[dadipentak]

I've sent Sigma lenses in for service a few times here in the US to the Sigma USA headquarters in New York, and each time their service and results have been outstanding-

Me too.

[Digitalis]

It's too bad that you have to go through a 3rd party for service.

And this third party has maintained a stranglehold on sigma products for some time

I have conducted a small scale comparison between the FA31 and the and the 18-35mm f/1.8




All images un-sharpened ( only adjustments used were for WB)

From what I am seeing the FA31 has higher amounts of fringing at f/1.8 but it is simply smoother in the OOF regions, the sigma has more contrast but looks harsher in general. Bear in mind my copy is de-centered so take these results with a hearty pinch of salt.

[Edgar_in_Indy]

Are those 1:1 crops from the center? Focusing on the rim of the glass?

As a follow up, do you ever sleep? According to Google, it's close 2:00 in the morning when you posted that.

[Digitalis]

Are those 1:1 crops from the center? Focusing on the rim of the glass? As a follow up, do you ever sleep? According to Google, it's close 2:00 in the morning when you posted that.

Those are 1:1 crops lightly left of the center - I wanted to avoid including the part of the image that is affected by de-centrering on the Sigma lens. It was a friday night when I posted that - I can stay up as long as I want on the weekends.

[Digitalis]

I loaned my Noct-Nikkor 58mm f/1.2 so I could borrow a colleagues 18-35mm f/1.8 for use on my Nikon D800E, with DX crop mode on it is basically the same sensor as the Pentax K5IIs.


A Bokeh comparison between the Pentax FA31mm f/1.8 and Sigma 18-35mm:


Left Pentax K5IIs - SMCP-FA31mm f/1.8 Limited - Right Nikon D800E with Sigma 18-35mm f/1.8 @ 31mm f/1.8 [ DX crop mode]

The Sigma 18-35mm f/1.8 Lens needed a +6 adjustment on my D800E to focus accurately. However the anomaly that has been driving me up the wall is the frog egg bokeh, I'm stumped as to what is causing it. I have a hypothesis about what could be causing it, but so far I have been unable to replicate or isolate the cause of it under controlled conditions.

Here is an example where the effect rears its profoundly ugly head:


Nikon D800E With Sigma 18-35mm f/1.8 @ 18mm f/1.8 [DX crop mode]

Other than that I have been impressed with the close focus performance of this lens (on the D800E). Sigma has a history of playing fast and casual with term "macro" on their lenses and having less than optimal close focusing distances on their lenses, While the sigma 18-35mm f/1.8 isn't explicitly regarded as a macro lens, it is good to see the lens is capable of producing excellent results at close focusing distances:


Nikon D800E With Sigma 18-35mm f/1.8@ 35mm f/4 [DX crop mode]

[inextenza]

FYI - Lightroom 5.6 now has a lens profile for the Sigma 18-35mm f/1.8 in pentax K mount.

Seriously? How does it work?

Because, I've made the upgrade, then import new photos, and the Sigma is still an unknown lens… look:



No mention of Pentax K mount, and no identification

(BTW Sigma on Pentax had never worked perfectly in LR)

[ElJamoquio]

(BTW Sigma on Pentax had never worked perfectly in LR)

Yeah, they've never been great for me, either. I had assumed it was because of the 8mm (less than 10mm) limitation on the Pentax gear, but maybe it's just Sigma+Pentax.

[Class A]

(BTW Sigma on Pentax had never worked perfectly in LR)

I believe Adobe cannot be *rsed to improve the support for Sigma lenses on Pentax.

If you look at the EXIF data of images taken with the Sigma, I'm sure you'll find all the necessary information.

Adobe is perhaps facing a challenge because Sigma reuses lens IDs for Pentax lenses (I'm not sure they actually do, this can be easily checked) but clearly the support could be a lot better. Some data could be displayed correctly straight away and if there is a lens ID ambiguity, the user could be asked to supply a default assignment. Something analogues already happens for choosing the right lens profile (the user can manually designate a default profile for a particular lens).

[distudio]

Adobe is perhaps facing a challenge because Sigma reuses lens IDs for Pentax lenses (I'm not sure they actually do, this can be easily checked) but clearly the support could be a lot better. Some data could be displayed correctly straight away and if there is a lens ID ambiguity, the user could be asked to supply a default assignment. Something analogues already happens for choosing the right lens profile (the user can manually designate a default profile for a particular lens).

Not from my experience, I've always been able to extract unique lens ID info from my EXIF shot with Sigma glass.

[Edgar_in_Indy]

Not from my experience, I've always been able to extract unique lens ID info from my EXIF shot with Sigma glass.

Hmmm...that's interesting, since I've had the opposite experience. What specific Sigma lens have you owned that are correctly identified by Adobe? What what specific software are you using?

I use Adobe Bridge CS6 / Photoshop CS6 with the latest ACR, and here's how my various Sigma lenses that I currently or previously owned show up in the "Lens" field in Bridge CS6:

Just to be clear, the EXIF information as far as aperture and focal length still shows up correctly (except for the 8-16mm which does not register any focal length for images shot wider than 10mm). But the lens ID field is not correct on ANY of my Sigma lenses. I guess maybe if I owned a Sigma 70-200mm f/2.8 it might be correctly identified?

