Stuart, David, you have hit on exactly the problem I have with the lp/mm statement.
We're being told the minimum performance guarantee. I suspect the "guarantee" holds true over the entire image circle, but to be clear that is my supposition--Sinar did not specify what region the lp/mm figure was for.
That being said, if the typical lens resolves over 100lp/mm over most of its image circle (which would not be unreasonable for glass of this caliber), then a 50% improvement in the minimum might not be noticable--and indeed this is what Stuart is reporting.
On the other hand, if the typical lens struggles to get much above the lp/mm guarantee, then the AFD lenses could represent as much as a 50% improvement in resolving power.
In practice, I am aware that the former case is usually the norm. In fact, Zeiss (Kornelius Fleischer) reported 250lp/mm resolving power back in 2001:
I get 250 lp/mm with the Zeiss Distagon on Agfaortho 25. It took me some years to develop the technique and eliminate all influence factors that usually prevent a tester from getting resolutions that high. By the way, I am not the only one who has mastered this technique. There are more Hasselblad users out there who reach 200 lp/mm and beyond.
I believe that Schneider glass should be comparable in capability.
That brings me to Stuart's suggestion of testing. Unfortunately testing these lenses is both difficult (none in my area) and potentially fruitless, since the digital back I have today (eMo 75LV) has a theoretical maximum resolution of 69lp/mm... Even the oldest glass should still be able to outresolve my sensor--so I need to move to 6x6 film, get a 6060 film back for the Hy6 (whoops, not available), and get my hands on a good Imacon FlexTight scanner, etc... There is also the time committment as well. Do the results hold true for the AFD lineup in general? Am I testing a good copy? A bad copy? You can see where this is going! :bugeyes:
Instead, I look at it this way: basically any significant increase in resolving power will show up in an MTF chart, provided the charts are created from measurements of real-world lenses (and I believe the Zeiss and Rollei charts are some of the few that do this). It doesn't really matter to me
how they do it--by better manufacturing tolerances, new optical formulae, or with "lasers"
, improved resolution is something the MTF is designed to reveal--it should show up in the results. The Sinar & F&H guys know what they're doing--I have more confidence in their ability to measure performance than I do in mine. Plus, I'd rather be...(insert beer/wine/biking/eating/dancing/mountaineering/and oh yeah, making art!)
Stuart, your experience agrees with others I have spoken with in that no one seems to be able to tell the difference (at least on today's backs). Based on that, until I can get a good look at an AFD MTF, I think going with the standard AF lenses for the time being is the most pragmatic approach.
As for the aperture ring, I don't think I'm as bothered about the loss of the as you might be, partly because I suspect I'll be leaving the ring on 'A' all the time anyway (the handle grip has controls for both the shutter speed and aperture.
I had thought you were going to say the tactile feel of moving the ring was the bigger issue. I'm a bit puzzled because given that we're usually looking through the viewfinder when we take pictures, why look away to check the ring--the camera shows what aperture it's set to right in the finder. But I can understand everyone has their preferences, of course. I just ask in case I'm missing something obvious...
Son, thank you for the writeup on the MF lenses. As you know, I now have several MF lenses and love the way they handle. But because I will also be using these in the field, I may not always have two hands available--I may be in the mountains, or in a tree scouting my quarry. It will be nice to have AF at least for those lenses that offer it--I can (and will) still use MF in many situations. I was also unaware of the difference in MTF between the MF 180/2.8 and the AF 180/2.8. Thank you!
Kind regards,
Brad