Rolling shutter

I'm currently using the R7 with the big zoom, because (surprisingly) it's better than the R5 at picking up dragonflies and other insects in flight and holding focus on them. When set to electronic shutter and shooting fast-moving creatures, the R7 can suffer from what's commonly called rolling shutter, but this hasn't worried me until now because I generally use the default Electronic 1st-Curtain shutter, which doesn't produce this problem. There are advantages to the fully electronic shutter though, most obviously the total absence of shutter noise and vibration, and I have started using it when I'm photographing nervous things. I just need to remember to change the setting again when I move onto subjects in flight.

Today I went for a walk around the village, looking mostly for crickets, grasshoppers and bugs, all of which are skittish, so I used the electronic shutter on both cameras, to pretty good effect. Just after I arrived home, hot and tired, I had cause to walk across the back yard, and on the way back to the house I spotted this Hummingbird Hawkmoth on a clump of red valerian by the patio wall. I dashed into the house, grabbed the R7 from the snug, and rushed back outside while turning it on and extending the zoom - only to find that the moth had gone. Cursing, I ran back through the house and out of the front door, and picked it up again on another patch of valerian in the front garden. Despite tricky light, the R7 did a good job for the few seconds the moth allowed me before zooming off elsewhere, and I walked back into the house feeling reasonably smug. Then I checked some of the images in camera, and went "AAARRRGGGHHH!!! Rolling shutter!" 

Insofar as I understand it, the way a fully electronic shutter works is that the camera turns pixels on and off to begin and end the exposure; but while it can turn them all on at once, it turns them off by reading-out the sensor, which happens one row at a time - a scanning technique, in effect. The efficiency of this depends on the readout speed of the sensor, and in the R7 this is relatively slow (it's much quicker in the R5, which is part of the reason that body costs three times as much). Each exposure you take therefore ends at a fractionally different time on successive pixel rows, and although this isn't a problem with static or slow-moving subjects, if your subject is moving very fast or you're panning, it can lead to weird effects or artefacts within the image. 

In quite a few of my Hummingbird Hawkmoth images the moth appeared to have thin, curved wings like the blades of a food processor, and in some of them parts of the wings appeared completely detached, so the vast majority ended up in the trash. Of the handful I've kept, this one almost works, though I don't think you need to be a competition judge to spot that there's something very odd going on with the wings. I rather like it though: the contrast between the moth's impassive facial expression and the orange explosion going on behind its head makes me smile. I always think that Hummingbird Hawkmoths look slightly mad, and this image speaks to me of that.

By the way, if you're still pondering rolling shutter, the reason you don't get this effect when using the Electronic 1st-Curtain setting is that in this case the camera begins the exposure by switching on pixels, but ends it by rapidly closing mechanical shutter blades in the traditional way. This combines the advantages of the two types of shutter - electronic involves no physical movement inside the camera that could introduce vibration at the beginning of the exposure, and mechanical is able to end the exposure instantaneously - and therefore it's thought to be the ideal shutter mode, especially when working with macro and super-telephoto lenses.