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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1309510" data-attributes="member: 68323">I tried a simple test suggested in this post<a href="http://birdforum.net/showpost.php?p=1161531&postcount=13" target="_blank">http://birdforum.net/showpost.php?p=1161531&postcount=13</a>where he looks for ghost images using a small AAA Maglite flashlight in candle mode (with the reflector assembly removed). It works well to see ghost images (and even estimate their order ... how fast they move as the bin is panned ... reflections from one than one surface move quicker) and so to evaluate the effectiveness of the AR coatings.The same test can be used to observer residual diffraction spikes from the roof edge of the prism and so evaluate the effectiveness of the phase-correction coating on the roof prism.So in a dark room at a range of 6m I looked at the flashlight's filament against a dark background.<ul> <li data-xf-list-type="ul">Winchester 8x32: no PC. Large diffraction spikes noted in each barrel. Not particularly sharp.</li> <li data-xf-list-type="ul">Promaster 7x32: no PC. Large and very sharp diffraction spikes (the upside is the optics are quite good so the spike is very sharp ... but that's a bit like being the tallest midget).</li> <li data-xf-list-type="ul">Vortex Diamondback: with PC. Some diffraction spikes seen but much weaker than in the two no PC examples above.</li> <li data-xf-list-type="ul">Bushnell Discoverer 7x42: with PC. Some diffraction spikes. Much less than the Diamondback but I was rather supised to see any in this bin.</li> <li data-xf-list-type="ul">Pentax WP 8x32: with PC. No diffraction spikes</li> <li data-xf-list-type="ul">Zeiss Conquest 8x30: with PC. No diffraction spikes</li> <li data-xf-list-type="ul">Leupold Yosemite 6x30: porro so no roof prism. No diffraction spikes as you would hope.</li> </ul>So this rather points out that the quality of a phase-correction coating varies from model to model and maker to maker. The cheaper PC bins still show some diffraction effects and even the mid-range Discovery has some effects visible (though that are much reduced compared to the low end bins). Both the Pentax (with Pentax's first PC coating) and the Zeiss show no diffraction effects.So it's possible that the effects are common in the 8x36 Monarch. Or it might be this is just a bin with bad coating. It's difficult to tell from a sample of one. If you have a Monarch and a flashlight you can test this. The diffraction spikes have different orientation in each barrel (so check each barrel separately). I'd like to hear the result.This is a nice portable test so should be able to try it out at REI next time I'm there.</blockquote>

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