MA Inconsistent

Mathmans wrote in post #18746710
>> This is what throws me off when I do this. While the text is sharp it still looks like it is back focusing. 1 is sharper than 2 yet the text at 3 looks more OOF than 4. The can to the right of centre is turned is turned more to the left than the centre and left one. It is more than likely fine but when I go back to review my shots I see these things I'm not sure. Even with everything orientated in line. The gold text below the name looks more in focus on the left can as well. <<


This is the original image without using horizon tool in post.
This method is not 100% accurate but gives me good enough results and I get sharp eyes in real life shooting.

I think LensAlign also is not 100% accurate because ruler is on the side of the target.

It is a pretty good method that I use as a reference if unsure. The second image helps a lot.

Hosted photo: posted by Mathmans in
./showthread.php?p=187​46710&i=i59101985
forum: General Photography Talk

Hosted photo: posted by Mathmans in
./showthread.php?p=187​46710&i=i213100577
forum: General Photography Talk

I didn't read the whole thread, but since the OP hasn't replied, I suspect it when off on a tangent.

The problem is you have a Sigma prime lens. Yes, it may have been fine on you 5Dc and may be fine on other cameras, but also may not be on the one you really want to use it on.

I've had the same issues, as have many others.

If you really want to use the Sigma with your 5DIII, you will have to send both to sigma for them to calibrate it. I have not done this myself, but it seems like they are usually able to get the lens/camera combination working well. Obviously the big issue is having to send your camera to sigma (they won't mess with it).

ejenner wrote in post #18759175
If you really want to use the Sigma with your 5DIII, you will have to send both to sigma for them to calibrate it. I have not done this myself, but it seems like they are usually able to get the lens/camera combination working well. Obviously the big issue is having to send your camera to sigma (they won't mess with it).

True...
..unless your lens can be micro adjusted through a USB dock, like most new Sigmas and Tamrons can.

D-Noc wrote in post #18759287
True...
..unless your lens can be micro adjusted through a USB dock, like most new Sigmas and Tamrons can.

Still trying to understand how that works. Is the camera physically involved when using this process? Is a target of some type analyzed?

digital paradise wrote in post #18759413
Still trying to understand how that works. Is the camera physically involved when using this process? Is a target of some type analyzed?

Basically you do it the same way as you would MA your lens in-camera.
I use the Dot-tuning method mentioned earlier in this thread.

The difference is that in the camera you can MA at the wide end and at the long end.

With the USB dock (at least the Tamron dock), you are allowed to MA at e.g. 24, 35, 50 and 70 mm and at 45 cm, 1m and infinity distance. This should, if done right, give you an overall better MA.

Also, you can save the MA’s as a file, so that you can upload different “profiles” to the lens, which could be useful if you own multiple cameras.

D-Noc wrote in post #18759514
Basically you do it the same way as you would MA your lens in-camera.
I use the Dot-tuning method mentioned earlier in this thread.

The difference is that in the camera you can MA at the wide end and at the long end.

With the USB dock (at least the Tamron dock), you are allowed to MA at e.g. 24, 35, 50 and 70 mm and at 45 cm, 1m and infinity distance. This should, if done right, give you an overall better MA.

Also, you can save the MA’s as a file, so that you can upload different “profiles” to the lens, which could be useful if you own multiple cameras.

So the body is attached. I seen one image of the lens sitting in a dock without a body and connected to laptop. What does it do for targeting if it is sitting face down in the dock? I'll have to look it up as well.

davesrose wrote in post #18745609
The diagonal ruler has the 0 point right at that plane of focus, so it should be apparent if the 0 point is not in focus (and if a tick mark on the ruler is sharper in front of or behind).

.
Well, of course the zero is going to be in focus, because that's what you're focusing on.

I would want to know what part of the 0 is in the very sharpest focus - the part of the 0 that is closer to me, the part that is further from me, or somewhere in between.

This is, after all, about MICRO focusing adjustments, where we are trying to get things right down to the very fraction of a millimeter. . When I look at a 0 , I can't always tell which part of the 0 is the very sharpest, because I simply don't have that level of visual acuity.

Many will say that DOF is sufficient to cover those minute differences ..... to that I say, "oh no it isn't!" . DOF is actually a nebulous thing that is very subjective. . I want to work with precise absolutes, the way scientists do .... not within tolerances, the way engineers do. . The way I see, it, "reasonable tolerances" are neither reasonable nor acceptable, when it comes to focusing.

.

digital paradise wrote in post #18759529
So the body is attached. I seen one image of the lens sitting in a dock without a body and connected to laptop. What does it do for targeting if it is sitting face down in the dock? I'll have to look it up as well.

I just watched a video. The person put the lens on a camera and verified it needed MFA. He then removed the camera without adjusting MFA, put the lens in the dock and made the adjustments there. So does the lens do something like Magic Lantern and add more MFA focal length options beside the standard 2 the body does? I can't see that happening.

While writing this just occurred to me. If the lens only is doing MFA it must be taking into account the camera mirror assembly variation or whatever else might be throwing it off. So camera MFA has nothing to do with it. Looks like you have to select a value in the dock, put the lens back on the body, re-check by taking another shot, repeat until you get it and then do the next focal length.

digital paradise wrote in post #18759551
I just watched a video. The person put the lens on a camera and verified it needed MFA. He then removed the camera without adjusting MFA, put the lens in the dock and made the adjustments there. So does the lens do something like Magic Lantern and add more MFA focal length options beside the standard 2 the body does? I can't see that happening.

