Getting a new prime lens to match two DSLR bodies

[yakman]

I was in a local shop to get a new Sigma 50 1.4 ART for my 70D and 5D (yes, the "original/classic" one).

I went through 3 copies of the lenses and only one of the them autofocus well enough on the 70D without AFMA. Unfortunately that copy is part of a kit (with Sony mount converter). I couldn't buy on its own.
The other two copies AF are off on both the 70D and 5D.

My question here is that
1. Shall i just grab any copy and send the lens and cameras to Sigma for calibration right after purchase..
2. Or shall I at least get one copy that AF sharp on 5D, since it does not have AFMA, or 70D? Assuming I use both cameras evenly.
3. Is the USB dock really helpful in this situation?

P.S.
1. Looking at the roadmap now. Most likely I will upgrade to 6D mark II in early 2018. I'm assuming by that time, the Sigma 30 month warrantly here would cover calibration the ART again on the new body. From then on I should just have one DSLR and one Mirrorless
2. My other primes were already calibrated by Canon to match my DSLRs.
3. I'll 90% upgrade from EOS M to EOS M5 mid- 2017. Tried on the same day, seems great.
Thanks in advance for your reading and suggestion

 

[drmikeinpdx]

My old 5D classic proved to be a poor choice for use with large aperture primes, due to the weak autofocus system. As you mentioned, it didn't have microfocus adjustment, so I went crazy trying to get it to focus accurately enough for F/1.4 work with the Sigma 50 I had at that time. Oddly enough it worked quite well with an old Tamron 28-80 F/2.8 zoom I picked up via Craigslist, although some of that may have been simply due to the smaller aperture.

So trying to combine the 5D classic with a Sigma Art lens that is known for focus issues is probably a lost cause.

Sorry I can't comment on the 70D, as I don't have one.

 

[rfdesigner]

I was in a local shop to get a new Sigma 50 1.4 ART for my 70D and 5D (yes, the "original/classic" one).

I went through 3 copies of the lenses and only one of the them autofocus well enough on the 70D without AFMA. Unfortunately that copy is part of a kit (with Sony mount converter). I couldn't buy on its own.
The other two copies AF are off on both the 70D and 5D.

My question here is that
1. Shall i just grab any copy and send the lens and cameras to Sigma for calibration right after purchase..
2. Or shall I at least get one copy that AF sharp on 5D, since it does not have AFMA, or 70D? Assuming I use both cameras evenly.
3. Is the USB dock really helpful in this situation?

P.S.
1. Looking at the roadmap now. Most likely I will upgrade to 6D mark II in early 2018. I'm assuming by that time, the Sigma 30 month warrantly here would cover calibration the ART again on the new body. From then on I should just have one DSLR and one Mirrorless
2. My other primes were already calibrated by Canon to match my DSLRs.
3. I'll 90% upgrade from EOS M to EOS M5 mid- 2017. Tried on the same day, seems great.
Thanks in advance for your reading and suggestion

I have the 6D and changed the focus screen for an EG-S (fine ground).. I can now, with care, manually focus.

I had the 30D before, which is the same era as your 5D, the lack of live view too is a real pain.

 

[Maximilian]

...
My question here is that
1. Shall i just grab any copy and send the lens and cameras to Sigma for calibration right after purchase..
2. Or shall I at least get one copy that AF sharp on 5D, since it does not have AFMA, or 70D? Assuming I use both cameras evenly.
3. Is the USB dock really helpful in this situation?
...

My first guess would be to get an EF lens, but... we all know how it looks like on this side, esp. ahsanford
So no choice right now, if you aren't looking for the 50 mm L.

So what you didn't mention is, if you know how far your two bodies are apart when it comes to AFMA (I know, the 5D doesn't have it). So what I mean is how was the one working on the 5D that was working well on the 70D? If they are not too far apart, I'D go for solution #2. Maybe you'll still have to add #1 later on, if it is not matching 100%.
That's the way I'd go, since I don't have experience on #3 or latest Sigma lenses I cannot make any further recommendation.

 

[tpatana]

USB dock can do the AFMA even if your body doesn't.

 

[Alex_M]

There are couple of things that we need to accept first:

A. Sigma Art lenses can be AF adjusted:
1. In camera
And
2. In lens via Sigma USB dock

B. On the usb dock adjustment is a global type of adjustment that affects AF performance of the given lens for all of your camera bodies

Sigma Art prime lens can be adjusted at 4 various distances from MFD to infinity.
In camera AFMA is a local settings that does not affect AF performance on any other camera body and can be performed for a single distance to subject, usually x50 of the lens focal length.

The most efficient way to calibrate a Sigma Art lens to 2 or more bodies:

1. Nominate primary and secondary camera body that the given lens will be used on.
2. Calibrate The lens via Sigma USB dock for the primary body at 4 distance points as per Sigma sotware instructions.
3. Calibrate the lens in camera via AFMA settings menu of the secondary body.

There is no need to AFMA the lens in camera on the primary body. It was taken care of on the dock.

I hope it helps. My apologies for a somewhat sketchy instructions. The subject is quite technical in nature.

P.S. Sigma technicians calibrate lens to a given camera body at x50 the focal length only.

 

[yakman]

Got my Sigma 50 ART a while back, thanks for all the advice here.
Just to share my experience:

My 5D focus was off which I knew before the lens purchase. I didn't realize my 70D was off a bit as while, (less than a year from last Canon service center adjustment).

The new thing I learned is that, due to the mechanical stuff in natural, the PDAF in DSLR is bound to focus shift, just a matter of time, normally back focus due to the mirror support wear and tear.
For 70D, i had to apply -5 to bring it to focus.
For 5D, I had to add a layer of 3M tape at the back of the mirror (instead of adjusting the screw). (http://www.fredmiranda.com/forum/topic/938174?TopicID=938174)

After aligning both my cameras in focus again, I headed to the shop and grab a copy of Sigma ART together with the USB dock.

 

[Mt Spokane Photography]

USB dock can do the AFMA even if your body doesn't.

For two different camera bodies? The subject line says he wants to match two camera bodies.

Its probably a lost cause, bodies vary as do lenses, so a lens that is optimal for two very different bodies in unlikely.