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http://www.apug.org/forum/index.php?threads/how-to-measure-pc-flash-sync-port-ohms-hasselblad-500c-m.131648/#post-1736101
Here is a link to apug where i made oscilloscope trace of contact bouncing...

I have a Speed Graphic 4x5 here . Serial 910819.
It has a 2 pin socket on the clockwork cover.

In case it is of any use, I copy here some measurements I did with oscilloscope some time ago..
...

Here is my latest method of replicating the Graflex boards, out of solid 6061 Al.
(In this case a 2x3 and next time I will do the 4x5 board the same way)...

I use a photodiode in photoconductive mode and an old Tek466 storage oscilliscope.
the p/d is arranged to receive a narrow beam, of scatter from the ground glass, usually.

This link should be Dir...

According to my calc, the tax is 8.75%, maybe some shipping in there too?

(Posted before)
The picture shows my approach to the conversion, by adding a small electronic flash in to the existing reflector.

Not as accurate as the metal spacer, but perhaps easier, just requiring drilling a scale rule.
The scale can be non destructively mounted on the bed using existing screws. ( At least, on the 4x5...

https://app.box.com/s/ph2jel7gupxl1tiifi4flatrv1uvrrrb

Here is one way to do it, using a gauge table with the camera back resting on parallel blocks

I admit I have been winging it. I have a vintage Pentax 3/21 spot meter but now I am not going to take it out in public due to its shape.
Pehaps I need a little Sekonic, but my budget does not...

You should edit your post, as you correction is on next page.

Drew, Does exposure level (errors) affect the color balance of these C41 negs?

Thanks Drew.
Did you mean that an 81A filter would have helped the early morning color cast?
I have not used filters so far . I see the 81A effectively reduces the color temp by attenuating the...

This image is on 120 film Ektar 100 taken early morning
https://app.box.com/s/mbi6jx0kykx6ga1h6as30l1xibslqy2n
It was scanned using Pacific Image PrimeFilmPro120 to a 16 bit tiff
Dynamic range...

Do you have the "C41 Digibase Instruction Manual" that comes with each kit?

Unless it has been corrected since my last purchase, there is an error in that instruction, in that the stabiliser...

Interesting discussion.
It is understandable that difference components are generated in a non linear transfer function, eg the ear or a diode modulator/detector.
We treat the em propagation as...

Here are some numbers I am putting together for scanning 6x7 C41 with a PrimeFilm120 Pro
Scanner:
optical res = 3200 dpi >> Nyquist Pitch = 16 micrometre or 63 cycles/mm

Film:
Dye clouds are...

This oscilloscope trace is of the Graflex Graftar f/4.5 103mm.
This shutter has no sync selector.

The cable was connected to fire the modified Graflite with the electronic flash in the reflector...

I have a 4x5 Speed and a 2x3 Crown.
I non-destructively modified the Graflite 5 inch 3 cell unit to hold an old electronic flash. The left over parts were bagged in the remote chance the flash will...

Koh, Good find, looks ideal for the job.
I take the liberty of putting the description here in case the above link goes away, when somebody comes to this thread looking for a similar capacitor
...

Yes, on the #3 here, while it is not threaded, there is a shoulder that will contact the board, leaving the aperture arm free to rotate.

David,
I recommend you wait until you can measure it.

The Ilex #3 here is of partially of metric dimensions; the front and rear element female threads are 45 mm by 0.5 mm pitch.
So I used the...

What thread do you need?

Part of my camera building hobby is making lens threads.
I have a South Bend 9A with inch and metric gear sets, and tools for 60 degree (USA & metric) and 55 degree...

Yes,
Have a trial run first so you do a neat job.

The heatshrink tube needs to be of the right size so it grips the soldered joint when it is shrunk.
Wrap the flex lead around the solid...

Yes, to use the above Amico capacitor in your unit you would need to solder flexible tails on, and slide heatshrink back to cover the bare leads. The body can be attached to the case with silicon...

Hi, Bvy,

Your capacitor is in the "hard to find" category. These days, capacitors around that value are not really required/ available , it must have been a small/ unusual motor.

What you need...

Hi Steve,
I just did a modification on the rear of an old Ilex #3 so I re-set it up to show how i would safely get rid of your unwanted adaptor.
The shutter rear boss here is quite soft and...

Changing R38 & R38 will not do anything to the system transfer function that can be done by only adjusting R 53.
The C2 capacitors should not be removed because the value is already down around the...

While I know almost nothing about photo-multipliers, I can contribute to the OA bit.

The present steady state transfer function is about 0.65 Volt per microAmp

To reduce that by about 5, you could increase R53 from 500 Ohm to between 2700 ~ 3000 Ohm.
The 47 Ohm and 17800 Ohm...

Here is my latest 6x7 back adaptor for my home built medium format bodies which are solid to the lens register.
This adaptor is milled from 0.25 inch 6061 Aluminum stock.
I try to keep the flatness...

2x3 Crown Century with the Graftar 103 mm, top vf and side Kalart and the rollfilm back (no film)
3 pound 13 oz = 61 oz * 28.35 = 1729 gram
The gg back is 6 oz = 170 g

In case it is relevant,
I have a 1950's Federal enlarger here
It is a condensor type with a big glass lens.
The lamp is a GE Photo enlarger type 211 75 watt which I see is still available.
That...

Some searching indicates this company
http://www.newportglass.com/achromat.htm
http://www.newportglass.com/share.htm
(I have no affiliation)
provides semi finished concave lenses for amateurs ...

Hi, Toguko,
For your request post #28, here is an OpticalRayTracer .ini file for a Periscop of focal length 88mm.
I am unable to locate the original prescription on my files here , perhaps you...

Hi, Toguko,
I suggest you download the freeware "OpticalRayTracer" It runs on java, so will work on any computer o/s.
It is primitive, but has all the main functionality for ray tracing, and does...

As a hobby I am building medium format metal bodied cameras which are really of the most elementary box camera concept.
Sitting in armchair, the idea seems rather simple. But I find the details to...

You should get a lens design app.

I use OpticalRayTracer and it is too simplistic but simplistic is sometime desirable.

I used it to model a very old periskop prescription from a link given by...

But, for a perfect lens, it has to be a curve, does it not?
Reason : (1/u) +(1/v)=(1/f)
And I attach a graph of variation of subject focus distance (u) with linear changes in v for the case where...

Yes, the camera I built was for lenses with a fixed and known register ( Takumar 6 x 7 ) so it was easier.

For moving lenses, better by trial and error, I think. Or use a lens bench to get the...

I dunno either !

But it is telling us that if you set the lens to f/22, the hyperfocal distance is about 7 metre
And everything from the near Depth of field of 3.6 metre to infinity should be in...

Randy, If you can't read this quick hand calculation, I can email it to you.
Hope the camera works out!