p.20 #3 · Zeiss "Batis" AF lens line to be released for FF E-mount
The flip side is that for very precise mf adjustment, FBW is pretty amazing. The FE90/2.8 Macro will be amazing with DMF.
sebboh wrote:
that's good to hear charles, the 35/1.4 still changes the throw depending on how fast you turn it though doesn't it?
i agree the FBW can be better than the manual focusing of most AF lenses when taking your time shooting non moving subjects, i haven't found it to be any better than most good manual focus lenses though. i agree that some MF lenses have nicer throw and damping, though i don't really like nikkor AI lenses (better than the AIS ones though). i actually like the rokkor MCs almost as much as the leica Rs with takumars following close behind.
p.20 #4 · Zeiss "Batis" AF lens line to be released for FF E-mount
The Zeiss Touit 50/2.8 MP as well as the Zuiko Digital 50/2 Macro has a focusing throw of 720 degrees from infinity to the near limit.
The Olympus M.Zuiko 60/2.8 can give you 6 x 360 degrees from infinity to the near limit. This last example is the most stunning I've come across regarding FBW. The lens is optically excellent too.
This just to name two examples of what FBW lenses can do.
p.20 #5 · Zeiss "Batis" AF lens line to be released for FF E-mount
TheEmrys wrote:
The flip side is that for very precise mf adjustment, FBW is pretty amazing. The FE90/2.8 Macro will be amazing with DMF.
i don't find it to be amazing, just a little better than a standard AF lens and no better than a good manual focus lens (worse than most actually in my experience). most manual focus macros are quite good for manual focus in the macro range, it's lost longer distances they suffer. i doubt the new FE will offer any improvement. though i admit i usually just move the whole camera and lens to focus at macro distances anyway.
p.20 #6 · Zeiss "Batis" AF lens line to be released for FF E-mount
MTF-values worthy of being called MTFs should be the result from measurements made using an optical bench. They would thus include no PP at all.
Am I missing something here?
p.20 #7 · Zeiss "Batis" AF lens line to be released for FF E-mount
I think that I don't need to worry about the 3% distortion in my forest images or landscapes. On rare cases I shoot something humanmade stuff it may be visible.
I tried the distortion correction in Lightroom and it added some dullness to image. Luckily it seems that I'll have needed functionality in ImageMagick, in which I can control:
- how the distortion correction is done
- what image resampling method is used
In my workflow, no matter which RAW converter is used, I do final steps with ImageMagick (e.g. adjust acutance, downsizing to websize etc.). So this is just adding one (or two) command line options to ImageMagick command in the script.
I would prefer option in Focus By Wire to not have the speed steps. I shoot only non-moving objects & manually focusing instead of AF with FE55&FE35. To me the focusing is really annoying because of the focusing speed changing all the time. For me the FE55 "slow throw" seems too slow, and camera/lens kicks in way too easily the "faster throw". It makes me easily go to cycle "front focus"-"back focus"-"front focus"... which rarely happens with manual focus lenses. Luckily I don't like the FE55 boke rendering and therefore don't have to suffer using it very often. We can just hope that Zeiss has done this better than Sony with FE55.
In perfect world there would be parameter in camera menu "use speed steps for MF: yes/no" and if "no" selected then one could select the constant speed from 1-10 or something (or switches on lens barrel would be preferred by me but not likely to happen anymore in 2015...).
I find it very annoying that macro lenses have 720+ degree focusing; takes forever to focus from 1:2 to 1:1 and the added accuracy by long throw is never needed, but then 2 meters (6 feet) to infinity is in last 5 degrees. Good example is ZE/ZF Makro-Planar 2/100, which is pretty annoying to focus on normal use due to extreme short throw, but at same time annoying in makro use due to too long throw. If I would make FBW makro lens I would program it to have 270 degree turn of which 90 degrees is for 1m to infinity and the rest for 1m to 1:1. On helicoil based lenses this cannot be done because much more lens extension is needed on 1:1 than at infinity.
p.20 #8 · Zeiss "Batis" AF lens line to be released for FF E-mount
Jonas B wrote:
MTF-values worthy of being called MTFs should be the result from measurements made using an optical bench. They would thus include no PP at all.
