Sigma 150-600 Sport Further Update On Auto Focus Micro Adjustment

After the loss of the settings from the AFMA table, I was miffed to say the least and decided to do a bit more work and report on the method and accuracy of the results.

As mentioned previously the Sigma 150-600mm Sport has the ability to be MA'd at 16 different points across the focal range using the Sigma Dock.
Unfortunately there is a lot of guess work involved, by this I mean you have to

1. take a shot of your target, 
2. review it, 
3. remove the camera body from the lens,
4. put the dock on make an adjustment, 
5. remove the dock, 
6. put the body back on
7. repeat the process

This has to be repeated for all 16 points multiple times for each point, which is daunting and time consuming.

So I thought I would try and come up with a similar method or at least a more streamlined method.
The first thing I did was get a DOF calculator out, using the widest aperture and the following distances 2.6m,6m,15m and infinity @ 600mm gives the DOF as .55cm,3.34cm,22.9cm and 93.4cm
which is ok but you need a target with a front to back length of at least a metre if not more.

Repeat these DOF calcs @ 400mm and you get 1.36cm, 8cm, 52.2cm and 211.7cm
Repeat these DOF calcs @ 250mm and you get 3.72cm, 21cm, 135.1cm and 548.5cm
Repeat these DOF calcs @ 1500mm and you get 10.5cm, 59.6cm, 383.2cm and 1619.7cm
The infinity calcs were done at 30m which is questionable, and to be honest I never bothered attempt any infinity adjustments.

How the hell do can you see how accurate your focal point is when you have such a huge DOF ?
the smaller distances are fine you can easily see the edges of the DOF as the sharp edges become less defined.
As for attempting to MA 150mm @ infinity/30m I'm jiggered if I have a scale that is 16.197m long in me back pocket !

At this stage I kind of lost the will to live.

I  did MA the lens at all focal lengths up to 15m took a long time, I used Reikan Focal Pro, first off I used Canon's built in MA adjustment to see if the Sigma needed tweaking.
At 2.6m no adjustment required  across the focal range Reikan reported 0 was the correct setting
At 6m no adjustment required @ 150mm and 250mm, @ 400mm and 600mm it needed tweaking final setting of -5 and -3 respectively.
At 15m 150mm needed +1, 250mm 0, 400mm 0, 600mm +5

In my humble opinion whilst it sounds like a light bulb moment having all these focal points to MA at in reality and practically it is too much of a faff to use the Sigma Dock, whilst initially I had loads of enthusiasm for this facility it has gone down hill fast.

I will probably end up using the inbuilt Canon MA and just MA it at 150mm and 600mm and be done with it !
Life is too short to be spending any more time on it.

Strange But True

Recently the results I have been getting with my Sigma 150-600 have been somewhat dismal, so today I connected it too the Sigma USB Dock and checked the AF settings only to discover that the entire AF table was empty !!

Note to self: next time write the bloody settings down !!!!

What has happened to em I dont know but that will hopefully explain the soft focus results I have been seeing of late.

Now all I have to do is go through the long drawn out process of setting it back up grrr !