And for what it's worth, my Tamron 17-50mm f2.8 and 28-75mm f2.8 were ID'd correctly as follows:

TAMRON SP AF 28-75mm F2.8 XR Di
Tamron AF 17-50mm F2.8 XR Di-II LD

[distudio]

Hmmm...that's interesting, since I've had the opposite experience. What specific Sigma lens have you owned that are correctly identified by Adobe? What what specific software are you using?

I use Adobe Bridge CS6 / Photoshop CS6 with the latest ACR, and here's how my various Sigma lenses that I currently or previously owned show up in the "Lens" field in Bridge CS6:
Just to be clear, the EXIF information as far as aperture and focal length still shows up correctly (except for the 8-16mm which does not register any focal length for images shot wider than 10mm). But the lens ID field is not correct on ANY of my Sigma lenses. I guess maybe if I owned a Sigma 70-200mm f/2.8 it might be correctly identified?

And for what it's worth, my Tamron 17-50mm f2.8 and 28-75mm f2.8 were ID'd correctly as follows:

TAMRON SP AF 28-75mm F2.8 XR Di
Tamron AF 17-50mm F2.8 XR Di-II LD

I was just disagreeing that they re-share Pentax ID's, I should have been more specific, lenses profiled by the Adobe Lens Profile Creator are thereafter correctly identified. I have 8 recent Sigma lenses.

[Edgar_in_Indy]

From past discussion along these same lines, my understanding is that the lens identification in the EXIF is a result of collaboration between the lens maker, the camera maker, and possibly the software maker (Adobe, etc). The lens communicates a code to the camera, which the camera is supposed to use to link to a specific lens ID, which is then read by the computer software. I found this link for the Pentax EXIF lens codes:

Pentax Tags

I'm not sure how up to date it is, but I do see that it contains codes for some of my Sigma lenses that are not being identified correctly, such as the 50-150mm f2.8 and the newish 85mm f1.4. I wonder if there are firmware updates from Sigma and/or Pentax that would result in my Sigma lenses being correctly identified on my K-30?

That reminds me...it's been a few years now, but it seem like when I sent my new Sigma 50-150mm f2.8 in for calibration back in 2010 or early 2011, that I mentioned to them that the lens was not being identified in EXIF information, and asked if there was anything they could do about it. I think that upgraded the firmware, and when they sent it back, that's when it started being identified as the Sigma 70-200mm f2.8, rather than just generic "Sigma lens". I considered it an improvement, since I didn't own the 70-200mm, so I knew that whenever I saw 70-200mm in the EXIF, it was actually referring to my 50-150mm.

[Digitalis]

Seriously? How does it work?

Because, I've made the upgrade, then import new photos, and the Sigma is still an unknown lens… look:

No mention of Pentax K mount, and no identification

(BTW Sigma on Pentax had never worked perfectly in LR)

Strange, All I have to do is specify the Marque (maker) of the lens to "sigma" and Lightroom automatically sets it to the 18-35mm lens*. Even though my copy is defective, at least LR5 gets it right - sometimes my Sigma 100-300mm f/4 gets mistaken for the Sigma 120-300mm f/2.8 APO, the Sigma 70-200mmm f/2.8 or the Sigma 70-300mm f/4.5-5.6 at which point I silently curse and mutter "keep guessing, lightroom". Lightroom also has issues with the sigma 8-16mm specifically below 10mm on pentax DSLRs**. I get issues when I use Zeiss or Voigtlander lenses on my Canon or Nikon DSLRs cameras so pentax isn't the only victim of incorrect lens ID's here.

Lens mis-identification is disruptive to my workflow as I rely a lot on the lens metadata search feature in LR5, and having incorrect lens labels drives me up the wall as I like to keep my catalogs ordered.


*even on the D800E which isn't exactly suited to the Sigma 18-35mm f/1.8.
** 8mm setting does appear on the "input focal length" menu when using manual lenses, and this is correctly recorded in EXIF so I don't think this is a pentax problem...more like a sigma issue.

[thibs]

Adobe is perhaps facing a challenge because Sigma reuses lens IDs for Pentax lenses (I'm not sure they actually do, this can be easily checked) but clearly the support could be a lot better. Some data could be displayed correctly straight away and if there is a lens ID ambiguity, the user could be asked to supply a default assignment. Something analogues already happens for choosing the right lens profile (the user can manually designate a default profile for a particular lens).

Simga indeed does (or did) with the Sigma 28/1.8, indentified as the Pentax SMC-F28/2.8 (by LR until 3 at least). I own both lenses so this is a PITA.
And yes, you're suggestions are obviously what Adobe should do but they don't care at all.

[jatrax]

This might be of interest: https://forums.adobe.com/message/4678814

Essentially they are saying that if a lens is not identified correctly, manually select the correct profile and then click the arrows next to 'Setup' and select 'Save New Lens Profile Defaults.' Then you need to update your import preset to make this happen automatically.

Of course this only works if a lens profile is present for the lens in question. I think what you are doing is 'training' Lightroom to associate a particular EXIF lens ID with a particular lens profile in LR.

Be careful which lens profile you select as LR will sometimes suggest a close match. For example my F 50mm 2.8 macro was not recognized in LR, but by selecting Pentax as the Make LR suggested the DFA 50mm macro. I followed the procedure above and now the F 50mm is recognized automatically, but as the DFA 50mm macro. It seems to work so I'm leaving it that way, but on a different lens combo the results might be negative.

I have no Sigma lenses but would be curious if this helped with auto identification of those lens as well.

Also note that LR uses different lens profiles for RAW and non-RAW files so if you associate a RAW lens profile it still might not work with a jpeg file.