The first comparison I posted is indeed quite flawed, only vaguely illustrates the general issue; the second one is more accurate, I posted the link as the image is too large , and a smaller view not clear enough .
Okay guys OT from the current discussion, but I have a question.
Rokkor 135/2 MD Conversion. Is it reversible? Similar to the 85/1.7, or is the aperture mechanism controlled by a 'thin' rear mount part like on most MD lenses?
I can't even find a photo of the lens, nevermind of the rear mount to guestimate!
Tomser wrote:
Good stuff, thanks for the replies !
The first comparison I posted is indeed quite flawed, only vaguely illustrates the general issue; the second one is more accurate, I posted the link as the image is too large , and a smaller view not clear enough .
Bifurcator, what camera are you using ?
Me, GH1. Others are using APS-C and FF tho if we're still talking about the PF thing. And on that note, isn't PF usually equal across the entire frame or are corners sometimes worse? I thought it was usually even across the whole. (?)
ricardovaste wrote:
Okay guys OT from the current discussion, but I have a question.
Rokkor 135/2 MD Conversion. Is it reversible? Similar to the 85/1.7, or is the aperture mechanism controlled by a 'thin' rear mount part like on most MD lenses?
I can't even find a photo of the lens, nevermind of the rear mount to guestimate!
no idea. i've never seen one for sale or even seen one. here's a review with some unhelpful pictures of the lens: http://www.rokkorfiles.com/135mm.htm
Bifurcator wrote:
Me, GH1. Others are using APS-C and FF tho if we're still talking about the PF thing. And on that note, isn't PF usually equal across the entire frame or are corners sometimes worse? I thought it was usually even across the whole. (?)
Yup, the PF is across the frame; the APOs have a little CA as well, but that's the lateral kind mostly; all my Minolta MF lenses have noticable PF/ longitudinal CA wide open , no matter what kind of scene, distance, lighting etc., and only get better 2-3 steps stopped down .
Looking at all the clean samples I see shot with Nex and Alt lenses, or other cameras and Rokkors, I'm quite confused .
Below the lenses I tried, fwiw ...
Well, enough of that, it's getting too OT, sorry ...
Tomser wrote:
Yup, the PF is across the frame; the APOs have a little CA as well, but that's the lateral kind mostly; all my Minolta MF lenses have noticable PF/ longitudinal CA wide open , no matter what kind of scene, distance, lighting etc., and only get better 2-3 steps stopped down .
Looking at all the clean samples I see shot with Nex and Alt lenses, or other cameras and Rokkors, I'm quite confused .
Below the lenses I tried, fwiw ...
Well, enough of that, it's getting too OT, sorry ...
honestly, i've never shot with a reasonably fast prime lens that didn't show easily noticeable loCA, even modern high quality auto focus designs. with most of these lenses it is not too distracting though unless you fixate on it, it is definitely something to pay attention to in your compositions though. if you want loCA free lenses you need to shoot zooms, apo lenses (even these aren't totally corrected for it), or slow wide angles. apparently it just isn't much of a priority in lens design.
sebboh wrote:
honestly, i've never shot with a reasonably fast prime lens that didn't show easily noticeable loCA, even modern high quality auto focus designs.
I beg to differ - I have not once experienced that amount of longitudinal CA - in the focus plane (!) - with any lens made for digital cameras .
Tomser wrote:
I beg to differ - I have not once experienced that amount of longitudinal CA - in the focus plane (!) - with any lens made for digital cameras .
"that amount" meaning what you show in the examples? i haven't seen much of that either, but easily noticeable i've seen lots of. out of curiosity what primes have you used that don't show loCA? i've been looking for one and failing for a long time.
sebboh wrote:
out of curiosity what primes have you used that don't show loCA? i've been looking for one and failing for a long time.
The CV 180/4 APO-Lanthar is the most LoCA-free lens I have used in the 100-200mm range, apparently as a tradeoff for a tiny bit of lateral CA; in my experience, it has even less LoCA than the Mamiya 200/2.8 APO and Leica 100/2.8 APO-Macro (which are already extremely well corrected for LoCA compared to non-APO primes), comparing at equal apertures.
Bifurcator wrote:
Me, GH1. Others are using APS-C and FF tho if we're still talking about the PF thing. And on that note, isn't PF usually equal across the entire frame or are corners sometimes worse? I thought it was usually even across the whole. (?)
Tomser wrote:
Yup, the PF is across the frame; the APOs have a little CA as well, but that's the lateral kind mostly; all my Minolta MF lenses have noticable PF/ longitudinal CA wide open , no matter what kind of scene, distance, lighting etc., and only get better 2-3 steps stopped down .
Looking at all the clean samples I see shot with Nex and Alt lenses, or other cameras and Rokkors, I'm quite confused .
Below the lenses I tried, fwiw ...
Well, enough of that, it's getting too OT, sorry ...
I don't think it's off topic. (I think) the entire reason to have a image thread on a lens or lens group is to discuss how to use them, convert them, what their strengths and weaknesses are, and of course to brag a little. So you seem perfectly on-topic to me.
