Saturday, June 13, 2020

Ruby-throats! - 11 Jun 2020

The past several days have been just lovely. Sunshine, warm weather, and dinner on the back deck w/ spotting scope, digiscoping equipment, and hummingbirds. Ruby-throated Hummingbirds.

I've been playing with the Sony a7RIV and its 61 Mpx sensor attached to the Digidapter™. As always, its a waiting game. And, you have to react quickly when the hummers come into to the feeder as they are in-and-out! But, the late afternoon sun means a chance to capture that gorget display that is one of the most challenging subjects for this digiscoper.  I'm getting closer, but still trying to capture that perfect focus, and perfect angle.

Saturday, June 6, 2020

Whimbrel! - 01 Jun 2020

I found a single Whimbrel at Pt. Mouillee SGA in Monroe Co., MI this afternoon and got close enough for some nice Digiscoping w/ the Sony a7III.

Yard Birds - 23 May 2020

I spent some time w/ the scope and Sony a7III this morning while the Sun was shining and the birds were cooperating!

Sunday, April 19, 2020

Focus-stacking in the Snow - 15 Apr 2020

Today brought snow flurries through SE Michigan. Less than 1" fell, and none of it stuck, but it was fun to digiscope yard birds through the window as the Sun shone while snow was falling.

I digiscoped this Northern Cardinal male by stacking 3-4 frames at a time to bring out the snow from the background. The composite images concentrated the snow while the bird and branches were still.

single frame
3 frames stacked

ISO 3200
1/1600 sec. at f/2.8
Swarovski STX85, 25-60X eyepiece at 25X
Sony a7III + Zeiss 35/2.8
Distance 25'

Saturday, April 11, 2020

Full Moon and Sony a7RIV - 08 Apr 2020

1/500 sec., f/2.8, ISO 3200

The last day of a full "Pink Moon" was washed out due to storms. However, this morning I was taking out trash and noticed clear skies and a bright, full moon. It was 6 am so I had time to run in and grab the tripod and put the Sony a7RIV on the Digidapter™. Although it took only about 5 minutes by the time I got back outside there were wispy clouds passing in front of the moon. I was able to still digiscope the full moon, but I could see the distortion in front of the subject as clouds were moving past very quickly. In another 5 minutes the moon would be completely obscured.

1/320 sec. f/2.8, ISO 3200

1/160 sec., f/2.8, ISO 3200

Sunday, April 5, 2020

Digiscoping with 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.

Thursday, April 2, 2020

Some Thoughts on Chromatic Aberration - 02 Apr 2020

Hooded Merganser, SOOC, 1:1 crop, Sony a7RIV, Zeiss 35/2.8, Digidapter™, Swarovski STX85@25X
I had the opportunity to digiscope a pair of Hooded Mergansers this past Monday in the ponds next to our house. With the early morning Sun shining on the pair as they swam in the dark waters I knew that exposure would be a challenge, especially with a gorgeous drake displaying a bright white hood bordered in black feathers. I made sure to expose for the white, and for the most part, did well. However, I noticed chromatic aberration (CA) creeping into some of the photos, and decided it was worth a discussion. I made sure to be selective in culling the images so that I could demonstrate some of the challenges that we digiscopers will run into when trying to capture high-contrast situations.

I was shooting with a Sony a7III and Zeiss 35mm f/2.8 pancake lens attached to a Swarovski STX85 and 25-60X Zoom eyepiece set to 25X using a Digidapter™. I had just mounted the camera to the Digidapter™that morning and thought it was properly aligned (trying to get the sharpest vignette circle at the edges of the frame and even illumination throughout the field-of-view, FOV). However, as I reviewed images in Lightroom CC I noticed some very slight CA even the center of my view, where I should not see any. The following is a series of images where the drake swam across my FOV with the first image of the duck in the center of the camera:

There is a very slight amount of CA along the edges of the white border on the hood and in the shoulder. Its not bad, but noticeable, and is easily removed during post-processing.

Now, look at the drake when its toward the edge of the frame. You'll notice more pronounced CA along the white edges with purple-fringing on one border and blue-green fringing on the opposite. Again, it can be removed in post, but it does highlight the fact that CA becomes progressively worse in all scope eyepieces as you move from center to edge

Top of the line scope manufacturers have glass and coatings that minimize CA, but cannot remove it entirely. That's why proper alignment of the camera in front of the scope eyepiece is critical to optimizing image quality and reducing CA. One of the great strengths of the Digidapter™is the ability to achieve proper alignment by being able to adjust camera position in front of the scope eyepiece. 

Luckily for me, it turned out that the locking screw on the Digidapter™ had prevented me from pushing the adapter completely in position. So, when I removed the adapter and replaced it on the scope the system operated as expected and the CA issue was greatly reduced. 

How does focusing influence CA? I found that Alignment, not Focus,  is the culprit behind the CA issue I was experiencing. I typically roll focus through the subject when I digiscope; that is, I shoot a high-speed burst while adjusting focus in front, on, and behind the subject so that I improve my chances of getting one frame as sharp as possible. I find that CA does not improve no matter how sharp the image is. That said, I also find that out of focus subjects remain CA-free when proper alignment is achieved. The images below illustrate this last point:

To expand on this, also note that zooming a scope's eyepiece will alter the critical point of focus and can magnify CA if it is a problem. There may be more detail, but typically it is at the sacrifice of image sharpness. Therefore, its a general rule of thumb that cropping an image for magnification is better than zooming an eyepiece for magnification. That said, I still tend to try my luck at zooming an eyepiece to improve magnification BUT ONLY AFTER I'VE EXHAUSTED LOW-MAG CAPTURES. 

The takeaways from this discussion?

Proper alignment of the camera in front of the scope eyepiece is key to reducing/eliminating chromatic aberration.

CA gets progressively worse toward the edges of the scope's field of view, so make sure to keep your subject in the CENTER OF YOUR FOV and CROP FOR COMPOSITION (don't frame for composition).

Digiscoping will expose any flaws that are inherent in a spotting scope or digital camera. If you are in the market for a spotting scope the first thing I recommend to potential buyers is to point the scope at a subject of high contrast, like white siding in bright sunlight to evaluate the amount of CA that you'll likely encounter. Most scopes do great in normal lighting and show no CA, so this is a great way to evaluate the quality of the optics. The same goes for testing eyepieces, whether they are zoom or fixed. And just know that adding another camera and lens in front of the scope eyepiece with magnify any flaws.

Finally,  did you notice that the first image in this post was taken with a Sony aRIV but I talked about the a7III? That's my next post.

Keep shooting, and stay well. And Stay Home!