Thanks for all the input, majority is against the brass knob as a cause for veiling glare. So I grabbed my torch and Noctivid again.
Please fasten your seatbelts and we will do a dive into the stargate. Ok, it´s only Noctivid flare. Psychedelic enough.
Please could someone tell me what is going on in the Noctivid? Henry Link? Optical designer from Leica,
I marked all bins on the left objective at 12o´clock with a white dot. I used a dimmed and diffused LED torch because with strong light the direct, colorful lens ghosts will make it hard to see anything inside. It´s a bit tedious because the macro lens is bulky etc., but the LED is just a bit tilted from axis so this is light which easily enters the glass under normal conditions.
No. 1 is Nikon EDG, you see a reflection of the roof at 6 o clock. And nothing else, no matter where I put the torch. That's a pretty unique point of the EDG probably. Applause.
No. 2 is Leica UVHD+ 8x32, a favorite but definitely not as flare suppressed as the Nikon. This is most of the reflection I could provoke.
No.3 is the Nocti 8x42, the LED just hitting the roof.
No. 4 with the torch tilting a bit differently, this is the flare thing. Seems to be in a focus plane close to the field stop.
No. 5 another pic of the flare thing, different light angle.
A reflection this bright should scatter back into the image path and cause veiling glare. I´d be very surprised if it did not.
Although I did heavy contrast correction in the images, so flare brightness should not be quantified by the images, the Nocti flare is much brighter than the UV flare, and comes from a much bigger area.
Seen from the ocular it is veiling glare.
Again, it is always "directly compared to what" - I don't know about SF, Swarovision etc. as I don't have direct comparison at hand.
But compared to the 10 years older Nikon EDG the Nocti disappoints me.
Because the Ultravid has a similar, although much weaker reflection, I think a manufacturing defect in my Nocti sample is improbable. This looks like a design flaw.