Looks pretty clear that there's two lineups now with the new images.
I hope the 90mm is as smooth as the 45mm, but the press material for the 45mm describes how the smooth rendering came about because they couldn't get rid of all aberrations with that size constraint, but they started to like it. Unless a 90mm will always have those same physical constraints, they could choose to go with different priorities.
EDIT:
Pretty sure that Sigma, and competitors, would always choose sharpness over character when possible. It's just not worth it to get bad press from reviewers - as opposed to lots of free press.
Kermoedu wrote:
Looks pretty clear that there's two lineups now with the new images.
I hope the 90mm is as smooth as the 45mm, but the press material for the 45mm describes how the smooth rendering came about because they couldn't get rid of all aberrations with that size constraint, but they started to like it. Unless a 90mm will always have those same physical constraints, they could choose to go with different priorities.
EDIT:
Pretty sure that Sigma, and competitors, would always choose sharpness over character when possible. It's just not worth it to get bad press from reviewers - as opposed to lots of free press....Show more →
I believe Sigma could have corrected spherical aberration further for the 45/2.8i if that was a design goal even considering its small size.
For that lens specifically, it looks like the design decision was to prioritize axial CA correction and smooth transition bokeh rendering . The latter brought issues with phase detection AF as it's hard to get accuracy through high SA. Very likely the new 90/2.8i will better corrected for SA just by looking at the optical design and special glass used. I'm hoping is a little under corrected though as that works well for portraits. Curious to see what Sigma prioritizes for this lens.
Fred Miranda wrote:
I believe Sigma could have corrected spherical aberration further for the 45/2.8i if that was a design goal even considering its small size.
For that lens specifically, it looks like the design decision was to prioritize axial CA correction and smooth transition bokeh rendering . The latter brought issues with phase detection AF as it's hard to get accuracy through high SA. Very likely the new 90/2.8i will better corrected for SA just by looking at the optical design and special glass used. I'm hoping is a little under corrected though as that works well for portraits. Curious to see what Sigma prioritizes for this lens....Show more →
There was a Sigma Sein article on their website which said that they tried to correct SA better but couldn’t get in the elements needed in form factor required. They were disheartened, but when they looked at images from the prototype, liked the look and decided to go ahead….(presumably they meant they couldn’t correct monochromatic SA AND LoCA in the form factor).
DavidBM wrote:
There was a Sigma Sein article on their website which said that they tried to correct SA better but couldn’t get in the elements needed in form factor required. They were disheartened, but when they looked at images from the prototype, liked the look and decided to go ahead….(presumably they meant they couldn’t correct monochromatic SA AND LoCA in the form factor).
They prioritized rendering by under-correcting SA and that was a design decision. They had other options but realized that because of the lens' short length, the number of elements was limited.
I believe, Sigma engineers could have taken a different route though and develop a small 40mm f/2.8 better corrected for SA but still unable to achieve “superior MTF” -- similar to Sony's 35/2.8 ZA.
Thankfully, they decided developing a modern AF lens with a "classic look" that is still capable of high resolution a long distance. It's my favorite DG DN lens but I can't wait to try the new 90/2.8i.
Fred Miranda wrote:
It's a great article indeed. Thanks for the link.
They prioritized rendering by under-correcting SA and that was a design decision. They had other options but realized that because of the lens' short length, the number of elements was limited.
I believe, Sigma engineers could have taken a different route though and develop a small 40mm f/2.8 better corrected for SA but still unable to achieve “superior MTF” -- similar to Sony's 35/2.8 ZA.
Thankfully, they decided developing a modern AF lens with a "classic look" that is still capable of high resolution a long distance. It's my favorite DG DN lens but I can't wait to try the new 90/2.8i....Show more →
I’m sure they could have produced **somewhat** better MTF and less SA; but it’s clear that in the size constraint they couldn’t get the MTF that they wanted, and then changed the design direction towards the high SA look because of that..
We've read the same article but interpreted it slight differently.
The Sony 35/2.8 ZA and many other pancake lenses are proof that it's possible to design very good 35/40 f/2.8 AF lenses with "average/neutral" rendering. (well corrected for spherical aberration)
Sigma took a different approach with their 45/2.8i and under-corrected SA prioritizing rendering. It looks to me that this decision was not solely dictated by size constrain but also the desired to produce something unique knowing they could not get “superior MTF” wide open with only 8 elements and not many special glass.
My point is that it's possible to design a high resolution compact lens that is well corrected for SA and other aberrations if rendering and low price are not priorities.
