So yeah - the Sigma 50mm kinda sucks

My favorite focusing test nowadays is to simply use my LCD.

I can easily open up a file in photoshop, white bg, black dot. When the focus is "good enough" i'll see the resolution lines of the LCD itself.

I have never heard this sort of complaint about Sigma macro lenses. I have the Sigma 50f2.8 and it is right on.
Of course, the aperture is not f1.4, but I don't have any problem with my Canon 50f1.4, and wouldn't bother testing it with a focus test chart. AF is right on when using AF with both of my crop bodies.
While f1.4 lenses are useful, I would hesitate to get a Sigma 50f1.4 or 30f1.4 because my camera bodies do not have microadjust. I know that some people have complained about front focusing with their Canon 50f1.8, so the problem is not exclusive to Sigma.
I have read too many reports like this one to trust a Sigma f1.4 lens on my T2i.

drumnut01 wrote in post #13148062
....
One main thing to consider is that your camera's focus sensor may not be exactly where the square or dot is in your viewfinder. On most camera's, the marker in the viewfinder is MUCH smaller than the actual focus sensor. Therefore, if you are aiming the center point at the 16, the focus sensor may be covering all the way from 15 to 17. What the camera does is lock on to the area in the sensor area that has the greatest contrast. If you are hoping the camera will focus on the red 16, you are going to be wrong most of the time because there are a lot of black numbers and lines in the area that provide greater contrast against the yellow than the red. Because of this, the camera may choose to lock on to any one of those numbers or lines, even if your focus point is directly on the 16.

This is why a true focus alignment tool will have a large target that is parallel to the sensor. You focus on that because focusing on anything that is angled away from the camera like that is going to be inconsistent at best.

These same problems will also show in real world photos. If you are shooting a person and the camera and lens are front-focusing on the bangs, you might want to consider that the camera may have locked on to eyebrows or an area on the subject's nose. Sometimes, I will focus on an area of the face that is in the same plane as the eye. Like I said, shooting with this type of lens takes PRACTICE. Don't take it back just because you haven't figured it out on the first day.

That is a really good point and one that is often missed. Easy to miss focus due to the camera focussing point grabbing something other that the desired point.

Before I obtained the proper tools I found that a vertical plane with clear text standing next to a ruler was a good guide....because it more than covers the focus area it is more accurate, and I was able to get consistant results, albeit with more messing about than with the Lens Align tool.

It's inaccurate because there is no single area for the focus point to lock onto. There are lines every 1/16" and the camera can pick any of those lines in about a 2" span of the ruler that are in the center focus sensor's area.

The camera can't read your mind and know what you intended it to focus on. Therefore, when it locks onto something that you didn't intend on it locking onto, you may think your calibration is off when it isn't. In reality, the test itself is flawed because it doesn't account for how the focusing mechanism works. A ruler test doesn't produce reliable results.

This is why actual lens alignment tools have a flat surface that is parallel to the camera sensor to focus on. The focus target intersects with the zero on the ruler and you never try to focus on the ruler itself. Trying to focus on a ruler is unreliable.

kfreels wrote in post #13150224
How is it that people think a tape measure test is somehow less accurate than "real world"? DOF is DOF and it doesn't matter what the subject is.

I bought a 30mm 1.4 at adorama. It was front focusing off by 2 inches at 24 inches. This is bad. In the "real world" this means the eyes are clearly out of focus at a shallow DOF but the tip of the nose might be in focus. I sent it back, got another. Bad as well. Worse in fact. So I contacted adorama and they went out of their way to test and find a good one for me before they shipped it. The third was is fantastic and I'm glad I went through the trouble. This appears to be a common problem with Sigma. I would either see if you could get a replacement or send it to sigma for calibration. If you do that they will say that they prefer you to send the camera so they can "calibrate it to your body" but what you are dealing with here is likely not a camera/lens mismatch. It's a lens that is out of spec right off the production line.

I have a guess that they don't calibrate these lenses before they leave. They just make them and ship. The few that people both with can be handled through warranty. Alternatively it may be that they are sensitive to jarring and many get screwed up in transport. That I won't be able to tell unless I have an accident so I don't plan to test it. Whatever the case, when you get a good one, they are fantastic lenses, but getting a good one can be a PITA..