While writing this just occurred to me. If the lens only is doing MFA it must be taking into account the camera mirror assembly variation or whatever else might be throwing it off. So camera MFA has nothing to do with it. Looks like you have to select a value in the dock, put the lens back on the body, re-check by taking another shot, repeat until you get it and then do the next focal length.

Yes... and no..
Let’s say you use Dot-tune, and you end up with a MA of -4 at the wide end and +3 at the long end. Write down the values. You then set the MA settings in camera back til 0 and place the lens in the dock. In the dock/lens adjustment software you then enter the values you wrote down. Upload these MA settings to the lens and place it on the camera again. It will now be correctly adjusted without using the in-camera MA.

D-Noc wrote in post #18759612
Yes... and no..
Let’s say you use Dot-tune, and you end up with a MA of -4 at the wide end and +3 at the long end. Write down the values. You then set the MA settings in camera back til 0 and place the lens in the dock. In the dock/lens adjustment software you then enter the values you wrote down. Upload these MA settings to the lens and place it on the camera again. It will now be correctly adjusted without using the in-camera MA.

Finally. I have asked this question a few times at other site's and couldn't get a answer. I'm not sure I see an advantage with the Dock for all camera manufacturers since you have to know the values required ahead of time before using it. As for having more than two entries Canon bodies that have near and far MFA point automatically adjusts when in between. For cameras with one AF adjustment, two MFA points but no scaling and no MFA it would be very helpful.

Thanks very much.

digital paradise wrote in post #18759622
Finally. I have asked this question a few times at other site's and couldn't get a answer. I'm not sure I see an advantage with the Dock for all camera manufacturers since you have to know the values required ahead of time before using it. As for having more than two entries Canon bodies that have near and far MFA point automatically adjusts when in between. For cameras with one AF adjustment, two MFA points but no scaling and no MFA it would be very helpful.

Thanks very much.

You’re welcome.

I am not sure I follow you regarding knowing the values ahead of time. Once the lens is adjusted it keeps the settings.

Also, Even though the camera adjusts MA adjust for focal lengths in between the wide and long ends, it is a linear adjustment. E.g. -3 at the long end and +3 at the wide end would most likely result in 0 at the middle , but what if you find out that the need for adjustment is not linear? What if you need -3 at the long end, -3 at the middle and +3 at the wide end?
The point is that with the dock, you can adjust at 4 focal lengths (with the Tamron 24-70mm G2) at 3 different distances. This gives you a total of 12 adjustment points. In camera you get 2 focal lengths at 1 distance. This only gives you 2 adjustment points.

If you want to go crazy you can really tweak your lens to the max. Do you need to? Most likely not. Personally I have MA my Tamron 24-70mm G2 two times. First time I wasn’t 100% satisfied, so I tried again and found a couple of values that differed from my first attempt. Since then I have been happy with the lens at all distances and focal lengths.

D-Noc wrote in post #18759636
You’re welcome.

I am not sure I follow you regarding knowing the values ahead of time. Once the lens is adjusted it keeps the settings.

Also, Even though the camera adjusts MA adjust for focal lengths in between the wide and long ends, it is a linear adjustment. E.g. -3 at the long end and +3 at the wide end would most likely result in 0 at the middle , but what if you find out that the need for adjustment is not linear? What if you need -3 at the long end, -3 at the middle and +3 at the wide end?
The point is that with the dock, you can adjust at 4 focal lengths (with the Tamron 24-70mm G2) at 3 different distances. This gives you a total of 12 adjustment points. In camera you get 2 focal lengths at 1 distance. This only gives you 2 adjustment points.

If you want to go crazy you can really tweak your lens to the max. Do you need to? Most likely not. Personally I have MA my Tamron 24-70mm G2 two times. First time I wasn’t 100% satisfied, so I tried again and found a couple of values that differed from my first attempt. Since then I have been happy with the lens at all distances and focal lengths.

Doesn't the dock need to know how much the mirror assembly or anything in the camera may be out if you don't take a reference shot? That is what that fellow did. He took a shot with the body on, figured out what MFA was required and put it back to 0, then put the lens in the dock, applied the correct amount then re-tested with the body on.

Just in case I'm not wording this correctly. You don't or can't MFA using LV because it is direct to the sensor. Same goes for ML bodies. So how can you MFA for PDAF without involving the body. I'm not saying to use the cameras MFA for this but the dock would need to know if the mirror assembly, etc is out. Yes once you achieve correct MFA you leave it.

digital paradise wrote in post #18759818
Doesn't the dock need to know how much the mirror assembly or anything in the camera may be out if you don't take a reference shot? That is what that fellow did. He took a shot with the body on, figured out what MFA was required and put it back to 0, then put the lens in the dock, applied the correct amount then re-tested with the body on.

digital paradise wrote in post #18759622
Finally. I have asked this question a few times at other site's and couldn't get a answer. I'm not sure I see an advantage with the Dock for all camera manufacturers since you have to know the values required ahead of time before using it. As for having more than two entries Canon bodies that have near and far MFA point automatically adjusts when in between. For cameras with one AF adjustment, two MFA points but no scaling and no MFA it would be very helpful.

Thanks very much.

Perhaps this answers your questions?
https://www.sigma-global.com/en/download​/lenses/tutorial/
Chapter 3

Capn Jack wrote in post #18759840
Perhaps this answers your questions?
https://www.sigma-global.com/en/download​/lenses/tutorial/
Chapter 3

Thanks that does. It was similar to that video I watched. You still have to verify you have it spot on when the body is attached.