Test : Teleconverters vs Enlarging in Photoshop

[TerryDanks]

I have shot images with both of Canon’s teleconverters using the EF300/2.8L IS and the EF600/4L IS lenses. I compared images taken with no TC at all and enlarged to the same scale as those taken with the EF2X II and then did the same with the EF1.4X II.

The methodology and images begin at this page

The conclusions, for those not wishing to take the time to plow through the test results for themselves are:

1/The EF2X II produced poorer results that using PS to enlarge images taken with the EF1.4X II to the same scale. The difference is clear, and quite striking

2/ Enlarging images taken without any TC at all to the same image scale as taken with the EF2X II, may or may not produce better results. In cases where the lens can be locked firmly and a cable release used, The EF 2X II may offer a slight advantage. In the “real” world, long lenses are seldom used that way and there is very little discernible difference in images enlarged in PS to those taken with the EF2X II.

Considering #1, why would one care about #2?

Don’t use the EF2X II. Use the EF1.4X II and enlarge the image in PS. You get a better result that way.

[MICHAEL_BARNES]

I have had a similar experience using a 70 - 300 DO IS lens and a Kenko C_AF1 1.5X Teleplus.
The Pictures were not as sharp or as good color.
So I did some experiments with other lenses, 28 _135 IS and the 17 - 40 just for grins, and had the same experience. I tried using auto focus ( which does work ) and manual focus and the best results by far were obtained in every instance using Photoshop to digitally enlarge the pictures where the teleplus was not used. This was using a 20D camera.
In other words I have a useless Kenko lens as far as I can see. Any offers?!! [img]/ubbthreads/images/graemlins/mad.gif[/img]

Best regards, Michael

[Noel_Carboni]

I have reached exactly the same conclusions in my own testing, and have since stopped using my 1.4x teleconverter. Probably says that there's more than meets the eye to the lens designs, in that they simply work best when used as they were intended.

This is doubly true when you consider lens performance is not just what happens with the focused subject, but also with the blurred background or foreground. My bokeh went to hell when I put my 1.4x on my 100-400.

Digital technology has obsoleted another optical crutch.

-Noel

[Will_Mass]

Cool,

I've considering the 1.4 TC. It seems you guys just found me another $279 towards a second 20D body!

Thanks, Bill

[Doug_Kerr]

Hi, Terry,

If you didn't upsize the TC-less image but just cropped it and viewed it at the same size as the (entire) TC image, or printed it to the same size, how would it have looked?

The underlying question here is of course "does upsizing it do anything beneficial?".

(I didn't read your test protocol description yet, so that may be answered there. If so, sorry!)

Best regards,

Doug

[David_Schnieder]

I take tens of thousands of shots with Canon 1.4x on 70-200L a year. And I take a few shots with 2x. The newer (II) 2x is better than the older 2x, but both give inconsistant results. Sometimes the quality is quite good and the next shot it can be pretty bad. I could never figure that out. The 1.4x is very consistant and wonderful.

-David Schneider

[Paul_Gardner]

I'm not sure what is going on with the 70-200 non IS but I went back to last years images taken with the 10D and 70-200 + 2XTC and redeveloped the raw files with DPP 1.5. I can't hardly beleive the difference in increased sharpness. Its almost like having a new lens.

I'm planning on trying it on my 20D and see what happens.