A DIY retro digital camera project - Blog #9 First ever shutter lag testing for screen-free digital camera

[lxforrest]

One of the biggest pain points for screen free digital cameras is the shutter lag. With 0.5s-1s shutter lag, users are not lived in the moment but 0.5s-1s later.

I tried many screen free digital cameras in the market (pre Pro Models) to try to capture a good/clear picture of my nonstop moving kid. Successful rate = pretty low.

Since I am building my own screen free digital camera, shutter lag testing is always haunting me. How can I set up a serious test environment? Even though I tried to capture flying Seagull in close range multiple time with my camera.

Today, I finally completed might be the first shutter lag testing for screen free digital camera with my camera: Rewindpix.

Test Tool: an analog stopwatch website (Analog Stopwatch - Mechanical Stopwatch - Online Stopwatch), a Rewindpix Camera, a Cell phone for recording

Test method: Press the shutter button when analog stopwatch point at 55s.

Test sample size: 3 samples, take average

Vision reaction delay compensation: Based on the “A literature review on reaction time" by Robert J. Kosinski, Clemson University, 2013. Average vision reaction time for an normal individual = 200ms or 0.2s. So I am thinking it is safe to use it as a compensation for final reading.

Without further ado, below is the workflow of the first ever "Scientific" shutter lag time testing for screen-free digital cameras in the family's short history!

Set up

Cellphone records through viewfinder

See reply for image





Load = Winding the winder

See reply for image





3 try out:
See reply for image






Shot1 = 55.501s
See reply for image


Shot2 = 55.477s
See reply for image


Shot3 = 55.401s
See reply for image


Conclusion:

0.26s, not too shabby.

Video​

 

[lxforrest]

 

[lxforrest]

 

[Freakscene]

For comparison, a film Leica M has a lag of 12 ms (M7), 17ms (M3 and mechanical M cameras), but ~250 ms is in the range of a lot of decent cameras: Shutter lag - Wikipedia

 

[lxforrest]

For comparison, a film Leica M has a lag of 12 ms (M7), 17ms (M3 and mechanical M cameras).

Haha. Solute to mechanical shutter

 

[Freakscene]

Haha. Solute to mechanical shutter

The mechanically fired, electronically controlled M7 shutter is the fastest.

 

[lxforrest]

The mechanically fired, electronically controlled M7 shutter is the fastest.

Got it. I guess it is due to the CMOS vs film? And for my camera, mechanical winder structure is the bottleneck I think. To mimic winding action, shutter pressed and release spring which attach with a hammer. The hammer then hit the electric tact switch as the electrical shutter. This way the shutter sound would be a "click", mimicing the cheap film camera sound and no speaker buzzing sound

 

[shawn]

Good thing to test but I am not sure subtracting 200ms makes sense. Those reaction times are likley based on when a stimulus appears at a random interval. In your test you know exactly when the stimulus is going to appear (55s) so it isn't as much about as reaction time but more about your own natural timing. For example, this is a test of me trying to stop the stopwatch at the whole second.

 

[lxforrest]

Good thing to test but I am not sure subtracting 200ms makes sense. Those reaction times are likley based on when a stimulus appears at a random interval. In your test you know exactly when the stimulus is going to appear (55s) so it isn't as much about as reaction time but more about your own natural timing. For example, this is a test of me trying to stop the stopwatch at the whole second.

View attachment 4879341View attachment 4879342View attachment 4879343

Very good point! I tried click the mouse directly and get 55.05-55.15 range. However, for the sake of avoiding the ambush timing, I deliberately wait till the needle point went pass 55s then press shutter. I think the "analog" needle as a visual signal also contributed some room of error. Checked online, the most accurate testing is to use a flash and high speed camera to record slow motion. However, lack of the resource.

 

[shawn]

If you can electrically fire the shutter (I'm assuming just needing to close a switch with a relay or transistor or whatever) maybe an arduino running a stopwatch on on a LCD and progam it to fire the trigger at a set time. Then the difference with whatever the picture actually shows on the LCD gives you a pretty good idea of delay and takes away the human variability.