Saturday, September 12, 2009

As I mentioned in an earlier post CPM has moved. On the last weekend in the old building they held a garage sale to get rid of what they didn't want to cart away. Among the goodies was an ancient 500 mm Cambron lens that I remembered seeing for sale at an earlier fundraiser.

The Cambron name is not synonymous with quality, but the bigger problem was the oddball bayonet mount that fitted some equally oddball camera of the 1970's. (a Kiev perhaps) So I moved on to buy other things--lightstands, a photoshop book and a Nikon enlarger lens that may make an excellent UV lens if it turns out not to have a coating that blocks UV.

After I'd gone home I had an idea. As a lens the Cambron may have been useless but if I removed the front lens element it might work as an achromatic close up lens. This idea became even more appealing when, after some Internet research ,I discovered the lens was actually a relabeled Tamron--a lens maker noted for its excellent optics.

So I went back over to CPM on Saturday, saw that the lens was sitting where I left it, and came home with my very inexpensive prize. Turns out I was the only customer that showed up that morning and it was, 'you want it--name a price" day.

Later when I was trying to decide if I should borrow or buy a spanner wrench to remove the lens retaining ring or do a cheapie and take a hacksaw to the barrel, I happened to give the oddball bayonet mount a good twist. To my great surprise it loosened slightly and then unscrewed off. I had bought a T-mount lens!

Tamron was and still is a manufacture of after-market lenses. They had invented the T mount forty odd years ago. No matter what brand of camera a prospective customer owned all the salesman in the camera store had to do was to screw on the proper mount to make what was then a $250-300 sale. And all I had to do was get on ebay, buy a Nikon mount, and up my total investment to $15. Love those garage sale lenses.

Warning--at first I thought it was a M42 lens and almost ordered that adapter. The T mount has the same diameter (42 mm) but has a .75 mm thread pitch rather than M42's 1mm pitch.

So what can this lens do?

The duck picture was taken handheld at a Madison conservation park. I hadn't planned to do my first tests that way and had brought along a tripod. But when I set it up I discovered I'd left the mounting screw in my homemade close up kludge (staring in a future post). Using two rules of photographic thumb, when hand held the minimum shutter speed is equal to your focal length (750 mm equiv on my D60) and the sunny 16 rule (iso 800 to go with the lens's widest f#) it was shot at 1/1000sec at ISO 800 and f8.0.

An ok image once it is reduced for posting it is softer than I hoped when it it viewed full size.

The image quality does improve with a smaller f#. The hand held shot of the swing set was taken from my computer room window across the greenway and a 100 yards away. The noise is higher at 1600 ISO but the nuts holding the swings to the top cross bar must be no more than 1/2 inch in diameter. For a comparison the second image was taken with my 35mm "normal" lens.

Now for a few nature shots. I drove to Fish Camp Park where the Yahara river emptied into Lake Kegonsa--a spot where where swans gather. No swans when I arrived. Then as I stepped out of the car to test the lens on the local ducks, I looked up to see a flock of Mute Swans fly in. Twenty seconds of great images with the camera still locked in the trunk--if only I hadn't stopped for a muffin and coffee at PDG.

Oh well. With luck a power boat would come down the river and I could photograph them taking off. Which didn't happen. By the time the only boat I saw came by the swans had swam up river and around a bend. But I did take my share of feeding swan images. This one was taken from about 100 yards at iso 100, f16 and 125 sec using a tripod.

The other two images are of a pair that were hiding in the reeds across the river. After they decided to visit my side of the river I shot them from about 25 yards using the same settings. The image with the flapping winds is uncropped. The one of the head was cropped to remove a sidewalk in the background.


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