> Hi there All,
>
> Just got one of the wacky lenses. I was wondering if anyone in the group
has
> used one and might have tips for exposure compensation. It is the screw on
> the front of your lens type with a variable aperture (has a system for
> working with 30-200mm focal lengths). It came up recently when any of the
> group fanged one.
>
> I undersatnd that you set the focal length and then this allows you to get
a
> recommended aperture range. If that is the wrong way a correction would be
> appreciated.
>
> Aparently this type of lens was used to build HAL's eye.
>
> Dan.
I picked up one of these recently in unused condition, but it arrived minus
the adapter on the back that allows you to screw it on to the lens. Anyways,
the seller was good about it and gave me a partial refund that made the
price of it into almost a gift. I removed the glass from a 49mm Osawa filter
I had, and with a little grinding that removed the forward threads of the
filter ring, it just fit snugly onto the back perimeter of the body of the
Kenko adapter lens. I epoxied it in place, so have a pretty cheap lens
adapter. It now screws directly onto any of my 49mm lenses. I think the
original was supposed to be a 52mm. I can add another filter to the back
that works as a lens cap (or other modifying filter) to protect the back
element, but didn't have any in place for these tests. I don't think the
spacing matters much, as you can add filter ring adapters to them for use
with different sizes. But I may try spacing mine a bit further from the
front element to see if that helps.
From the first tests, I wouldn't want to have a lot of money tied up in it.
I was only shooting handheld, with it mounted on a 50/1.8 on the OM10, and
it produced some fun images, but quite soft. Here are a few scans.
http://www.photo.net/photodb/folder.tcl?folder_id=346810
Keep in mind I lose some image quality with my scanner, so the originals are
better, but still are nothing to write home about in quality.
For exposure, I just took a reading before putting on the adapter, and made
no compensation. I used the OM10 in manual mode. Basically it was just
following the sunny day rule. I included the sun in one pic just to see what
flare it would produce. On the one with yellow flowers, I held the lens just
a few inches from the closest flowers. I think you can use one about as well
without bothering to look through the viewfinder. That way you can keep your
feet out of the image a bit easier.
I have no instuctions with mine, but quickly figured out that you just use
your primary lens wide open, set at infinity, and set the aperture manually
on the adapter. You just have a few basic f/stop settings on the adapter.
The other ring setting just tells you the relative f/stops you get with the
other focal length lenses, it does not actually change the iris opening. But
of course this gives you the info you need when using the different length
lenses in order to set the proper f/stop.
I haven't tried it yet with other length lenses, but just looking through it
with my Z.100/2.8, it looks to give the full rectangular image.
Wayne
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