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04-17-2020, 12:38 PM - 1 Like   #1
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Shutter speed tester

I few months ago I asked if anyone had any experience of the "Photoplug" shutter speed tester. Apparently, no one had so I eventually got round to buying one myself to try out.

Photoplug is a very small device which plugs into your smartphone headphone socket and is used in conjunction with a dedicated app. It costs 29 euro plus postage.

Essentially, you shine a strong light (LED preferred) into your lens and point the Photoplug device from the rear at your shutter and you fire the shutter. This generates a waveform on the app which has a couple of spikes which represent the shutter opening and closing. You enter your selected shutter speed into the app. There are 2 movable marker points on the app. You move the first one to the start of the opening spike and you move the second one to the start of the closing spike. This gives you the recorded shutter speed and the deviation, in 1/3 stop intervals, to the selected speed on your camera. Here is a screenshot of a 1/30th shot. Note that I didn't quite line up the second marker with the start of the second spike. That was just for the screengrab. :-



So I've played with this device for about a week, trying to get the best out of it. I've found that it seems more accurate at lower shutter speeds. The device will only test up to 1/500th but the second spike on the waveform does not seem so well defined at 1/250 and 1/500. See below:-



I've got a theory that it has something to do with the two shutter curtain system being harder to read at higher shutter speeds. When I tested my Yashica 24 TLR with its leaf shutter, it seemed fine at 1/500. I did find it was important to get your light source well positioned and very important to get the Photoplug device really close to the shutter.... about 5mm or so.

You can add all your cameras into the app and it will save and display your recorded shutter speeds:-


Pentax MX



ME Super



Yashica 24


All in, I'm reasonably happy with this product although I think it is more accurate at 1/125 and below. You do need to set it up carefully for best results. I have no connection to this product, just a user. I am particularly happy with the Yashica results. Earlier this year I notice the shutter speeds were out badly at lower speeds. I did my own CLA on the Yashica, including the delicate work of stripping and cleaning the shutter blades. It was nice to see that the shutter is now reasonably accurate

04-17-2020, 01:45 PM   #2
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QuoteOriginally posted by Vendee Quote
I've got a theory that it has something to do with the two shutter curtain system being harder to read at higher shutter speeds.
The time (hence slit width) between leading and trailing decreases at higher speeds. Perhaps a brighter light source?


Steve
04-17-2020, 02:09 PM   #3
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QuoteOriginally posted by stevebrot Quote
The time (hence slit width) between leading and trailing decreases at higher speeds. Perhaps a brighter light source?


Steve
I'll certainly give that a try although I'm using a bright LED torch (flashlight) which is pretty much the diameter of the 49mm lens and pressed right to the front element.
04-17-2020, 02:44 PM   #4
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QuoteOriginally posted by Vendee Quote
I'm using a bright LED torch (flashlight) which is pretty much the diameter of the 49mm lens and pressed right to the front element.
I think that's the wrong way to do it! As Stevebrot notes, the slit width varies depending on shutter speed.

Do you have a laser pointer? I would shine its narrow beam onto the photodetector and try your measurements again. (Line things up in Bulb mode) And, remove the lens if you can - that leaves just the narrow slit of the shutter to let the light through. With a lens, the input light is more-or-less dispersed over the entire focal plane.

Also, judging from the light curve you show, this gizmo has a differentiating effect on the light it detects. The time constant of that effect will have some affect on the result.

The proper way to do this is to just use a high-speed photodetector and an oscilloscope. I am lucky enough to have all that, and I could measure your shutter speeds to an accuracy of a millionth of a second or so (if you really care!!). Other than the few hundred dollar 'scope, the parts cost for the detector is a buck or two.

04-18-2020, 03:48 AM - 1 Like   #5
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Unfortunately I don't have a laser light to test your theory but I have repeated the 1/500 test with various strong light sources at various distances and have also tried with and without the lens fitted. The results are pretty much the same.

I still think the limitation is the equipment (including the smartphone) and that's not a criticism given the modest price of the device. Given that even some older film bodies can operate at 1/2000 and 1/4000, the fact that this device maxes out at 1/500 suggests to me that the designer knows he can't go higher with his device. Regarding the waveforms I posted above, I would just like to clarify that they don't initially appear like that on the screen. The wave form is stretched out on the screen by the user with a couple of fingers to make the peaks easier to see and measure.
04-18-2020, 05:48 AM   #6
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QuoteOriginally posted by Vendee Quote
Unfortunately I don't have a laser light to test your theory but I have repeated the 1/500 test with various strong light sources at various distances and have also tried with and without the lens fitted. The results are pretty much the same.
Thanks for checking.

