Series III 2X TC Gut Reaction & More on Depth of Field (Though Beyond Me….) « Arthur Morris/BIRDS AS ART

Series III 2X Gut Reaction & More on Depth of Field (Though Beyond Me....)

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This Anhinga was photographed this afternoon at Anhinga Trail, Everglades National Park with the 70-200mm f.2.8L IS II lens, the 2x III TC (hand held at 342mm), and EOS-1D Mark IV. ISO 400. Evaluative metering at zero: 1/320 sec. at f/5.6.

Series III 2X TC Gut Reaction

I got to try my brand new Series III 2X today and my gut reaction is that it is quite a bit sharper than the old 2X, the EF Extender 2X II. I have not done any formal testing and will not be able to do any for several months, but the sharp images that I created today with the new, new combo were exceptionally sharp. This Anhinga seemed about ready to jump off of the screen of my HP laptop…..

More on this to follow soon.

Ah, BTW, there is a post in the gear Forum with some examples of test images that showed that the new 2X was a bit sharper than the old 2x. Scroll down here to see some test images.

More on Depth of Field (Though Beyond Me….)

I received the e-mail below from Daniel Gomez-Ibanez in response to my comments on depth-of-field in the last blog post here. He covers lots of technical stuff, most of it far beyond me….. I am sure, however, that it will be of interest to at least a few of you. If you post any questions for Daniel, I will make sure that he sees them.

After reading your blog on depth-of-field I went to the DOF MASTER site and tried it out. The DOF calculations on this site seem very generous (that is, they yield a DOF which is much deeper than I’ve experienced using Canon digital bodies). Why? It’s because DOF MASTER is using a standard for “acceptably in focus” (the so-called “circle of confusion”) which doesn’t come close to doing justice to the resolving power of our lenses and our modern digital sensors.

If you examine the circle of confusion numbers used by the DOF MASTER calculator, they are based on a 0.03mm circle of confusion for a full-frame sensor, like the 5D Mk II. For example, the calculations for a Canon 7D or any of the 1.6 crop-factor bodies use a circle of confusion of 0.019mm. (0.019 X 1.6 = 0.03). Similarly, the circle of confusion for the 1D Mk 4 (1.3 crop factor) is 0.023mm. (0.023 X 1.3 = 0.03)

What is the practical result of using a 0.03mm circle of confusion for a 36x24mm negative or sensor? It means that detail on an 8×10-inch print (about a 7x enlargement) will appear acceptably sharp when viewed from a distance of about 10 inches. This is because the human eye can just separate two points that are about 0.2mm apart at a viewing distance of 25 cm (ten inches). A 0.03mm detail on the negative becomes 0.2mm when enlarged seven times. Leica used 0.03mm as their standard for the circle of confusion when engraving depth-of-field marks on their lens barrels. Good lenses are capable of much greater resolving power than this, but “acceptably in focus” (depth-of-field) depends on how much you enlarge the image, and how far it is from your eyes. Leica settled on an 8×10 print held in the hand at ten inches.

But we have digital sensors now, and we view images on our computer monitors. Now we want to see sharp detail when we enlarge the image to view “actual pixels!” This is much more demanding than the old Leica standard! The size of an “actual pixel” on a 1D Mark IV sensor is 0.0057mm! It’s only 0.0043mm on the 7D or the 60D. Our lenses are quite capable of resolving details down to the size of a single pixel. But if we base our depth-of-field calculations on a circle of confusion of 0.03mm and enlarge the image to view the actual pixels, details will look fuzzy because a 0.03mm circle of confusion will span five, six, or even seven pixels. This would be fine for an 8×10 print, or even for a large exhibition print (say 20X30 inches) providing it is viewed from farther away (30 inches). This assumes you don’t crop your image before enlargement.

But if you want to limit the depth of field to the detail that modern lenses and sensors can resolve you need to use a much smaller circle of confusion for the calculations, one that corresponds to the physical dimensions of a single pixel on your sensor. Then your image will be “acceptably in focus” when you enlarge it to view “actual pixels.”

Fortunately, the DOF MASTER site lets you do this. At the bottom of the drop-down menu you can select a circle of confusion that corresponds more nearly to the size of a pixel on your sensor — say 0.005mm for your 1D Mark IV or 0.004mm for the 7D. You’ll get a much more accurate sense of what will appear acceptably sharp in the image when you enlarge it to “actual pixels” in Photoshop.

As a practical matter, however, you probably don’t have to use a circle of confusion that’s any smaller than two pixels — say 0.01mm. That should provide photos that are plenty sharp for most applications, including producing big enlargements from cropped images.


