Looking at Depth Of Field (part III)
Jan 10, 2022 06:41:46 #
Below is another entry in a series of periodic discussions that look at the intersection of art / artist vision with the technical aspects of photography. This post is more reading than images, consider grabbing a fresh cup of coffee.
In this discussion, two specific issues will be examined using real-life images from ZooTampa at Lowry Park in Tampa, Florida.
The issues:
1. Where to focus on wildlife / animals close-ups? (That is, portraits in general)
2. How much / how little depth of field is afforded by a wide aperture setting?
The equipment involved is a Canon EOS 5DIII with an EF 135mm f/2L. Other than the wide f/2 aperture options of this 135mm Canon lens, the issues presented are relevant to all photographers working on portrait-style images at relatively wide apertures and relatively close distances such as you might create in your portrait studio setting.
Consider the details of this first image. The edited full-image shows a very narrow depth of field (DOF) covering maybe just the distance between the beak and the eyes. I say 'maybe' because this full-screen version doesn't reveal the actual pixel-level details.
Sunbittern by Paul Sager, on Flickr
The annotated version below is a 1:1 crop of just that in-focus section of the image. With these details revealed, we can begin to ask some critical questions:
1. Where is the focus?
2. Are the details actually in focus?
3. Is the image focused on the correct details? That is, are the features between the eyes more important for 'success' than the eyes?
Somewhat unrelated to these three analysis questions, is this image a keeper? If 'no' or 'maybe', what aspects of the capture technique are candidates to adjust?
Depth of field is the distance between the closest and farthest objects in a photo that appear acceptably sharp.
As noted in the crop above, the DOF is probably about 1.4-inches (35-mm) of the bird's head between the end of the beak and the middle of the eyes. I'm assuming I was about 6-feet from the bird in this aviary. The use of the 1.4x Canon extender, as well as a guesstimate of the distance, makes the use of an online DOF calculator somewhat confusing. I get calculations between 1- and 2-inches as I vary the focal length between 135mm and 190mm and the shooting distance between 5-feet and 8-feet. Anyway, knowing the equipment and seeing the details of a result, we can see for this focal length (135mm/extended 189mm), the f/5 aperture and the 5- to 8-foot shooting distance, we have a DOF clearly between 1- and 2-inches.
To return to the questions above, are the details 'in focus' for that narrow 1-ish inch strip between the beak and eyes? To me, yes. When I reviewed the image in Canon DPP, a single AF point was positioned directly on the bird 'forehead', between the two red lines of the annotated image above.
For the second question, is the image focused on the correct details, here I say maybe, leaning toward no. I want that eye on our left, the eye nearest the camera, to be in sharper focus. Because of the bird's slight head angle relative to the camera, the DOF might actually pass through the nearest eye. But, it still could be better.
The necessary change is to use a smaller aperture, say f/5.6 to f/6.3. I know this aperture change from experience, as well as, I can plug-in the new aperture value to a DOF calculator and see the measure of the DOF increase. Also from the EXIF details, we see the shutter speed was 1/800 sec against the 189mm effective focal length, meaning we have 'room' to go slower on the shutterspeed for the same ISO-200 while closing the aperture to f/5.6 or smaller.
Consider this next image. It's almost the same image, but with some of the exact changes made to the parameters as discussed above.
Sunbittern by Paul Sager, on Flickr
Given the same camera with the same lens and extender combo, we can judge from the wider view, I was a bit further back from the bird, but still so close that the bird doesn't fit within the frame.
The image is extremely sharp, where in focus, with a depth of field that covers the entire head, but not both the head and the beak. The DOF seems to cover the entire breast / front of the bird, see details above. The image is so sharp, we can see an insect (lice?) below the bird's eye, as well as all the feather details around the eye, see the cropped and annotated version, below.
In the EXIF data, we see the changes discussed earlier being implemented for this image, specifically: aperture now f/5.6 (from f/5), the shutter at 1/400 sec (down from 1/800 sec), and the ISO jumped way up to ISO-2000 (from ISO-200, the first image was very sharp, but grossly underexposed, it was 'saved' in post from the RAW). Being probably 1-foot further away, I gained maybe 2-inches of overall DOF using the smaller aperture and longer shooting distance.
Conclusion
Is one image better than the other? Who knows. The second has more distractions in the background. The first is more 'artistic', but my own style is to have more DOF to capture the entire face / head in sharp focus, especially including the eyes.
(The first image has grown on me over the course of editing and writing, especially when I look closer at the nearer eye and consider it to be in better focus than I initially thought.)