As you note, I think you've hit the limit of the inexpensive equipment. I'll have to drag out my ME and give it a whirl with my higher speed system. I did something similar some years ago when I sold my Dad's old Pentacon on Ebay. As I recall, up to around 1/250 the speeds were pretty accurate, but clearly got worse (too short) for 1/500 and 1/1000.
04-18-2020, 06:49 PM   #7
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QuoteOriginally posted by AstroDave Quote
Thanks for checking.

As you note, I think you've hit the limit of the inexpensive equipment. I'll have to drag out my ME and give it a whirl with my higher speed system. I did something similar some years ago when I sold my Dad's old Pentacon on Ebay. As I recall, up to around 1/250 the speeds were pretty accurate, but clearly got worse (too short) for 1/500 and 1/1000.
I'm just going to contrast that in my head with what I usually see on eBay...

"Despite the fact that I have sold hundreds of cameras on eBay in the past ten or more years, I don't know anything about them, so I think it works great..."

or

"Speeds sound right...", which is about the same as "slow speeds are off..." on any 50s leaf shutter...

I don't often see "tested it and the highest speeds are off 10%..."

-Eric
04-19-2020, 06:48 AM   #8
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I have a couple of questions on this...
Does this tester let you position the sensor...such as left edge, center, and right edge? This gives you info on curtain travel...is it even across?
You correction numbers...are they in stops? If 1/125 reads 1/100 (approx) that is more like -1/2 stop... -1 would be 1/60.



04-19-2020, 08:29 AM   #9
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As I said, the device plugs into the headphone socket of your phone. It actually looks like a 3.5mm headphone jack plug without the cable. It really is that small. You can point it at any part of the shutter you like. I pointed it fairly centrally but I rested the phone on something solid rather than hand holding it.... for more accuracy hopefully. The correction numbers are in 1/3rd stops, not full stops.
04-23-2020, 12:54 PM   #10
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I normally use an oscilloscope to test shutter speeds but for those who want to play with the simpler system using a phone app there is more information on the link below ( there is also a link about the free app)

Finding the Shutter speed of a Vintage Camera | Art Deco Cameras
05-22-2020, 12:06 AM   #11
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QuoteOriginally posted by Vendee Quote
I few months ago I asked if anyone had any experience of the "Photoplug" shutter speed tester. Apparently, no one had so I eventually got round to buying one myself to try out.

Photoplug is a very small device which plugs into your smartphone headphone socket and is used in conjunction with a dedicated app. It costs 29 euro plus postage.

Essentially, you shine a strong light (LED preferred) into your lens and point the Photoplug device from the rear at your shutter and you fire the shutter. This generates a waveform on the app which has a couple of spikes which represent the shutter opening and closing. You enter your selected shutter speed into the app. There are 2 movable marker points on the app. You move the first one to the start of the opening spike and you move the second one to the start of the closing spike. This gives you the recorded shutter speed and the deviation, in 1/3 stop intervals, to the selected speed on your camera. Here is a screenshot of a 1/30th shot. Note that I didn't quite line up the second marker with the start of the second spike. That was just for the screengrab. :-



So I've played with this device for about a week, trying to get the best out of it. I've found that it seems more accurate at lower shutter speeds. The device will only test up to 1/500th but the second spike on the waveform does not seem so well defined at 1/250 and 1/500. See below:-



I've got a theory that it has something to do with the two shutter curtain system being harder to read at higher shutter speeds. When I tested my Yashica 24 TLR with its leaf shutter, it seemed fine at 1/500. I did find it was important to get your light source well positioned and very important to get the Photoplug device really close to the shutter.... about 5mm or so.

You can add all your cameras into the app and it will save and display your recorded shutter speeds:-


Pentax MX



ME Super



Yashica 24


All in, I'm reasonably happy with this product although I think it is more accurate at 1/125 and below. You do need to set it up carefully for best results. I have no connection to this product, just a user. I am particularly happy with the Yashica results. Earlier this year I notice the shutter speeds were out badly at lower speeds. I did my own CLA on the Yashica, including the delicate work of stripping and cleaning the shutter blades. It was nice to see that the shutter is now reasonably accurate
Those all look good to me!
A skilled techie would stop and send the camera back! When using Kodachrome25 I only used 1/125 Or slower...
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