Understanding Depth-of-Field with Telephoto Lenses

What’s Up?

My MacBook Pro (and the almost surely messed-up back-up drive) are on the way to the data recovery outfit in California by Fed-Ex Overnight Priority. I should find something out late today or early on Wednesday. My fingers still crossed. I will spare you the details when I learn more.

If you need to get in touch with me before I get my laptop back, please shoot an e-mail to staffbaa@att.net with the “ATTN: artie” as the Subject Line. Or try me on my cell at 863-221-2372.

Today is Tuesday February 1 2022. It is 10 degrees warmer than it was yesterday with clear skies and little wind. Though I have no place to put my images right now, I will head down to the lake by 7:30am. Wherever you are, and whatever you are doing, I hope that you too have a great day. This blog post took about ninety minutes to prepare and makes 81 days in a row with a new one.

Please remember that you can find some great photo accessories (and necessities, like surf booties!) on Amazon by clicking on the Stuff tab on the orange/yellow menu bar above. On a related note, it would be extremely helpful if blog-folks who, like me, spend too much money on Amazon, would get in the habit of clicking on the Amazon logo link on the right side of each blog post when they shop online. As you might expect, doing so will not cost you a single penny, but would be appreciated tremendously by yours truly. And doing so works seamlessly with your Amazon Prime account.

Please remember that if an item — a Delkin flash card, or a tripod head — for example, that is available from B&H and/or Bedfords, is also available in the BAA Online Store, it would be great, and greatly appreciated, if you would opt to purchase from us. We will match any price. Please remember also to use my B&H affiliate links or to earn 3% cash back at Bedfords by using the BIRDSASART discount code at checkout for your major gear purchases. Doing either often earns you free guides and/or discounts. And always earns my great appreciation.

Sony Alpha 1 Bodies in Stock at Bedfords/free card offer!

Steve Elkins of Bedfords let me know recently that he had several Sony a1 bodies in stock. If one of them has your name on it, please click here and be sure to enter the BIRDSASART coupon code check the box for free shipping to enjoy free Second Day Air Fed-Ex. Right now, in lieu of the 3% credit refunded to the card you used for your purchase, you will receive a Sony 160GB CFexpress Type A TOUGH Memory Card, a $399.99 value!

Brand New and As-Good-As-Ever Bedfords BAA Discount Policy

Folks who have fallen in love with Bedfords can now use the BIRDSASART coupon code at checkout to enjoy a post-purchase, 3% off-statement credit (excluding taxes and shipping charges) on orders paid with a credit card. The 3% credit will be refunded to the card you used for your purchase. Be sure, also, to check the box for free shipping to enjoy free Second Day Air Fed-Ex. This offer does not apply to purchases of Classes, Gift Cards, or to any prior purchases.

Money Saving Reminder

Many have learned that if you need a hot photo item that is out of stock at B&H and would like to enjoy getting 3% back on your credit card along with free 2nd Day Air Fed-Ex Air shipping, your best bet is to click here, place an order with Bedfords, and enter the coupon code BIRDSASART at checkout. If an item is out of stock, contact Steve Elkins via e-mail or on his cell phone at (479) 381-2592 (Central time). Be sure to mention the BIRDSASART coupon code and check the box for Free Shipping. That will automatically upgrade to free 2nd Day Air Fed-Ex. Steve has been great at getting folks the hot items that are out of stock at B&H and everywhere else. The waitlists at the big stores can be a year or longer for the hard to get items. Steve will surely get you your gear long before that. For the past year, he has been helping BAA Blog folks get their hands on items like the SONY a 1, the SONY 200-600 G OSS lens, the Canon EOS R5, the Canon RF 100-500mm lens, and the Nikon 500mm PF. Steve is personable, helpful, and eager to please.

Important Note

As an Amazon Associate, I earn a small percentage when you purchase from Amazon after using any of the Amazon links on the blog (including the logo-link immediately above). My link works with Amazon Prime and using it will not cost you a single cent. Huge thanks, BTW 🙂

Please Remember Also

Please, if you enjoy and learn from the blog, remember to use one of my two affiliate programs when purchasing new gear. Doing so just might make it possible for me to avoid having to try to get a job as a Walmart greeter and will not cost you a single penny more. And if you use Bedfords and remember to enter the BIRDSASART code at checkout, you will (still!) save 3% on every order and enjoy free second-day air shipping. In these crazy times — I lost about fifty thousand dollars in income due to COVID 19 — remembering to use my B&H link or to shop at Bedfords will help me out a ton and be greatly appreciated. Overseas folks who cannot order from the US because of import fees, duties, and taxes, are invited to help out by clicking here to leave a blog thank you gift if they see fit.

