Crosstalk can be successfully profiled out in both LR and C1. The BSI sensors have us spoiled now, but even they don't resolve every problem for every lens. There are tools for it if you want to get fancy, but all you really need is a KEM wipe, a rubber band, and a sunny day. And you'd certainly want to do it with this lens because the crosstalk is going to make the cyan side of the lateral shift that much worse.
Reading Optical Limits test I wonder if it's the same lens! Including 'Lateral CAs are well controlled' Did 'Bobu' get a dud? Is there sample variation? My 9mm on Fuji is very good and I was considering this a manual focus 14
Gerry
Nov 11, 2020 at 04:09 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
gyoung143 wrote:
Reading Optical Limits test I wonder if it's the same lens! Including 'Lateral CAs are well controlled' Did 'Bobu' get a dud? Is there sample variation? My 9mm on Fuji is very good and I was considering this a manual focus 14
Gerry
No optical limits' test for CA misses a lot of CA. It reports low CA for a number of lenses where I see CA as a problem.
In this review on L-mount camera mid-zone resolution dip is described. Can anybody confirm on Sony sensor (different cover glass thickness, though that should affect corners the most)?
Steve Spencer wrote:
No optical limits' test for CA misses a lot of CA. It reports low CA for a number of lenses where I see CA as a problem.
Lateral CA?
Can you give a couple of examples? Klaus' tests are pretty good. But lateral CA is sometimes distance dependent, even more commonly with lenses with complex compensating groups, and I expect Klaus (like me) only tests at one distance.
Nov 12, 2020 at 01:03 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
DavidBM wrote:
Lateral CA?
Can you give a couple of examples? Klaus' tests are pretty good. But lateral CA is sometimes distance dependent, even more commonly with lenses with complex compensating groups, and I expect Klaus (like me) only tests at one distance.
Yep, that is part of the problem. Lateral CA can be distance dependent and I believe it can be dependent on how strong the illumination/exposure is as well. I believe he only test in even illumination with spot on exposure. Of course in the real world light isn't always like that and we need to understand lateral CA in less than even illuminate without perfect exposure if we want to know how a lens functions.
A couple of examples where Optical Limits claims seem not to match performance are the FE 55 f/1.8 ZA (which Optical Limits claims has a "very low amount" of lateral CA) and the FE 35 f/1.4 ZA (which Optical Limits claims has a "fairly low amount" of lateral CA). There are also many lenses that test at Optical Limits as having more to a lot more lateral CA as you stop down. Now lateral CA does not decrease as you stop down, but it doesn't increase either. This suggests that their testing may not capture all the lateral CA at wider apertures (I suspect it may be masked in their tests by SA). So suffice it to say, that I am not impressed at all with the lateral CA tests at Optical Limits. I do like their distortion tests. I find the bokeh tests to be useful when they do them and the basic sharpness tests are limited but fine if you know the limits. I find the lateral CA tests, however, to be much less useful.
Im about ready to buy this. Ive done the CV 15 3 times the Laowa 15 twice. This one is tough as some reviews sound positive than one member here sounds like he go a dud. I think we need a Guy review with the new A7C.
Steve Spencer wrote:
Yep, that is part of the problem. Lateral CA can be distance dependent and I believe it can be dependent on how strong the illumination/exposure is as well. I believe he only test in even illumination with spot on exposure. Of course in the real world light isn't always like that and we need to understand lateral CA in less than even illuminate without perfect exposure if we want to know how a lens functions.
A couple of examples where Optical Limits claims seem not to match performance are the FE 55 f/1.8 ZA (which Optical Limits claims has a "very low amount" of lateral CA) and the FE 35 f/1.4 ZA (which Optical Limits claims has a "fairly low amount" of lateral CA). There are also many lenses that test at Optical Limits as having more to a lot more lateral CA as you stop down. Now lateral CA does not decrease as you stop down, but it doesn't increase either. This suggests that their testing may not capture all the lateral CA at wider apertures (I suspect it may be masked in their tests by SA). So suffice it to say, that I am not impressed at all with the lateral CA tests at Optical Limits. I do like their distortion tests. I find the bokeh tests to be useful when they do them and the basic sharpness tests are limited but fine if you know the limits. I find the lateral CA tests, however, to be much less useful....Show more →
Hi Steve
Yes I think there is another reason that LaCA sometimes seems to increase with stopping down. It's because of an interaction with LaCA and LoCA. LaCA is of course a difference in magnification or distortion that is frequency dependent. So let's suppose we have in focus green elements in the corner with magenta fringing because the magenta channel is not perfectly overlapping due to different mag.dist. But now suppose that there is LoCA as well, causing the magenta to be OOF when the green is in focus. This then softens the LaCA effect. As you stop down, the magenta will get more in focus, and will start to look like a hard, classic LaCA magenta fringe.
I'm not sure what Klaus means by "low"; but I have used the 55ZA a lot over the years, and have never been annoyed by post-correction LaCA (I wish I could say the same for LoCA) but that doesn't mean it doesn't have any, of course.
I have it but have not officially tested it as I'm waiting on capture one to process . Waiting on new ball head too since I need my tripod. That comes today. Sorry slow on this test as well as the A7C and Samyang 75 1.8
memzinla wrote:
I really want a wide lens for L Mount.
