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

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Rob de Loe
Rob de Loe Contributing Member • Posts: 883
Veiling flare and the Schneider-Kreuznach Componon-S 180mm f/5.56
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The Schneider-Kreuznach Componon-S 180mm f/5.6 is an excellent enlarging lens that can work really well as a taking lens. It's sharp wide open at close distances, and excellent at infinity when stopped down to f/11. The image circle is enormous, which is important to me because I use it to get tilt and shift via my Toyo VX23D and Fuji GFX 50R.

S-K Componon-S 180/5.6 riding on my Toyo VX23D

Unfortunately, if you don't take steps to control stray light, it's almost useful because of veiling flare. The solution to this problem is both simple and inexpensive. It applies not only to this particular lens, but also to other enlarger lenses, especially long ones designed for large format negatives.

My copy of the Componon-S 180/5.6 is in the old-style mount that has 19 aperture blades that make a beautiful circle. I used cells from the early 2000s, but the coatings aren't noticeably better than on the original 1970s-era cells.

Componon-S 180mm f/5.6 in the old-style iris mount with the 19-bladed aperture. The cells are easily switched between iris mounts. Note the M50x0.75mm thread mount on the rear cell.

19 blades make a nearly perfect circle

The Componon-S 180/5.6 lens I'm writing about today was for sale on my eBay account a week ago because I'd given up on it. Even on a cloudless, grey day, veiling flare destroyed contrast and sharpness. I couldn't build a hood long enough to make a difference. Remember, these lenses were designed for enlargers, so while they have good coatings, they're not the kind of coatings that can handle any stray light.

No, it wasn't a foggy day. The morning was bright and clear. The sun was above and to the right, so this is almost as bad as it gets. The front element was inside a 6" lens hood lined with flocking paper. Even this enormous hood wasn't enough to deal with the stray light.

Thankfully, I pulled it off eBay after thinking that maybe the problem was at the back end. And that's exactly where it was. The same lens design that allows huge amounts of of shift without breaking a sweat also pulls in loads of stray light that bounces off any shiny surface and destroys contrast. Remember, this lens was designed to enlarge 5x7 film. The filter diameter is 62mm, but to give you an idea for how oversized the image circle is for a 33mm x 44mm sensor, only the central 25mm of the front element is needed to cover the sensor and allow 20mm of shift. The rest of the front element is stray light gathering glass!

Long-story short, long enlarger lenses can be superb taking lenses, but in adapting them you have to manage stray light by (1) using a good hood (necessary but not even close to sufficient), and (2) installing a baffle as close to the mount as you can.

I mount my Componon-S 180/5.6 with a simple aluminum adapter. The baffle is that circle of flocking material with a rectangle cut out.

I mount the lens via this aluminum adapter, that goes from M50x0.75mm on the lens side to M42x1 on the rear. The M42x1 male thread on the rear goes into a flat Toyo board with an M42x1 female mount. The inside of the adapter was painted black. That wasn't enough. I lined it with telescope flocking paper -- still not enough. It's that little disk with the rectangle that solved the whole problem.

The baffle sits inside the adapter, at the rear, which puts it close enough to the mount board to block all the stray light, but far enough away to allow the 20mm of shift I need.

Baffle inserted into adapter.

With this simple baffle installed, this is a sharp, high contrast lens that gives me the longer focal length I've been searching for on my GFX 50R + VX23D outfit, with as much shift as I can use.

Componon-S 180/5.6 out for a quick shoot down at the creek on a bright, sunny afternoon with light bouncing off the snow and water. Veiling flare? What veiling flare?

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