Canon Series III EF Extenders (tele-converters to me :))

[Arthur Morris]

Below is an excerpt from Chuck Westfall's article here (http://usa.canon.com/dlc/controller?act=GetArticleAct&articleID=3508&fromTips=1). This is Chuck's job title: Canon USA Advisor, Technical Information.

I will be glad to attempt to answer any questions as best as I can.

Extenders EF 1.4X III and EF 2X III

Extenders EF 1.4X III and EF 2X III have been newly developed in conjunction with the new Series II Image Stabilizer EF super-telephoto lenses. They can also be used with all previously announced extender-compatible EF lenses, but maximum performance is achieved when they are used with the new 300mm, 400mm, 500mm and 600mm lenses. The following sections provide more detailed information.

Image Quality

There are two significant improvements related to image quality when using the new Series III Extenders with the new IS II super-telephoto lenses: Anomalous dispersion glass elements are used in both new extenders to effectively reduce chromatic aberration to the greatest possible extent. This results in higher resolution and contrast, especially when the new extenders are used with IS II super-telephoto lenses.

Each Series III Extender features a newly developed microcomputer that increases AF precision when the extenders are used with an IS II super-telephoto lens. AF precision remains the same as the Series II Extenders when the Series III Extenders are used with earlier extender-compatible EF lenses.

As a result of these improvements, users of the new IS II super-telephoto lenses can expect significantly improved image quality when using Series III Extenders.

New Lens Coating

The front and rear elements of both Series III Extenders feature Canon’s new Fluorine anti-smear coating. The new coating is extremely oil-and water-repellent so that the front and rear elements can be cleaned without lens cleaning solvents using a soft, dry cloth.

Durability Improvements

The Series III Extenders are significantly more durable than earlier models due to the following improvements:

Seven screws instead of four are used to attach the lens mount to the body of the extender.

The lens lock pin and lens mount stopper pin have been improved for higher endurance.
The Series III Extenders are equivalent to the Series II Extenders in terms of weather resistance, with gaskets on both the front and rear lens mounts as well as the lens mount release switch.

The durability improvements of the Series III EF Extenders were made in response to feedback from professional photographers who use EF super-telephoto lenses and extenders regularly in their daily work.

Lens Compatibility

A list of compatible lenses for the new Series III Extenders can be seen by following the link to Chuck's article at the start of this thread.

*AF may not focus accurately when a Series III EF Extender is combined with certain discontinued EF lenses marked with an asterisk in the table above. This problem can be resolved through AF Microadjustment on EOS cameras equipped with that feature. Manual focusing is recommended when using Series III EF Extenders with those particular lenses on compatible EOS bodies that do not have an AF Microadjustment function.

Camera Compatibility

The new Series III Extenders are compatible with all EOS Digital SLRs as well as the EOS-1V 35mm SLR. However, they cannot be used with other film-based EOS cameras because their signal relay system is not compatible with those models.

Other Operational Issues

The new Series III Extenders are basically the same as the Series II Extenders in terms of operation with compatible cameras. Here are a few bits of information related to usage and performance:

The Series III Extenders support autofocus when used with compatible master lenses and EOS cameras, with some restrictions as follows.

With most EOS cameras, the maximum aperture of the compatible EF lens/EF extender combination must be f/5.6 or larger to support autofocus. With EOS-1 class digital SLRs, autofocus with the center focusing point is supported for compatible EF lens/EF extender combinations with maximum apertures of f/8 or larger.

AF may not focus accurately when a Series III EF Extender is combined with certain discontinued EF lenses marked with an asterisk in the table above. This problem can be resolved through AF Microadjustment on EOS cameras equipped with that feature. Manual focusing is recommended when using Series III EF Extenders with those particular lenses on compatible EOS bodies that do not have an AF Microadjustment function.


The Extenders EF 2x III and EF 1.4X III (pictured above) make ideal companions to the new supertelephotos, adding up to twice the focal length of these, and many other Canon EF lenses without significant additional weight or cost.

Usage of Series III EF Extenders has no effect on AE (Automatic Exposure) or IS (Image Stabilizer) functionality.

Canon does not recommend stacking Series III EF Extenders because the extenders’ optical performance and AF precision cannot be guaranteed in such cases.

Similarly, Canon does not recommend combining a Series III EF Extender with an extension tube because the extenders’ optical performance and AF precision cannot be guaranteed in such cases.

