Canon 300mm f4 IS + 2x III, Sharpness test with a 10€ note

Hello,

For those who are interested I made a sharpness test with my Canon 300mm f4 IS and my recent aquired 2x III.
I know this isn't the best combination, specialy because I use a Canon 40D and have to manual focus, but the results come as a surprise.

I used a 40D on a tripod, a 10€ note and set the camera settings to 0 (Contrast : 0; Sharpness : 0; Color saturation : 0; Color tone : 0).
These are 100% crops of the center with no post processing!!!!!

Well, to be honest I wasn´t expecting good results, but as you could see below the results were better than I expected. Remember that there are no post-processing and camera settings are all 0.

On the last two images I post two examples of the same photo (center and corner crop), with these camera settings (Contrast : 0; Sharpness : 3; Color saturation : 0; Color tone : 0), just to see how good could it get with a litle sharpness.......

Now I'm just waiting to have enought money to get the new 300mm f2.8 IS II , and get even better results.

Any comments?
Hope this is usefull for anyone.

Best regards,
Paulo Anjo

thanks for your efforts... yes very good results indeed, I'm always interested in seeing these... just recently got the 2.0 III, and looking forward to experimenting

What was the camera to target distance? This was the f4/L, correct? If not, then that's why you probably needed to manually focus.

I'm happy with mine with and without 1.4xTCIII on a 50D. AF works nicely. I did pick up a bit of sharpness with AF when I MFA'd it. Most of the MFA correction was for the body based on a couple of lenses and the default set with the camera body (global) when I purchased it.

I used 50xeffective focal length for lens to target.

Anyway I can get some good cropping out of it with a minimum of sharpening on a tight crop in post processing. I prefer f8 and occasionally f11 (where diffraction starts) at ISO 400 to ISO 800.

As I've said from my own testing in at least two other recent threads, the new Canon 2X III seems to be a real advance over its predecessors. Good luck with acquiring the 300mm f2.8 II; I have one as well as both version III extenders. You're in for a treat.

What was the camera to target distance? This was the f4/L, correct?

About 2 meters and yes I use a 300mm f4 IS L.

best regards,
paulo anjo

Two meters? Is that a typo?

For a 40D crop frame the Canon recommended distance is 24 meters for the bare lens. (50 x 300mm x 1.6 \ 1000 where 1.6 is the crop factor.) With the 2x extender it would be 48 meters.

The specified minimum distance is 1.5 meters. Is this your distance of main interest?

paulo wrote:

What was the camera to target distance? This was the f4/L, correct?

About 2 meters and yes I use a 300mm f4 IS L.

best regards,
paulo anjo

Ronzie, that's a common recomendation for focus micro adjustment, not examining sharpness or anything else to do with lens performance.
Also, I've never heard of factoring in crop factor in the target distance calculation. Maybe it was in my manuals and I missed it. Can you point to a source?

2X-III is the best thing that happened in the TC world of Canon for quite some time. Although the AF suffers, the combo is usable, especially if the distance limiter is used.

For a 40D crop frame the Canon recommended distance is 24 meters for the bare lens. (50 x 300mm x 1.6 \ 1000 where 1.6 is the crop factor.) With the 2x extender it would be 48 meters.

Maybe I'm missing something here, but how could I manual focus properly a 10 euro bill from 48m of distance?

This is just a simple test to show how good could be the new 2x III.

best regards,
paulo anjo

Paulo, at that distance you'd have over 1m of dof at f8! You could probably guess the focus. Although you may never use the lens like that in the real world.

I think the crop factor comment was in one of the Canon on-line tutorials about this. It is the FOV as determined by the sensor size to pick expected average distance use of a single focal length. It also might be in the FoCal manual but not sure. You are also adjusting to the modified circle of confusion with a crop sensor. It is the same principle applied to DOF and hyperfocal calculators that take the crop factor into consideration.

Yes, 50x is for MFA adjustments but in a non-zoom even with that depth of field wide open it still gives a clue for sharpness as cropping might be applied to the original image. I expect that is Canon's determination for expected average use of a particular focal length.

I just assume a telephoto application is used more for distant subjects and distant subjects put more of a "strain" on IQ measurement.

For a prime lens the optical quality is consistent whatever the range. It is not unusual to qualify distant object testing as seen on many common testing sites. They frequently crop down to just a window grid on a distant building looking for resolution, CA, and other characteristics.

This site has a gallery of practical images along with test reports:
http://www.photozone.de/canon_eos_ff/611-canon300f4ff

as do these;
http://the-digital-picture.com/Reviews/ ... ipment=111
http://photo.net/equipment/canon/300-4

At the moment I can't find the site with the cropped images for this lens.

In summary for comparison both ranges could be included.

The MFA target supplied by FoCal has at its center concentric rings of a diameter of about 1.25 inches outer ring. Each ring progresses to a thinner drawing width. In addition there is a "digital distribution" of rectangular shapes on the rest of the target. During the process a highly cropped sharpened view is presented at the center and surrounding rectangles within the target on the computer monitor and is also included in the .pdf report at the conclusion. You can estimate the resolving power of the lens. I could clearly see edge CA and resolving qualities on the solid rectangles and resolving down to the almost the thinnest ring which is about the limit of my printer resolution.

I'm not a member yet here so I can't upload a sample but they can be seen at the FoCal site slide shows:
http://www.reikan.co.uk/focal/index.html

Now nothing is wrong with the WOW factor of the ten-pound note test for close-up work. I am just commenting that I would test a lens at its most practical expected object distance to judge quality.

Neil Fitzgerald wrote:Ronzie, that's a common recomendation for focus micro adjustment, not examining sharpness or anything else to do with lens performance.
Also, I've never heard of factoring in crop factor in the target distance calculation. Maybe it was in my manuals and I missed it. Can you point to a source?

ronzie wrote:Now nothing is wrong with the WOW factor of the ten-pound note test for close-up work. I am just commenting that I would test a lens at its most practical expected object distance to judge quality.

True, but unless one is exclusively a distant landscape fanatic, I think the minimum focus distance is at least as appropriate as a building in the distance. You might choose a distant object if you couldn't find anything with fine enough detail to shoot closer, but you then introduce a lot of atmosphere into the equation.
"For a prime lens the optical quality is consistent whatever the range". Although there will be some Nikon long lens shooters who may disagree, I think we actually agree here. It doesn't matter what distance is used, as long as there is enough detail in the subject (small thing close, or big thing far), and there are not atmospheric effects (which can be significant at anything from a few m on) it doesn't matter what the target distance is.
Here is an old thread on it:
http://www.naturescapes.net/phpBB3/view ... 7&t=187527

As for changing the definition of COC for different crop factors; that's a debate out there with downsizing to an arbitrary value like 8MP to compare high MP sensors. Some other time