Century Optics wide angle adapters

iangreenhalgh1 · Expire: 2014-01-07

I've been playing around with different high quality wide angle adapters to use in front of my Schneider WA Cinelux 2x Anamorphic scope lens. Century Optics (now owned by Schneider) make probably the best available, costing many hundreds of pounds for their pro models. Luckily I was ale to pick up some of them on ebay for a pittance. WA adpaters are of two types - those which do not affect focus and those that do. The latter are intended to be used with broadcast grade video lenses that have a macro mode.

The two I am working with are the largest two in physical size as, in order to avoid vignetting with the Anamorphic scope, they have to be large diameter. One is a two element 0.55x, the other is a huge and heavy 0.7x with either 4 or 5 elements. The 0.7x is of the type that retains focus, so it works fine; however the 0.55x adapter is one which requires the objective lens be set to macro mode, otherwise infinity focus cannot be achieved and all you get is a blurry mess. The rear glass of this adapter is 60mm in diameter and the front glass of the anamorphic scope I wish to use it with has a 70mm diameter, so a large dioptre with a diameter of not less than 60mm is needed. I happened to have a huge Schneider WA G-Claron 9/240, a wide field process lens of little value or usefulness as it is not suited to large format use. The outer elements of this 4-element dialyte are very heavily curved, almost like a hemisphere; they are positive lenses so can function as a strong dioptre when placed behind the 0.55x adapter, thus restoring correct focus.

I did a quick, crude test of the functionality using my NEX-3 and a Schneider Super Cinelux 2/37.5 objective lens.All I am looking at here is the width of the FOV and if the correct focus is achievable, image quality is mot as I was handholding the camera and using one hand to hold the adapter in front of the lens. IQ tests can come later once I have verified correct function of the adapters.

Cinelux alone:

with Century 0.55x adapter - I had to use a 10mm extension tube to achieve focus:

with Century 0.55x adapter and dioptre:

with Century 0.7x adapter:

As you can see, adding the G-Claron element as a dioptre cures the focus issue but it also has the unwanted side-effect of reducing the FOV. In comparison to the 0.7x adapter it is slightly narrower, so it is probably a 0.75x adapter when the dioptre is fitted behind it. Therefore, it's an annoying situation, the dioptre cures the focus issue but you lose the width of the 0.55x adapter so you might as well just use the 0.7x instead. An annoying conundrum that I may not be able to solve, but I will try to using alternative dioptres and adjusting the spacing between dioptre and WA adapter.

I took a couple more shots comparing the 0.55x + dioptre to the 0.7x.

0.55x:

0.7x

0.55x

0.7x

The sharpness and some smeariness on the edges is to be overlooked as I was handholding both camera and adapter, but I think it is clear that both adapters work well; they don't reduce contrast, alter colours or introduce noticeable distortion.