Gear Questions and Advice

Too many folks attending BAA IPTs and dozens of photographers whom I see in the field and on BPN, are–out of ignorance–using the wrong gear, especially when it comes to tripods and more especially, tripod heads… Please know that I am always glad to answer your gear questions via e-mail. If you are desperate, you can try me on my cell at 863-221-2372. Please leave a message and shoot me a text if I do not pick up.

Sony FE 70-200mm f/2.8 GM OSS Lens

BIRDS AS ART Record Low Price

Good friend and multiple IPT veteran Mark Hardymon is offering a Sony FE 70-200mm f/2.8 GM OSS lens in near-mint condition for the BAA record-low price of $1,348.00. The sale includes the front and rear lens caps, the factory soft case, the strap, the original box, the manuals, and insured ground shipping via major courier to lower 48 U.S. addresses only. Your item will not ship until your check clears unless other arrangements are made.

Please contact Mark via e-mail

The versatile 70-200mm f/2.8 lenses have long been big favorites of many nature photographers. They are great for landscapes. I have used this lens with Canon and Nikon and SONY. I used my Canon version to photograph granddaughter Maya’s dance recitals and to create bird-scapes and pre-dawn blast-off blurs at Bosque del Apache NWR in New Mexico. They are fast and sharp and have 1,000 uses. The 70-200 f/2.8 lenses are a specialty lens for bird photographers. Like the bad little child, when they are good, they are really, really good! I’ve used mine mostly for flight photography at point blank range where their performance is unmatched, especially in low light. I’ve killed with these lenses on the gannet boat in the UK, in Homer for eagles, for pre-dawn and blizzard blast-offs at Bosque, and at Merritt Island on single birds from huge feeding sprees right next to the road.

This super-fast lens weighs only 3.26 pounds and is easily hand holdable by just about everyone. As it sells new right now for $2,298.00, you can save a cool $800.00 by grabbing mark’s lens asap. artie

ps: To see what the 70-200 zoom lenses can do, see below, and also see the images in the blog post here. artie

This image was created on 15 January 2022 at La Jolla, CA. I used the hand held Sony FE 70-200mm f/2.8 GM OSS II lens with the Sony FE 1.4x Teleconverter (at 280mm) and The One, the Sony Alpha 1 Mirrorless Digital Camera.. The exposure was determined via Zebras. ISO 640: 1/320 sec. at f/4 (wide open) in Manual mode. AWB at 7:11:54am before the sun came over the hill to the northeast. Tracking: Spot S AF/C with Bird-Eye/Face Detection performed perfectly. Click on the image to enjoy a high-res version. Image #1: Brown Pelican sitting on dirt ridge on cliff

The Consensus Favorite

In the Eight Seconds Later and 165mm Wider blog post here, I posted the image above and the image below. Everyone who commented preferred the large-in-the-frame pelican image above to the habitat shot of the same bird below. Several folks trashed Image #2:

• With the small in frame (subject), the bird seems to be lost.
• #1 because I want to see the bird, not a busy, out-of-focus environmental shot.
• #1, for the exact same reasons as the previous poster.

I actually liked Image #2 a lot, for several reasons. It helps to tell the whole story. It gives viewers a good idea of the setting. It gives the viewer an idea of the distance from the subject to the background. It shows the great versatility of all 70-200mm lenses. I thought that the o-o-f birds on the far wall provided an interesting background, and did not find the background very distracting at all. Lastly, when presented with Image #1 above, I saw the opportunity to teach a good lesson on depth-of-field, a topic that many bird photographers have serious misconceptions about.

Do understand that I respect the thoughts of the folks who did not like Image #2, and as always, am glad that they posted a comment. Above I am just sharing my two cents on the image.

