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  • Writer's pictureSteve Gemmell

Trial and Error with GFX Focus and Rolling Shutter

Updated: Aug 31, 2020

Saturday I had a chance to to engage in some trial and error with GFX focus. I wrote in my earlier post that I would try the camera out in situations that required quicker reactions. A visit to the grand kids offered that opportunity.

Testing focus on Fujifilm GFX 50R
GFX 50R with 32-64mm FL 64mm 1/60th at F5.6 ISO100

It was tricky to say the least. Max and Maisie were whizzing around on their bikes and my hit ratio of in focus captures was low. I wasn't expecting the same success rate that I would achieve with my earlier Fujifilm X cameras however. I just wanted to see if it was possible to use the camera in these types of situations. I am sure with more time and experience I will get better results. The tracking options were tools that I omitted to use on this occasion although I did have face detection set to on. Max's face is fairly sharp in the above shot and it looks almost as if he is stationary but if you look at the front wheel you can see that it is moving.

Sharpness in the second shot of Masie is not so successful but again you can see the movement in the wheels of the bike.

Trial and error focussing with Fujifilm GFX 50R
GFX 50R with 32-64mm FL 64mm 1/180th at F5.6 ISO100

Auto focus on this camera is obviously slower than on other cameras. it has a simple contrast detect system and this wasn't a particularly contrasty day. I believe the GFX 100 has phase detection so I am guessing it would perform better. I also think I should have upped the shutter speed and ISO. The mechanical shutter can go to 1/4000th of a second. To go even higher you can use the electronic shutter rather than the mechanical. It goes to 1/6000th of a second.

However having tried the electronic shutter I did notice a big difference using this camera in that mode compared to the smaller X system cameras. The rolling shutter effect!

When I was shooting weddings the electronic shutter was a great option in church during the ceremonies. No shutter noise! However even with the smaller APS C cameras any movement of the camera could result in the jello rolling shutter effect if you were not careful. I often noticed that if I took an image and moved the camera immediately afterwards I would get this strange distorted effect. With the GFX 50R camera and my experiments so far, the much bigger sensor makes the effect occur much more often. It can occur with fast moving subjects but also with any camera movement as well. I have read elsewhere that the electronic shutter takes one quarter of a second shutter transit time to scan the image one line at a time. So it is no surprise that this effect occurs. In summary I think I will avoid the electronic shutter unless absolutely necessary. Here is an example from Saturday.

Rolling shutter on Fujifilm GFX 50R
Example of Fujifilm GFX rolling shutter 4000th sec @ F7.1

Heres a link that explains all the technical stuff if you are really interested.Warning it's very technical!

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