Digiscoping w/ the Sony a7RIV - 05 Apr 2020

Ever since Sony announced the new a7RIV (16 July 2019) I'd been wondering, "What would it be like to digiscope with a near-Medium Format camera?". 61MP! 10 fps! 26 MP in APS-C 35mm mode! I'd been jonesing for it ever since. The reviews were coming in. YouTube after YouTube video hailing it as Sony's best camera yet, even surpassing the great a9 as a wildlife and bird camera.

After several months of testing the reality of such a camera was setting in. Uncompressed RAW images coming in at 120 MP, and compressed RAW images at 61 MP were filling up cards and computers faster than expected. With extended burst rates the user would have to wait to change shooting modes and settings until the buffer cleared. Computers crashing due to file sizes and long download times. And the noise; images showing noise at base ISO and noise making images unusable above ISO 3200. And more lately, issues with the a7RIV and 200-600 mm f/5.6-6.3 G producing soft images. Was this a camera worth the money? I decided it wasn't.

Uncle Sam put me in the mood to buy another camera, and I was waffling. A new Sony a9II would run $4500. Too much, can't justify; after all the a9 is everything I need in a bird photography camera. I could pick up another a9 and digiscope with that. But, the Sony a7III image quality is just as good. I decided to take another look at the a7RIV. As an alumnus of UofM with an email address I could take advantage of B&H's EDU deals, and the camera was discounted almost $1000. I decided to pull the trigger. Wow, am I glad I decided NOT to listen to the critics.

After just 2 days of shooting with it I found this camera to be amazing! I charged a battery and put the 100-400 mm f/4.5-5.6 GM OSS lens on the newly-received Sony a7RIV and ran outside to take some test shots. It was overcast and drizzly, so photos were nothing to write home about. But, I did take a pic of Yara when I came in and was overjoyed at the quality of the image I'd just taken. Straight out of the camera this is a 1:1 crop hand-held.

The following morning skies had cleared and the Sun was rising over SE Michigan. I decided to put the Zeiss 35mm f/2.8 on the a7RIV and mount it to the Digidapter™. Good news is that the a7RIV fit the Digidapter™ without adjustment; this means I can swap both the a7III and a7RIV without having to realign the platform screws. After a couple of test frames through the window I decided to take the Swarovski STX85 and 25-60X eyepiece out onto the deck to digiscope some Dark-eyed Juncos on the ground and American Goldfinches at the thistle feeders just 10-15' away. The a7RIV was set to Aperture-Priority (f/2.8) and Auto ISO 100-3200 with a base Shutter Speed of 1/2000 sec. This junco in early sunlight was captured at 1/800 sec. Again, SOOC:

I found ISO 3200 very usable, and the detail to be stunning. Focus-peaking with the high-resolution EVF on the camera made for many keepers in a single burst. Card-writing was a non-issue with the Sony Tough 64GB G SD cards. 

The goldfinches are beginning to molt and the digiscoping rig produced some wonderfully-detailed images.

Next, I decided to take a walk over to the ponds in front our complex. A pair of Hooded Mergansers were there a few days ago and the a7RIV would give me a chance to compare image quality against those from the a7III a few days ago under similar lighting conditions.

1/2000 sec., ISO 1000

1/2000 sec., ISO 1600

1/2000 sec., ISO 1600

1/2000 sec., ISO 1000

1/2000 sec., ISO 800

Chromatic aberration was non-existent, and the detail from the camera was exquisite. I was able to get tighter crops relative to the a7III, and the 26MP APS-C 35mm crop file size was a huge boost over the 10MP crop from the a7III. Make no mistake, though; the a7III is a wonderful camera and is currently back on the Digidapter™. 

Sony a7III, 1/2000 sec., ISO 2000

The following morning brought still more sunshine, so I sat at the base of the deck and digiscoped the American Goldfinches in the morning light. 

1/2000 sec., ISO 1000

1/2000 sec., ISO 640

Again, the a7RIV handled feather detail quite nicely with no evidence of CA, and noise was quite manageable up to ISO 3200. 

Meanwhile, a resident Chipmunk made a dash back and forth between the house and feeders, and I managed a few images while it froze next to the downspout. Even in shade the camera produced very nice detail with manageable noise.

1/1250 sec., ISO 3200

1/1000 sec., ISO 3200

1/1250 sec., ISO 3200

A Song Sparrow then appeared.

1/2000 sec., ISO 2000

1/2000 sec., ISO 1250

And finally, one last Dark-eyed Junco to highlight some feather detail.

My conclusion? The Sony Alpha a7RIV is an excellent digiscoping camera that will provide arguably the most detail one could ask for in a digiscoping rig. At $3500 retail it may be overkill for a digiscoping camera, but the results make the purchase worth it for those who can afford it. With a Custom Key setup it would be possible to dial the camera in at lower shutter speeds and ISO for those subjects that aren't moving, and the results would be eye-popping. For me, I'll continue to digiscope with the Sony a7III and put the 100-400 mm f/4.5-5.6 GM OSS lens on the a7RIV for carrying, especially with warbler season coming up. But, when I absolutely need the highest detail in my digiscoping images I'll happily put the Sony a7RIV on the Digidapter™and know that it won't disappoint. Glad I decided not to listen to the critics.

Thanks to B&H Photo for sending the camera despite the current crisis.