Saturday, December 16, 2017

“There are two kinds of people in the world, those who believe thereare two kinds of people in the world and those who don’t.”

Ok it’s an old joke but it does sum up those that read my blog, eg those that use my Focus Bar and those that don’t ;-)

But it also is a serious observation on how we think/work differently to each other. For example, some like thinking/learning through images, others through text.

So the latest version of FB (downloadable on the right) adds some additional information to help you decide when to stop focusing as you approach ‘infinity’, irrespective of what type of person you are. 

It provides infinity focus info in two ways. You still see the infinity (vertical and visual) focus breakdown, but now you also, when in ‘full info mode’, get numerical feedback via the ‘Focus Quality Factor’, in addition to the near depths of field data.

The FQF is simply the % increase of the defocus (sic) infinity blur relative the hyperfocal defocus blur (an FQF of 100%), which, as we know, is the minimum acceptable (diffraction corrected) blur that we set in the ML menu as the CoC; as focusing beyond the hyperfocal means that infinity blur gets less and, of course, becomes zero when we focus at infinity.

But we also know that we can not resolve line-pairs less than two sensor pixels. Thus the Focus Bar uses the 2xsensor limit blur to define the maximum focus quality.

These next two screen shots show the FQF in action:

As we can see in the top screen capture, we are focused at 1.27m and the infinity focus breakdown is shown on the right, ie the white total CoC criterion, as set in ML, the blue total blur at infinity, the yellow shows the diffraction component and the green bar shows the defocus component. 

Because we have the Full info selected in the FB menu, we also see the textual (data) on the left, ie the near DoF based on the CoC criterion is 55cm, the near DoF based on the infinity defocus blur is 64cm and that based on twice the infinity defocus blur is 43cm. We now also see the FQF, which is 137%, relative to the hyperfocal point.

The second screen capture shows that we have refocused towards infinity and are now focused at 1.94m. The visual feedback on the right tells us that we are focusing beyond the sensor limit, as the green bar has turned red, ie we shouldn't focus towards infinity anymore and could afford to back off. The focus bar has also turned cyan over the entire DoF, meaning that, once again, we are less than the sensor limit.

We also see, on the left, that the FQF has maxed out and is telling us that at the camera settings we currently have, we can't get a (defocus) FQF greater than 170%.

In the end it is all down to you to decide what information works best for you, however, there is no doubt about it, the Focus Bar provides the best info available, in any camera!

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