As with previous EF Extenders, usage of Series III EF Extenders lowers AF drive speed to improve AF performance. When Extender EF 1.4X III is used, AF drive speed is reduced by 50%. When Extender EF 2X III is used, AF drive speed is reduced by 75%. This may seem like a drawback, but in reality subject tracking performance remains quite high when Series III Extenders are used with IS II lenses. This is due to improvements in AF precision made possible by the new microcomputer in the extenders.

[jackmos]

What would the the comparison in image quality between the tc II and tc III when using an older lens? All the comparisons are with the new lenses.

[Jay Gould]

Jackmos, welcome to the BPN, the best teaching forum on the internet! Looking forward to your posts.

There is another thread about the TCs: http://www.birdphotographers.net/forums/showthread.php?76984-Canon-v-III-TCs

In that thread you will find the comment:


Roger
I just ran comparision tests of a static subject with 300/2.8,400DO,500,800 lenses with 2.0xIII and 2.0xII. This is with the 7D, I didn't have time for similar tests with the 1DmIV.

The subject was a line of (tops only for 500-800) decidous (leaves gone) trees with lots of fine detail against a snow covered peak. Since it was taken across a cold wide retention pond, there isn't any shimmering heat effects with the air temperature at 38 degrees.

Looking at the images in Lightroom, without sharpening (CR2s), I believe I can tell a difference in the sharpness of the two image sets. I haven't sharpened or modified the images. I'd like to try a blind test with some other people later today. Will have to post later when I have a chance - I have company right now.

Regards
Don


So, the first suggestions are that the new TCs are going to give somewhat better IQ even though they will not work to optimal design/usage with the older lenses as they will with the newer ones.

[Arthur Morris]

What would the the comparison in image quality between the tc II and tc III when using an older lens? All the comparisons are with the new lenses.

What is your first name???

IQ with the II TCs vs. the III TCs is almost surely gonna be very close with either the older or the new lenses.... I am thinking that the thing that will improve most with the Series III TCs and a Series II lens will be AI Servo tracking and accuracy.

Do understand that Image Quality with an new lens will be better than with the same older lens, i.e., the 600 f/4L IS II will make sharper images with and without TCs than the current 600 f/4L IS.

Let me know if any of that makes sense :)

[Arthur Morris]

Don said somewhere: "I believe I can tell a difference in the sharpness of the two image sets."

I gotta say that Don does not exactly sound convinced.

[Don Nelson]

Don said somewhere: "I believe I can tell a difference in the sharpness of the two image sets."

I gotta say that Don does not exactly sound convinced.



I haven't completed the requisite imaging of a lpmm chart that would absolutely prove to some on this forum that this is true (or not). The difference is small. A blind test would likely show that viewers could tell the difference, for at least the subject of the short test I did.
I won't be selling my TC II's.

The optics, of at least the TC 2x, have been redone between the II and III. (you can see that in the Canon EOS literature published "fall 2010" book(let). The other lines hinting at improvement were mentioned previously in the referenced article.

By the way, the interface pins are the same as the 2xII, so that while it communicates with the newer II lenses the new "features", there is nothing in the embedded program in the older I lenses that interprets the newest commands from the embedded processor in the TC IIIs. The TC III's do focus and "talk" to the older I lenses for everything that we are used to.

Canon has hinted at one change in the III TC's -- the fact that the focusing speseds (by using the USM motor in the II lens) have been slowed (300-400-500-600)when the TC III's are in the system, and this is said by Canon to enable better focus. We can presume that the older I lenses of these focal lengths (and others) are "deaf" to this command sequence. Slowing the focus speed (compared to the system with the TC II's) can improve the time to "stop" when maximum contrast is found on the sensor, thereby improving the accuracy of focus.

The $500 price point isn't a surprise -- but there were places that had them in stock at $599 - that was a surprise(and people purchased them at this price as the availability of "in stock" disappeared). I'm sure everyone has seen Canon's announced target prices(disclosed by Canon Aug 26,2010):


Canon EF 8-15mm f/4L Fisheye USM (~$1400)
Canon EF 70-300mm f/4-5.6L IS USM (~1500)
Canon EF 300mm f/2.8L IS II USM lens (~$7000)
Canon EF 400mm f/2.8L IS II USM (~$11000)
Canon Extender EF 1.4x III (~$500)
Canon Extender EF 2x III (~$500)
Best regards to all

[Arthur Morris]

I haven't completed the requisite imaging of a lpmm chart that would absolutely prove to some on this forum that this is true (or not). The difference is small. A blind test would likely show that viewers could tell the difference, for at least the subject of the short test I did.
I won't be selling my TC II's.

