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Frequently Asked questions

I’m sure you have questions about this device. Here’s some answers:

Can I test my digital camera (DSLR)?

Any camera that allows access to both sides of the shutter can be tested. If the DSLR only has access to the sensor from the front (most are like this) then you CANNOT test this camera.  If you are looking to test the shutter of a DSLR, a professional will have to disassemble it before it can be checked.

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What is the fastest speed it can test?

The sensors can detect pulses as short as 1/10,000 second as evident by the calibration mode. But in reality, because of an effect called the prenumbra effect, light passing through a narrow slit creates a shadowing that makes measuring this narrow pulse difficult.  It is the same reason it doesn’t get totally dark in a total eclipse of the sun. This is why it is only rated to 1/4000th of a second. A specialized sensor is required to measure anything faster than that.

What batteries does it take?

It uses two AA batteries. Rechargeables can be used.  Battery life is exceptionally long.

Can I measure flash duration?

Yes! You can use the Phochron to measure the duration of an electronic flash. Set the tester to Simple shutter test, and start the test. Then trigger the flash. You don’t need to point the flash at the tester, in fact best results are seen by picking up reflected light. Make sure the waveform displayed doesn’t show a flattened top.  If it does, the light received is too strong . Move the flash away from the tester. Bounce it off a far wall.

Do I need the external sensor?

No. You can test EVERY shutter with the single in-built sensor.  The only reason you need to buy the external sensor is if you are looking to test the performance of  the sliding curtains of an SLR camera. It provides you with additional timing information that can help you maintain uniform exposure over the film plane.

Can I test my Leica Camera?

Some of the Leica cameras have the curtain shutter buried in the case and you would have to remove the frame from camera housing to have access to both sides of the shutter. This is not a simple task.

Are there other kinds of cameras that are difficult to test?

There are some of the Leica clones such as the Zorki and the Zenit that are similar to the Leica in that the shutter is buried inside, and without pulling the housing off, you cannot get to the back of the film plane. Any camera that has a hidden film plane could not be tested without some disassembly.

I’m testing a curtain shutter and I can’t get enough light on the sensors. Do I have to use the built-in light source?

No. The light source is just a handy light source. Any bright light will do. I have used my phone’s built in light as a light source.  You can use any flashlight or even a work light. Florescent light sources don’t work well as they actually flicker at 60 times per second, and the sensor picks this up.

How do I hold the light source steady in front of the lens?

As my pictures show, a block of wood worked very well  as a holder for the light source. I just used a rubber band to hold it to the block of wood.  You can use playing cards as shims to prop it up to the right height. Or you can use books or magazines to get the light up to the right height.

I am testing a very old box camera, and because it has a built in f/ stop of about f/16, I can’t get enough light to hit the sensor. What do I do?

In this case, simply reverse the sensor and light source. In other words, put the tester in front of the lens and the light source inside the film chamber up close to the lens. It doesn’t matter which direction you test it.

What do I set the f/ stop to during tests?

Always open the aperture all the way open to let as much light in as possible.

How do I get the batteries out?

Open the battery cover, and swing the tester into your open hand, with your palm under the batteries. If you pop it onto your hand the batteries will pop out. You can also put a small piece of ribbon under the batteries when you insert them to help to pull them out.

If you hold the blue button down for 5 seconds, it will shut off. If you forget, after 5 minutes of no use, it will shut itself off.

How do I shut it  off ?