Silly question: verify that onboard metering works, without film test

wiltw · Apr 26, 2023

ic-racer said:
I think I'll visit B&H or Freestyle and get one of those.. Ha ha!

Actually a good substitute is available, in fact I'm building one now: https://github.com/srozum/film_camera_tester

The one you buy provides precise luminance values and color temperatures for reference use
The one you make has to be calibrated for its brightness.
The DIY in the link needs an oscilloscope.

"For the time counting method, you need a light sensor, a time counter, and a simple light source. With such setup you can measure exposure time(s) provided by a shutter, curtains travel speed of a focal plane shutter, flash sync contact delays, etc.
For the second method, you'll need a photosensor able to measure the amount of light and a calibrated light source. With such setup, you'll be able to measure actual exposure produced by a system "camera+lens", light meter accuracy, operation of auto-exposure cameras, etc."

RalphLambrecht · Apr 26, 2023

Alan Edward Klein said:
Testing together two variables - meter accuracy and shutter accuracy - will drive you nuts. If the film test results are off, how would you know which is causing it or both? Check each separately.

I agree in principle, but the nice thing about EV is that shutter speed and aperture can be combined into one single value which illuminates the issue of having to deal with two variables.

jay moussy · Apr 27, 2023

Update, so far:
- FG seems fine after along period of inactivity
- constant gray weather, no brightness to do a "natural" test

I was thinking about sticking to 100 ISO film for air travel scanner fears, but I may be limiting myself unnecessarily?

Extra: this FG was found at the local dump goods exchange, and someone had been inside before: it is missing a few top plate retaining screws, but functions well. Are most Japanese camera assembly screws similar in size/pitch?
I just replaced film door, did not look safe.

I like handling it, feel, features I can expand on - need to re-learn the viewfinder LED sign language though!

ic-racer · Apr 27, 2023

Chan Tran said:
You sent me the link for the sensor but I don't think I find the information on the sensor. I am most interested in the sensor.

There are two sensors specified for GitHub device. One for the shutter speed modules and one for the EV and EE tests (as discussed in this thread). I attached the PDF for each below.

The reason I laugh at the suggestion of the Kyoritsu is I tried many times to buy one but they are no longer made. The ones for sale are broken. The working ones are not for sale. One would need to find a repair person going out of business and buy his or her stuff.

Here is Sover Wong's...I don't think he will be selling it to me

kykr · Apr 27, 2023

jay moussy said:
Update, so far:

I think the biggest question is about your expectations. If you’re not expecting perfection and “you get what you get” then it’s fine - have fun! Since you’re not familiar with this one, I’d guess this might be the case.

If that’s not what you had in mind, then an untested and unfamiliar camera is probably not the best option.

Saganich · Apr 27, 2023

wiltw said:
A shutter tester verifies the speed accuracy of the shutter (vs. the marked speed)...it cannot tell if the meter is telliing the shutter the wrong speed to use when the camera has no display of the shutter speed commanded by the meter

Who has one of those hanging around? Send it to me.

Chan Tran · Apr 27, 2023

ic-racer said:
There are two sensors specified for GitHub device. One for the shutter speed modules and one for the EV and EE tests (as discussed in this thread). I attached the PDF for each below.

The reason I laugh at the suggestion of the Kyoritsu is I tried many times to buy one but they are no longer made. The ones for sale are broken. The working ones are not for sale. One would need to find a repair person going out of business and buy his or her stuff.

Here is Sover Wong's...I don't think he will be selling it to me

I know it's kinda near impossible to get a good working one and if you can the price would be quite expensive. But it would verify the OP Nikon EM exposure system without having to run film through it for sure.

Alan Edward Klein · Apr 27, 2023

RalphLambrecht said:
I agree in principle, but the nice thing about EV is that shutter speed and aperture can be combined into one single value which illuminates the issue of having to deal with two variables.

But if the film results are off due to both shutter/aperture and meter errors, how would you know which is causing the errors and how much?

wiltw · Apr 27, 2023

Alan Edward Klein said:
But if the film results are off due to both shutter/aperture and meter errors, how would you know which is causing the errors and how much?

Indeed, 'bad exposure can be

shutter speed inaccuracy
aperture close inaccuracy
light meter inaccuracy

...which on can be determined primary by calibrated test instrumentation that can demonstrate the point of failure, which most of us do not have access to.
We can test against a 'known good' control unit, but the old saw recognizes, "Compare two devices and you are uncertain which one is right'

faberryman · Apr 27, 2023

wiltw said:
Indeed, 'bad exposure can be

shutter speed inaccuracy

aperture close inaccuracy

light meter inaccuracy

...which on can be determined primary by calibrated test instrumentation that can demonstrate the point of failure, which most of us do not have access to.
We can test against a 'known good' control unit, but the old saw recognizes, "Compare two devices and you are uncertain which one is right'

