New to the forum. I’ve been eagerly awaiting these I-Series lenses and enjoying your sample images so I thought I’d join so I could report on my experience.
I got the 35 and unfortunately I’m going to have to return it and try another one. The bottom left corner is very blurry in comparison to the others. I did some centering tests and it looks fine but every other way I’ve tested it shows a lot of blur in just one corner. I think something must be tilted or out of alignment. To put it in perspective, even my tamron 28-75 is better at 35mm and f/2.8 than the Sigma at 2.8...at least in that one corner.
Where it’s sharp, it’s very sharp, and I really like the rendering. I’m bummed I have to return it but I know I won’t be happy if I don’t at least try another one. I hope my second try works out because I really like the handling and aperture ring (I’m also a Fuji shooter).
Anyway, that’s my story. Thanks to everyone else for sharing.
My first Batis 25 was sharp in all 4 corners a every aperture at distance, but when I focused on something closer, the lower right corner always was blurry. Almost like it had a different depth of field. So I've seen some crazy things....
PaulMoorePhoto wrote:
Hi Everyone,
New to the forum. I’ve been eagerly awaiting these I-Series lenses and enjoying your sample images so I thought I’d join so I could report on my experience.
I got the 35 and unfortunately I’m going to have to return it and try another one. The bottom left corner is very blurry in comparison to the others. I did some centering tests and it looks fine but every other way I’ve tested it shows a lot of blur in just one corner. I think something must be tilted or out of alignment. To put it in perspective, even my tamron 28-75 is better at 35mm and f/2.8 than the Sigma at 2.8...at least in that one corner.
Where it’s sharp, it’s very sharp, and I really like the rendering. I’m bummed I have to return it but I know I won’t be happy if I don’t at least try another one. I hope my second try works out because I really like the handling and aperture ring (I’m also a Fuji shooter).
Anyway, that’s my story. Thanks to everyone else for sharing....Show more →
Fred Miranda wrote:
Hi Nehemiah,
I received a second copy just to confirm how the 35/2 performs at infinity and it did just as good as the first copy. Now I can post the review crops with confidence.
The performance from my infinity test is very similar to the ephotozine's chart and different than what lenstip posted. I know the former uses IMATEST at closer distance which suggests that the 35/2 DG DN performs similarly at close and long distance.
So does the latter. I think (but am not sure) that EPZ might refocus at different chart locations like photo zone does, if only because they often show less difference one stop down than other people, suggesting that closer in FC is taken out of the equation. That would also explain the difference, since Lenstip's sample would have been centred too - they don't test uncenterd ones.
I was going to say I'll do a quick close range FC test, but actually, not now: for surely it doesn't matter. A flat field is important for infinity shooters, and we know it's flat there (mine certainly is, and perfectly centred). A bit of FC at closer distances (if there is any), where your subject is very unlikely to be planar, doesn't matter at all. But it will make a difference to chart tests that don't refocus.
DavidBM wrote:
So does the latter. I think (but am not sure) that EPZ might refocus at different chart locations like photo zone does, if only because they often show less difference one stop down than other people, suggesting that closer in FC is taken out of the equation. That would also explain the difference, since Lenstip's sample would have been centred too - they don't test uncenterd ones. I'll do a quick close range FC test...
Is an FC test done as an infinite test, but at closer distance on a flat surface? Say 10 feet away brick wall type thing?
nehemiahphoto wrote:
Is an FC test done as in infinite test, but at closer distance on a flat surface? Say 10 feet away brick wall type thing?
Th kind I have in mind is something like 40x focal length, with a chart or some other high resolution targets, focus on centre, make image, then focus or corner or edge, make image, and compare the corner or edge image made with focus on centre and focus on corner/edge. If they are the same, no FC, if they are different, FC.
Annoying test to do (which is why I don't often do it) because it is incredibly sensitive to target/sensor plane parallelism.
This is also a reason to prefer the Photozone methodology of refocussing for chart distance tests. Sure, you don't learn about FC, but it does massively mitigate the problem of parallelism, as small deviations won't matter.
DavidBM wrote:
Th kind I have in mind is something like 40x focal length, with a chart or some other high resolution targets, focus on centre, make image, then focus or corner or edge, make image, and compare the corner or edge image made with focus on centre and focus on corner/edge. If they are the same, no FC, if they are different, FC.
Annoying test to do (which is why I don't often do it) because it is incredibly sensitive to target/sensor plane parallelism.
