Kodak Portra lenses and their function

[mattk]

I am just getting around to looking at all the goodies that came with a 4x5 Speed Graphic that I purchased a few months ago. In the case I found 3 Kodak Portra (+1,+2,+3) lenses as well as adapters to fit them over the 90 and 127mm lenses that came with it. Anyone have any experience with these? Are they worth the trouble trying to work with? What can I expect? I also fired off my first flash bulb--the kids thought that was way cool!

[fschifano]

Sounds like they might be close up diopters, very much the same as those "close up filters" that you currently see for sale. They could come in handy for doing that sort of work without extending the bellows too much. If you can keep the distance between the lens and the film plane to less than 1/2 the focal length of the lens in use, you will not need to worry about compensating for light lost to the bellows factor. The rangefinder will be useless, if it isn't already, and you'll need to do your focusing on the ground glass.

[John Koehrer]

[QUOTE=fschifano;679849]Sounds like they might be close up diopters, QUOTE]

That's exactly what they are.

[Nicholas Lindan]

3 Kodak Portra (+1,+2,+3) lenses

They were meant for taking close-ups with a box camera. Most box cameras are pre-focused for ~12ft/infinity and with a close-up lens it was possible to take head-and-shoulders portraits. A +1 lens would put a box camera about 3 feet from the subject and a +3 at 1 foot. They are useful for closeups with any camera: handier than extension tubes & cheaper than a macro lens. However, close focusing with a Graphic isn't an issue and there is no real reason to use them for portraits with a press camera.

To muddy the waters, 'portrait lenses' make lousy portraits. They work by making the lens focal length shorter - just the thing one _doesn't_ want.

An old trick was to use close-up portrait lenses as wide-angle adapters, this may the be reason for their inclusion with the camera. Put a +3 on the 150mm lens, crank the lens board in, flip the focusing hood up and take a look at the resulting view: It should be that of a 100mm or about the same as the 90mm. The combination is best used at f22 or a bit smaller. It was (and I think still is) possible to get minus diopter auxiliary lenses for lengthening the focal length - sort of a poor man's telextender for a view/press camera.

[nemo999]

I am just getting around to looking at all the goodies that came with a 4x5 Speed Graphic that I purchased a few months ago. In the case I found 3 Kodak Portra (+1,+2,+3) lenses as well as adapters to fit them over the 90 and 127mm lenses that came with it. Anyone have any experience with these? Are they worth the trouble trying to work with? What can I expect? I also fired off my first flash bulb--the kids thought that was way cool!

As the other posters say, they are close-up lenses. The diopter numbers means that, with a lens at its normal infinity position, the #1 lens will give you a focus at 1 meter, the #2 at 1/2 meter (50 cm) and the #3 at 1/3 meter (33 cm). Conversely (and bizarrely), if you start with a lens at its infinity position and then put on a close-up lens and rack the lens backwards, it will behave like a lens of a wider angle (but it probably won't illuminate evenly)