PulseHPT 3-in-1 shutter speed tester experience?

I recently purchased this shutter speed tester with the lighter sensor module to check the shutter speeds of my cameras. It works quite well with shutter speeds up to 1/500s. However, at speeds from 1/1000s and over, it seems to read slow. I checked with a lot of my cameras from all mechanical to electronic shutter cameras. The behaviour seems to be the same.


Have anyone used this also? I would like to hear your experience.

I have no experience with this device, but what kind of light source are you using with it? I can see how a PWM-ed LED light source would throw measurements off, depending on PWM frequency. LED flashlights for instance can employ pulsed LEDs, depending on their design.
Welcome to Photrio btw!

koraks said:

I have no experience with this device, but what kind of light source are you using with it? I can see how a PWM-ed LED light source would throw measurements off, depending on PWM frequency. LED flashlights for instance can employ pulsed LEDs, depending on their design.
Welcome to Photrio btw!

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I am using a LED flashlight. It is difficult to find any light source that is not LED these days.

LED in principle is fine, as long as it doesn't flicker. Some LED flashlights will work fine, while others may not.

If your flashlight happens to have an intensity/dimmer setting, be sure to dial it all the way up and see if that helps. Otherwise try a different light source.

I contacted the seller. I am told it is a single light sensor system and can not cope with SLR with two shutter curtains. It will only be able to measure shutter speeds at or below flash sync speeds accurately. It can measure all shutter speeds with leaf shutters.

Oh, right, that makes sense I guess. Sorry, I didn't spot that obvious property of this tester!

How big is the light sensor? It should work with caveats for focal plane shutters, as long as the slit opening is larger than the sensor receiving light, if you position the sensor close behind the shutter curtains. "Caveats" meaning you understand the accuracy will be degraded a little, as it will probably read a little slow due to the finite size of the sensor.

I have used a homemade 3mm phototransistor setup (like a homemade Photoplug) with a single sensor to measure focal plane shutter speeds and it works, but I keep in mind that: I'm not concerned with more than 1/3 stop accuracy, and I'm not terribly concerned about the fastest speed. Ideally for a focal plane shutter one wants two sensors to measure curtain travel times and uniformity of exposure, but to first order, I just want to know if the shutter is far out of spec.

My experience using a PWM switched LED bike light as a source, for one of my phototransistors that switches fast enough to resolve the PWM of the LED, is that the PWM switching frequency was over 16-20 kHz. Fast enough that it's not going to matter unless you are trying to measure a 1/8000 sec shutter speed. For a slower phototransistor and possibly some capacitance in the circuit, it would be slow enough to integrate over the PWM anyway (but limit the highest speed that could be measured).

The light sensor is very small, only a few 3mm wide.