just right, without having to struggle with the tripod. Here's a pic of mine with my bellows rig sitting atop it. Notice the front to back and left to right graduated rails. Not shown are the adjustment knobs (over on the right side) for positioning the rig exactly where it needs to be. The one knob shown in the photo is for locking the stage into its position. I bought this macro stage off eBay for about $40 plus shipping.



Last edited by cooltouch on Thu Feb 17, 2011 5:04 pm; edited 1 time in total


PostPosted: Wed Oct 21, 2009 2:14 am    Post subject: Reply with quote

Shocked
Very nice result.