Both images have options for cropping into the details, as used for these annotated discussion versions and for using on IG and similar, where extreme close-ups are more useful. I haven't finished editing all the images from the zoo visit. I'm not sure either of these are even my single favorite image of this session with the sunbittern.
Hopefully, a few other items are useful from this discussion, specifically:
Replace the bird with a human face, would you want to see just the bridge of the nose in focus similar to the first image, or the entire face in focus, similar to the second image?
When people ask about portrait lenses, here is a 135mm 'traditional' portrait lens focal length in real-life action on a full-frame body. The subject is close enough to the camera to fill the frame. A human face would require you to be a bit further back, but you can see f/5.6 or smaller might be needed for a DOF that accomplishes the entire face in focus, even with a larger subject at a greater shooting distance. Probably all of us own lenses covering 100mm to 200mm that look great around f/5.6 to f/8 that can function as a 'portrait lens', especially for a close-cropped headshot.
Consider too the importance of focusing on the nearest eye to the camera. If you miss that critically sharp focus at the 1:1 details, the portrait isn't going to work. As I've said in other posts on where and how to focus, you should be using a single AF point (or small group), set specifically on where you want the sharpest focus. Selective focus is needed when working at these wide(r) apertures, longer focal lengths, and very close distances.
Finally, note the impact of a slight angle of the subject relative to the camera / sensor. If your subject is facing directly into the camera, you need to consider a DOF that covers the tip of the nose through maybe their ears, with the focus set on an eye, or possibly an eye brow or maybe the bridge of their nose. Your own artistic style for aperture / depth of field will determine where exactly to focus. Take images from all these AF point positions to determine your own preferred location. If you adjust the subject to be slightly angled relative to the camera, you might need less DOF to cover the tip of their nose through just the one ear that can be seen in the image.
In the links below, you see some of the same issues being presented, especially in the cat portraits where maybe a bit too narrow a DOF was used for an overall successful 'portrait' in some of the examples.
Links to prior posts on Depth of Field
Looking at Depth of Field w/ cat portraits - https://www.uglyhedgehog.com/t-685940-1.html
A discussion of Depth of Field w/ lilac blossoms - https://www.uglyhedgehog.com/t-694277-1.html
In this discussion, two specific issues will be examined using real-life images from ZooTampa at Lowry Park in Tampa, Florida.
The issues:
1. Where to focus on wildlife / animals close-ups? (That is, portraits in general)
2. How much / how little depth of field is afforded by a wide aperture setting?
The equipment involved is a Canon EOS 5DIII with an EF 135mm f/2L. Other than the wide f/2 aperture options of this 135mm Canon lens, the issues presented are relevant to all photographers working on portrait-style images at relatively wide apertures and relatively close distances such as you might create in your portrait studio setting.
Consider the details of this first image. The edited full-image shows a very narrow depth of field (DOF) covering maybe just the distance between the beak and the eyes. I say 'maybe' because this full-screen version doesn't reveal the actual pixel-level details.
Sunbittern by Paul Sager, on Flickr
The annotated version below is a 1:1 crop of just that in-focus section of the image. With these details revealed, we can begin to ask some critical questions:
1. Where is the focus?
2. Are the details actually in focus?
3. Is the image focused on the correct details? That is, are the features between the eyes more important for 'success' than the eyes?
Somewhat unrelated to these three analysis questions, is this image a keeper? If 'no' or 'maybe', what aspects of the capture technique are candidates to adjust?
Depth of field is the distance between the closest and farthest objects in a photo that appear acceptably sharp.
As noted in the crop above, the DOF is probably about 1.4-inches (35-mm) of the bird's head between the end of the beak and the middle of the eyes. I'm assuming I was about 6-feet from the bird in this aviary. The use of the 1.4x Canon extender, as well as a guesstimate of the distance, makes the use of an online DOF calculator somewhat confusing. I get calculations between 1- and 2-inches as I vary the focal length between 135mm and 190mm and the shooting distance between 5-feet and 8-feet. Anyway, knowing the equipment and seeing the details of a result, we can see for this focal length (135mm/extended 189mm), the f/5 aperture and the 5- to 8-foot shooting distance, we have a DOF clearly between 1- and 2-inches.
To return to the questions above, are the details 'in focus' for that narrow 1-ish inch strip between the beak and eyes? To me, yes. When I reviewed the image in Canon DPP, a single AF point was positioned directly on the bird 'forehead', between the two red lines of the annotated image above.
