Does the Sigma 45 have Focus Shift?.
Looyd Chambers at https://diglloyd.com/blog/2019/20190907_0530-SigmaFE35f1_2_DG_DN-ReaderComment.html says "... is a sleeper lens that might have potential when used appropriately... It is very compact and nice on a Sony body, so it might actually be very good for landscape, focused properly accounting for focus shift
Enri wrote:
Does the Sigma 45 have Focus Shift?.
Looyd Chambers at https://diglloyd.com/blog/2019/20190907_0530-SigmaFE35f1_2_DG_DN-ReaderComment.html says "... is a sleeper lens that might have potential when used appropriately... It is very compact and nice on a Sony body, so it might actually be very good for landscape, focused properly accounting for focus shift
I think he's making a mountain out of a molehill. On Sony cameras you can pretty much control whether the lens will focus (nearly) wide open or at working aperture:
Set the camera to Live Preview: ON, then it will behave like this:
- in MF it will focus at working aperture
- In AF-C it will do an initial reading at open then it will keep adjusting focus at working aperture
- In AF-S it will focus at working aperture if you also set "Aperture Drive in AF" to Silent.
There are a few lenses that are not compatible with the "Aperture Drive in AF" setting (i.e. the setting is fixed to Standard with no way to change it), those may give you trouble in AF-S if they also have focus shift. As in that scenario the focus reading may happen at a different aperture than the one you selected for the exposure.
So a good alternate question here is whether the Sigma 45 is compatible with that setting or not.
vdo1 wrote:
I think he's making a mountain out of a molehill. On Sony cameras you can pretty much control whether the lens will focus (nearly) wide open or at working aperture:
Set the camera to Live Preview: ON, then it will behave like this:
- in MF it will focus at working aperture
- In AF-C it will do an initial reading at open then it will keep adjusting focus at working aperture
- In AF-S it will focus at working aperture if you also set "Aperture Drive in AF" to Silent.
There are a few lenses that are not compatible with the "Aperture Drive in AF" setting (i.e. the setting is fixed to Standard with no way to change it), those may give you trouble in AF-S if they also have focus shift. As in that scenario the focus reading may happen at a different aperture than the one you selected for the exposure.
So a good alternate question here is whether the Sigma 45 is compatible with that setting or not....Show more →
scalanc2 wrote:
@VDO1@
The behavior is not what you mention here also with Sony lenses.
There are variations and I wish there was a table somewhere listing which exact lens does what. Unfortunately there isn't, so best course indeed is to ask the owners of the lens to confirm each scenario one is interested in.
When using AF-C, the lenses focus always at working aperture (except for the first focusing when Setting Effects = Off). Therefore AF-C is good when there's significant Focus shift, but the focusing may be less precise than with AF-S.
When using AF-S instead, the majority of lenses focus WO or more open than at the working f/ (once focus is locked, camera changes to working aperture), irrespective of Settings Effect = On/Off. This is not good when there's significant Focus shift...
With a compatible lens, even in AF-S, with the option "Aperture Drive in AF" = Silent you may force the lens to always focus at shooting aperture "to minimize the sound of the aperture opening during focus acquisition”, but the AF will get more slow and dubitative.
For the Sigma 45 there could be a better workaround for AF-S as it has an aperture ring. You may use this ring to adjust f/ (instead of with the camera control)... then the lens diaphragm stay at he adjusted aperture, irrespective of setting effect = off/on.
You can do the same on Sony lenses with the front gear in manual mode as you told.
Then no added value, I think.
Is the any list around on how various lenses work?
Sep 09, 2019 at 04:27 PM
imagesfromobjects Offline • • • • Upload & Sell: Off
Yeah, was going to say that I'm almost positive that with the physical aperture ring, it just stays wherever you put it. So unless you have the aperture on "A", focus shift would be a non-issue anyway. At least on a mirrorless.
I don't have the lens on hand to check, but I don't believe the diaphragm opens up to focus. If I'm incorrect, I welcome the clarification.
Enri wrote:
When using AF-C, the lenses focus always at working aperture (except for the first focusing when Setting Effects = Off). Therefore AF-C is good when there's significant Focus shift, but the focusing may be less precise than with AF-S.
When using AF-S instead, the majority of lenses focus WO or more open than at the working f/ (once focus is locked, camera changes to working aperture), irrespective of Settings Effect = On/Off. This is not good when there's significant Focus shift...
With a compatible lens, even in AF-S, with the option "Aperture Drive in AF" = Silent you may force the lens to always focus at shooting aperture "to minimize the sound of the aperture opening during focus acquisition”, but the AF will get more slow and dubitative.
For the Sigma 45 there could be a better workaround for AF-S as it has an aperture ring. You may use this ring to adjust f/ (instead of with the camera control)... then the lens diaphragm stay at he adjusted aperture, irrespective of setting effect = off/on....Show more →
Enri wrote:
Does the Sigma 45 have Focus Shift?.
Looyd Chambers at https://diglloyd.com/blog/2019/20190907_0530-SigmaFE35f1_2_DG_DN-ReaderComment.html says "... is a sleeper lens that might have potential when used appropriately... It is very compact and nice on a Sony body, so it might actually be very good for landscape, focused properly accounting for focus shift
There is no focus shift with the Sigma 45 at close or infinity distance.
