I decided to do a little upgrading and thought the new Canon extender would be an inexpensive place to start. I've read that the new extender is noticeably better. I have two "D" bodies so the only time I use this is when it is attached to the Canon 300 2.8. I performed the dollar bill test with a tripod and shutter release; attached to the same body and the 300. I compared the shots and I couldn't tell the difference between the two at 100 and 200%; no sharpening. I"m not sure what to think. Either I have a bad copy of v.III or an incredibly good copy of v.II.
Thoughts?

Can't see the image Charlie..

Charlie I wouldn't suggest using a shutter release for testing, either use high enough shutter speed with long lens technique, resting your hand on top of lens mount or set it up so that illumination is 100% flash to take camera movement out of the equation. You need to rule out that camera movement is masking any improvement. Have a look at the digital picture site and compare test images from there so you can see the sort of difference you are looking for. You can comapre the 300mm f2.8 with type II and Type III converters from there.

Always use a flash at the fastest sync speed for something like this. That said, did you do a microadjusment first. Virtually every lens and camera with a TC require microadjusment to get critical focus. When you are close enough to do the dollar test with a 2x on a telephoto, you have virtually no depth of field so focus accuracy is super critical.

Live view manual focussing is mandatory as well, IMO.

Thanks guys! I'll take another swing at it with the advice you've provided.

Not so sure about mandatory. May be setup and user dependent. I've done it both ways, side by side with multiple reps of live view and AF in the same setup. (Mirror lockup and IS off.) Maybe it's because my setup is in my basement, with relatively dim lighting, making it difficult to judge live focus accuracy. But AF usually bests my live focus efforts. The most recent case happens to be my test of a new Canon 300mm f/2.8 II and type II extenders -- similar to Charlie's situation. Should add that I use the USAF 1951 based resolution test target available from Edmund Scientifics. It's possible to get both quantitative and repeatable results from this target.

Doesn't hurt to try both ways and see which works best. For what it's worth, the guy at The-Digital-Picture.com uses multiple samples of both center point AF and externally magnified live view. Not sure what he does for external magnification, but that could make a significant difference. One thing to add to the setup is to weigh down the tripod. I use a couple of heavy beanbags, which almost totally quenches vibrations as seen in fully magnified live view.

By "read that the new extender is better", are you referring to the tests posted on various internet camera forums? The reason I ask is that none of those tests --based on either the methodoloy used, or the results posted -- have convinced me that the 2XIII is better than the 2XII. Your own result may simply be the reality: that the basic IQ available with the two versions of this extender is the same.

In other words, it's unlikely there is anything wrong with the 2XIII you purchased. It's just not any better than the 2XII you already have (except it costs twice as much).

John

How you do it is your business , but if you don't remove as many variables as possible such as inaccurate focus and camera shake, there is no way you can be sure of what you are seeing.

Scott, I think the "How you do it is your business" comment is a little over the top. I'm not attacking you, just suggesting that there may be situations were live view isn't the only viable solution. That's certainly been my experience more than once. If that is true (and it is) then there are hidden variables associated with live view that in fact are not as controlled as one might think -- at least in some test setups, which is all I was implying. And anyway, what is harmed by trying both approaches side by side? As I said, T-D-P.com does both, and they seem to know a thing or two about testing.

Here's the comparison between the type II and III for the 300mm f2.8 at f8 from the digital picture:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=249&Camera=453&Sample=0&FLI=2&API=4&LensComp=249&CameraComp=453&SampleComp=0&FLIComp=4&APIComp=4

Also the 400mm f2.8 wide open, improvement is quite clear on this one:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=327&Camera=453&Sample=0&FLI=2&API=2&LensComp=327&CameraComp=453&SampleComp=0&FLIComp=4&APIComp=0

My comment refers to the mechanics of testing, whether you use test charts, currency, flash or whatever. Irregardless, my point is that focus accuracy is essential and camera shake has to be removed if any test is to be valid. IMO, if you use autofocus your results hinge on camera and lense being calibrated perfectly, otherwise it's an autofocus test.

You've mentioned camera shake twice. Not sure where that's coming from. One must conduct a proper test to achieve valid results. As I said, in my setup I weigh down my tripod with two heavy beanbags. I use mirror lockup for all testing, and after AF is achieved shutter release is on a 10 second timer delay. No camera shake. The live view part of the testing confirms that the camera/lens combo is dead steady -- even with a 300mm lens and 2X extender. Lenses are microadjusted beforehand. Every individual test instance is a separate AF activation, and yet my results with AF are very consistent and repeatable; less so with live view, perhaps because I just can't judge critical focus on the rear LCD as well as the AF system can.

