Canon nFD: A little helper for lens testing

[Andreas Thaler]

Today I tested the functionality of this nFD 35-105/3.5~4.5 and also looked at the lenses with the LED lamp.

With Canon nFD lenses, the aperture is closed when they are removed from the camera, and the aperture blades remain locked.

This makes testing the lenses with the LED lamp only possible to a limited extent.

The aperture blades also cannot be checked for possible oil contamination, as they have to be moved to do this.

With a self-made „aperture key“ from the bayonet ring of a discontinued Canon T90 (or another Canon with FD bayonet), the aperture can be opened and closed to the preselected value using the aperture lever.

The lens now behaves as if it were attached to the camera, see

Canon New FD: from bayonet ring to aperture key

A special feature of Canon New FD lenses is that their aperture remains fixed at a value as long as they are not attached to a camera. The aperture blades cannot then be moved and checking the optics and aperture blades with an LED lamp is only possible to a limited extent. “Aperture key”...

www.photrio.com

Now the nFD lens can be checked without any restrictions.

In this case I only had to clean the rear lens.

A slight lens separation further in will most likely not affect the image, nor will some small damage to the coating of the front lens.

An „aperture key“ can also be made from the rear lens cap of an nFD lens:

Canon nFD 28/2: Outsmarting and cleaning the aperture blades

For years, oil has been shining at me when I look at the aperture blades of my fast wide-angle lens. And this has saddened me for years. This should be over now 👍 One of my favorite lenses and quite heavy. The rear optical unit can be easily unscrewed and is already removed here...

www.photrio.com

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All information provided without guarantee and use at your own risk.

 

[mtnbkr]

Pretty neat. I use a Fotodiox M43-FD lens adapter to do the same thing, but yours is smaller and easier to bring along if you're shopping.

Chris

 

[kl122002]

I use an extension tube ( not tele converter) instead. It is super cheap in ebay even it is originally made by Canon.

Sometimes the camera stores' junk or bargain box might have it.

 

[tokam]

There also use to be reversal ring sets which allow lenses to be mounted in reverse for macro / closeup photography. One ring for the front of the lens which had an FD bayonet mount to match with the camera body and another ring to go on the bayonet end of the lens to simulate mounting the lens and thus unlocking the aperture which had to be set manually for each picture.

Somewhere I have the instructions detailing which pin on the nFD mount to depress which allows the nFD ring to rotate and simulate the lens being mounted to a body.

These days I just use a short extension tube as mentioned by @kl122002 above.