Sunday, August 23, 2009

G9 Shutter Lag


I’m one of the complainers about shutter lag with my G9 – even in manual mode – and, in the midst of a debate on a DPReview forum decided to conduct my own tests. But how to do so? At first, I imagined all sorts of timer circuitry, switches, etc. but since I don’t really know how to do that sort of thing, finally decided to try simply taking a photo of my computer screen. This crude approach actually worked surprisingly well – sort of.

I searched for an on screen timer and downloaded XNote Timer . This is a basic and free version of their more comprehensive XNote Stopwatch. The image above is one of the several hundred shots I took of XNote Timer from my LCD. (I know, I know – sort of sad, isn’t it?)

I was especially curious about differences in shutter lag with and without Image Stabilization (IS), the effect of the half-pressed shutter button (sometimes called pre-focus) and the quickness of all manual mode with IS off, display off, etc.

Both Imaging Resource and DPReview publish shutter lag values but their test results did not completely satisfy my curiosity. According to Imaging Resource, the G9 shutter lag is from 0.57 seconds at wide angle to 0.69 seconds at telephoto. When prefocused, the shutter lag is 0.088; with manual focus (but presumably auto exposure) the shutter lag is 0.58 seconds. According to DPReview, the full press lag is about 0.6 seconds; the half press lag is about 0.12 seconds with the LCD turned on but decreases to about 0.05 seconds if the LCD is off. I don’t have any particular reason to dispute these values.

No, the shutter lag of my G9 was never the 40.63 seconds in the picture. After starting XNote Timer, I took a picture every 10 seconds. (I watched the computer monitor – not the G9 display.) So the example represents the 4th shot and the delay was 0.63 seconds. I usually took a dozen shots (2 minutes worth), discarded any obvious long or short times and averaged those remaining. Here’s what I found.

Base Case (my typical setup): Av mode, RAW+JPEG, display on, evaluative metering, small flex frame focus, shot only IS on, AWB. Full press lag = 0.61 seconds.

Same as Base Case (above) but timed from shutter button half-pressed: Lag = 0.15 seconds! In spite of the crudeness of my method, the improvement in shutter lag was obvious. Additionally, I found that the half pressed shutter button reduced shutter lag time to about 0.15 seconds no matter what options were selected in the menu or function settings.

Base Case but with manual exposure, manual focus, IS off. Lag = 0.23 seconds. This test was done with a full length press of the shutter button. Again, lag was reduced to about 0.15 seconds when the shutter button was half pressed prior to completing the press.

In some tests, turning IS off shaved about 0.1 seconds from the shutter lag but other times there was no measured effect on the average time. All these tests were hand held and perhaps I was more steady some of the time. I’d guess that IS probably adds about 0.1 seconds to the lag.

Interestingly, I found that by turning off RAW and using JPEG only, setting white balance (instead of using auto white balance) and reducing resolution to M3 with Normal compression reduced shutter lag by about 0.2 seconds from the Base Case. This was unexpected but perhaps not really correct because by that time I was getting pretty good at taking the shutter lag test. As I got better and better at taking the shutter lag test, I even recorded some negative shutter lag! That is, I jumped the gun a bit while anticipating the 10 second interval. As my own lag improved, the first series of tests had to be repeated.

So I learned some things about shutter lag. The very best technique is, as expected, to first press the shutter button halfway to obtain focus, exposure, set the IS, etc. Complete the shutter button press on seeing/hearing the G9 confirm that it is ready. Full manual mode (manual exposure and manual focus with display off, IS off) is better than I’ve been crediting it.

Granted, this technique isn’t great but it was an instructive exercise and perhaps will be useful to others. My own reflexes are not particularly quick so these speeds should be easily beaten. Try a few variations and learn more about shutter lag.


1 comment:

Rafael Edwards said...

thank you. your experiment is a big help to me.