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How anti reflective....

Started by Gilles Cohen, 03/28/2009 10:52AM
Posted 03/28/2009 10:52AM Opening Post
.... an antireflective coating can be smile

Left, perfectly cleaned 155EDF. Right, perfectly brand new 130GT, image taken with flash of course smile

Gilles

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Gilles Cohen
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http://www.ovision.com/Gilles_Home.html
Posted 03/28/2009 06:35PM #1
Even 17 year old ones can look good.

Tom


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Posted 04/08/2009 12:26PM #2
Gilles Cohen said:

.... an antireflective coating can be smile

Left, perfectly cleaned 155EDF. Right, perfectly brand new 130GT, image taken with flash of course smile

Gilles

Well Gilles I don't like to rain on the parade but here is a simple humble C14 shot which I took, also with a flash, which you can see from the metal on the secondary holder. The glass is showing no reflection and we are at an angle as you were. I was putting some flocking in at the time. The corrector has not been cleaned yet as the project was not done.

So I'm thinking well maybe the Celestron coatings are as good as AP's (unlikely) or maybe the test isn't a very rigorous test? Along these lines I note that when shooting from an angle the light may not bounce directly back at the camera.

regards
greg n

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"Scope will get you through times of no money better than money will get you through times of no scope." --Freewheelin' Franklin
Posted 04/09/2009 05:52AM #3
Gilles Cohen said:

.... an antireflective coating can be smile

Left, perfectly cleaned 155EDF. Right, perfectly brand new 130GT, image taken with flash of course smile

Gilles

Pursuant to my other post, which has a Celestron corrector showing no reflection with a flash picture (C14 with Starbright coatings), I found this additional picture of Minox binoculars. These are also photographed at an angle, and you can also see that the only evidence of the flash is from the internal metal, not the objective.

My conclusion is that the "flash test at an angle" is something that most companies-who-know-the-optics-biz can pass, on a wide variety of optics. I suspect that multi-hour exposures with ccd cameras is where AP optics show their sharpness, color correction, and general top notch execution. It is of course possible that there is a certain threshold of execution that the angle/flash photo test provides, and that Minox, Celestron, and AP all pass that threshold. Possibly there are much lower end optics that would not pass the test. I have a c8 which has no coating decal on it so maybe I'll try with that. For me this is actually getting rather beyond the AP-is-great issue into a more interesting topic, which is whether this very simple to perform test, camera-flash-at-angle, actually tells us anything useful. I'll try to post my no-coating c8 (at least it says there is no coating sticker) later. The previously posted C14, I repeat, had Starbright. The Minox like all upper-half-of-the-market binooculars has something like two dozen multicoatings.

regards
Greg N


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"Scope will get you through times of no money better than money will get you through times of no scope." --Freewheelin' Franklin
Posted 04/09/2009 06:30AM | Edited 04/09/2009 06:30AM #4
Following up on my previous posts, I have a shot of a c8 which presumably has no coatings; or whatever coatings were used, when no sticker was applied.

This picture to me pretty much shows that just parking a flash camera at an angle to an optic is not going to give a good test of the presence of lack of coatings.

HOWEVER....

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"Scope will get you through times of no money better than money will get you through times of no scope." --Freewheelin' Franklin