Fred Miranda wrote:
I tried under lower light yesterday and the issue persists. With FW2.0, AF-C still misses consistently and when changing to AF-S, accuracy greatly improves. (A7R4)
On my previous test, I was shooting outside under high contrast lighting and the lens did very well under both AF-C and AF-S.
Perhaps with PDAF (AF-C), the lens needs high contrast to focus accurately.
The closest the distance, the more spherical aberration which mean more misses with PDAF. This seems to be exacerbated under low light.
I did my testing with new firmware in reasonable light outdoors (cloudy but not so dark) so far where it seemed to work fine with AF-C, but I think there was enough contrast to not make it really challenging.
Are the AF failures happening mostly when shooting portraits with eye-AF or with any kind of static subjects with AF-C in low light as long as it's at close distance?
In my own regular use with original firmware I mostly saw some AF failures when I used the lens during travel last year and took quite many family shots at around 1-2m range using AF-S (at f2.8) with eye AF. Several of those were slightly OOF when I checked the photos later, but I didn't have noticeable problems on any other type of shots with AF-S.
imagesfromobjects wrote:
It could be that this is just Sigma trying to get me to ditch the a7S and buy their fp.
Well played, guys.
Yeah, I didn't get a chance to shoot at all today, except for around the house. Seems pretty much the same as before. AF-C is useless, AF-S seems decent enough, but not for fast action.
I still like the lens, but I have some reservations on my current Sony body. It sounds like it does great on fp, but not stellar on Sony with AF. In fairness, I haven't tried it in full daylight yet, though.
It might not be best idea to buy Sigma fp and 45/2.8 for great AF experience, but otherwise I really like the fp and my M/LTM lenses work very well on it with much less sensor stack related field curvature than on Sony. I recently got a few more M-mount CV lenses to have a nice focal length coverage for the fp, now using it mostly with CV 21/3.5, 28/2, 35/2, 40/2.8 (with Shoten helicoid adapter), 50/2, 75/1.5, all of which work very well on it. Also my M-Rokkor trio and M-Hex 90/2.8 work nicely on it, as do the CV 75/2.5 and 50/3.5. I prefer shorter focal lengths than 90mm when there is no stabilization.
When using the fp with 45/2.8 I find that it's best to stick to AF-S for close to mid-range and when I want to shoot infinity cityscapes I switch to MF to get reliable corner-to-corner sharpness. AF-C doesn't work all that well on the fp and AF-S can give some false focus confirmations quite easily but those are usually easy to spot on the screen and correct by re-acquiring focus. For infinity shots, I find that when I focus in relatively central area at f5.6 by AF even at very long distance, central area is sharp but corners are not great and subject distance seems to typically be around 14m based on EXIF. Better results can be acquired by MF, focusing based on distance indicator and stopping at first apperance of infinity symbol (checking with peaking and/or magnification also helps to confirm). On Sony A9 + 45/2.8 I seem to get better infinity results with AF and don't have to switch to MF for this type of shots.
The main limitation with fp for me is the lack of EVF, so I got the LVF-11 viewfinder for it which makes it very nice for precise MF focusing, but then it's not so small anymore. When focusing just using the plain screen it's sometimes difficult to see properly in bright daylight and not as enjoyable shooting that way. It would be great to have a small good quality EVF option. I still keep using it with the LVF-11 attached as I enjoy the MF experience a lot more that way and the viewfinder is quite light even though it's relatively big.
sergun wrote:
Put a new firmware. The network mentioned that the new firmware fixes a bug in the open aperture when using stabilization but there was no talk of AF )
p.s By the way how to see what firmware is on the lens ?
When the lens is attached, you can see the lens firmware version in Camera's UI in the same screen that shows Camera's firmware version. I'm not sure what that menu item is called in English as my Camera is having Japanese menu language only, but I think it's something like Setup / Version.
tuomkok wrote:
Sigma 45 seemed to be the ideal lens for street- and everyday photography, but the af-performance is really disappointing.
What do you think, is it fundamentally a hardware issue? Or something that can be (will be) corrected with firmware update?
It has been discussed several times in this thread. The AF-S performance is very good, AF-C also works well in bright daylight.
I personally have no complaints about the AF in general.
When contrast is not very good (dim light) and in close range, the focus struggles. This is most likely due to spherical aberration and cannot be fixed with a firmware update.
I think it is rather on the side of Sony where improvements would be possible to account for SA in their AF algorithm (but I doubt that they will do that).
Hahaha, oh the fp has my name all over it, there's no way I'm *not* getting one. Just waiting until used prices fall a bit.
I'll also definitely be swapping for the L mount version of the 45/2.8 when that happens. Not hoping for any AF miracles, I love the lens and it generally works fine for my usage. It's great to hear about less FC on fp, too. I plan to use it mainly with all of my compact M lenses for an ultra-compact stills setup, and on a mechanical gimbal for high quality video in a lightweight setup. Also hoping for a smaller EVF add-on, because my vision is not so great for getting critical focus off an LCD at waist level anyway, but I'd love to just use it in zone focus with the Elmarit 28 from the hip.
