p.2 #1 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
hlavo wrote:
It can be sharper if the lens is sufficiently sharp to work well with the telextender vs. the loss of detail involved in the upsizing process of the 300mm "bare" file.
That is where pixel-peeping can be misleading. Is individual pixel clarity reduced by a teleconverter. Yes. Is this enough to offset the loss of clarity from having to do a 4X upsize from use without the teleconverter? That depends on the lens.
That is what this test seems to be telling us.
Oh, I didn't really notice that all pictures were the same size regardless of focal length.
The loss of IQ wasn't that noticeable with the 2x Kenko. I might actually buy one for my 70-300VR so I get a longer lens until Nikon makes a 300/4VR.
p.2 #3 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
Have you tried the 2x Kenko with the Tamron 90/2.8? That would be the only other lens I would have any use of a TC for. Getting 2:1 magnification would be rather sweet.
p.2 #4 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
hlavo wrote:
That's why whenever possible I try to do my own tests....it sometimes adds a different perspective than all the theoretical discussions.
Unfortunately your test results are unlike any other such comparison I've seen at least with the 70-300VR. Like I said before I appreciate you doing this as I'd appreciate anyone taking the time to do such comparisons and sharing the results with others. It just doesn't make any sense that this lens is sharper with a TC than cropping or that the 2x TC is sharper than the 1.4 TC, sorry. TC use always results in some IQ degradation ( ranging from minimal to significant), even with a fine lens like the Nikon 300mm f4, and especially with a consumer grade zoom. Curious...
Then there's the inherent problems with TC use. One must weigh the benefits of the extra reach vs the IQ degradation, loss of light, and possible AF hunting. It's always a subjective determination with regard to the above issues.
p.2 #5 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
lorac wrote:
Unfortunately your test results are unlike any other such comparison I've seen at least with the 70-300VR...
That's one of the things that confused me too at first, until I realized that probably NONE of the images shown are actually 100% crops. Harry has probably downsized the 2X image slightly, and upsized the 1.4X and non-TC images in an attempt to match the subject size in all three final images. All images were taken from the same spot. (Harry correct me if I'm wrong.)
Personally, I would have taken the non-TC image, then "zoomed" backwards with my feet to take the 1.4X TC shot, being careful to get the same framing of the subject. The final 2X TC shot would require further "zooming" backwards. The comparison would show the full 100% image or a crop(s) thereof.
p.2 #6 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
Your understanding of what I did is correct, Albert.
There are practical reasons I did it the way I did it.
As Lora points out above, their are practical considerations and how/when to use a TC is a judgement call. The situation in which I took these pictures represents such a case. There is only one small spot in which to shoot this turbine without a mass of overhead wires being in the way, so changing location was simply not an option. Moreover, whenever contemplating using a 300mm lens (and in many cases even a 200mm) the option of foot adjustment is often not practical....that's why telezooms are so popular. So as a practical matter, it often comes down to:
* Do I use the 2X?
* Do I use the 1.4x and crop in a bit?
* Do I not use a tele and crop up a lot?
I would argue that this is "real-world" and my test is designed that way. Which option is best depends on the TC's used, the resolution of the bodies used, and the lens itself. Better lenses and/or TC's leans one towards TC use; higher resolution bodies leans one towards a crop/upsize. Specific lens/tc matches or mismatches can alter the result as well. So judgements are called for. What I really wanted to see was: with this 12mp body and these lenses of mine, what were the results of these practical trade-off options. For me, the test was useful.
All I can say is: if you don't think the results are representative, do your own test designed the way you think is best, and see what it gives you. I'd love to see a posting by someone else of this kind of thing. But more importantly, I think every serious photographer should be doing their own testing to really get to know their lenses and lens options.
p.2 #7 · Five Lens rigorous test with Kenko Pro 300 1.4x and 2.0x Telextenders
Harry
I know I'm a number of months behind on this thread.
My main interest is shooting birds and animals. Zooming with your feet often (as in usually) means no shot at all, since the subject will have taken off or worse yet may view you as a threat or as food, resulting in personal harm.
Last week, I took photos of a bald eagles nest, where the only practical shots were from 300' away. I have the Canon 7D, the EF-400 F5.6, and the Kenko Pro 1.4X and 2x TCs. With the bare lens, the autofocus is quick and accurate, with the TCs less so. So with the TCs, I reverted to manual focus using Live View and 10X screen zoom. My best close-ups, after cropping to the same size view and carefully comparing these, was with the lens, and both the 2X and 1.4X in series for 1100mm F16 (the light was good that day). The next best was with the 2X TC. The bare lens and the 1.4X TC were close to equal. Of course, this was with a captive audience, with the parent and chick in the nest.
So my real-world experience seems to match your testing somewhat.
The reporting of focal length and focal ratio was accurate with the TCs, even when stacked.
For birds in flight or serious motion, requiring accurate autofocus, it's the bare lens all the way. The 1.4X TC was fair. The 2X or the 2X-1.4X combo, try to autofocus, but it's a lost cause.
