PTX-110 adapter - project continues

New adapter with preset iris in the making.

Last year several digital pictures were taken with adapted Pentax-110 small film format lenses. Lenses were capable of producing sharp and fine images. However, some problems were encountered with the available commercial adapter product.

First and biggest problem was that the lenses do not have iris so they always operate wide open at f2.8. This reduces image quality compared to stopped down to f4 or more. Another problem was that the adapter part meeting with the lens back was not manufactured up to Pentax standards. Lens position was not quite right limiting image quality.

Suitable model for the Pentax camera bayonet was found in the plastic bubble delivered with the lens. The plastic bubble lens mount is certainly up to Pentax standards and could be used to duplicate the lens mount part for the new adapter. Once the design has been transferred over to software new lens mount parts could be 3D printed including iris hole acting as the stopped down aperture.

Image above shows the lens mount part of the current adapter and plastic bubble lens mount used as the model for the new adapter including fixed iris. It is not yet decided whether the new lens mount plate will be used together with the existing adapter or some other adapter base suitable for digital Micro Four Thirds cameras.

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