Nikon S2 Close Focus Calibration

chaosreigns

chaosreigns

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Hello All,

I bought an user S2 with 5cm f/1.4 lens and it's fabulous. I think this will be the first of many RF's to come....

Thanks to many posts, I adjusted the horizontal and vertical alignment for infinity. However, close focus is another issue. Focusing on an object 3 feet away falls on 3.5 on the distance dial.

Am I correct to assume that the dial should be very accurate?

How do I adjust the gain of the system so that patch and dial align properly at multiple distances?

Thanks!
 
nikon s2 focus accurate ??

nikon s2 focus accurate ??

the helicoid (focus mount in the body is not ajustable .
perhaps your adjustment of infinity is off as the differance gets worse in closer focus .
you should shoot pictures of a known setup .

you can arrange a line of objects at distances about three inches apart .
i use cans as i have many in stock .
set up a line of cans with one odd can in the center .
about 25 total is correct .

if you focus at the lone object (fosters ) at all the settings useing the s2 rangefinder spot ( use the nikkor wide open at 1.4)
ie 3 3.5 4 4.5 5 6 7 8 10 12 15 20 30 50 inf
your results should give you an idea as to the exact focus point useing the
rangefinder spot . you will always be able to tell if the lone object is in focus.
a little behind or in front (consistant for all shots ---your inf focus is off in that dirrection .

in all seriousness -- the focus mount is fixed pitch -- so
a real world test like this is best .
 
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focus wheel hang up?

focus wheel hang up?

Is the spring-loaded wheel that bears against the helical hanging up at around 3.5 feet? Take out the lens and look up and inside. As you move the focusing mount through its range, the little wheel should stay in constant contact with the heloid. If it doesn't, that may be part of your problem. You can "Exercise" the wheel with a finger, and that usually solves the problem. WES
 
> the helicoid (focus mount in the body is not ajustable .

There are shims under the Helical. I had one S2 that was not correctly shimmed. I took the helicoid off and shimmed it. The shims look like washers, and sit under the points where the screws go in.
 
It could be that your close focus problem can be the much vaunted "Sonnar" focus shift. I have not really tested my 50f1.4 Nikkors for this. Probably should as I have at least 6 of them (no, I dont know why - they just keep multiplying).
 
chaosreigns said:
Thanks to many posts, I adjusted the horizontal and vertical alignment for infinity. However, close focus is another issue. Focusing on an object 3 feet away falls on 3.5 on the distance dial.

Am I correct to assume that the dial should be very accurate?

How do I adjust the gain of the system so that patch and dial align properly at multiple distances?
Click to expand...

The distance scale on the focus helicoid is very accurate. If infinity is adjusted properly, when focusing on an object three feet away, the focus helicoid should indicate three feet.

Since its not, I'm inclined to agree with Wes's explanation that the spring loaded wheel that bears against the helicoid is hanging. Does the rangefinder focus patch stop moving at a certain point as you focus closer even though you're still rotating the lens?

Focus problems caused by incorrect shims under the focus helicoid can only be seen by actually taking photos, and will show up as front focusing throughout the entire focus range if the shims are too thick, and back-focusing throughout the entire focus range if the shims are too thin. If this is the problem, the rangefinder should still appear to be working properly, but in your case its not.

Have you run any film through the camera?
 
I ran film through the camera and images were soft, but I didn't think that my focusing "skilz" were that rusty or my hands that shaky. That is why I started examining the helicoid-lens and helicoid-rangefinder. First here, the helicoid-lens system:

The infinity focus of the frame-helicoid-lens system is accurate. I performed the very clever "backsighting" test described here (second method). My test image was very sharp.

For close focus, I modified the above setup and used an LED flashlight to project the image through the lens onto a white board. At 3 feet on the dial, aperture f/1.4, the image front-focused by about 1 inch. At 10 feet, f/1.4, the focusing was spot-on.

Next, I'll look at the helicoid-rangefinder system and report back. Thanks for the all help.
 
Close Focus Problem Fixed*

Close Focus Problem Fixed*

I think I have fixed my close focus problem. I first determined that the wheel that rides the helicoid wasn't the issue. Then, I opened the top of the S2 and found two eccentric rings that adjust the gain of the helicoid-rangefinder system. The eccentrics act like adjustable-length levers and can increase or decrease the deflection of the right RF prism for a given turn of the helicoid.

For me, it was a long and tedious process to adjust the eccentrics because the slightest twist of the eccentric affected infinity alignment. But I finally got the rangefinder and helicoid scale to match spot-on at infinity, 30 ft., and 3 ft.

*Now, I need to run a roll of film to see if it's really working properly.

Cheers!
 
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