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Kern Aspheron 5.5mm Supplementary Lens


Guest Glenn Brady

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Guest Glenn Brady

Recently, I bought a Kern Aspheron 5.5mm supplementary lens for use with my Kern-Paillard 10mm f/1.6 H16 RX Switar preset lens. Cosmetically both are in mint condition. The Aspheron is mechanically compatible with the Switar (both have 38mm threads), but the image formed when they're put together is very far out of focus (the Switar forms a sharp image on its own). I've attached the Aspheron with and without the stubby lens shade on the Switar, but the image remains very blurry.

 

Has anyone experienced this problem? Might the Aspheron, despite its new appearance, be defective? Is the Aspheron incompatible with all but the very late series all black 10mm Switar lenses?

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Guest Glenn Brady

Hi, Jean-Louis

 

I've run the focusing on the Switar to its near limit and the image is still significantly out of focus. The image is sharp at full aperture only when the subject is about three inches in front of the Aspheron.

 

Best regards,

Glenn

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Guest Glenn Brady

Using a 0.25mm Edmund Optics Brass C-mount spacer (a component of a set - C-Mount Spacer Kit - recommended to me a while ago by Jean-Louis) to increase the ffd of the Switar lens, I managed to focus the lens at infinity with the Aspheron in place.

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Guest Glenn Brady

That's not normal. The 10mm lens' distance scale must be improperly set.

 

. . . and yet the 10mm lens focuses properly at infinity when its scale is set to infinity. It's only when the Aspheron is added that there's a problem.

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  • 2 months later...

. . . and yet the 10mm lens focuses properly at infinity when its scale is set to infinity. It's only when the Aspheron is added that there's a problem.

 

Because of the large depth of field on a wide angle like the 10mm, it's best to check the focus at closer distances too, like 20 or 30 cm. This will tell you whether your distance scale is accurate.

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  • 8 years later...

Hi Everyone, 

I've also found that my Switar 10mm (Silver Preset Version) is blurry with the Aspheron 5,5 and was wondering what's going on? 

I can almost get focus at infinity when the Switar is focused close, but cannot get any closer focus with the Aspheron attached. Stopping down the aperture seems to help a little but it's not really usable for shooting.

The Switar itself seems to focus... except that infinity is at about 10" on the lens markings, past which point everything is just a blur... but it can foucs clearly up to about 5cm, so guessing there's something wrong with the scale too. Does it also need the black step up ring I've seen on some models?

Would really appreciate any advice on what's going on and the correct attachment of the Aspheron for this lens to work! ?  (I studied photography but just getting into film making with my first Bolex Rex 5). 

Best Regards,
Alexander

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  • Premium Member
On 8/14/2020 at 2:33 AM, Alexander Perry said:

The Switar itself seems to focus... except that infinity is at about 10" on the lens markings, past which point everything is just a blur... but it can foucs clearly up to about 5cm, so guessing there's something wrong with the scale too. 

The focus scale on your lens needs calibration. If you can take it to a Bolex specialist or lens tech familiar with Switars they can reset it in a very short time. Ideally take your camera as well so that it can be checked too, since both camera and lens need to be accurately set for correct focus.

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