I just bought a Sigma 135 f/1.8 Art lens. Did a quick and dirty focus test with a yardstick and I have just a whisper of front focus. If I want to adjust this, do I have to get the Sigma USB port to adjust the lens, or can I use my in camera focus adjustment? I have the D-810.
With Sigma Art lenses you can use the Nikon fine tune AF value adjustment. If you have issues it is great to have the Sigma USB dock to adjust over 4 distances. Also you need the USB dock for FW updates.
You need to check the lens at multiple focus distances. If it's off the same amount at all subject distances, you can use the Nikon calibration which simply applies a blanket average correction across the entire range of subject distance and focal length. If it's off a different amount at different focus distances, you will need the dock to get any improvement. Since it's a prime this is a lot easier to do than with a zoom. Or exchange the lens for a better copy and don't worry about AFFT which is always my primary recommendation.
PDAF by nature also has a tiny bit of variation, so depending on how critical you're being, make sure you test each scenario multiple times to make sure there is in fact a consistent, repeatable, issue. If there is just a "whisper" of front focus after one test, it's possible that no AFFT is needed but more data is needed to be sure.
Whilst I totally agree with the above posts, you should be aware of one of the pitfalls the Sigma doc leads us too.
I recently added a D850 and have been happily using a Sigma 150-600 OS Sport on a D800 and D500 for some time. D800 was back focused a bit, (-4), so set it using the doc and have pin sharp shots. The D500, not wanting to tinker with the lens /doc settings again , I adjusted using Nikons AF Fine tune and got where I should be.
The D850 was front focusing at +2, so again adjusted the Sigma via the doc. Flawed thinking. (had the lens set for - on the D800 and then on + for the D850 so one camera isn't going to work on the money and my view being whilst I'll use the D850 most of the time now, I still want the choice),
Point being that if using more than one body, it might be best practice to throw away using the doc and use the limited Nikon AF Fine tune.
Did that today and I now have gone back to having three bodies that I can put the Sigma on without feeling I've screwed up as having workable options. (tested and happy).
^^ Yes, multiple bodies with the dock can be annoying. If you have multiple bodies, simply exchanging the lens for one that requires no AFFT is the ideal solution IMHO.
If you just stick with Nikon's AFFT, it won't work unless the lens is off by the same average amount at all combinations of subject distance and focal length (rare for a zoom, less so for a prime), so that is often not viable either - again, simply getting a proper lens in the first place solves all the issues assuming the camera body(ies) themselves aren't defective or out of adjustment.
CanadaMark wrote:
^^ Yes, multiple bodies with the dock can be annoying. If you have multiple bodies, simply exchanging the lens for one that requires no AFFT is the ideal solution IMHO.
If you just stick with Nikon's AFFT, it won't work unless the lens is off by the same average amount at all combinations of subject distance and focal length (rare for a zoom, less so for a prime), so that is often not viable either - again, simply getting a proper lens in the first place solves all the issues assuming the camera body(ies) themselves aren't defective or out of adjustment.
Sorry Mark. Don't get that at all. 1. Exchanging the lens for one that requires no AFFT is the ideal solution . Crikey.. how many attempts would you suggest before the retailer gives you the F off.
Re the second comment about the differences at all combinations, (distance), you get from the Sigma isn't really relevant as it is just not available on the Nikon AFFT so the compromise has to be accepted to use that. It is not a question of being viable, but a question on what is acceptable.
The proper lens in the first place comment is not a viable proposition for most customers as we need to define "proper". Retailers will have in mind "acceptable tolerances".. The suggestion of "proper" is a perfection that does not exist...
I have the 24, 35, 50, 24-105 Art and 150/2.8 Macro. As mentioned in other threads the fine tune AF adjustment is for 50x FL and works great but generally the 3 distances for Art lenses are closer with the 4th being at infinity. Once you have checked the Art lens for any non linearities and adjusted via the USB dock the lens can then be used on other Nikon bodies with the appropriate fine tune AF adjustment. Most of the time there is no or little adjustment needed via the USB dock. The reason to take the time is that lenses are very sharp and minor tweaking does improve having f/1.4 at very close and far to infinity distances.
You can send the lens back to Sigma if you do not wish to adjust the lens via the USB dock, but with primes it does not take long. Of course with zooms it takes more time.
Seawolf wrote:
I just bought a Sigma 135 f/1.8 Art lens. Did a quick and dirty focus test with a yardstick and I have just a whisper of front focus. If I want to adjust this, do I have to get the Sigma USB port to adjust the lens, or can I use my in camera focus adjustment? I have the D-810.
Thanks much.
A "whisper" Was off a similar "tad" on mine. +1 took care of it. No dock necessary.
FWIW it's dead on with (2) D500's and my backup D7200. My D800 was -2 again, no dock.
Was off a similar "tad" on mine. +1 took care of it. No dock necessary. 