Telephoto lens showing only white frame

jabobjo

I received a Danubia 8.0/500mm T2 telephoto lens. It is listed as being good for outdoor wildlife and sports, etc., but when I take a photo outside in the sunlight, the result is an all white photo.
I tried it indoors and if I am careful not to point it at a window or other large light source it attempts to capture the picture. It also works well at night.
I set the D5100 on "Manual", with the normal settings, that is to say, no special settings being selected.
The camera works perfectly with the Nikon lens attached, so there isn't a malfunction with it.
I have checked and double-checked, trying to find some setting on the camera that would cause it to respond like this to normal sunlight photographing but I can not find anything.
Any thoughts on what might be my problem would be appreciated.

bruto

Since this is a completely manual lens, and the camera cannot meter with it at all, you're going to have to calculate exposure and set your ISO and shutter speed manually. No metering means also no auto ISO, so your ISO will remain at whatever you set it at.

The T2 mount also does not have an automatic aperture, and this means that you must preset your aperture, and remember to stop down when you shoot. If you set the aperture to, say, f/32, and try to view through the lens, it will be too dark to see. You must open it up to f/8 to view, but unlike an ordinary lens, it will not drop down to f/32 by itself when you shoot. You must do this every time.

Most preset lenses have two aperture rings. One has detents, and is the one which you use to preset the aperture you intend to shoot at. The other has no detents, and can be used to quickly open the lens for viewing, and then quickly to return it to the point at which the first one was preset. Since it stops at the preset point, it allows you to open and close the aperture without having to look at it.

For outdoor shooting, start with "sunny 16", which is the rough manual exposure rule that in broad daylight, if your lens is set at f/16, the shutter speed should be the reciprocal of the ISO. If you're hand holding, the shutter speed should probably be in the 1/750 range, so you'll have to adjust ISO and aperture accordingly. If you leave it set at f/8, your shutter speed must be twice the reciprocal. So, for example, at f/8 on a sunny day, and ISO 400, you should have a shutter speed of about 1/800.

Your best bet here is to make sure that you have enabled the "overview" option in the playback menu, which will show a histogram diagram of your shots. The histogram is an exposure graph, and when you have your exposure right, you should see the information on the graph distributed between the right and left margins. If all the information is crowded to the left, it's underexposed, and if it's all to the right, it's overexposed. The right margin denotes the point at which highlights are blown out and lost.

If you want an example of what a histogram should look like, the easiest thing to do is to put your kit zoom back on, make a couple of good pictures, and look at the histogram. The camera's meter generally does a pretty nice job.

Once you get used to this, it's actually not such a chore. I use several old manual lenses with my D3200, including a manual preset 35mm f/2.8 shifting lens, and it doesn't take that long to learn to estimate the basic exposures, and to become adept at setting it.

I am assuming here that this is the refractive lens with an aperture control.

Danubia also makes a 500mm f/8 mirror lens. A mirror lens has no aperture control at all, and must, therefore, be controlled entirely by ISO and shutter speed, unless filters are added.

jabobjo

I cannot thank you enough. I read and study and practice and then my brain just dies and I do something stupid. Of course the problem was the aperture opening on the camera. The night before I had been experimenting with some night shots and completely forgot to reset it.
It just makes me feel good to have a forum like this where I can embarrass the heck out of myself. :) Thanks again for bailing me out.