Sirrith wrote in post #13149483
Send them in for recalibration.

Do I have to send my body in or only my eyes?

sbattey wrote in post #13150503
Do I have to send my body in or only my eyes?

Just the eyes the first time, if they come back and still have issues, send your body in with them.

Some real world examples since my test is flawed. I used center focus point and focusses on the eye in the human shots and then on the barcode in the box shot. I took a lot more of these and the focus (to me) looks off in every shot. Maybe it`s my eyes but it looks like it is focussing on the nose. What do you think ?

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You seem to be getting consistent front focus, which is an easy fix for sigma. Send it in with sample photos to show them what is wrong, and you'll have a working lens back soon.

I'd send it to get calibrated. Just my two cents. I'm thinking about sending my 85 in soon.

yea that is consistent front focus. if your camera can do micro adjust you can fix it yourself. if not send it to sigma and when you get it back you will be amazed at how sharp it is when its calibrated and working properly

From Edmonton too? You are right, the sigma 50mm f/1.4 sucks. I tried 3 copies from mcbain, they are all front focusing like never before, one of them is very inconsistent with it's AF. I finally went with the canon f/1.4 and dump the sigma. The canon AF is spot on and AF is very consistent, I am more than happy with it.

People said your tape measuring method is not accurate, I don't 100% agree with that. At least it shows the canon is spot on and not the sigma. Being mounted on the same body, that proven it is the lens issue not the camera body.

I am very disappointed with sigma 50mm f/1.4, I am targeting this lens only, not sigma as a whole. They do have lens that are great, but sorry, not the 50mm f/1.4! If this particular lens doesn't have issue, why there are lots of thread talking about it. Have you ever seen a thread saying " canon 50mm f/1.4 front/back focusing issue" like 5 million times on the forum? No, only the sigma. That lens hardly work out of the box. Just my 2 cents

thestone11 wrote in post #13150811
I am very disappointed with sigma 50mm f/1.4, I am targeting this lens only, not sigma as a whole. They do have lens that are great, but sorry, not the 50mm f/1.4! If this particular lens doesn't have issue, why there are lots of thread talking about it. Have you ever seen a thread saying " canon 50mm f/1.4 front/back focusing issue" like 5 million times on the forum? No, only the sigma. That lens hardly work out of the box. Just my 2 cents

Have you ever seen a thread saying "sigma 50mm f1.4 focus motor died/lens not focusing"?

thestone11 wrote in post #13150811
From Edmonton too? You are right, the sigma 50mm f/1.4 sucks. I tried 3 copies from mcbain, they are all front focusing like never before, one of them is very inconsistent with it's AF. I finally went with the canon f/1.4 and dump the sigma. The canon AF is spot on and AF is very consistent, I am more than happy with it.

People said your tape measuring method is not accurate, I don't 100% agree with that. At least it shows the canon is spot on and not the sigma. Being mounted on the same body, that proven it is the lens issue not the camera body.

I am very disappointed with sigma 50mm f/1.4, I am targeting this lens only, not sigma as a whole. They do have lens that are great, but sorry, not the 50mm f/1.4! If this particular lens doesn't have issue, why there are lots of thread talking about it. Have you ever seen a thread saying " canon 50mm f/1.4 front/back focusing issue" like 5 million times on the forum? No, only the sigma. That lens hardly work out of the box. Just my 2 cents

Yeah I am from Edmonton. I was dissapointed in McBain`s customer service as the sales person was annoyed when I asked if I could try another copy and wouldn`t let me. So I bought from Vistek but now I`m kinda worried cause their return policy states "subject to managerial approval" so I hope they will be able to exchange it or at least send it off.

N.O.R.E. wrote in post #13150837
I hope they will be able to exchange it or at least send it off.

I strongly suggest you send it to sigma. The copy you have here is exhibiting a minor problem that can be very easily fixed under warranty. Don't risk the chance of getting a copy that might be even worse and potentially unfixable, and then being refused permission to exchange it.

Sirrith wrote in post #13150943
I strongly suggest you send it to sigma. The copy you have here is exhibiting a minor problem that can be very easily fixed under warranty. Don't risk the chance of getting a copy that might be even worse and potentially unfixable, and then being refused permission to exchange it.

makes sense - do I send it in myself or does the store typically do it for you?