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Message: <blockquote data-quote="Chosun Juan" data-source="post: 3333169" data-attributes="member: 92780">Henry, Tobias, (and Ed), I agree that the light intensity will be the same regardless of aperture, but I am also in agreeance with Ed that there is a systematic dimming of the brightness illustrated in the photographs shown correlating with reducing aperture. There is definite truncation of the exit pupil shown in the 8x32 UVHD(+?), and like Ed posted above I am thinking that the differences in brightness photographed are likely due to something along the lines of the camera 'seeing' the image as a fully dilated pupil would, thus making the smaller exit pupil sizes seem dimmer. I don't know exactly the equipment used, and it's modes of processing, or how the manual settings set-up Tobias is using has been affected, but given the systemic nature of the variance shown I would go looking in the metering arena, to see if somehow the dark surrounds of the smaller exit pupils are being integrated in the evaluation. There are also the effects of truncation and vignetting to consider, and it may indeed be very valid to include these as important consumer information (Note to manufacturers: If you don't want the brightness of your binoculars reduced by these - then design them out! I don't think there is really any excuse for truncated exit pupils .....).  In terms of outright brightness, I agree with Ed's suggestion that a masked aperture to represent say a 2.5 -3mm exit pupil should eliminate any of these effects.  It would be  v - e - r - y  interesting to compare the results of the two methods.Finally, Tobias, I am a bit floored by the notion that the 8x32UVHD+ would not contain any actual HT glass!, although like you, I am thinking it has to be a consideration. Perhaps you could double check this with the factory in general for this 32mm model, and particularly in reference to the unit you tested?    :cat:Just a reference (and acknowledging the vagaries of the internet and specification updating delays /inaccuracies), here is a link to the UVHD+ series that comes up from the main Leica site that comes up by searching from here .... note that the 32mm UVHD model is not listed as a 'Plus' ???<a href="https://uk.leica-camera.com/Sport-Optics/Leica-Birding/Binoculars/Leica-Ultravid-HD-Plus" target="_blank">https://uk.leica-camera.com/Sport-Optics/Leica-Birding/Binoculars/Leica-Ultravid-HD-Plus</a>Curiouser, and curiouser, .......   :cat::cat:[EDIT]: I just double checked the photos of the physical bins in your x42, and x32 UVHD+  reviews, and the badging on the bins is indicating them as "Plus" model - The difference being the "HD" is in Red which indicates the "Plus" model.  Source:  <a href="http://www.birdwatching.com/optics/2015_titans/review.html" target="_blank">http://www.birdwatching.com/optics/2015_titans/review.html</a> Chosun  :gh:</blockquote>

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