Veiling flare and the Schneider-Kreuznach Componon-S 180mm f/5.56

Started 2 months ago | Discussions thread
Rob de Loe
OP Rob de Loe Contributing Member • Posts: 920
Re: Veiling flare and the Schneider-Kreuznach Componon-S 180mm f/5.56

fferreres wrote:

Great hunch...probably would not have occurred to you had you not listed it. That's why it's important to list it at a ridiculous price first (hehe).

That's almost exactly what I did! The price wasn't outrageous -- more like what I call the "I don't really want to sell you but let's see what happens" price.

I posted some examples with old Dagor lenses intended for similar large format, some can be used on 8x10 or larger stopped to f16+. I don't recall what it was, I think in terms of FF the image circle can over 64x to 100x. That's about 1 photon we need and 99 that are there just to ruin the contrast. The other aspect to leaks is stopping down. One would think stopping down would improve contrast and sharpness. But again, contrary to what one may think, stopping down is a veiling magnifier. Why? Because whatever stray light got into the front of the lens and is bouncing there, still needs to get absorved, go out, or pass thru the iris. So stopping down reduces the intended light by 100% of the reduction in iris diameter, but only reduces a fraction of the veiling light. This gets worst with shiny blades. A hood, in these cases, make for a dramatic improvement.

I also found that a bellows absorbs more light than a tube, maybe because the material is often at a steeper angle, which reflects less, and also makes light bounce a lot more times before reaching the wrong side, and also has a baffle of sort automatically.

Once the light gets past the mount, it's inside the bag  bellows on my VX23D, so that helps.

Part of the problem with tubes is for some reason manufacturers often paint them shiny black. Even attempts at matte black are still too shiny. Every adapter and tube I've ever had I've had to cover the inside with adhesive telescope flocking paper. It makes an incredible difference. It's hard to get that inside longer tubes though, so bellows are definitely better

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