Lloyd's business model is partly based on turning molehills into mountains that can only be scaled with the assistance of one or more of his subscriptions.
vdo1 wrote:
I think he's making a mountain out of a molehill. On Sony cameras you can pretty much control whether the lens will focus (nearly) wide open or at working aperture:
Set the camera to Live Preview: ON, then it will behave like this:
- in MF it will focus at working aperture
- In AF-C it will do an initial reading at open then it will keep adjusting focus at working aperture
- In AF-S it will focus at working aperture if you also set "Aperture Drive in AF" to Silent.
There are a few lenses that are not compatible with the "Aperture Drive in AF" setting (i.e. the setting is fixed to Standard with no way to change it), those may give you trouble in AF-S if they also have focus shift. As in that scenario the focus reading may happen at a different aperture than the one you selected for the exposure.
So a good alternate question here is whether the Sigma 45 is compatible with that setting or not....Show more →
Sep 09, 2019 at 09:08 PM
imagesfromobjects Offline • • • • Upload & Sell: Off
Looking at these sample images, it is just incredible how smooth this lens renders (I already knew that but it is again a confirmation).
Over at the Sony 35/1.8 thread, my eyes hurt when I look at some of the sample images (really harsh rendering).
It seems like day and night between the Sony 35 and Sigma 45.
Don't know how the new Sony 35/1.8 but Loxia 35 bokeh just "explosion at the pasta factory" ), This Sigma is really quite smooth. Sorry, Dustin not found the background a little better, but still the principle is clear.
Photo from Dustin review. F4
As far as I can tell Dustin has some beef with the lens, he mentioned he was going to test it against a Tamron zoom in a future video. Probably to do with sharpness and/or AF.
Don't know how the new Sony 35/1.8 but Loxia 35 bokeh just "explosion at the pasta factory" ), This Sigma is really quite smooth. Sorry, Dustin not found the background a little better, but still the principle is clear.
F4
cwnchkn wrote:
As far as I can tell Dustin has some beef with the lens, he mentioned he was going to test it against a Tamron zoom in a future video. Probably to do with sharpness and/or AF.
I think he is not quite yet convinced that an F2.8 prime makes sense in addition to an F2.8 zoom, and it is indeed a tough sell if one just looks at the specs and the price tag.
In terms of bokeh, the difference will be obvious. Sharpness maybe not so much, Sigma probably prevails at the edges.
Definitely looking forward to his comparison.
Interesting article from head of Sigma product planning on the lens
Some excerpts from the article:
There we were, unable to raise the MTF performance and unsatisfied with the bokeh, when we received a surprising proposal from our optical engineers in charge: to develop the lens with the highest priority given to its expression of bokeh...
1 — The overall MTF performance is lower due to the flares caused by spherical aberrations, but all other aberrations – especially color aberrations – are wonderfully suppressed, resulting in unexpectedly great MTF performance in high frequencies. In other words, the image is covered by a very thin veil, but its optical resolution is extremely high.
2— The remaining aberrations are spherical in nature, meaning that an aperture stopped down two stops already results in an MTF profile to rival our Art series lenses.
3— With our optical design, the spherical aberrations are low towards the infinity focus and increase towards the minimum focusing distance, so we achieved sharpening the distant view area with few bokeh and making soft and beautiful bokeh at the distant view area where many bokeh occurs.
As predicted, the optical performance in the close-up range was not that high, and we also could not rule out the possibility of being called a poor lens. But upon seeing the soft, rich flare created by spherical aberrations, and the seamless, creamy bokeh they cause, I almost gasped.
Interesting article from head of Sigma product planning on the lens
Some excerpts from the article:
There we were, unable to raise the MTF performance and unsatisfied with the bokeh, when we received a surprising proposal from our optical engineers in charge: to develop the lens with the highest priority given to its expression of bokeh...
1 — The overall MTF performance is lower due to the flares caused by spherical aberrations, but all other aberrations – especially color aberrations – are wonderfully suppressed, resulting in unexpectedly great MTF performance in high frequencies. In other words, the image is covered by a very thin veil, but its optical resolution is extremely high.
2— The remaining aberrations are spherical in nature, meaning that an aperture stopped down two stops already results in an MTF profile to rival our Art series lenses.
3— With our optical design, the spherical aberrations are low towards the infinity focus and increase towards the minimum focusing distance, so we achieved sharpening the distant view area with few bokeh and making soft and beautiful bokeh at the distant view area where many bokeh occurs.
As predicted, the optical performance in the close-up range was not that high, and we also could not rule out the possibility of being called a poor lens. But upon seeing the soft, rich flare created by spherical aberrations, and the seamless, creamy bokeh they cause, I almost gasped.
Thanks for posting!
This is just incredible as it pretty much describes how the Sigma 45 performs.
Basically, depending on subject distance, one can say the lens produces 'soft' or 'very sharp' images.
For those who want very sharp images even at close range, an achromat close-up lens add-on is a simple way to achieve this.
However, for portraits, I very much like the SA look from wide open. This is one of my favorite lenses this year.
