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View Full Version : Shutter Speed iPhone App. How accurate?



Timothy Blomquist
1-Oct-2014, 13:33
I have seen examples of other LF photographers using this app to test the accuracy of their shutter speeds. If your're not familiar, it's an iPhone/iPad app you buy, then pickup a plug in device off of eBay. It uses light through the shutter instead of sound to test the speed. Has anyone here tried this and what kind of accuracy are you getting with it? Thanks.

Randy Moe
1-Oct-2014, 16:04
I use it and it compares to my ears real well.

I have nothing else to compare it against, but I have clicked a lot of shutters and listened to them.

It's so cheap and appears to be the only thing like on the market.

I was happy to buy it and use it often.

Graham Patterson
2-Oct-2014, 12:26
The optical sensor seems accurate enough. Mostly I am after consistency - I want to know if the shutter is wildly out, the steps are uneven, or changing with time. Between several light meters, many shutters, and other variables, accuracy is far less important than consistent and repeatable performance.

The pure audio method is inherently less accurate as you have to decide which part of the sound envelope is significant, which is more subjective. The optical to audio conversion is cleaner.

towolf
2-Oct-2014, 17:48
With just a bit of signal processing they could auto-detect the shutter speed when the photodiode is connected. Why let the user selected the zero-crossings manually?

Randy Moe
2-Oct-2014, 18:25
Shutters can be 20% off and still within some spec.

Timothy Blomquist
3-Oct-2014, 13:36
So, when using this device, do you remove the front and back lens elements and just shine the light through the shutter, or do you leave the lens in place?

Graham Patterson
3-Oct-2014, 14:56
I leave the lenses alone unless I happen to have the shutter loose. With the optical sensor you just have to be reasonably central in the light cone. If you are testing a focal plane, Packard, or drop plate shutter then different locations across the shutter opening might be significant. With large format it actually helps to have the lens/shutter mounted on the camera to keep stray light away (unless you use the pure audio method).

Timothy Blomquist
3-Oct-2014, 15:29
With my Sinars, I would just remove the rear frame/bellows, leaving the front standard with lens in place, and have the wife hold the iPad with the sensor while I shine the light and trip the shutter. I am using only modern Copals, with the exception of one lens in a Seiko shutter.