Good. Seems like something that might be useful to add to the user manual. If it's in there, I didn't see it. If not for Geoff's primer, I would not have had a clue how to do it.
I am going to ask the factory to publish their recommended AF offset calibration routine. Hopefully they will have time.
That would be great to know. Also, I just noticed there is an apostrophe (') next to the frame number on the film back. I looked in the manual, but find no mention of what that indicates--although it is present in some of the images. I don't recall seeing it before.Here is another question that might be addressed in an updated "primer." What is the deviation for the "Focus Bracket" mode? If one could correlate that to the focus offset, one might easily set the focus offset with a single 5 frame "Focus Bracket" and then examine the negatives looking for the frame that is in focus. If you knew how the "Focus Bracket" worked, you could figure out where to set the focus offset.
This matches my observations exactly. Irrespective of how my insert came to have a channel of 0.3mm, that measurement works well with my camera and Hp5 film. Produces an infinity focus at the hyperfocal for f2.8 and my focus offset is around -10.Please note that film (including the paper) has a certain thickness and has to be moved in a channel between 0.3mm and 0.7 mm
Right after opening the Hy6 kit, our dog got hold of the film insert without my knowing.
When I tested my camera for focus, all negatives had focal point in front of the subject.
I measured the 4 posts of the insert and found 0.533, 0.635, 0.700 and 0.610
Suspecting maladjustment, I delivered the item to my local independent repair facility where the problem was promptly diagnosed based on my description and out of focus photographs.
The film insert was re-set to factory specs for a nominal fee and now the camera is fine.
I checked the pressure plate and all 4 posts measure 0.3mm.
Might the issue of offsets be getting too much attention? More important than offsets are the basic alignments, such as focus screen to film plane; even more important (and more fundamental) is basic focusing, such as being able to reach infinity. Offsets are a final tweak. Many cameras don’t have this feature but I hope we don’t overdue our affection for it.
Summary. Erik and DW Photo are recommending only the AF Offset be adjusted by the user:
Lens Infinity Stop: Adjustable; set at factory to hyperfocal distance for widest aperture
Focus Screen Offset: Adjustable; set at factory
Pressure Plate Location: Adjustable; set at factory
AF Offset and AF Area: User Adjustable
Prints from 50mm and 80mm lenses f2.8 at the infinity stop. Hyperfocal point depends on viewing distance. These 8x8" prints, at a about 1-2 foot viewing distance are sharp.
View attachment 258382
View attachment 258383
I progressively advanced the pressure plate from 0.6 to 0.3 in 0.1mm increments, testing infinity along the way. I wanted to go closer than 0.3mm, because it was not quite at infinity yet, but read the posts about the lens set at hyperfocal distance. I went back to re-evaluate my 0.3 negatives (posted above) and, it does appear about 45 meters* to be the focal point. So I stopped testing at 0.3mm.Interesting findings. Are the two (.3 and .4) both shot wide open? It would seem then for max accuracy, you also “tune” to a particular film thickness? How easily does some of this specificity go away with a bit more aperture?
FYI- this is much less an issue with digital, I guess because the sensor plane is always in the same spot and is very flat.
Paper+HP5+Tape = 0.4mm. But the tests showed focus at the hyperfocal distance for f5.6 (25meters), not f2.8!
Having mentioned that, the negatives at f11 are razor-sharp at infinity even when the pressure plate was at 0.4mm. So, if one has a film binding issue at 0.3, setting to 0.4 might be a reasonable compromise.
HP5 + Paper = 0.27mm so it should theoretically pass through a 0.3mm channel OK.
I progressively advanced the pressure plate from 0.6 to 0.3 in 0.1mm increments, testing infinity along the way. I wanted to go closer than 0.3mm, because it was not quite at infinity yet, but read the posts about the lens set at hyperfocal distance. I went back to re-evaluate my 0.3 negatives (posted above) and, it does appear about 45 meters* to be the focal point. So I stopped testing at 0.3mm.
*Rollei DOF tables for 80mm Planar on 6x6 format show hyperfocal distance at f2.8 from 55 to 40 meters depending on etc., etc, etc. the usual things on which hyperfocal distance is dependent.
On-line Hyperfocal Calculator shows 48 meters with CoC 0.045mm.
Paper+HP5+Tape = 0.4mm. But the tests showed focus at the hyperfocal distance for f5.6 (25meters), not f2.8!
Having mentioned that, the negatives at f11 are razor-sharp at infinity even when the pressure plate was at 0.4mm. So, if one has a film binding issue at 0.3, setting to 0.4 might be a reasonable compromise.
HP5 + Paper = 0.27mm so it should theoretically pass through a 0.3mm channel OK.
By definition, that 45-55 meters the distance that is in focus as determined by high magnification of my negatives and where the focus ring would be set. Again, by definition, when the print is held at a pre-deterimed viewing distance, YES, infinity will appear to be in focus, as well as subjects as close as 25 meters.When you say hyperfocal 45-55meters, do you mean that at that distance, then infinity is in focus too?
The travel direction of the film in the Hy6 is opposite the 6008. Makes it easy to distinguish which camera was used.The frame numbers fall slightly different from the 6008i,
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