I wonder which one is better:
Laowa 10-18mm
Laowa 14mm
Laowa 11mm
I haven't used the 11, but owned and sold the 10-18 and the mirrorless 14. Between those two, which one is better is a matter of preference. My copy of the zoom peaked at 14 with the least amount of distortion and the flattest field (which was still not all that flat). Except for the more severe vignetting, it kept up well with the little 14. One of the bigger problems with the zoom is the lack of electronic communication, so correcting distortion and vignetting has to be taken on a shot by shot basis if you're using the full range. I liked using the zoom on my APS-C camera, but the distortion and wavy FC made it tough to love on FF. Plus, the performance fell off sharply from 15-18, where I was most likely to use the lens on FF, so off it went.
For it's size and price, the mirrorless 14/4 isn't bad, but I think you really need to value the size above all else to be satisfied with it. It's great that it can take a filter (one, thin-framed filter that, unless you have hands roughly the same size of a young raccoon, you'll need a silicon vacuum wrench to install, and good luck with circ-pols). If you want to use NDs, I recommend hand-holding them.
I ended up with Laowa's F-mount 14/4, which I use both on an F100 and adapted to Sony mirrorless (https://www.venuslens.net/product/laowa-14mm-f-4-zero-d-dslr/). It's larger, and larger again with the adapter, but it's fairly compact for an SLR lens and decently light (360g in F, 320g in EF, but you will need a smart adapter for EF as the aperture is electronically controlled). It also has a removable hood and a 67mm filter thread. It's not a perfect performer, but it's significant improvement in all ways over the mirrorless 14 and the zoom.
I'm hoping the prototype 12-24/5.6 they showed off last year sees production this year.
I'm excited to use the 10-18mm just because I've never used anything that wide. I think I'll end up returning the lens due to the weight and manual focusing even though it's probably easier to focus with wide lenses.
If Sigma doesn't release a wider prime, I might end up with a Laowa 11mm or 14mm if the price is right.
Steve Spencer wrote:
Now lateral CA does not decrease as you stop down, but it doesn't increase either.
Apologies for dropping this in here late, I've just registered after reading a few threads on lenses of interest. Lateral colour can increase on stopping down. It will do this if there is chromatic astigmatism. In that case, the lateral colour is not constant across the pupil, and if you stop down, you might lose the 'best' bit of the pupil and see an increase in lateral colour. The effect is most pronounced on some telephotos. However for the majority of lenses it's fairly stable.
You can see this effect on some of the lateral colour profiles tested on DXOMark.
I agree with you that Optical Limits does a poor job of checking Lat colour.
Dec 28, 2022 at 01:25 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
Mark_OptDes wrote:
Apologies for dropping this in here late, I've just registered after reading a few threads on lenses of interest. Lateral colour can increase on stopping down. It will do this if there is chromatic astigmatism. In that case, the lateral colour is not constant across the pupil, and if you stop down, you might lose the 'best' bit of the pupil and see an increase in lateral colour. The effect is most pronounced on some telephotos. However for the majority of lenses it's fairly stable.
You can see this effect on some of the lateral colour profiles tested on DXOMark.
I agree with you that Optical Limits does a poor job of checking Lat colour....Show more →
That is not lateral CA, however, that is lateral CA interacting with other aberrations to affect what we observe. Lateral CA does not change, but that doesn't mean that what we observe doesn't change. In practice what we observe is always a complex interaction between many different types of aberrations. What you are describing is the interaction of lateral CA with astigmatism (to at least that is what you seem to be describing) and I have no doubt that can affect what we observe even though lateral CA doesn't change.
Well if you are purely referring to 'lateral colour' as C2, then you are correct, since C2 is a paraxial quantity.
What I'm talking about is more of a stop-shift effect where indeed the C2 is mixed with chromatic variation of astigmatism, so depending on which parts of the full exit pupil you take, you can see better or worse lateral colour as a whole, ie. the colour fringing you see on the image.
Here is an example of a lens whose lateral colour gets worse when you stop down, for the above reasons -
Mark_OptDes wrote:
Well if you are purely referring to 'lateral colour' as C2, then you are correct, since C2 is a paraxial quantity.
What I'm talking about is more of a stop-shift effect where indeed the C2 is mixed with chromatic variation of astigmatism, so depending on which parts of the full exit pupil you take, you can see better or worse lateral colour as a whole, ie. the colour fringing you see on the image.
Here is an example of a lens whose lateral colour gets worse when you stop down, for the above reasons -
I wasn't referring to lateral color at all (whatever you mean by that), and I am not sure what you mean by C2 either. I was referring to lateral chromatic aberration, but I think we agree. Lateral chromatic aberration does not change when you stop down, but what you perceive can be worse when you stop down because of the interaction of lateral chromatic aberration with other aberrations.
PS - I read your profile and see you are a lens designer. I suspect you are just using technical language (C2, etc.) that I just don't know what you are referring to, but I don't think we disagree. Correct me if I am wrong, however. I am glad to learn, but please let us know what you mean by the terms you use.