Thanks again, Artie, for all your wonderful images and helpful writing. I’m always learning a lot from you and I’m a big fan!

Thanks for sharing your technical expertise with us Daniel.

Shopper’s Guide

Below is a list of the gear that I used to create the image above. Thanks a stack to all who have used the Shopper’s Guide links to purchase their gear as a thank you for all the free information that we bring you on the Blog and in the Bulletins.

Canon 70-200mm f/2.8L IS II lens. Man, I am loving this lens on my shoulder with the 2X teleconverter.
Canon EF 2X III TC. As above, my initial reaction is that the new 2X III TC is much sharper then the 2X II TC. Both of the new (Series III) TCs have computer chips that will communicate only with the new Series II Super-telephotos. With those lenses we are hoping to see faster initial focusing acquisition and increased AI Servo AF tracking accuracy.
Canon EOS-1D Mark IV professional digital camera bod.y And this is the very best professional digital camera body that I have even used..

And from the BAA On-line Store:

Delkin 32gb e-Film Pro Compact Flash Card. Fast and dependable.

If you are considering the purchase of a major piece of photographic gear be it a new camera, a long lens, a tripod or a head, or some accessories be sure to check out our complete Shopper’s Guide.

15 comments to Series III 2X TC Gut Reaction & More on Depth of Field (Though Beyond Me….)

  • Arthur Morris/BIRDS AS ART

    Welcome Selwin, There are lots of images created with the 70-200 and the 2X both here on the blog and in the Bulletins. Most feature my clean backgrounds so not a lot to learn about the BOKEH.

  • Selwin

    That is an amazing catch! I found this page while browsing through dpreview Canon lens forum, looking for clues as to whether to get the 70-200/2.8II + 2xExtenderIII combo. I hope I am not posting against the rules of this community, but I would really appreciate your opinion for what you would do in my situation. I travel a lot with a light 5D kit, but my longest focal length lens (a 70-200/4IS) is too short for shooting wildlife. I think I’d be fine with 400mm. My question is: I read reports that this new 70-200II/2xTCIII combo @400mm is as sharp or sharper than the 400/5.6. OK. But how about bokeh? Can anyone comment on bokeh amount and quality for the 70-200/TC combo vs 400/5.6? This anhinga shot above has outstanding bokeh, but the bird was quite close, closer than most of the wildlife I shoot.

  • …But I’m still delighted that I was able to purchase the 2x II.

  • @ Bryan: I know what you mean; I just purchased Artie’s older 2x II, and now I’m wishing that I could afford the 2x III. LOL

  • The Anhinga image is so sharp, it almost looks like 3D.

  • ann pacheco

    This anhinga is so sharp , I mean sooooooo sharp that I don’t need glasses! Thanks Art, now I can save for equipment!

  • Arthur Morris/BIRDS AS ART

    Robert, Thanks for the heads up on the bad link. It has been repaired.

  • Artie, your Anhinga photo is amazingly sharp with that combo. That’s the good news. The bad news is once again, you have encouraged my addiction to upgrade and spending money. 🙂

  • Artie,

    The link in the DOF article above is not working correctly. Daniel is quite correct in his assertions regarding Circle of Confusion. I have been working in the same vain to come up with DOF charts using Circle of Confusion more in line with our actual viewing preferences. Daniel brought up some good points.

  • Patrick Sparkman

    Here is a link to a photo using the 70-200 II, and 2X III. If you scroll down you can see the photo with some changes suggested by helpful BPN members.

  • Arthur Morris/BIRDS AS ART

    Good catch Arne. I have fixed the typo.

    Bill, Please do not take this personally as I have great respect for lots of Nikon stuff and lots of friends like Todd Gustafson and James Shadle who are both world class photographers and Nikon users, but the 80-400 could not shine the shoes of the EF 70-200 f/2.8 L IS lens with any 2X TC. Heck, for me Canon finally has a lens to compete with the Nikon 200-400, the EF 70-200 f/2.8 L IS lens with any 2X TC!

    Patrick. Please post the link here.

  • Arne Kiis

    We all know that you have a steady hand but “hand held at 3242mm” must be a new #1 🙂

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  • Bill Clausen

    I guess I wish I was a Cannon guy. All my stuff is Nikon My 80 -400 doea a great job on alot of situations!!

  • Patrick Sparkman

    I agree with your “Gut Reaction” Artie. I was using the new 2X III on the 70-200 II at La Jolla last week, and the images do seem sharper to me. In fact, they seem really sharp. I posted a Heerman’s gull on BPN if anyone wants to take a look. I know that I really like this combo.