There would seem to be a lot of confusion around this issue.
My first series of images went as follows... taken at about 40 feet, with not a lot of detail in the test subject.
DA*200
DA*200 plus 1.4
DA*200 plus 1.7
DA*200 plus stacked TC
* it should be noted, there are slight but insignificant increases in detail when viewing these images as pixel peepers, but when reduce to the same size they are really insignificant.
The biggest difference would be smoother and smoother bokeh in the back ground, not more detail on the test subject.
You could reasonably look at these images and say, well, the TC doesn't really add anything to the image. to understand how TC's work this is a critical point. The problem with this as an illustration was, there was no detail in this image the DA*200 couldn't resolve, at this distance. So adding a TC added nothing.
You can see this in the old comparison on the site years ago where someone compared a K-01 image with a D800 image and found them to be about equal. The simple fact is if the K-01 can resolve all the detail, then the D800 can't really add anything. So you can see how it would be quite possible to assume that both extra resolution and using a TC doesn't increase detail, after some testing.
For a higher res image to be better than a lower res image, there has to be detail in the high res image that the low res image can't resolve. This is not true in every image, so there are cases where neither a higher resolution sensor or TC do not increase IQ. The above images being a case in point.
But what if I back up to 60 feet, and use a target with finer detail than the DA*200 and K-3 combination can resolve from that distance.
Then both the 1.4 and 1.7 TCs produce increasing level of detail not available in the original image.
HD DA 1.4 TC
F 1.7x AF adapter
- note- these are 1:1 crops of these images, reducing the image size of larger image can mean the gain in detail is lost in the image reduction.
The TCs allow us to capture detail not available in the DA*200 image by itself. I believe the confusion in this area is because, using an inappropriate target, it is possible to do a series of tests where the TC's don't really add anything new. However it is also possible to do a series of tests where TCs add a considerable amount of detail. And those would be in that zone after which the original lens and sensor combo is able to resolve visible detail in a scene, and in the zone where the TC is able to resolve more detail, before getting beyond that to where neither lens or lens and TC combo can resolve available detail. After getting a TC perhaps the first thing to realize is, in some cases it is just a framing aid. In other cases you can bring out more detail. It's all about understanding the circumstances where these things might happen.
Another situation where the TC won't add anything would be where there is some very fine detail that can't be resolved by the original lens, but that can't be resolved by the TC either. I'm sure I could fine tune the above test, so that both th DA*200 and the DA*200 plus the 1.4 didn't do a decent job of defining the bar code, but the 1.7 did. A TC is kind of like a higher resolution camera. You might not get any benefit from it, in a given image, but, on a subject filling less than half the frame, you won't get any less. But you might get more.
Last edited by normhead; 05-24-2016 at 01:08 PM.