For the second question, is the image focused on the correct details, here I say maybe, leaning toward no. I want that eye on our left, the eye nearest the camera, to be in sharper focus. Because of the bird's slight head angle relative to the camera, the DOF might actually pass through the nearest eye. But, it still could be better.
The necessary change is to use a smaller aperture, say f/5.6 to f/6.3. I know this aperture change from experience, as well as, I can plug-in the new aperture value to a DOF calculator and see the measure of the DOF increase. Also from the EXIF details, we see the shutter speed was 1/800 sec against the 189mm effective focal length, meaning we have 'room' to go slower on the shutterspeed for the same ISO-200 while closing the aperture to f/5.6 or smaller.
Consider this next image. It's almost the same image, but with some of the exact changes made to the parameters as discussed above.
Sunbittern by Paul Sager, on Flickr
Given the same camera with the same lens and extender combo, we can judge from the wider view, I was a bit further back from the bird, but still so close that the bird doesn't fit within the frame.
The image is extremely sharp, where in focus, with a depth of field that covers the entire head, but not both the head and the beak. The DOF seems to cover the entire breast / front of the bird, see details above. The image is so sharp, we can see an insect (lice?) below the bird's eye, as well as all the feather details around the eye, see the cropped and annotated version, below.
In the EXIF data, we see the changes discussed earlier being implemented for this image, specifically: aperture now f/5.6 (from f/5), the shutter at 1/400 sec (down from 1/800 sec), and the ISO jumped way up to ISO-2000 (from ISO-200, the first image was very sharp, but grossly underexposed, it was 'saved' in post from the RAW). Being probably 1-foot further away, I gained maybe 2-inches of overall DOF using the smaller aperture and longer shooting distance.
Conclusion
Is one image better than the other? Who knows. The second has more distractions in the background. The first is more 'artistic', but my own style is to have more DOF to capture the entire face / head in sharp focus, especially including the eyes.
(The first image has grown on me over the course of editing and writing, especially when I look closer at the nearer eye and consider it to be in better focus than I initially thought.)
Both images have options for cropping into the details, as used for these annotated discussion versions and for using on IG and similar, where extreme close-ups are more useful. I haven't finished editing all the images from the zoo visit. I'm not sure either of these are even my single favorite image of this session with the sunbittern.
Hopefully, a few other items are useful from this discussion, specifically:
Replace the bird with a human face, would you want to see just the bridge of the nose in focus similar to the first image, or the entire face in focus, similar to the second image?
When people ask about portrait lenses, here is a 135mm 'traditional' portrait lens focal length in real-life action on a full-frame body. The subject is close enough to the camera to fill the frame. A human face would require you to be a bit further back, but you can see f/5.6 or smaller might be needed for a DOF that accomplishes the entire face in focus, even with a larger subject at a greater shooting distance. Probably all of us own lenses covering 100mm to 200mm that look great around f/5.6 to f/8 that can function as a 'portrait lens', especially for a close-cropped headshot.
Consider too the importance of focusing on the nearest eye to the camera. If you miss that critically sharp focus at the 1:1 details, the portrait isn't going to work. As I've said in other posts on where and how to focus, you should be using a single AF point (or small group), set specifically on where you want the sharpest focus. Selective focus is needed when working at these wide(r) apertures, longer focal lengths, and very close distances.
Finally, note the impact of a slight angle of the subject relative to the camera / sensor. If your subject is facing directly into the camera, you need to consider a DOF that covers the tip of the nose through maybe their ears, with the focus set on an eye, or possibly an eye brow or maybe the bridge of their nose. Your own artistic style for aperture / depth of field will determine where exactly to focus. Take images from all these AF point positions to determine your own preferred location. If you adjust the subject to be slightly angled relative to the camera, you might need less DOF to cover the tip of their nose through just the one ear that can be seen in the image.
In the links below, you see some of the same issues being presented, especially in the cat portraits where maybe a bit too narrow a DOF was used for an overall successful 'portrait' in some of the examples.
Links to prior posts on Depth of Field
Looking at Depth of Field w/ cat portraits - https://www.uglyhedgehog.com/t-685940-1.html
A discussion of Depth of Field w/ lilac blossoms - https://www.uglyhedgehog.com/t-694277-1.html
Jan 10, 2022 07:40:05 #
steve49
Loc: massachusetts
Good analysis. Thanks.
I use an 85mm 1.8 and find it covers a face pretty well at 5.6 at the distances I use it and softens the background pretty well. Practice makes perfect though.
I use an 85mm 1.8 and find it covers a face pretty well at 5.6 at the distances I use it and softens the background pretty well. Practice makes perfect though.
