What constitutes "no peripheral distortion"?

Merlin · Joined: 08 Apr 2007 Posts: 3

Could you help me understand the definition of "no peripheral distortion"?

I recently purchased a NVM which is advertised as "equipped with a premium quality 2nd+ generation intensifier tube that guarantees superior viewing experience and produces exceptionally bright and clear images at increased distances with no peripheral distortion."

The first unit I received had a flaw in (on) the view screen, and was returned for exchange. Through both former and later units I note that while the center 1/3 to 1/2 of the image is sharp, the surrounding perimeter becomes more distorted the further one looks to the edge of the image. It is a radial-type distortion which appears as a stretching of the object (point light source, etc) around the circumference. To me, this constitutes "peripheral distortion," but as the only experience I have with other makes and models is an associates 3rd Gen (ABSOLUTELY SHARP IMAGE FROM EDGE TO EDGE), I have little to draw upon for comparison.

Is this manufacturer blowing smoke?

opticsplanet.com · Posted: Mon Jun 04, 2007 8:31 am Post subject:

Hi

If it is a true Gen 2 product, it will have less distortion at the edge (peripheral) of the field than a Gen 1 product and here we are talking about curvature of the image. As you scan right and left with a unit that suffers from barrel distortion, the image will appear to bend and flex. Gen 1 units are notorious for this, but it should not be an issue with a good Gen 2. There may be some, but it should not be annoying.

The other edge of the field consideration is image sharpness. A unit can be free of barrel distortion at the edge of the field, but still appear to be out of focus at the edges. This can occur to some degree with any Gen 2 or even Gen 3 product, but is definitely less likely to be a problem in a higher priced model.

Not sure how I would rate your Gen 2 without actually looking through it, since there is a wide variety of performance and quality on Gen 2 products. I've seen some that were little better than a Gen 1, but some of the high performance (and expensive) XD4, CGT, HPT Gen 2 models I have seen will give a good Gen 3 a run for its money.
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