Measuring shutter speed accuracy

[Barry Kirsten]

I built a sound card shutter tester a few years ago for my LF lenses. It works very well. I'm now hoping to get a Barnack Leica shortly, but can't see that the tester would work with one since there is no easy access to the camera's shutter. The only work around would be to replace the photodiode with one similar to that used in the Leica CLE, which might be thin enough to slip down inside the camera back. A bit messy, I reckon.

 

[webOSUser]

There is an app that can be used called 'Shutter-Speed by Lukas Fritz. It natively uses the shutter sounds, but they sell a small 'Photo-Plug' thru the Filmomat store that plugs into the device's headphones jack. The device lists at €25 inc. VAT excl shipping.

I did not have great luck testing higher shutter speeds when I used it. It is available for both iOS and Android. I used the iOS version. It is an iPhone application, but will work on an iPad.

Steve W.

 

[David Hughes]

Hi,

As the original question was about film cameras I wonder how accurate we need it for exposure. I mean, a lot of us are quite happy thinking we have a top speed of 1000th or 500th of a second available but I have my doubts about the exact speeds in use.

Luckily both film and digital have a bit of latitude...

Regards, David

 

[Joao]

Hi,


... I wonder how accurate we need it for exposure. ...


....Luckily both film and digital have a bit of latitude...

David
You are right - and I took advantage of the film latitude many times.
But knowing a reasonably accurate measurement of the shutter speeds will allow me to compare the results of different cameras (same film, same exposure). Sometimes I find differences in the results- and very different real shutter speeds may help to explain them.
What is a "reasonably accurate" measurement is subjective, im my opinion...
Regards
Joao

 

[johnnyrod]

I have been using the phototransistor setup and Audacity for a couple of years now. It's cheap and works well. For focal plane shutters, the phototransistor is prone to light coming from the side, so you either need to fit a tube to the phototransistor to narrow its field of view, or just use a laser instead of a bare bulb as the light source - I use the laser on a spirit level which are dirt cheap from Aldi. I do amateur CLA and this is perfectly adequate. You could do a twin-phototranssitor setup to get opening and closing of the shutter curtains and record them simultaneously as left and right audio channels.

Sorry, added notes on exposure. 20-25% accuracy is considered good enough in shutter speeds - about half a stop. Most of my cameras are old leaf shutters from the 1950s and 60s (or earlier), most of these even on a good day run anything down to half speed, so overexposing - good for film lowlights, bad for camera shake. The few SLRs I have are accurate though.

 

[Ko.Fe.]

All you need is a digital camera, a desk lamp and a black t-shirt.

I’ve been using this method for years to check film cameras - it’s accurate, fast and easy. Details here. The image on the website has gone AWOL - so I’ve attached a copy to this post.

I followed, but lazy.
With bright screen of the phone, shutter on top of it, taking camera on top of it via tripd. 4 sec taking exposure at ISO100 and f5.6.

all at 1/250:

ebay FED-5D with OK exposures.

FED-2 from ... needs service.

M4-2 serviced in 2018.

26CAD Nikkormat from charity store.

 

[Murray Kelly]

https://www.ebay.com/bhp/shutter-tester

 

[SimonKlanfurt]

I am using a vfmoto Shutter Speed Tester made by Florin in Romania (sold on eBay) right now, and I am thinking to buy a Phochron XA instead, as the vfmoto one does not work reliably for me.
Has anyone used both of those devices and can tell me, if buying a Phochron instead of a vfmoto is a worthy upgrade?

Thanks and Greetings, Simon.

 

[monopix]

I've not used the Phocron so can't comment on it but I have a vfmoto one. I also had problems getting consistent results and emails to Florin didn't help. The issue, I believe, is the width of the sensors compared to the width of the slit you're trying to measure. At high speeds it's not precise enough and I found I could get significantly different results just by moving the light source closer or further away. Having previously built a tester myself I was aware of the issue. On mine, I used a mask in front of the sensor with a slit so that the effective sensor width was very narrow. I made a similar modification to the vfmoto using some foil with, in this case, a pinhole punched in it taped over the sensor. The problem then was insufficient light getting through the pinhole so I used a laser as a light source. With that setup, the tester works consistently.

Maybe you should try doing a similar modification before moving to something else. The Phocron uses the same basic method so may also suffer the same problem but it depends on what sort of signal processing is done to the signal received from the sensor and it might be a lot cleverer/better.