Hyper-focasing is about using the Depth of focus range of the selected aperture to cover the area of interest in your composition, and focusing using focus scale, rather than by eye through the view finder. (or letting the AF system 'guess' what you want!)
For big-stoppa, ND filter shots, where you cant actually see bog all through the welding glass to focus by eye.... seems like a good trick to me.....
Rule of thumb is acceptable focus extends 1/3 infront & 2/3 behind point of focus, so lets say you have a child in a park; focus ON the child, and you get I don't know, a soccer ball in front of them out of focus, and hedge behind in clear focus.... but you want to concentrate viewers attension on the child and ball..... and selective focus on the kid would be good.
Now if you focus on the ball, instead of the child... you get the back-ground hedge out of focus.... BUT through the view-finder, child probably also looks fuzzy, because the aperture is probably not stopped down to show true DoF, but left 'wide' until moment of exposure to give brightest view-finder image.... so you may not be able to tell, if the child will be within the DoF until after you have taken picture.
Modern Digi-Cam... you press shutter and peek at screen, you may be able to tell.... though no-where near as good as on old manual focus cameras that had Depth-Of-Field preview to stop the lens aperture down so you could see through the view-finder.... or better still, Hyperfocus scale on the lens!
Scale has marks either side of the focus index, for each apperture setting; that suggest the Depth of focus range on the focus distance scale.
So.. on that lens (a 58mm Helios 44 BTW), aparture is set to f4, focus at 4m, and DoF scale offers acceptable focus from aprox 3 1/4m to about 5 1/2m... 3/4m in front of point of focus, 1 1/2m behind, roughly the 1/3 to 2/3 proportion suggested.
Using same scale, and point of focus; if you set f16, you'd have DoF from just over 2m to just shy of infinity......
See how it works? Using a Hyperfocusing scale, you 'set' the focus range, you don't focus on a subject.
Your situation..... unable to actually see very much through heavy density ND filter.... PERFECT situation to use Hyperfocasing, set by scale, rather than looking through the lens and trying to focus on a subject point.....
Except, you dont have a Hyper-focus scale, I suspect.... and if you DID?
Well, Helios 44 runs out of f-stops higher than f16, but stopped down as far as that lens will go, and setting infinity focus mark just inside the f16 bracket on the far-side.... your near-focus point would be aprox 3 1/2 meters for your closest acceptable focus... which is unfortunately about 8ft, 3ft beyond your point of foreground interest.
Grabbing a Zeiss 50mm that does stop down to f22, slightly shorter lens, gives slightly deeper DoF, and f16 gives aprox 6ft to infinity; f22, JUST on your limits, about 4.5ft to infinity.
Grabbing a pentacon 29mm (yup... I have bag of M42 primes to hand!), f22 gives about 20" to infinity... going the other way, 135mm Hanimex, gives about 40ft to infinity at f22.
So, without a hyperfocus scale, it's a tad more awkward, but; wider the lens, and the tighter the aperture, bigger the DoF range.
Principle remains, you set focus by scale, not by eye.... so into manual mode...
Worth noting that the 1/3 to 2/3 guide is only a guide; the ratio increases favouring the behind focus depth, the closer you approach infinity focus distance. In macro-photography, the DoF can be almost 50/50 front to rear, but on most cameras, at closest focus distance its usually close enough to 33/77 and increasing behind. And 5ft is reletively close focus for most lenses.
So to get your 5ft for-ground interest acceptably sharp, you are likely to need to draw back and focus quite a long way short, maybe less than ten feet, to be sure to get the near interest sharp, and still shop down f22 or tighter to make sure you get far distance infinity within the bracket.
And may be a case of taking a few test shots without the filter to get your best focus range by a bit of guestimation, focusing between near subject and infinity stop...
May be possible to lay a tape measure and pegs down a lawn, and take some test shots at different appatures and focas distances, and use that to create and calibrate a 'paper' hyperfocal scale to sticky-tape to the focus ring.
Its one feature of digital, I really do miss, TBH, and the big LCD display at the back seems to tell me loads and loads of really irrelevent infor, but nothing so remotely useful as the focus distance, let alone DoF around it! (Nikon take Note! This would be good!)
Alternativeley; adaptor mount and old manual focus primes with scale! (except that on a Nikon... you either get a mount that acts like an extension tube and wont allow infinity focus, or one that has a correction lens to allow infinity focus, but screws the focus scale calibration!)
