MC Sandwich

I am writing this as a documentation of my use of multicoated optics to enhance the performance of vintage camera lenses. A common problem old lenses face is flare and other aberrations resulting from the limited capabilities of primitive coatings. Hypothetically, introducing multicoated optics in the front and rear of the optical path would improve image quality somewhat. The extent of the effect is unknown, and may vary from lens to lens.

I tested this theory on a cheap Makinon 400mm f6.3 optic by placing a well coated Hoya HD filter in front, and using the Olympus EC14 teleconverter behind it. Before using the MC optics, flare was objectionable and the image appeared to be soft due to extensive optical aberrations. After adding on the optics, the image quality was greatly improved and the lens combo could render passable results.

Trying again on the Olympus 300mm f4.5 (a non-MC optic), there was a small but noticeable amount of CA and subtle flare in the images when shot wide open. After the introduction of MC optics, CA and flare completely disappeared. This was unexpected. Of course, being no expert in optical design, I'd expect there are explanations for how/why this happens; besides the obvious ability of MC optical glass to resist flare and the teleconverter's ability to collimate light.

It is expected that similar combinations may be used on other legacy optics to similar effect, and may provide a way to rejuvenate old lenses. However, further experimentation is necessary before it can be established exactly which optics respond best to the treatment. Initial findings suggest that a relatively fast lens is required in order to maintain a usable level of light transmittance for general photography.