By the way, I have a M-Hexanon 50/2 on the way to me. I'm hooked on the 90.
Juha Kannisto wrote:
It might not be best idea to buy Sigma fp and 45/2.8 for great AF experience, but otherwise I really like the fp and my M/LTM lenses work very well on it with much less sensor stack related field curvature than on Sony. I recently got a few more M-mount CV lenses to have a nice focal length coverage for the fp, now using it mostly with CV 21/3.5, 28/2, 35/2, 40/2.8 (with Shoten helicoid adapter), 50/2, 75/1.5, all of which work very well on it. Also my M-Rokkor trio and M-Hex 90/2.8 work nicely on it, as do the CV 75/2.5 and 50/3.5. I prefer shorter focal lengths than 90mm when there is no stabilization.
When using the fp with 45/2.8 I find that it's best to stick to AF-S for close to mid-range and when I want to shoot infinity cityscapes I switch to MF to get reliable corner-to-corner sharpness. AF-C doesn't work all that well on the fp and AF-S can give some false focus confirmations quite easily but those are usually easy to spot on the screen and correct by re-acquiring focus. For infinity shots, I find that when I focus in relatively central area at f5.6 by AF even at very long distance, central area is sharp but corners are not great and subject distance seems to typically be around 14m based on EXIF. Better results can be acquired by MF, focusing based on distance indicator and stopping at first apperance of infinity symbol (checking with peaking and/or magnification also helps to confirm). On Sony A9 + 45/2.8 I seem to get better infinity results with AF and don't have to switch to MF for this type of shots.
The main limitation with fp for me is the lack of EVF, so I got the LVF-11 viewfinder for it which makes it very nice for precise MF focusing, but then it's not so small anymore. When focusing just using the plain screen it's sometimes difficult to see properly in bright daylight and not as enjoyable shooting that way. It would be great to have a small good quality EVF option. I still keep using it with the LVF-11 attached as I enjoy the MF experience a lot more that way and the viewfinder is quite light even though it's relatively big....Show more →
I hope you like the M-Hex 50/2 I've never tried one but I did have the LTM Hexanon 50/2.4 which was very good optically.
I'm also mainly using the fp with my compact M lenses and it was supposed to be a very compact setup until I started using LVF-11 all the time It works fine with the Sigma 45/2.8 as well but I'd rather use it with MF with that lens too and MF handling experience is a bit better with the M lenses.
I like it that there is no AA filter (resulting in very sharp details) and the overall IQ including color is really good. High ISO results are great up to ISO 6400 so I usually use auto ISO between 100 and 6400 fixing the shutter speed minimum to about 1/2*fl (in artificial light I use shutter speeds synchronized with local electric frequency to avoid banding). I like being able to use it silently all the time with electronic shutter (like I use my A9). I don't really use it for any action shots but most of my shooting is with still subjects anyway.
I'm hoping to see some new fp related announcements from Sigma at CP+ in 1 month, perhaps some new small lenses like the 45/2.8 and maybe some new accessories.
imagesfromobjects wrote:
Hahaha, oh the fp has my name all over it, there's no way I'm *not* getting one. Just waiting until used prices fall a bit.
I'll also definitely be swapping for the L mount version of the 45/2.8 when that happens. Not hoping for any AF miracles, I love the lens and it generally works fine for my usage. It's great to hear about less FC on fp, too. I plan to use it mainly with all of my compact M lenses for an ultra-compact stills setup, and on a mechanical gimbal for high quality video in a lightweight setup. Also hoping for a smaller EVF add-on, because my vision is not so great for getting critical focus off an LCD at waist level anyway, but I'd love to just use it in zone focus with the Elmarit 28 from the hip.
By the way, I have a M-Hexanon 50/2 on the way to me. I'm hooked on the 90.
Not a Sony user but I just received this lens yesterday and am enjoying it so far. This was just a quick snap on my SL. Transferred and edited on my phone so hopefully it doesn’t look too bad on here.
Dunno, but firmware update made AF *much* better. At least with AF-S on my first Gen Sony, I can say now after a few weeks that it's spot on almost 100% of the time.
fredmirandafan wrote:
Is spherical aberration really the only reason for poor AF?
Are there lenses with worse spherical aberration but Sony bodies could still AF properly using these lenses?
If yes, then there is something wrong with the 45 f2.8 that Sigma must be pressured to address.
Pros:
- very solid, sealed casing,
- excellent image quality in frame centre,
- good image quality on the edge of the APS-C sensor,
- acceptable image quality on the edge of full frame,
- very low lateral chromatic aberration,
- slight longitudinal chromatic aberration,
- sensible coma correction,
- moderate astigmatism,
- low vignetting on APS-C/DX sensor,
- sensible performance against bright light.
Cons:
- not especially accurate autofocus,
- high vignetting on full frame which, additionally, decreases slowly on stopping down.
I've never tried one but I did have the LTM Hexanon 50/2.4 which was very good optically.
