Test Target: The EF2x II vs Enlarging in Photoshop

The EF2X II vs "upressing" with no TC

 

Below are images of the same test target shot with a Canon D60 at ISO 200:

On the left with the EF300.2.8L IS lens and the EF2X II teleconverter. This is a 100% crop unsharpened.

On the right,the same lens on its own, with no teleconverter. This image is enlarged to the same scale as the image using the teleconverter using bicubic smoother in Adobe Photoshop CS at increments of 10%. It is also unsharpened.

Both RAW images were converted to 16 bit TIFFs in Adobe CS ACR v2.3 using identical settings and then converted to 8 bits and saved as medium quality jpgs for the web. Exposure for both was identical : 1/3200sec at f11.0. The camera was focused with the EF300/2.8 set to AF without the TC. The AF switch was then turned off and the focus ring left untouched for the shot with the EF2X II. The tripod was, of course, not moved between the two shots. So, the focus setting was identical for both. The tripod was a heavy duty Gitzo 410 and the head a full Wimberly mount.

Included immediately below are thumbnails of the full frames for reference.

 

Discussion

The image from the EF2X II is indeed sharper and less grainy in appearance. However the difference is not very startling in my opinion. Furthermore, it is seldom, if ever. one can use settings like f11.0 and 1/3200 sec in the field with long lenses. It is also unrealistic to expect to use the same settings with and without the TC. After all, there are two full EVs difference! This test was set up deliberately using identical settings for the two shots so that differences caused by using different f stops and shutter speeds were removed from the equation. In this respect, the test is rather unrealistically skewed in favour of the EF2X II as detailed in the following paragraphs.

In the field, one invariably has to use either a larger f stop, or a slower shutter speed to accommodate the EF2X. Either of these options usually has a detrimental effect on the final image. The end result, again in my opinion, is that use of the EF2X II in "real world" photography will often yield results no better and, on occasion, actually worse than just enlarging the image,using good technique such as bicubic smoother in Photoshop. I would expect the "worse" situation to occur when use of the EF2X II forces the user to resort to a shutter speed inappropriately slow for the increased magnification.

In my experience using a 600mm, it is always a battle to get a shutter speed fast enough to nullify lens movement, even with IS. Adding the 2 stop light loss entailed in using the 2X converter, all too frequently, means dropping the shutter speed to values slower than ideal. Stopping down to improve image sharpness at 1200mm equivalent focal length is just not very practical. F8 at 1200mm is a tough enough challenge without trying to go to f/11 or slower! If you are able to clamp the lens down and expose with a cable release, you may well be consistently better off in using the 2X rather than upressing. In my experience with wildlife however, this is just not how these lenses are used. They are used wide open and without being rigidly clamped down.

A final thought: These are D60 images, a camera body with a 6MP CMOS. Cameras with lower resolution will not allow the same degree of cropping that this "upressing" entails. Any advantage to using the EF2X II over upressing with lower resolution cameras may well be more apparent than with the D60. Conversely, I would expect even higher resolution cameras to show the differences between using the TC and "upressing" to be even less apparent than the images presented here.

My conclusion is that it is rarely productive to use the Canon EF2X II teleconverter at all with my 300 and 600mm lenses. I might just as well upres images taken with the lenses alone in Photoshop. This was the impression that first hit me while I was processing the heron images and led me to perform these test shots.

The question that naturally arose was what about upressing images from the EF1.4X teleconverter, universally considered a far better performer than the EF2X II? Those results, using the EF600/4L IS lens instead of the EF300/2.8L IS, are on the next page.

Use "Back" button or Return to Home