This image was created on 15 January 2022 at La Jolla, CA. I used the hand held Sony FE 70-200mm f/2.8 GM OSS II lens with the Sony FE 1.4x Teleconverter (at 115mm) and The One, the Sony Alpha 1 Mirrorless Digital Camera.. The exposure was determined via Zebras. ISO 640: 1/320 sec. at f/4 (wide open) in Manual mode. AWB at 7:12:04am before the sun came over the hill to the northeast. Tracking: Spot S AF/C with Bird-Eye/Face Detection performed perfectly. Click on the image to enjoy a high-res version. Image #2: Brown Pelican sitting on dirt ridge on cliff/bird-scape

Trying Yet Again to Explain the Relationship Between Depth of Field and Focal Length

In the Eight Seconds Later and 165mm Wider blog post here, I wrote:

Though I was standing in just about the same spot when I created both images, why are the birds in the background so much more sharply defined in Image #2 than in Image #1?

The question generated a series of comments (in part, below):

Adam: January 28, 2022 at 10:05am

To your question about DOF, the answer is that assuming you didn’t change the distance to the subject or aperture, the absolute DOF remains the same. The apparent DOF appears greater because you are zoomed out and smaller images appear sharper because they are more numerous and contrast is more apparent. However, if you were to enlarge/crop the second image to match the first image, the background would appear nearly the same.

Arthur Morris/BIRDS AS ART: January 28, 2022 at 2:34 pm

Thanks for commenting, Adam. You wrote, in part:

“To your question about DOF, the answer is that assuming you didn’t change the distance to the subject or aperture, the absolute DOF remains the same”

That would be true if and only if the size of the subject in the frame was the same. Cropping will not get you there. You are missing something important 🙂 with love, artie

Adam: January 28, 2022 at 4:24pm

Yes, how could I forget focal length? It must have been Covid-brain?

Next up was good friend and a many multiple IPT veteran John Dupps: January 28, 2022 at 3:49pm

You changed the focal length so the depth-of-field changed.

Morris/BIRDS AS ART: January 28, 2022 at 3:51pm

Hi John, I am glad that someone has been paying attention :).
with love, artie

John is of course, correct. Standing in roughly the same spot, the d-o-f increased dramatically. How dramatically? With a full frame camera body and an aperture of f/4, and assuming that I was about 10 feet from the subject, the d-o-f behind the bird for image #1 was about .48 inches. From the same spot, zooming out from 280mm to 115mm, the d-o-f behind the bird increased to 6.36 inches. Thus, the d-o-f increased by a factor of 13.25. And that explains why the birds on the far wall were more sharply defined than the few birds in the background in Image #1.

Some suggested that they might have liked Image #2 better had the birds on the far wall been in sharp focus. That shows a complete lack of understanding of d-o-f with telephoto lenses. The smallest aperture available with the gear in question is f/32. Going to f/32 would have required a much higher ISO along with a tripod and a much slower shutter speed. But here is the bigger problem: the far limit of d-o-f would have been about 12.7 feet, but the wall behind the birds was well more than 150 feet away. As they say frequently in Japan, “Not possible!”

The data above is from the excellent PhotoPills website here.

The Main Lesson

If you are at a given aperture and work at two different focal lengths, the d-o-f will be identical if and only if the subject is the exact same size in the frame. If you are at 400mm and you get twice as close to the bird working at 200mm, the d-o-f will be identical.

The angle of view, however, will change. Your frame will include much more background at the shorter focal length; being a lot wider, the image will look totally different, but the degree of sharpness of the background will be identical..

Related Telephoto Depth-of-Field Lessons

Probably 90% or more of my bird photography is done at the wide open aperture. Why? I love those creamy, dreamy backgrounds. Consider the following advice:

• 1- Unless you can verbalize a specific reason for stopping down to a smaller aperture, shoot wide open.
• 2- That said, understand that when you wish to create those smooth backgrounds, the distance from the subject to the background is at least as important as the f/stop.
• 3- Since depth-of-field is a function of the distance to the subject, the time to work with smaller apertures is when you are working near the minimum focusing distance of the lens with a large-in-the-frame subject.
• 4- Remember that WYSIWYG: what you see is what you get. If the whole subject looks completely sharp in the viewfinder, that means that it is covered by the d-o-f. In those case, there is no need to stop down at all.
• 5- That said, do understand that in such situations with long focal lengths d-o-f is measured in tiny fractions of an inch. Stopping down, therefore, will not help a ton.
• 6- As flying birds are generally a good distance away, you should — as a general rule, shoot flight at the wide open aperture so that you can maximize shutter speed at a given ISO.

As always, questions and comments are welcome.

Typos

With all blog posts, feel free to e-mail or to leave a comment regarding any typos or errors.