This is also a reason to prefer the Photozone methodology of refocussing for chart distance tests. Sure, you don't learn about FC, but it does massively mitigate the problem of parallelism, as small deviations won't matter....Show more →
My first thought is when you get closer distance that plane parallelism issue. Have fun doing that, it really does sound like a choir. And thanks for explaining.
DavidBM wrote:
Annoying test to do (which is why I don't often do it) because it is incredibly sensitive to target/sensor plane parallelism.
I recently attempted something like that to try check the corners of a 35mm lens. It wasn't difficult since it happens that the large mirror in a bathroom here is glued right to the wall. Focusing at 1.4 meters in the middle of the reflected image of the lens gave me what I thought was a pretty good crack at the parallelism problem, and I just taped paper currency on the mirror near center, at midfield, and at the edges and corners. It wasn't a precise test (I'm a biologist, not an engineer), but the corners all looked equally sharp (or, since the lens was a ZM 35/1.4, equally unsharp) in this test, just as they do at infinity on my copy of the lens.
zugzwang2 wrote:
I recently attempted something like that to try check the corners of a 35mm lens. It wasn't difficult since it happens that the large mirror in a bathroom here is glued right to the wall. Focusing at 1.4 meters in the middle of the reflected image of the lens gave me what I thought was a pretty good crack at the parallelism problem, and I just taped paper currency on the mirrors near center, at midfield, and at the edges and corners. It wasn't a precise test (I'm a biologist, not an engineer), but the corners all looked equally sharp (or, since the lens was a ZM 35/1.4, equally unsharp) in this test, just as they do at infinity on my copy of the lens.
My 35/2, 45/2.8, and 65/2 are all perfectly centered. Still waiting on the 24/3.5. I’m a Sigma convert now. The release of 18mm and 90/100mm I-Series lenses would enable me to dispose of most of my Sony FE lenses.
Here are crop of 35mm on SL2, corner only. I did both test with center focus only and didnt spend time on fine tune focus. And Leica L mount focus wide open only, so if there is focus shift, the result will not be optimized. However, I mainly do this test to make sure they are not decentered copy and this will be the way I shoot most likely. I didnt try to focus at corner or do anything optimize cross frame sharpness and it looks like not needed given at f4 and above, both lenses are very sharp.
Based on results, I would say I definitely saw some lens out solve both on extreme corner at f2. I don't think this is important for my photography though. I wouldn't worry about it even if I have to use both at f2 at infinity for landscape. Maybe SL2 is not the best platform to test this. We wouldnt know unless someone can tested them on S1R. Sigma doesn't have a body do them justice.
Dustin likes the 24mm Siggy: 'I think that Sigma has managed to strike a nice balance between a high quality rendering along with excellent sharpness. This isn’t a cold, sterile lens, but rather one with some character despite being well corrected. I was actually pleasantly surprised by the optical performance of this lens'
Here's his sample gallery: https://dustinabbott.net/2021/02/sigma-24mm-f3-5-dn-image-gallery/
Fred Miranda wrote:
I'm pretty sure the 24/3.5 will beat the Sigma zoom @24mm at center but the Loxia 25 will do better at mid-zone where the Sigma is weakest. I will test it today with more precision if this is due to FC, resolution dip or a combination of both. In the case for the 45/2.8, it's a combination of both.
Thanks Fred; yes, what we need is a series where you focus on the midframe and corners, like you just published for the 35mm. The mid-frame field curvature looks pretty huge on the 24mm, just judging by how sharp that green tree (bottom left of frame) in the mid-ground is, relative to infinity.
genji wrote:
My 35/2, 45/2.8, and 65/2 are all perfectly centered. Still waiting on the 24/3.5. I’m a Sigma convert now. The release of 18mm and 90/100mm I-Series lenses would enable me to dispose of most of my Sony FE lenses.
My 65/2 was the only I series lens with a 0.07 tilt and 0.02 mount swing. I could adjust it easily with shims but have another review copy arriving next week. My 24/3.5, 35/2 and 45/2.8 are perfect on my A7R IV as well.
Petegh wrote:
Thanks Fred; yes, what we need is a series where you focus on the midframe and corners, like you just published for the 35mm. The mid-frame field curvature looks pretty huge on the 24mm, just judging by how sharp that green tree (bottom left of frame) in the mid-ground is, relative to infinity.
I still have not tested it if it's FC, resolution dip or a combination of both. I will know more today.
Fred Miranda wrote:
My 65/2 was the only I series lens with a 0.07 tilt and 0.02 mount swing. I could adjust it easily with shims but have another review copy arriving next week. My 24/3.5, 35/2 and 45/2.8 are perfect on my A7R IV as well.
