Focus free lens

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Hi!

I got a camera with a lens that says "Focus Free - Real Glass Lens f:8 - Japan" Is that a good lens?

-- Ingela (ingela17@hotmail.com), July 12, 2001

Answers

The lens is so-so, but this is what you need to do to make it really good:-

Process the lens in XTOL+2 for 8 mins at 68 degrees and agitate every 30 seconds for 2 seconds.

The results would be excellent!

Good luck!

-- Mike Foster (mike567@acgecorp.com), July 12, 2001.


The point above is that this is not posted on the correct photography board as it has nothing to do with black and white film processing:

However, that won't stop me from responding!

The answer is, "No!" "Focus Free" is just a way of making "dosen't focus" sound like a feature rather than a limitation. Having said this, who says you always need a good lens?

-- Ed Farmer (photography2k@hotmail.com), July 12, 2001.


A focus free lens is a lens where the focus (distance from the camera to the subject) is fixed and cannot be adjusted. The lens is probably fixed focused at about 20 feet. Because the lens aperture is fairly small (and therefore the depth of field is fairly good) the manufacturer is assuming that everything from about 10 ft to infinity will be in focus.

-- Michael Feldman (mfeldman@qwest.net), July 12, 2001.

Back in '72 I was in the photo club in Jr. HS. We were each given a Kodak Instamatic. One of the assignments was to find the distance range of its "focus free" lens. Marketing had come up with that lovely term yet though.

-- Tim Brown (brownt@flash.net), July 13, 2001.

From Richard Knoppow on USENET: The single meniscus lenses used on box cameras effectively have several focal lengths so the image is really a combination of a relatively sharp image and a blurry image of objects within a rather large range of distances. The sharp part of the image will be brighter than the blurred part so the result is very large depth of field but a rather low sharpness overall. A well correct lens will always focus on one plane only. Usually it will "pop" into focus, the point of best focus being very easy to find. Lenses which seem hard to focus usually will be found to have excessive uncorrected spherical aberration and really do not have a definite point of best focus.

-- Tim Brown (brownt@flash.net), July 13, 2001.


A "focus free" lens is a lens with small aperture. For 35mm format focus free camera, such as Kodak, Konica Memorysaver etc, the lens is about f8 to f11, enough to cover a great depth of field.

Camera with 'focus free" lens is not necessarily cheap. For exampe Minox ECX, which has a four element tree group Tessar type lens Minor lens, sells for over $300. And the miniature Leica IIIf camera is nearly $400, focus free lens

-- martin tai (martin.tai@capcanada.com), July 27, 2001.


I forgot to mention that the Minox ECX camera has a 15mm/f5.6 lens its depth of field range is from one meter to infinity--- practically focus free.

-- martin tai (martin.tai@capcanada.com), July 28, 2001.

Kodak Brownie, Baby Brownie all used such kind of lenses. However these lenses were rather simple.

-- martin tai (martin.tai@capcanada.com), July 28, 2001.

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