Lenses curves

Inspired by distance scale issue, I measured all lenses in hand, combine same focal length lenses into one, and plotted the curves representing them.

Most lenses marked as same focal length have same characteristic curve, except 120mm lenses I have.
One is Schneider Angulon 6.8/120mm, and another one is a vintage Tessar 4.5/12cm lens from Cocarette folder. Their characteristic curves are totally different, funny thing isn't it? That means two 120mm lenses need different distance scale.

Distance Scale is not so correct.....

I received feedback from Raymond who told me that "the focus scale, the ground glass and the rangefinder did not agree on the focus distance." That brings me curiosity how precise the RF on 110B? I never doubt about the distance scale that camera shows me, until this time.
So I managed to measure the REAL distance scale that read out from ground glass panel. After some cameras were measured, a curve plotted to represent the relationship of focus distance and the rail movement.
Black curve represents the measure I made from ground glass, the blue curve is what distance scale on camera marked.

The curve tells me some facts that I should let all of the polaroid 110A/B owners to know, that is "the distance scale on camera is IN-CORRECT"!!
How surprise! I did trust the credits of Polaroid, their reputations of the quality control on productions......., but I should check before that!!
The curve tells me that 127mm lens actually can not focus as close as 3 feet, like  the distance scale shows, 3.6ft (110cm) is the nearest distance that camera can focus.
And the curve tells me more, that the distance scale is somewhat correct from infinity to about 5 feet, and then incorrect increase when focus closer.

BEWARE!!!

I should re-mark the distance scale on Byron.

(afternoon the same day Added...)

I received a mail, James from US told me that 'Actually Polaroid did make the distance scale inaccurate on purpose. What they did was based on ordinary people who are not aware 'focal plane', estimating distance between subject and the front end of lens, not knowing that real focus is on 'focal plane', about 20cm behind the lens, thus Polaroid marked the scale a little bit shorter, to compensate the common errors. When subject is far out of 5feet, that 20cm error won't bother anything, but if subject is very close, say 4feet (120cm), that 20cm deliberated shortage then become obvious! That is exactly what my curve shows me!!

And Mr.James pointed out that '110B camera was made in a closed system, that is, fixed lens, so as long as the range finder is coupled with the lens, no matter how the distance scale marked, it won't bring errors, but Byron now makes its range finder an open system, not only coupled with one lens only, and it also becomes reference for other lenses, for un-coupled setting, that makes distance scale in-correct.'

Thanks James, your explanation released me, bring back my faith to Polaroid!

German Bear sent me a letter.....

----I could not catch up his schedule, delivered Byron to him before his new year trip, so I lend my own Byron with 127mm and 90mm lenses to him, asking him post some photos (a silly bear holding the camera, smiling...) during his two weeks vacation. And this is the first letter he sent to me this morning.----Daniel

Hi Byron worker,
at home in Odessa with jet-lag, that's why just some proof pics of working Byron at -30 degrees Celsius! I was fixing lens with some strips of Gaffa tape on the plate, otherwise was not handle changing the exposure time on the small wheel. People from Japan, USA, Germany, GB, China locals was looking at Byron...:-)
Byron just goes out today on the way back to you, thanks a lot!!!
More next days, sleepy Sebastian needs resting...

(I saw your Fuji 6x9 on you neck.......)

(Locomotive fans, frozen lollipop....)

I envy my Byron, it will travel all over the world!

New version of Front Standard for big eyes is under development

In the Project I'm possible, I saw the possibility to expand the lenses selection range even wider.
When I tried to solve the problem on inf. stop of 150mm lens, a new protruding lens board was developed, and that makes lenses who use #1 shutter becomes feasible on Byron, though some lenses need in-directly mounting procedure, makes them inconvenient to operate.
Now with this 8mm Enforced plate, I can drill hole as big as 60mm in diameter, that means all those lenses who was inconvenient to use on protruding lens board, become no problem at all, most of them could be directly mounted, no matter their #1 or #2 shutter size!!
(Thanks to Jeff providing the link of Compur shutter spec, I found out that Xenotar 2.8/150 is actually on a #2 shutter!, not #3)

That is really crazy! I never thought of such big shutter size on Byron before!

For those people who wants Byron light weight, tiny, easy to fold up and carry, please stick on the original lens board system I developed.

For those people who doesn't care about weight, carry, but love to use those "Big  Eyes", "Big Rear", "Big Shutter", please wait for my new version of lens board system.

And Jeff, that is you!

Nearest distance Xenotar 150 can get

Just measured, almost stretch the temporary bellows in totally flat, I managed to pull the lens to rail's limit, the nearest distance that Xenotar 2.8/150mm focus is about 107cm, from focal plan to subject, that is about 3.5 feet.

Jeff, see that?

Consider the thickness that enforced plate is 8mm, what if I add it to 10mm? Possibly it get close to 100cm?

