Kenko 1.4x DGX - No image quality loss?

Just picked up the Kenko 1.4x DGX and, albeit after only a limited amount of use, can't see any image quality loss. Is this possible?

Teleconverters tend to work well with nice prime lenses. Was this with the 300 f4L?

themadman wrote in post #10116123
Teleconverters tend to work well with nice prime lenses. Was this with the 300 f4L?

Yup, that was indeed the 300!

CA much?

There is almost always SOME quality loss, but they can certainly still be used effectively. For example if you had avoided that really high contrast part of the scene it would've looked a lot better.

edit: In here: https://photography-on-the.net/forum/showthre​ad.php?t=867326 the first two are 400mm with the 1.4x, the third is the 400mm with the 2x. The 2x shot looks ok at that size with a little clean-up, but at full size you can see I missed the focus a touch and it is also a bit soft (and it's cropped a bit as-is, so cropping without a TC wouldn't work).

I tried a series of test shots with and without the Tamron 1.4x TC. They were controlled by keeping the camera on a tripod in the same place, zooming in and out to get the same field of view. On a 50mm prime, of course I had to move the camera to keep the same image with and without the TC.

I was amazed. Even in lab-like conditions, viewed at a variety of apertures at 200% crop, there was just about no perceptible difference. On cheaper lenses, the TC actually helps, since it uses only the middle of the lens image, so the soft corners are gone! This is one of the rare times in life when it is good to "cut corners"!

Of course, in real-life use, the loss of 1 f-stop can be a factor. However for daytime outdoor nature or portrait shots, this is rarely a problem.

...Cameramonger

i need to pick up one of these to use with my 70-200

I have been using a Kenko TC with my 135L and sharpness is excellent. CA is more noticeable when shooting wide open, but it is still rather good.

I received mine today, really excited!
I tried it first with Tamron 200-500mm, amazingly, at max focal length (700mm f8 ), I still can focus !!!
So, 500mm + 1.4TC + 1.6 Cropped Body = 1000mm ? (please correct me if I am wrong)
The exif file at max reads: 700mm (on cropped body)
here is a test shot (460mm, F8 ) this pic has no sharpening but does added a little vibrance

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dongson wrote in post #10124132
I received mine today, really excited!
I tried it first with Tamron 200-500mm, amazingly, at max focal length (700mm f8 ), I still can focus !!!

I believe that is F/9.

Here is my extreme use of the 1.4x: 20D->2x->1.4x->400mm F/5.6. 100%, lens wide open. So 1120mm F/16.

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dongson wrote in post #10124132
I received mine today, really excited!
I tried it first with Tamron 200-500mm, amazingly, at max focal length (700mm f8 ), I still can focus !!!
So, 500mm + 1.4TC + 1.6 Cropped Body = 1000mm ? (please correct me if I am wrong)
...

Ok, you're wrong. It (basically) equals a 700mm lens. But since you're only using the center of it you get the same field of view as you would with an 1120 mm lens on an ff body. Technical nit picking I know, but it's not an 1120mm lens.

Also, you need to remember that you're cropping the field of view of the TC as well as the lens itself.

So it's not : (.4 + .6 X focal length) + focal length.
It's : ((.4 X focal length) + focal length) X 1.6

Thanks for corrected me on that, I never good at that and yeah, it was a f9 (Not f8 ) - it was 2AM in the morning
Sonny

RandyS wrote in post #10124720
Ok, you're wrong. It (basically) equals a 700mm lens. But since you're only using the center of it you get the same field of view as you would with an 1120 mm lens on an ff body. Technical nit picking I know, but it's not an 1120mm lens.

Also, you need to remember that you're cropping the field of view of the TC as well as the lens itself.

So it's not : (.4 + .6 X focal length) + focal length.
It's : ((.4 X focal length) + focal length) X 1.6

anyone tried taking a picture of saturn with a 400 2.8 +2x tc +1.4x tc on a 7D body?

Focusing should be easier with live-view and F/8, was bloody hard through a 20D VF @ F/16!

phreeky wrote in post #10152777
Focusing should be easier with live-view and F/8, was bloody hard through a 20D VF @ F/16!

yea, i saw yours, pretty cool, i don't have a tracking tripod mount, so i'm hoping the f8 will help with the speed of the little dot, and getting a little xtra crop-reach outta it (and hopefully some more sharpness w/o the faster shutterspeed of 2 stops for less motion blur. Live view has been amazing for focusing on the moon, just zooming in to 10x on the lcd makes it much more obvious than the viewfinder when its right on.