Calibrating a Sigma 150-600S on a D4S (Reikan FoCal)

Started Sep 11, 2016 | Discussions thread
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rob_b Contributing Member • Posts: 885
Calibrating a Sigma 150-600S on a D4S (Reikan FoCal)

OK, I tried this for the first time today:

D4S, coupled to my macbook (USB) semiautomatic mode (I needed to enter the MFA values)


Target (just visible) provided by FoCal, about 15m away, max I'd expect to get a decent shot of a smallish bird . I had to wait for the sun to move and not part illuminate the target!

Software was quite easy to fathom, and once the target was acquired and focus fixed, I first tried it on the 150-600 at f6.3. I did the test at 1600ISO (to be realistic) and ended up with a recommended value of between +7 and +9:

Each symbol is a shot taken , quite a broad plateau around MFA of 8.

It was interesting to watch the process of optimisation - as a scientist - i found it very satisfying. I also felt that the lens was working well at this value afterwards, though no shots yet that really confirm that.

I then added the TC1401, giving me 850mm fl. This was a different story:

with a 1.4 TC in place, could not find an optimal.

So, two tings leave me..

1. Maybe I should send the TC back and ask for a replacement? It clearly shifts focus a lot. Although the system is now focusing at 'f9' the D4S never failed to acquire a focus though.

2. I thought 'aha! If I set the default MFA to +8, then the addition of the TC should give me a leeway to +28. But, when I optimized with the default of 7 dialed in a) the lens alone still optimized at +8 (??) and the TC+ still failed to optimise at +20.

Does this make sense?

Lastly, I was pretty impressed by the software and the wealth of information it gives you. I'm hoping this will translate into sharper pictures/more feather detail in our upcoming Florida trip. Anyone else have experience of this system?


was the set up:

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