f/0.75 lens

I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but
they are pretty fast glass. The advantage of buying glass from
recycling yards is that most lenses sell for less than a dollar.

I am wondering how hard it would be to make these lenses useful for low
light photography?
Has anyone experimented with making their own lens arrays and
mountings?
A few of the faster lenses are as follows:

KOWA 1:0.75 / 42mm
KOWA 1:0.95 / 33.5mm
KOWA 1:1.4 / 95mm
Rodenstock TV-Heligon 1:1.25 / 64mm

"Buy_Sell" wrote in message
oups.com...
I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but
they are pretty fast glass. The advantage of buying glass from
recycling yards is that most lenses sell for less than a dollar.

I am wondering how hard it would be to make these lenses useful for low
light photography?
Has anyone experimented with making their own lens arrays and
mountings?
A few of the faster lenses are as follows:

KOWA 1:0.75 / 42mm
KOWA 1:0.95 / 33.5mm
KOWA 1:1.4 / 95mm
Rodenstock TV-Heligon 1:1.25 / 64mm

Have you had a look at what is available in a "T" mount?

Buy_Sell wrote:

I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but
they are pretty fast glass. The advantage of buying glass from
recycling yards is that most lenses sell for less than a dollar.

I am wondering how hard it would be to make these lenses useful for low
light photography?
Has anyone experimented with making their own lens arrays and
mountings?


I've "hacked" some lenses onto medium format cameras and it's not too hard.
The biggest problem is the focus helix or the lack thereof.

--

Stacey

On 27 Nov 2005 18:54:08 -0800, "Buy_Sell"
wrote:



Has anyone experimented with making their own lens arrays and
mountings?

Yes - I am in the process of putting an Olympus OM 10 50MM on my Canon
20D....

I had a spare blanking cover for the body - Cut a hole in it that
would just accept the base of the OM lens. It does have an Iris but
the auto iris lever on the back of the lens needs to be in the
'closed' position...

The blank cover is thickish and sets the lens forward and the furthest
it focuses is about two feet. I have taken a couple of experimental
shots and it looks like in might make a reasonable macro setup...

The main problem I have is working out a way of sticking the lens to
the blanking cover - I might even try super glue. Hehehehe.... But I
am going down to the hardware store first and see if I can get some
tubing that I can fashion an extension barrel !!!!

Yes - I am in the process of putting an Olympus OM 10 50MM on my Canon
20D.... I had a spare blanking cover for the body - Cut a hole in it
that
would just accept the base of the OM lens. It does have an Iris but
the auto iris lever on the back of the lens needs to be in the
'closed' position...

Or you could buy a proper adapter for about US$50 on eBay

"Buy_Sell" wrote in message
oups.com...
I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but

By 'without apertures' I assume you mean they can't be stopped down?
In which case, the depth of field of such lenses would be absolutely tiny.

On 28 Nov 2005 07:24:52 -0800, "wilt" wrote:

Yes - I am in the process of putting an Olympus OM 10 50MM on my Canon


Or you could buy a proper adapter for about US$50 on eBay


Yeah - BUT....I don't want to use this lens other than to see if the
exercise will work....

At £3 ($5) it is 10 times cheaper...

My way is more fun & satisfying....

In article .com,
"Buy_Sell" wrote:

I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but
they are pretty fast glass. The advantage of buying glass from
recycling yards is that most lenses sell for less than a dollar.

I am wondering how hard it would be to make these lenses useful for low
light photography?

B.S.-

Also consider obtaining a cheap lens for a particular camera and using it
to house the glass from one of your salvaged lenses. If you can manage
it, there would be an aperture adjustment and a focusing mechanism.

Bear in mind that the f/stops are determined by aperture diameter and lens
focal length. To use the f/0.75 42mm, you would need an old lens with a
maximum aperture of at least 56mm. For example, suppose you found an old
250mm f/4 lens. That would have a maximum aperture of 62.5mm.

You might even figure out a way to use the existing AF motor. Talk about
a challenge!

One thing you may find, is that these salvaged lenses were used for a
different purpose than you want. For example they might be designed to
provide a flat-field image of a flat-field subject, rather than
flat-from-spherical as commonly used in photography.

Fred

According to Donald Gray :
On 28 Nov 2005 07:24:52 -0800, "wilt" wrote:

Yes - I am in the process of putting an Olympus OM 10 50MM on my Canon


Or you could buy a proper adapter for about US$50 on eBay


Yeah - BUT....I don't want to use this lens other than to see if the
exercise will work....

O.K. Then *I* would use a lathe to thread the body cap to fit
the lens' mounting thread.

Or -- most such lenses come with a mounting ring of matching
thread, which attaches to the lens board (or in this case, the body cap)
with three equally-spaced screws.

At £3 ($5) it is 10 times cheaper...

O.K.

My way is more fun & satisfying....

That I can understand.

I've got a 50mm f/0.95 lens (in C-mount) which I may experiment
with someday.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

According to Fred McKenzie :
In article .com,
"Buy_Sell" wrote:

I have been collecting lenses from old medical machines that have been
sent to the metal recycling yards. They don't have any apertures but
they are pretty fast glass. The advantage of buying glass from
recycling yards is that most lenses sell for less than a dollar.

I am wondering how hard it would be to make these lenses useful for low
light photography?

B.S.-

Also consider obtaining a cheap lens for a particular camera and using it
to house the glass from one of your salvaged lenses. If you can manage
it, there would be an aperture adjustment and a focusing mechanism.

Hmm ... you can't put the aperture just *anywhere*. It must be
put at the nodal point of the lens assembly. Anywhere else will result
in varying vignetting as you stop down. Placing this properly may
require quite a bit of detailed (and precision) construction.

Bear in mind that the f/stops are determined by aperture diameter and lens
focal length. To use the f/0.75 42mm, you would need an old lens with a
maximum aperture of at least 56mm. For example, suppose you found an old
250mm f/4 lens. That would have a maximum aperture of 62.5mm.

You might even figure out a way to use the existing AF motor. Talk about
a challenge!

An interesting one. Part of the problem is that most AF lenses
are designed to move only one or two elements which takes a lot less
force than moving a focus collar to move an entire lens. (Of course,
part of that it the grease used in the focus threads for manual focus
lenses to provide a smoother feel to the focus.

One thing you may find, is that these salvaged lenses were used for a
different purpose than you want. For example they might be designed to
provide a flat-field image of a flat-field subject, rather than
flat-from-spherical as commonly used in photography.

If they have "APO" as part of their names, this is quite likely.
(Though those would not tend to be f/0.75, so these are more likely to
be used for low-light surveillance cameras.)

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---