Digiscoping w/ the "New" Sony a7III - 12 Apr 2019
Yesterday Sony released Firmware version 3.0 for the a7III and a7RIII cameras. This upgrade has been highly anticipated by Sony users for its improved AF features: Continuous Eye-AF and the new Animal Eye-AF. The latter Subject Detection mode is supposed to improve animal and pet photography by accurately tracking the eyes of the subject. Naturally, everyone has been reviewing the new features on their pets, and wondering openly about which wild animals it will work on. I decided to give it the acid test by testing it out on the birds. Digiscoping birds!
I've been digiscoping birds with the Sony a7III since last November and have been in love with this camera. The low-noise capabilities, full-frame resolution, 10 fps continuous shooting, and focus-peaking has made this camera one of the best for digiscoping. One shortcoming I found with this camera (and previous Sony cameras: the a6300, RX100 III and IV) is that autofocus, while razor sharp with native lenses, fails miserably when trying to digiscope. When placed in front of a spotting scope eyepiece I found that the camera has trouble locking AF onto a subject, and when it does, it tends to produce inaccurate results. In a technique where depth of focus is literally millimeters anything but spot-on can produce soft results and added artifacts like chromatic aberration. The Mourning Dove below is a typical, slightly OOF autofocus result.
Hence, the reason for using manual focus and DMF (focus-peaking). I recently posted my a7III settings for digiscoping. I may have to reevaluate my settings after tonight. Firmware 3.0 has me rethinking this whole manual focusing thing.
The late afternoon sun shining on the feeders gave me an opportunity to try the Animal Eye-AF and the Lock-On AF: Flexible Spot focus mode. Initial attempts to focus on the Mourning Doves feeding 20 feet away resulted in the little green boxes staying firmly planted in the center of the viewfinder despite the birds moving around. Turns out the Subject Detection was on "Human". So, I switched to "Animal".
First thing to note: With Subject Detection = Animal the Lock-On AF: Flexible Spot WILL NOT WORK. The camera will give you an error indicating that "the operation is not available". It does work fine if Human is selected. So, I hit my C1 button and moved the Focus Mode to Expand Flexible Spot. Then to Center Focus, and even Wide. I did see indications that the green boxes were popping toward the eyes of the birds, but I was not seeing the single eye box you'd normally see with Human eye detection.
No matter, though. Focus was SPOT ON for the first time in my Sony digiscoping career! With the Zeiss 35mm f/2.8 I was getting razor sharp images of the Mourning Doves. And the Dark-eyed Juncos. Even an all-black Red-winged Blackbird. And House Finch! I've posted screen grabs from Lightroom of RAW images directly out of the camera with no additional processing. The following images are the 1:1 magnifications of images captures at an effective focal length (EFL) of ~875mm (25X eyepiece * 35mm lens).
My pied American Robin made an appearance on the lawn and allowed me to get some nice closeups from about 15' away. Tracking the birds through a scope is impossible so I was not surprised that the little green boxes did not follow the bird when it moved out of frame. But again, the AF nailed the focal point! Eyes are sharp and individual barbules are resolved. It doesn't get better than this.
At slightly longer distance (30') even the Blue Jays were popping.
No evidence of CA from slightly OOF exposures. Color me impressed!
As with most super-telephoto rigs, the AF works best in Manual-Assist mode, i.e., I need to initially get focus with the spotting scope close enough so that the AF kicks in when I press the BBF button. Otherwise, the camera will slowly hunt forward and backward and never find focus. This may not sound like much an improvement, but it is definitely easier than trying to use DMF (focus-peaking) on a moving bird; the technique is wonderful, but tracking a bird's head at 10X magnification is very difficult. And again, millimeters matter when depth of field comes into play.
So, I have to say that I'm thrilled with this Firmware 3.0 upgrade. Sony made a camera, that I already love, LOVE even more. I will be playing with settings even more this weekend to see if any of the focusing modes show advantages, see how it performs in lower light, and at longer distances. In the meantime, I have to go back and adjust my Settings post.