Regarding test accuracy, one of the benefits of using the USAF 1951 resolution test target is that one can calculate the resolution of a tested lens in line pairs per millimeter. It provides a good standard of comparison across different lenses -- and against the camera sensor's resolution potential. I've found that the center resolution of top quality Canon L lens, when tested with my 1Ds MkIII, calculates out roughly to what one would expect from the sensor density of that camera, realizing that there are losses due to the anti-aliasing filter. There likely is even more resolution there with the very best lenses, but if so the sensor/AA filter is limiting it's detection. This cross check of test results against system resolution potential suggests that the AF approach can produce very accurate results when done properly.

Michael, your reply above mentioned "dim lighting" when doing your tests, "making it difficult to judge live focus accuracy"(does that mean you are using slow shutter speeds?). Or are you using flash?
If your shutter speed is low, mirror lockup or not, camera shake/shutter vibration can be a problem, IMO. When in Liveveiw, are you tripping the shutter directly from liveview? If so, I have found that the images are not as sharp as when you only use liveview to focus, then exit liveview , THEN take the image with the mirror up. No idea why it is that way, but when I owned a 1Dsm3, I found that I had more consistent sharpness with macro work if I exited liveview first.
Anyway, this is just my 2 cents on what I have found helpful!

Scott, thanks for the reply and for sharing your experiences. I use multiple flashes for all actual exposures, but the live view focusing is done in relatively dim lighting, which undoubtedly contributes to some of the inconsistency I experience. I do exit live view first, and all exposures, however focus is achieved, are always on 10 second timer delay. I think the outcomes are inconsistent because I just can't eyeball focus as well as the AF system in my particular situation. I find it significant that Bryan at T-D-P.com (whom I've emailed several times about his test setup) uses externally magnified live view for increased accuracy. Some time in the future I may try shooting tethered to see if I can do better. And I agree with you fully about macro. I never take a single macro shot without using live view, mirror lockup and 10 second timer delay.

Micheal , the "externally magnified live view", is that through the Canon software? Can the focus be done in the software or do you have to turn the focus ring manually?

Reply delayed due to fact that I spent the morning with wife buying a bedroom full of furniture. Talking photography is much more fun!



Not sure how Bryan at T-D-P.com does his externally magnified live view; I've never specifically asked. In my case, I manually focus using the ring. One has to wait until vibration settles out, but that's easy to see on the live view display; it just adds a little extra time. As I type this, I've got my 1Ds Mk III tethered to my computer via EOS Utility as a quick and dirty test, and focus is much easier to control via mouse. Even so, the computer screen is a bit more difficult to read than I expected.

Whether that will make a difference on the really tiny lines of the USAF 1951 test chart remains to be seen. The answer will only come from a full scale tethered comparison test. That will have to wait as I've dropped my test target off this morning to have it mounted on glass and framed. In the past I've taped the target to the wall. Should be back in a week or two.

I am using a PC controlled software suite for MF adjustments. In the documentation it states to print the target with an inkjet, not a laser printer, to avoid any light reflection. Unless your target is transparent to be illuminated on a light box - which would introduce lens flare - exactly what do you mean when stating you are mounting your target on glass. I hope you mean that the glass is a rigid rear mounting medium and not in front of the target.

I framed my target by mounting it on the front of the inexpensive plastic used in place of glass. I can always print another one.

"On glass" means just that, not behind glass. I worked my entire career in systems engineering and testing -- among other things. Grandmother knows how to suck an egg.


You might consider spending $30 for a commercially produced full frame target. The benefit is that it will give you quantitative results that can be compared across lenses. And the entire lens can be tested, not just the center. Taping to a wall is OK, but it has to be done every time, which is why I'm finally having mine mounted. A glass backing should provide a bit more dimensional stability than plastic for a target that large. Also, it is incumbent on the tester to insure that the camera's sensor is centered on and parallel with the target. If it isn't, one or more corners may appear soft even though the lens itself may be OK.

http://www.edmundoptics.com/products/displayproduct.cfm?productid=1665

The frame is rigid and the target on heavy matte paper mounted between the frame and on the stiff almost glass type medium makes the whole thing rigid.

I use a crop camera and use the Canon recommended distance of 50 x effective focal length so a 300mm is set at 80 feet on my crop sensor. That would have to be a huge target to fill the frame.

I also mounted a level of the frame to give me a starting reference for adjusting the target so the camera is also level (pan wise) to help resist any twisting movements from shutter vibration.

My 300 plus 1.4 TCIII definitely benefited from this adjustment. That target was shot at 110 feet.

My kit walk around lens 18-200 ISII non-L 3.5-5.6 really improved. The body default is +7 and the lens peaked at a stable -6. A crop of a shot at 200 f/5.6 wide really looked pretty close with minor USM required and noise reduction (small bird on shaded branch with background snow cover peeking through).

I took shots at full max fl on the zoom and using the 300 with and without the TC of a woven aluminum fence and the corners looked OK with a bit of focus falling off on the 300 with the 1.4x TC. This was at 100 feet all taken wide open.

When it warms up I'll go find a brick wall to fill the frame as a confirmation.