All good reasons to establish a personal E.I. and optimal development time. Most exposure errors result from user error. Some photographers blame their equipment for user error. It's just easier that way, and provides an opportunity to buy a new camera.

jay moussy · Apr 27, 2023

wiltw said:
Great that there is a shutter speed indicator. Find yourself an area which is relatively featureless, and which can be illuminated uniformly by a light source...aim the cameras at that area. Set all meters to same ISO, and see if they all give 'same exposure' (equivalent combinations of shutterspeed + aperture)

That's what I just did, uniform grassy area in early afternoon sun, Sekonic hand meter and camera agree.
Good enough for me, and the mostly street photo I want to do on a trip, using the P mode for rapid capture, A mode if I want a specific DoF, manual if I feel frisky, it's a hobby.. screw around and find out!

Edit: that does not address the actual shutter operation speed, which gave good film a year ago... so I will roll with that.

Alan Edward Klein · Apr 27, 2023

wiltw said:
Indeed, 'bad exposure can be

shutter speed inaccuracy

aperture close inaccuracy

light meter inaccuracy

...which on can be determined primary by calibrated test instrumentation that can demonstrate the point of failure, which most of us do not have access to.
We can test against a 'known good' control unit, but the old saw recognizes, "Compare two devices and you are uncertain which one is right'

The old saw:
"Give a man a watch and he'll always know the time. Give a man two watches and he'll never know the time."

Sirius Glass · Apr 27, 2023

faberryman said:
All good reasons to establish a personal E.I. and optimal development time. Most exposure errors result from user error. Some photographers blame their equipment for user error. It's just easier that way, and provides an opportunity to buy a new camera.

The EI would mean more if the camera and light meters are calibrated, otherwise it is an random number grabbed out of the ether.

faberryman · Apr 27, 2023

Sirius Glass said:
The EI would mean more if the camera and light meters are calibrated, otherwise it is an random number grabbed out of the ether.

You may wish to reconsider your response.

Chan Tran · Apr 28, 2023

Alan Edward Klein said:
The old saw:
"Give a man a watch and he'll always know the time. Give a man two watches and he'll never know the time."

But that's an old saying. Today even if you have 100 watches or cameras you should know how accurate they are. You don't know exact but you know this watch is accurate within a second and this is within a minute. If I don't know I don't use them, watch or exposure meter.

ic-racer · Apr 28, 2023

My tester measures the shutter speed and the value of light that came through the stopped-down lens to determine if the auto-exposure was correct.

Sirius Glass · Apr 28, 2023

faberryman said:
You may wish to reconsider your response.

No. Uncalibrated equipment is naturally inaccurate.

faberryman · Apr 28, 2023

Sirius Glass said:
No. Uncalibrated equipment is naturally inaccurate.

Which is something quite different than you said in post #38, the post to which I was responding.

Bill Burk · Apr 29, 2023

Sounds like @jay moussy has done the necessary “quick and dirty” checkup before going out to take pictures.

It’s fun to adjust an automatic camera.

Last summer I got really deep into camera repair. I facilitated international trade in camera grease for a San Francisco group (sounds intriguing but all I did was accept shipment of 1000 grams each of two hard to find Kluber greases specified for Leica repair, then weighed out and repackaged 250 grams to send to different people).

I met up with one of the group… Serhiy Rozum who made a Kyoritsu-like tester and light source. You can’t get them now but you can follow his plans.

I cobbled together an oscilloscope and frequency counter and got electronic readings of the main mechanical travel speed (1/60 for ES-II). Then with an adjustable light source and an old Vivitar 283 flash, I watch that the curtain shadows half the frame at 1/125 mechanical speed, and so on.

Then I switch to automatic and adjust a variable light source to specific EV’s following a repair manual (light source has a Beseler type enlarger bulb so I add an 80B filter to “mock” daylight). Turn the 1/60 speed control variable resistor in the camera until the second curtain starts to peek into the gate (match the mechanical 1/60 to electronic 1/60), then I back it off a little. That kind of thing. Following the steps to adjust all the resistors to their different settings. There’s a ton of adjustments… battery check, low speed shutter, high speed shutter, stop-down low, stop-down high, indicator low, indicator high.

It’s fun, but now I have to go develop a bunch of film… I have quite a backlog and a number of people asking me for pictures.

jay moussy · Apr 29, 2023

As Bill said above, I took a very expired color print film through the A, P, and Manual modes, dropped it the the local camera shop that does C41.

All negatives seem fine, balanced, at first glance. No light leak either, but I had replaced the door latch seal. I am falling in love again....!

Huss · Apr 29, 2023

Bill Burk said:
… I have quite a backlog and a number of people asking me for pictures.

Can I have a picture?

Bill Burk · Apr 29, 2023

Huss said:
Can I have a picture?

Sure! Want a picture of scouts cleaning invasive plants or Doctor Demento?

Silly question: verify that onboard metering works, without film test

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