Am I missing something here?
I agree, and the same can be said about illumination fall-off and distortion. Touit data for fall-off and distortion, however, are measured on a NEX 7.
p.20 #9 · Zeiss "Batis" AF lens line to be released for FF E-mount
Jonas B wrote:
MTF-values worthy of being called MTFs should be the result from measurements made using an optical bench. They would thus include no PP at all.
Am I missing something here?
I think the MTF values should always be paired with Distortion calcs -
either (a) MTF and Distortion w/ zero correction
or (b) MTF and Distortion w/ corrections applied
and there should be clear labeling about what is going on when measurements are shown.
we're all grown ups and can make our own conclusions - provided we know what's going on when the measurements are being taken / reported.
p.20 #10 · Zeiss "Batis" AF lens line to be released for FF E-mount
Is there a current macro that uses DMF? For macro, portrait, and long teles, dmf/fbw is a pretty nice option.
sebboh wrote:
i don't find it to be amazing, just a little better than a standard AF lens and no better than a good manual focus lens (worse than most actually in my experience). most manual focus macros are quite good for manual focus in the macro range, it's lost longer distances they suffer. i doubt the new FE will offer any improvement. though i admit i usually just move the whole camera and lens to focus at macro distances anyway.
p.20 #11 · Zeiss "Batis" AF lens line to be released for FF E-mount
TheEmrys wrote:
Is there a current macro that uses DMF? For macro, portrait, and long teles, dmf/fbw is a pretty nice option.
i have yet to find a use for dmf (it's just about the slowest way to take a portrait ever), but the rx1 has it in macro mode and i imagine both e-mount macros must have it.
p.20 #12 · Zeiss "Batis" AF lens line to be released for FF E-mount
ecarlino wrote:
I think the MTF values should always be paired with Distortion calcs -
either (a) MTF and Distortion w/ zero correction
or (b) MTF and Distortion w/ corrections applied
and there should be clear labeling about what is going on when measurements are shown.
we're all grown ups and can make our own conclusions - provided we know what's going on when the measurements are being taken / reported.
The problem with measuring MTF with distortion correction applied is that you're no longer measuring the MTF of the lens, you're measuring the MTF of the lens / filter stack / sensor / image processing chain system. Values measured using say the A7R would not be applicable to someone planning to use the lens on an A7.
And what if you plan to sell lenses on multiple mounts? Which camera do you chose to do the measurement?
MTFs should be for the lens only, measured on an optical bench, without the use of cameras. The only reason things like Imatest etc. exist and are used by lens review sites, is that optical benches are prohibitively expensive (unless you're a lens manufacturer or hip lens rental site) so measuring the system MTF as a proxy for the lens MTF is all you can manage. Attempting to do so in the presence of distortion correction is dubious, as demonstrated by the fact that said hip lens rental site (I'm just jealous because they're not in the UK) measured worse resolution figures in the centre after correction, when mathematics would predict better results there.
p.20 #13 · Zeiss "Batis" AF lens line to be released for FF E-mount
How would it be slow? It is just as fast as the autofocus is. Give a tiny twist, achieve critical focus, done.
sebboh wrote:
i have yet to find a use for dmf (it's just about the slowest way to take a portrait ever), but the rx1 has it in macro mode and i imagine both e-mount macros must have it.
p.20 #14 · Zeiss "Batis" AF lens line to be released for FF E-mount
lag jumping to magnified view when I touch the focus ring (for some reason it's faster to just hit the magnify button in MF mode), slowness of the AF (more of a problem on the rx1), and slowness in composing since you have to move the focus point around or focus then recompose.