The optics, of at least the TC 2x, have been redone between the II and III. (you can see that in the Canon EOS literature published "fall 2010" book(let). The other lines hinting at improvement were mentioned previously in the referenced article.

By the way, the interface pins are the same as the 2xII, so that while it communicates with the newer II lenses the new "features", there is nothing in the embedded program in the older I lenses that interprets the newest commands from the embedded processor in the TC IIIs. The TC III's do focus and "talk" to the older I lenses for everything that we are used to.

Canon has hinted at one change in the III TC's -- the fact that the focusing speseds (by using the USM motor in the II lens) have been slowed (300-400-500-600)when the TC III's are in the system, and this is said by Canon to enable better focus. We can presume that the older I lenses of these focal lengths (and others) are "deaf" to this command sequence. Slowing the focus speed (compared to the system with the TC II's) can improve the time to "stop" when maximum contrast is found on the sensor, thereby improving the accuracy of focus.

The $500 price point isn't a surprise -- but there were places that had them in stock at $599 - that was a surprise(and people purchased them at this price as the availability of "in stock" disappeared). I'm sure everyone has seen Canon's announced target prices(disclosed by Canon Aug 26,2010):


Canon EF 8-15mm f/4L Fisheye USM (~$1400)
Canon EF 70-300mm f/4-5.6L IS USM (~1500)
Canon EF 300mm f/2.8L IS II USM lens (~$7000)
Canon EF 400mm f/2.8L IS II USM (~$11000)
Canon Extender EF 1.4x III (~$500)
Canon Extender EF 2x III (~$500)
Best regards to all

From an excellent article on Luminous Landscape here (http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml):

"The next thing to realize is that resolution is not a quantifiable scientific absolute. It is totally subjective, and therefore is different between individuals as well as with the same individual at different times. While one observer may be able to see a resolution of 50 L/mm on a particular test, another may see 45 L/mm or 55/ L/mm. A 10% variance with the same observer at the same time is not at all unusual. Add to this the other variables, such as focusing errors, and I've been told by experts that a variance of as much as 30% in such tests is not uncommon."

Thus it would seem that there is no such thing as being able to "absolutely prove to some on this forum that this is true (or not)." Especially when you are already sure of what you will find.

Whatever the new TCs can talk to the older lenses will not be able to take advantage of the new AI Servo AF tracking accuracy via micro-chip. The four new super-teles will.

I believe also that you have made an incorrect assumption by stating, "Canon has hinted at one change in the III TC's -- the fact that the focusing speseds (by using the USM motor in the II lens) have been slowed (300-400-500-600)when the TC III's are in the system...."

There is no change. The older TCs did the same thing: slowed AF considerably. Here is what they said (bold italics are mine):

"As with previous EF Extenders, usage of Series III EF Extenders lowers AF drive speed to improve AF performance. When Extender EF 1.4X III is used, AF drive speed is reduced by 50%. When Extender EF 2X III is used, AF drive speed is reduced by 75%. This may seem like a drawback, but in reality subject tracking performance remains quite high when Series III Extenders are used with IS II lenses. This is due to improvements in AF precision made possible by the new microcomputer in the extenders."

Thanks for the pricing info.

Here's what I am waiting for: weights and prices for the 500 and 600 f/4L IS II lenses...

[Alan Lillich]

Atrie,

Thanks for the LuLa link, a great read. I think the next paragraph to the one you quoted is also significant:

"And, to make things even more indeterminate, it can clearly be shown that the actual image quality produced by a lens does not correlate at all well with its measured resolving power. For this reason resolution test results alone should not be considered a valid measure of a lens' goodness. This is why the optical industry as well as those that really want to understand how a lens is performing rely instead on its MTF."

This is also why I never bother to seek out charts and numbers for lenses. I'm much more interested in aggregate wisdom from usage. The charts can sometimes help to explain perceived behavior, but they are no substitute for real use. And I really mean "perceived", not "measured". I don't hang test charts on my walls. I only care how real photos look.

Alan

[Arthur Morris]

Hey Alan, I could not agree more. The next formal test that I run will be my first. I go out, make images, and see how they look.

Funny thing is that I made and sold hundreds of great images with the 100-400 that I just sold. But if you follow the links on Luminous Landscape to the test images comparing the 100-400 and the 400 f/5.6 it would seem that nobody could ever make a sharp image with the 100-400. That brings up the question, what is a sharp image????

I have always used the "Pen Test" for judging sharpness.

If someone signs a check to pay for the image usage then it is deemed as sharp enough :)

At times my poor eye for fine detail can pay off.....