Fred Miranda wrote:
We've read the same article but interpreted it slight differently.
The Sony 35/2.8 ZA and many other pancake lenses are proof that it's possible to design very good 35/40 f/2.8 AF lenses with "average/neutral" rendering. (well corrected for spherical aberration)
Sigma took a different approach with their 45/2.8i and under-corrected SA prioritizing rendering. It looks to me that this decision was not solely dictated by size constrain but also the desired to produce something unique knowing they could not get “superior MTF” wide open with only 8 elements and not many special glass.
My point is that it's possible to design a high resolution compact lens that is well corrected for SA and other aberrations if rendering and low price are not priorities....Show more →
I agree it was a desire to produce something unique, but I think they only got that desire after attempting art level MTF in the compact size. Sure they could have got 35/2.8 level MTF but (while I think that lens is perfectly sharp
enough) it’s nowhere near current Art/GM/AL or Leica L or Canon RFL levels of MTF they seem to have been originally aiming for. Actually, if my memory serves me, the ZA 2.8/35 may have no better MTF than the Sigma 45, as well as not having the SAtastic look that many people like.
But of course I agree that you can make a very sharp compact lens if you fully correct SA. The Sony G series lenses are proof of that. I wonder whether the target Sigma tried to achieve was that level but couldn’t do it (might require a dance of multiple linear motors they can’t yet achieve?) or an even higher level?
It's Sigma's 60th anniversary today (they were founded in September 9th 1961). That's probably why they decided to set the announcement of new products specifically for today. Looking forward to the Sigma Stage online session from 9pm (JST) today.
I received a Sigma 60th anniversary handkerchief in the mail with a thank you letter aimed at Sigma customers (probably since I've used their Japan online store and also been in contact for the 28-70/2.8 DG DN replacement in recent months). The handkerchief has 60 years counted in years, months, days, hours, minutes and seconds. It's 1 893 456 027 seconds by the way
This conversation needs a caveat... At even f/4 or infinity, the 45 is nearly as sharp as my Art, GM or Loxia lenses. The issues with the 45 are at f/2.8 and close focus distances.
It's a great dial purpose lens, at least for my uses.
DavidBM wrote:
I agree it was a desire to produce something unique, but I think they only got that desire after attempting art level MTF in the compact size. Sure they could have got 35/2.8 level MTF but (while I think that lens is perfectly sharp
enough) it’s nowhere near current Art/GM/AL or Leica L or Canon RFL levels of MTF they seem to have been originally aiming for. Actually, if my memory serves me, the ZA 2.8/35 may have no better MTF than the Sigma 45, as well as not having the SAtastic look that many people like.
But of course I agree that you can make a very sharp compact lens if you fully correct SA. The Sony G series lenses are proof of that. I wonder whether the target Sigma tried to achieve was that level but couldn’t do it (might require a dance of multiple linear motors they can’t yet achieve?) or an even higher level?...Show more →
DavidBM wrote:
I agree it was a desire to produce something unique, but I think they only got that desire after attempting art level MTF in the compact size. Sure they could have got 35/2.8 level MTF but (while I think that lens is perfectly sharp
enough) it’s nowhere near current Art/GM/AL or Leica L or Canon RFL levels of MTF they seem to have been originally aiming for. Actually, if my memory serves me, the ZA 2.8/35 may have no better MTF than the Sigma 45, as well as not having the SAtastic look that many people like.
But of course I agree that you can make a very sharp compact lens if you fully correct SA. The Sony G series lenses are proof of that. I wonder whether the target Sigma tried to achieve was that level but couldn’t do it (might require a dance of multiple linear motors they can’t yet achieve?) or an even higher level?...Show more →
From Dustin's review and my own experience with the 40 G: SA is not perfectly corrected on the 40 at least. Not a lens designer, but feel like the secret sauce allowing these compact primes to be as performant as they are (aside from the lens design/element choice) are Sony's knowledge of aspheric lens design coupled with their use of dual linear motor focusing groups. Ever since the 24 GM, we've seen a trend for Sony to develop lenses that for their specification are remarkably performant for the size and cost, while simultaneously achieving MFD/reproduction ratios that are uniformly excellent for internally focusing lenses.
Dave Sanders wrote:
This conversation needs a caveat... At even f/4 or infinity, the 45 is nearly as sharp as my Art, GM or Loxia lenses. The issues with the 45 are at f/2.8 and close focus distances.
It's a great dial purpose lens, at least for my uses.
That's a great point, I'm always surprised how sharp this little lens is, considering I treat it as a "character" lens most of the time .
zz wrote:
