Dick, I think my wording is accurate, at least when comparing teleconverters versus extension. If you focus a lens on an object, and add a 2x teleconverter. the lens will not need to be refocused. You will have doubled the magnification but there will be no loss of working distance. Now instead of adding a teleconverter, you add extension tubes to double the magnification. Now the lens needs to be refocused, and the direction of refocusing has to be the direction that moves the aerial image backwards towards the sensor. In other words, you have to focus closer. So you lose working distance relative to the teleconverter solution. And the difference can be very large. That's what I was trying to say in the post.Lou, I agree with everything you say apart from your wording about extension tubes providing magnification at the price of working distance.
I think you may be using the term "floating elements" differently than me. Floating elements don't necessarily alter the point of focus, or the focal length. They are any elements that move within the fixed lens assembly when the lens is refocused, usually to maintain lens corrections. For example, some Mamiya RZ67 lenses have floating elements that move (manually) to maintain corner quality as the lens is refocused. Early Nikon lenses had floating elements for the same reason. They do not necessarily change working distance. They might, though. The main point is that lenses with mechanically controlled floating elements will have worse optical quality when used with extension than when used with a teleconverter, because the elements won't be set to their correct positions for that focal point.Floating element focussing and close up lenses extension tubes give you magnification at the expense of working distance.
As I understand the term, floating elements INCREASE image quality.Extension tubes give you magnification at the expense of some loss of image quality and some working distance, but a lot less than floating elements or diopters.
This isn't clear to me, so I have no opinion about this.You therefore gain working distance when instead of a close up lens you use an extension ring.
I don't see this, at least when compared to teleconverters. The teleconverter always wins over extension tubes for working distance.If working distance is the highest priority, you may gain working distance by focussing the lens to infinity and use extension rings to focus closer. Not ideal optically of course.
This should depend mainly on the resolution of the prime lens. I have seen tests showing that it does give additional resolution if you stay under the diffraction limit. Also, theoretically, if you upscale the original image by a factor of two, you will have very coarse color resolution relative to the image obtained from a 2x teleconverter. Each block of four pixels in the upscaled image is based on only one actual color measurement, while the corresponding block of four image pixels on the teleconverter image will be based on R, G, G, and B measurements.Have you ever tested whether using a 1.4x teleconverter gives you more useful resolution than cropping in your system?
You could ask the same thing about extension versus cropping and upscaling. For a given lens, I should think the answer will be about the same whether you use a teleconverter or extension tubes. as long as the teleconverter is a good one.
It's the f/1.8. Lovely lens.Interesting. Is yours the Apo Xenoplan 35/1.8 or the Apo Xenoplan 35/2.0?