center filter needed?

[Rob Rielly]

I have a suuper angulon f8 lens that I have not used much. I do plan to use it on an upcoming trip (landscapes). Will I be able to get away without a center f ilter, or do I really need to pick one up? Thanks for the advice. Rob

[Michael S. Briggs]

Some additional information would help us answer your question: what focal length lens and what size film?

There are some similar questions (with answers) under Older Messages: Filters.

--Michael

[Les Moore]

I use a Nikon 90mm f/8 for 4X5 landscapes. I have never experienced vignetting, even when using a lot of camera movement. In contrast, the 75mm I used to rent had noticeable vignetting, even with moderate movements. Almost all of my images were shot at f/22 to f/45.

[Bob Salomon]

All modern wide angles have similar fall off. If someone claims their's does not then the subjects they photograph are dark enough on the edges to mask the fall off or they dodge and burn in printing or overlight the edges of the scene.

ZDo you need one?

It depends on what you shoot and how you shoot.

You are the only one that can answer your question. If in doubt buy the filter.

[Pete Andrews]

It's not just a modern problem!

When the Zeiss Topogon was introduced in the 19th Century, it had such an extreme angle of view that fall-off had to be corrected. Unfortunately the technology didn't exist to make graduated glass filters back then. The elegant solution was a little black metal foil "star" on a needle-like axle that was placed directly in front of the lens and rapidly spun round during the exposure, thus shading the centre more than the edges. The device wasn't powered in any way, I think the photographer had to blow sideways across the thing to set it spinning, presumably being careful not to spit!

Sorry for my little diversion down the forgotten byways of technology. I just thought that the idea of a little spinning star in front of a lens might amuse you as much as it amused me.

[Pete Andrews]

Correction to the above.

It was the Goerz Hypergon that had the little star gizmo, and it was made in the early years of the 20th century.

Apparently a 75mm version covers 10"x8" !!!

Anyone got one they don't want in an attic somewhere?

[Simon_443]

I was in Lens & Repro the other day (33 W. 17th, in NY) and it looked like they had two Hypergon lenses with center fans in the case behind the counter (the fan seemed to be powered by a squeeze bulb and rubber hose). Don't know what focal length they were, and I understand they're very expensive, but if you're interested, contact them at www.lensrepro.com .

[Les Moore]

I regularly shoot sand, blue sky, and other subjects that should show fall-off i n the corners. With my 90mm f/8 using high contrast Velvia film, there is no no ticeable vignetting. With the 75mm the vignetting is VERY noticeable.

[Patrick Chase]

Hi Rob;

If it's a 90 f/8 (you didn't specify the F.L.), and you shoot slide film, and you plan to use substantial movements, then the answer is probably "yes".

I have a Nikkor SW 90/8, and I found that there was little falloff on 4x5 when the lens was centered w.r.t. the film, but that the falloff got more dramatic (up to ~1.5 stops) when I used extensive movements. I ended up getting a Heliopan 1.5-stop center filter to correct the problem.

I'd like to throw out a couple corrections:

1. It is very important to distinguish falloff from vignetting: They are completely different animals. Vignetting is what happens when you exceed the coverage of one of more elements in the lens (typically the front or rear elements, since they are often a bit undersized). Vignetting occurs only near the coverage limits, and typically decreases as you stop the lens down. Wide-angle falloff is more uniform in character, and is not affected at all by aperture.

2. Bob Salomon writes that "All modern wide angles have similar fall off". This is decidedly untrue. The exact optical layout of a lens has a significant effect on falloff. In particular, use of strongly negative front and rear elements reduces falloff by causing the entrance and exit pupils to "swing" as the angle of incidence changes. The catch is that strongly negative front and rear elements tend to cause aberrations, so the designer must balance sharpness vs. falloff. Before anybody mentions "cos^4", it should be pointed out that the cos^4 law only pertains to the idealized thin lenses of optical theory; Modern wide-angles are anything but "thin lenses"

-- Patrick

[Bob Salomon]

"2. Bob Salomon writes that "All modern wide angles have similar fall off". This is decidedly untrue. The exact optical layout of a lens has a significant effect on falloff. In particular, use of strongly negative front and rear elements reduces falloff by causing the entrance and exit pupils to "swing" as the angle of incidence changes. The catch is that strongly negative front and rear elements tend to cause aberrations, so the designer must balance sharpness vs. falloff. Before anybody mentions "cos^4", it should be pointed out that the cos^4 law only pertains to the idealized thin lenses of optical theory; Modern wide-angles are anything but "thin lenses" "

OK I'll change my statement.

All current Rodenstock, Schneider, Fuji, Nikon wide angle lenses have the fall off that is corrected by a center filter. In addition some the various focal lengths of the Symmar XL lenses also do.

Also the 16mm for the Contax and the WA lenses for the Xpan have similar fall off.

That is most of the current ones on the market for view cameras and some for 35 and other formats