And with that, I'm as confused as you are. I have a couple of hundred MF lenses and only a handful produce CA artifacts that show up in 100% screen displays. At 400% I can see more but that's kinda stretching things. Even a smaller handful yet produce PF. In almost all cases the the few with fringing and CA artifacts are slight enough that is would not show up at all in an 8x10 print out. Maybe in Double Quad Crown 60" x 40" (Movie Theater Poster) sizes it would be noticeable if you were to stand close enough tho. And even at that, again, there's only a handful in my collection that do that. There are some lenses that do it in an artistic why and I'm not really counting them - but there's only a few like hat too. A name that comes to mind for such a thing is Takumar - for example. There's a lot of CA in pre SMC takumars but it blends with the bokeh in a unique and "artsy" way so I dan't refer to it as CA - even tho it is.
mpmendenhall wrote:
The CV 180/4 APO-Lanthar is the most LoCA-free lens I have used in the 100-200mm range, apparently as a tradeoff for a tiny bit of lateral CA; in my experience, it has even less LoCA than the Mamiya 200/2.8 APO and Leica 100/2.8 APO-Macro (which are already extremely well corrected for LoCA compared to non-APO primes), comparing at equal apertures.
i was wondering about non apo lenses really. all the apo lenses seem to control loCA well enough for my taste even though it isn't eliminated.
i've been on the lookout for a CV 180/4 and even more so 125/2.5 macro at a decent price, but finding that seems unlikely these days. please voigtlander, lets get some SLII versions of those lenses?
sebboh wrote:
honestly, i've never shot with a reasonably fast prime lens that didn't show easily noticeable loCA, even modern high quality auto focus designs.
Tomser wrote:
I beg to differ - I have not once experienced that amount of longitudinal CA - in the focus plane (!) - with any lens made for digital cameras .
The Nikkor AF 85mm f/1.4 D (IF) is for digital right? That has PF and some CA too - shot wide open! That's a $1,500 lens too. :P
sebboh wrote:
i was wondering about non apo lenses really. all the apo lenses seem to control loCA well enough for my taste even though it isn't eliminated.
i've been on the lookout for a CV 180/4 and even more so 125/2.5 macro at a decent price, but finding that seems unlikely these days. please voigtlander, lets get some SLII versions of those lenses?
Though not alt, the Canon 100/2.8 macro that I used to have (pre-L, presumably the L version too) was quite well corrected against chromatic aberrations. The Mamiya 150/2.8A (one of Mamiya's "almost APO" lenses) is another reasonably inexpensive option (not quite as good as the Mamiya 200/2.8 APO, but close and significantly smaller/lighter/cheaper).
Bifurcator wrote:
And with that, I'm as confused as you are. I have a couple of hundred MF lenses and only a handful produce CA artifacts that show up in 100% screen displays. At 400% I can see more but that's kinda stretching things. Even a smaller handful yet produce PF. In almost all cases the the few with fringing and CA artifacts are slight enough that is would not show up at all in an 8x10 print out. Maybe in Double Quad Crown 60" x 40" (Movie Theater Poster) sizes it would be noticeable if you were to stand close enough tho. And even at that, again, there's only a handful in my collection that do that. There are some lenses that do it in an artistic why and I'm not really counting them - but there's only a few like hat too. A name that comes to mind for such a thing is Takumar - for example. There's a lot of CA in pre SMC takumars but it blends with the bokeh in a unique and "artsy" way so I dan't refer to it as CA - even tho it is.
<Shrug> I'm lost, I dunno what to tell ya man. ...Show more →
i agree with you about lateral CA on in focus regions being generally not a serious problem, but loCA, or bokeh CA, or lateral color, or whatever it's called is prevalent in most of the lenses i've used. to be specific about what i'm talking about it's the purple fringing in the oof regions in front of the focus and green fringing in the oof regions behind the focus point. here's an example of it that is readily visible at websize with rokkor 135/2.8: http://farm6.static.flickr.com/5225/5683349317_0263cf7541_b.jpg
this is a particularly difficult kind of shot to avoid this type of CA with, but i see it to some degree in every narrow dof shot i've taken with a lens faster than f/2 and in every narrow dof shot i've taken with a telephoto that wasn't a zoom or apo.
I get that too but I wouldn't say "most". Typically only lenses capable of f/1.4 or wider and then to varying degrees for each model. Sometimes it's quite strange... as the image is displayed in ACR briefly just before the demosaicing it's REALLY there (everything is totally fuzzy but the OOF CA colors are rich and bright) - then 2 seconds later when the image demosiacs and becomes sharp on-screen it's all (100%) gone. That's caused me to scratch my head on more than one occasion. But when I look at the ACR defaults for that lens/ISO anything that might do that is set to zero, or whatever.
Bifurcator wrote:
I get that too but I wouldn't say "most". Typically only lenses capable of f/1.4 or wider and then to varying degrees for each model. Sometimes it's quite strange... as the image is displayed in ACR briefly just before the demosaicing it's REALLY there (everything is totally fuzzy but the OOF CA colors are rich and bright) - then 2 seconds later when the image demosiacs and becomes sharp on-screen it's all (100%) gone. That's caused me to scratch my head on more than one occasion. But when I look at the ACR defaults for that lens/ISO anything that might do that is set to zero, or whatever. ...Show more →
maybe the way i shoot provokes it more. i have noticed that about ACR too, and i think part of their standard demosaicing algorithm corrects at least partially for PF.
So you seem perfectly on-topic to me.