Jan 10, 2022 07:46:41 #
tcthome
Loc: NJ
Great write up. I took a look at your lilac thread also & noticed you mention photos taken between 12" & 2' away. Since it was a macro lens, do you know the min focus distance of that lens. 
Jan 10, 2022 09:04:01 #
tcthome wrote:
Great write up. I took a look at your lilac thread also & noticed you mention photos taken between 12" & 2' away. Since it was a macro lens, do you know the min focus distance of that lens.
Aha, writing from memory of 2-days in May 2020, it seems I exaggerated what was possible with a lens with a MFD around 18-inches.
Maybe it was closer to 2-feet+ in shooting distance? Thank you tcthome!Jan 10, 2022 09:07:25 #
steve49 wrote:
Good analysis. Thanks.
I use an 85mm 1.8 and find it covers a face pretty well at 5.6 at the distances I use it and softens the background pretty well. Practice makes perfect though.
I use an 85mm 1.8 and find it covers a face pretty well at 5.6 at the distances I use it and softens the background pretty well. Practice makes perfect though.
Thank you Steve! I've had this 135L much longer than either of my two 85s. I've never found a subject the 135L doesn't turn into beautiful, simply by pointing the lens in that direction.
The 85 has been a learning experience, becoming much more useful with IS-support and using a 12mm tube to shorten the minimum focus distance.Jan 11, 2022 07:22:04 #
CHG_CANON wrote:
Below is another entry in a series of periodic dis... (show quote)
Interesting analysis and photos. You always keep us learning Paul and I liked the links you provided. Jim
Jan 11, 2022 08:32:58 #
CHG_CANON wrote:
The equipment involved is a Canon EOS 5DIII with an EF 135mm f/2L. ...
The equipment involved is a Canon EOS 5DIII with an EF 135mm f/2L. ...
A good photograph can be made better by just buying a mirrorless camera.
Jan 11, 2022 09:46:03 #
Paul to me depth of field is all about subject. Subjects like people, cats and dogs are familiar to people blurring out features enhance photographs. To me personally wild animals are totally different, I want to see every whisker, feather and foot in focus in most cases. Flowers like your first lilac blossom per https://www.uglyhedgehog.com/t-694277-1.html would look better to me if cropped in or composed where only the blooms in the frame. Example would be magnifying your photograph on the Flickr page on center blossom. A rose blurring around the edge is pleasing because we know what roses look like, however seeing a bloom from a rare plant or from a different geographical location would look best all in focus to me. This is totally a personal preference hope you understand. As always, your work and post always thought provoking.
Charles
Charles
Jan 11, 2022 10:24:09 #
junglejim1949 wrote:
Interesting analysis and photos. You always keep us learning Paul and I liked the links you provided. Jim
Thank you Jim. As I said in another reply, I purposefully shot a bit differently on this trip. As I work through the images, and the details of those images, I've come across a few ideas to try for posts on technique that people regularly ask for, but rarely get created into the UHH community. Glad you enjoyed.
Jan 11, 2022 10:24:14 #
jburlinson wrote:
A good photograph can be made better by just buying a mirrorless camera.
And the next best option is to use the 135L.
Jan 11, 2022 10:24:18 #
cedymock wrote:
Paul to me depth of field is all about subject. Su... (show quote)
Thank you Charles! This last trip, the first since 2019, had me trying a few different techniques, different than my typical approach. I shot a lot more wide-open / close to wide open to build images into my portfolio to analyze over this cold winter. I approached these birds in Tampa still with a narrow DOF, via closeness and long(er) focal length rather than wide aperture. In looking at the results of these (and others still being edited), I saw an opportunity to dig into the pixel-level details and the EXIF to demonstrate some of the 'how', and maybe some of the 'why' of the results.
For the question of 'are enough of the details in focus?', they probably are 'not enough' for me either, where the close-crop of the 2nd is promising, but still missing the details of the beak through the tip. Maybe that's why they were useful for a discussion of details rather than just a post for sharing the fully edited and final culling of the results.
Jan 11, 2022 11:16:37 #
Jan 11, 2022 11:30:53 #
Jan 11, 2022 11:33:39 #
Thank you Bob, Dave! I was afraid it might be a bit too much reading around just 2 picture and 2 diagrams.
Jan 11, 2022 12:19:57 #
CHG_CANON wrote:
Below is another entry in a series of periodic dis... (show quote)
Thank-you for sharing your expertise with us. It is always fun to learn more about a very challenging but enjoyable hobby.
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