TheEmrys wrote:
How would it be slow? It is just as fast as the autofocus is. Give a tiny twist, achieve critical focus, done.
p.20 #15 · Zeiss "Batis" AF lens line to be released for FF E-mount
Matt Grum wrote:
The problem with measuring MTF with distortion correction applied is that you're no longer measuring the MTF of the lens, you're measuring the MTF of the lens / filter stack / sensor / image processing chain system. Values measured using say the A7R would not be applicable to someone planning to use the lens on an A7.
And what if you plan to sell lenses on multiple mounts? Which camera do you chose to do the measurement?
MTFs should be for the lens only, measured on an optical bench, without the use of cameras. The only reason things like Imatest etc. exist and are used by lens review sites, is that optical benches are prohibitively expensive (unless you're a lens manufacturer or hip lens rental site) so measuring the system MTF as a proxy for the lens MTF is all you can manage. Attempting to do so in the presence of distortion correction is dubious, as demonstrated by the fact that said hip lens rental site (I'm just jealous because they're not in the UK) measured worse resolution figures in the centre after correction, when mathematics would predict better results there.
Matt, you're obviously a smart guy who understands a lot about this stuff. Unfortunately, sometimes when that happens, it lures one into thinking theirs is the only way.
Camera lenses are not unlike any other technical instrument in terms of measuring and reporting performance. There are many ways to do both.
The point I was making is that any such reporting should be clearly labeled as to whether or not it was with or without any corrections. Sometimes, it seems confusing as to whether or not certain corrections have been applied or not.
To your point regarding lens / camera combinations - I believe DXO's Lens measurements are already camera specific, so it's not out of the question to be that detailed as an option (even if one doesn't like their methods, it simply proves that it's not an insurmountable amount of work).
You are correct that measurements after any corrections or mounted on a specific camera are not just about the lens - but, as an option - that has value to some. I'd prefer to know the exact performance of the whole system I'm contemplating (camera, lens, corrections).
Certainly, none of this would preclude a 'lens only' measurement which itself would be very informative.
p.20 #17 · Zeiss "Batis" AF lens line to be released for FF E-mount
sebboh wrote:
i have yet to find a use for dmf (it's just about the slowest way to take a portrait ever), but the rx1 has it in macro mode and i imagine both e-mount macros must have it.
DMF was a must for me when using the Sony E 35mm f/1.8 on my NEX. I'd AF on a face, but AF doing what AF does didn't know what, exactly, I wanted to focus on. Eyebrow or nose instead of the eye, etc. The new eye detect AF probably improves on that, but it was a big frustration on the NEX until I started using DMF.
p.20 #18 · Zeiss "Batis" AF lens line to be released for FF E-mount
ecarlino wrote:
Matt, you're obviously a smart guy who understands a lot about this stuff. Unfortunately, sometimes when that happens, it lures one into thinking theirs is the only way.
Camera lenses are not unlike any other technical instrument in terms of measuring and reporting performance. There are many ways to do both.
When buying a technical instrument I expect to see measurement (however it is performed) of that technical instrument itself, not combined with random other instruments I may not plan to use it with. If I buy a car I'm happy to have torque specified at the driveshaft, not measured according to how much torque can actually be applied to the road when using an arbitrary set of tyres on a particular surface.
ecarlino wrote:
The point I was making is that any such reporting should be clearly labeled as to whether or not it was with or without any corrections. Sometimes, it seems confusing as to whether or not certain corrections have been applied or not.
I don't think they need to be clearly labelled, lens MTF charts indicate the performance of the lens, that is by definition without any software correction for distortion. There should be no confusion if the reader understands what an MTF chart represents.
ecarlino wrote:
To your point regarding lens / camera combinations - I believe DXO's Lens measurements are already camera specific, so it's not out of the question to be that detailed as an option (even if one doesn't like their methods, it simply proves that it's not an insurmountable amount of work).