Anyway, a bright sunny day again! I will wait my younger son off from school and then make an instant shoot, first model for Xenotar-Byron!!

So keep watching!!

Just curious to ask, is there any other crazy lens that uses #3 shutter, focal length under 150mm? 

Young model is hard to deal with, especially if he is you son! Bribe with 3 chocolate bars to make him cooperated.

Naughty boy!

 

Byron + Xenotar 2.8/150, f/2.8 1/200sec, FP-100C 4x5

 Same image as above, partial, focus at the eyes.

 Byron + Xenotar 2.8/150, f/2.8 1/200sec, FP-100C 4x5

Same image as above, partial, focus at the eyes.

All focus as close as possible (3.5ft), I found that DOF is really shallow, wasted about 4 instant films to get these two rather satisfied results. 
150mm, f2.8, focus at 3.5ft, DOF got only 0.08 ft (2.4cm!), means when I focus at the eyes, ears are already out of focus!
and I had not made the lens coupled with range finder yet, I made photos this afternoon by gg panel, ruler, and ordered my kid to hold still, not even breath! 

Project I'm possible--Xentoar Version

I just said that "don't even think about it!!" at 150mm lens test, about Xenotar 2.8. Then Jeff that New Yoker really good at persuasion, whispered: "If you made it, you will be the first and the only one who brings Xenotar to snaps, think about it!"
................
That really tempts.
Well, think it twice, its nearly impossible.
nearly.

I heard they say that fashion industry will love this kind of combination, a fast lens capture models' nature expression, and range finder helps shooter graping the timing.
That is what I heard from Lambis, my Sweden pal. Where are you now? seems you disappeared, you booked a Byron, remember?
Now, lets compare the lens size, a giant fits into the place for dwarf. and estimated about 700g in weight.

What I did first, is to find out if the front standard available for this giant or not, or should we make a brand new for it?
Asked my mechanist to expand the hole as big as possible, finally I got this, barely enough for rear element. It is hard to explain, the hole is much bigger than the shutter thread, but not for whole rear to pass. I did this for the reason to let the lens extruding out of the standard, to avoid the collision of the struts.

HEY! You won't think this Xenotar-version-Byron still got the ability for lens interchange? It will be dedicated for this lens only. But you can take it off when folding camera.

Now there are 3 main problems (and some minors) needs to be solved

1. front standard is made of a 2mm steel plate, strong enough for Ysarex, but not for this dino.
luckily we almost has solved it, so it is strong enough to hold the lens, but the plate is still too thin visually.

2. lens need to be extruded out, to avoid collision with struts.

I've ordered a special front plate, in 8mm thickness, to enforced the original 2mm plate, also providing lens extruding and flange fixing.

Enforced plate is coming, needs some further process, but it looks great, definitely strong enough for that BIG EYE! Four holes at corner for plate and standard, three by the lens hole, that is for flange.

Seems like that I really make it!

NY Jeff, happy now? 
Sweden Lambis, where is your Xenotar?
(13/01/10 ADD)

It's a sunny day, rarely happen in Taiwan's winter, always raining.
Lens mounted onto Byron, bellows was tailored by normal silk one, cut a few front folds for bigger hole, for temporary test, thus shorten it's length that I can not extend the lens to the limit, but no problem for infinity.

Surprised that it actually feel not bad when holding in hand, I thought it would be very heavy, but it is not, thats good.

Focusing in 2.8 aperture is very much easy and comfortable, image is bright and clear, edge to edge, with my gg panel, even no hood needed.

3. How to mount/unmount the lens?
Right now, screw/unscrew the front/rear element is the only way.
4. Bellows needs to be redesigned, for bigger rear element.

Bellows hold until next month, I need to do Jan batch of conversion works.

(to be continued)

Multi Infinity Stops Engraving

Each Byron is converted by clients' requests, especially for the lenses they picked. Different combinations of brands and types of lens, shutters, it definitely needs each lens' infinity stop be measured specifically.
After individual measurement for each lens, then the i.stop engraving work needs help by my mechanist.
First, a special T type lathe knife was ordered.

The knife will engrave the plate a 1 mm width ditch, to keep and hold the front standard on location. Measurements are precisely down to 0.01mm, and with a CNC lathe machine, that will do the job very well.
Secondary, my mechanist made a fixture tooling, to hold the plate in fixed position.

Fixture tool firmly holds the plate in vertical position, and knife lathes tiny ditch according to the measurements.

Then the plate is engraved the digits of focal length by the side of ditch, for identification. I need some more practice of engraving......

For my own reason, to ensure pairing the plate with matched camera body, I engraved each owner's name on the back of the plate.

Then the installation, and rechecked the focus. Noticed that 90mm lens distance scale at the right side? that is for un-coupled focus.