for which lens length to use center filter

[pepo007]

Hi,
I'm new in 4x5 format. Can you please tell from which lens length I need to use center filter?

Thx

[Ron Marshall]

That depends on your tolerance for light falloff and if you are shooting neg or pos film.

I find for neg film that anything shorter than 75mm I want to have a CF. But I have gotten images that I am very happy with using neg film and a 55mm, when I forgot to bring my CF.

[Matus Kalisky]

I am using Grandagon N 75/4.5 and in most of my photos taken with neg or lower contrast slide film the light fall-off is acceptable (but present). In few of my shots where I used more shift and higher contrast film (E100VS) the fall-off went beyond my liking.

Note - the light fall-off goes with either 3rd or 4th power of the cosine of the angle - depending on the lens design.

[IanG]

Unless you're shooting a lot of transparencies you can get away without using a centre filter.

I use both 65mm & 75mm Super Angulons and with negative film it's easy to compensate at the printing stage, the 65mm only just covers 5x4 anyway. Sure a centre filter would help but I use the 75mm hand held most of the time and the additional light loss using the filter would make it far less easy to use.

Ian

[Leonard Evens]

I have f/6.8 90 mm and f/4.5 75 mm Grandagon-N lenses I do a lot of architectural photography, and I found with the 75 mm lens that fall off was pretty objectionable. It is exacerbated by rise/fall or shift, which I regularly need. It is also more objectionable for color because the fall-off varies for R, G, and B, introducing color shifts in grays. These shifts are less objectionable with the 90 mm lens, but they are easy to see. Fortunately the same filter fits both lenses, so I often use it with the 90 mm lens.

For general landscape photography, the center filter is less important, even with the 75 mm lens.

I scan my negatives, so before I got the center filter, I used to digital methods to correct for the fall off and color shift, but it was time consuming and difficult to get right. So I finally got myself a center filter, and I am happy that I did.

[Richard Littlewood]

I've got a 65/8 super angulon with centre filter that requires an extra 1.5 stops. I suppose that means the corners and sides would get 1.5 stops or thereabouts less exposure than the centre if it were used without the filter. I found with b+w this was quite tricky to deal with in printing, with these parts being effectively underexposed. You may forgive this or you might not. Not all negs will suffer though, and others will look better, sometimes I leave the filter off because the darkening towards the corners could be a good thing.
They aren't half expensive though. Mine is 2nd hand, but I've been surprised with the cost of some new ones.

[Leonard Evens]

There is one additional problem if you correct by dodging in the dark room or digitally in a photoeditor. The overall dynamic range will be larger in the center than at the edges and corners. In principle you should expose for the periphery and correct in the center by such manipulations. It is difficult to get the contrast uniform across the field when doing this, and this is more of a problem in color than b/w. With transparency film, which has limited latitude, it will be specially difficult. When you use a center filter, you mostly avoid such problems.