Zeiss make lenses, I think it's perfectly reasonable for them to publish a chart detailing what that lens does with the light that hits it, what the camera then does with that light isn't really their problem. But for camera manufacturer's own lenses, yes that would be nice if in addition to a real measured lens-only MTF chart they somehow accurately measured every single lens against every single camera body and kept the results updated every time a new body is released.
But that's a lot of work for no real benefit (I don't think they'd sell any more lenses if they did this, after all most people don't even read the MTF charts), and you still have the issue that measuring modulation from image data is unreliable as it's sensitive to things like the choice of demosaicing algorithm and the type of interpolation used.
If you want to say it's misleading to sell lenses without this information then I'd disagree since you're buying a lens and they're telling you the performance of the lens, but consider this, they don't even tell you what the actual focal length (the most fundamental property) of the lens you're buying is! It's not unheard of for a "200mm" lens to have a focal length at infinity of 180mm. That is my eyes is misleading.
p.20 #19 · Zeiss "Batis" AF lens line to be released for FF E-mount
Matt Grum wrote:
When buying a technical instrument I expect to see measurement (however it is performed) of that technical instrument itself, not combined with random other instruments I may not plan to use it with. If I buy a car I'm happy to have torque specified at the driveshaft, not measured according to how much torque can actually be applied to the road when using an arbitrary set of tyres on a particular surface.
I don't think they need to be clearly labelled, lens MTF charts indicate the performance of the lens, that is by definition without any software correction for distortion. There should be no confusion if the reader understands what an MTF chart represents.
Zeiss make lenses, I think it's perfectly reasonable for them to publish a chart detailing what that lens does with the light that hits it, what the camera then does with that light isn't really their problem. But for camera manufacturer's own lenses, yes that would be nice if in addition to a real measured lens-only MTF chart they somehow accurately measured every single lens against every single camera body and kept the results updated every time a new body is released.
But that's a lot of work for no real benefit (I don't think they'd sell any more lenses if they did this, after all most people don't even read the MTF charts), and you still have the issue that measuring modulation from image data is unreliable as it's sensitive to things like the choice of demosaicing algorithm and the type of interpolation used.
If you want to say it's misleading to sell lenses without this information then I'd disagree since you're buying a lens and they're telling you the performance of the lens, but consider this, they don't even tell you what the actual focal length (the most fundamental property) of the lens you're buying is! It's not unheard of for a "200mm" lens to have a focal length at infinity of 180mm. That is my eyes is misleading.
And my point is that it's great if that's how you want to do things, but there are alternatives.
I would prefer to know how a lens is going to work on the camera I choose to shoot with and with or without software corrections. I care much less if a lens is awesome if I'm simply shining light through it but would have crappy corners on certain cameras, even though that can be informative as well.
p.20 #20 · Zeiss "Batis" AF lens line to be released for FF E-mount
DxO's work in this area is best regarded as pop science, and caused endless confusion and argumentation. Imatest is a guide at best. Anyone wanting to know about lens performance should put pressure on the myriad of makers who publish counterfeit measures - useful only as a guide to their designers - to put the results of their bench tests in the public arena, for all apertures too.
theSuede comes by at times to indicate the difficulties in the testing, in set up etc. as well as reporting of methodology. Even CZ offers scant information on this side of it, so the whole area is something of a black art. I'd like to see it become a certification issue, like compliance and safety testing for cars. I agree with Matt on the lens-camera separation, you have to know about lens performance long after any specific body is long gone. The specs published should be richer, too.
When it comes to MTF, most makers have their user base right where they want them - in the dark. Much easier to hide midfield curvature, embarrassing corners, heavy vignetting that never goes away, etc.
ecarlino, if you think Batis 85 corners will melt in front of your very eyes, don't buy one. Me, I trust the outfit that has been around since the beginning, to make judicious trade offs. This is exactly the art and science of lens design.
