Filters for Large Format Photography
By Q.-Tuan Luong for the
Large Format Page
Summary: a market survey and collection of tips on filters from the perspective
of the large
format photographer, including rear mounted filters, center
filters, polarizers, and rectangular filter systems.
Attaching filters at the rear of the lens
With LF, you have the option to attach filters at the rear of the
lens. This works for color correction filters which don't need to
The advantage is that a filter inside the camera is less likely to get
dust, dirt, smudges, fingerprints, and will cause less flare.
There are two precautions to take:
- You have to be super careful to keep your filter clean.
Any dust, dirt, smudges, fingerprints, as well as defects, will have
more of a detrimental effect on the quality of the image as the
light passing through the imperfections has already passed
through the lens.
- A filter mounted
behind the lens creates a focus shift equal to 1/3rd the thickness of
the filter so all focusing must be done with the filter in place,
except for gels, whose thickness is neglectible.
For most lenses, the illumination will go as cos^4 theta
where theta is the angle between the center of the lens
and the image point on the film. This is called Light
fall-off. It's basically the result of the law of optics. For
wide-angle lenses, this can result in the corners being two or
three stops darker than the center.
Two powers come from the light traveling a
greater distance and the inverse square law, one power comes
from the exit pupil of the lens being tilted and looking like an
ellipse rather than the full circe, another power comes from the
rays striking the film at an angle [the same reason for winter: the
sun's rays strike the earth at an increased angle].
The best aperture re light fall-off is any
aperture more than about 2 stops (maybe 3) down from wide
open. Further stopping down should not change the relative
illumination, center to corners.
This is well explained in the book Applied Photographic Optics by
Sidney F. Ray, published by the Focal Press. Excellent but rather
expensive. It is a big book, more than 500 pages. Michael Briggs
This is different from vignetting, caused by mechanical obstruction.
At wide apertures, lenses will vignete because
the glass elements aren't big enough (if they were made larger, the
lens would be more expensive and heavier).
Most wideangle lenses from SLR cameras are retrofocus
the nodal point is somewhere towards the front of the lens, in
some cases in front of the lens. This is necessary so that the lens
does not protrude into the mirror box area.
Retrofocus designs decrease fall-off, which is why
those lenses don't require a center filter. On the
other hand, Mamiya suggests a center filter for their 43mm M7 lens,
which has the distinction of being symmetrical thanks to the RF
I don't know of a retrofocus lens for LF. Retrofocus designs
are asymmetric and require floating elements for good performance
at close range.
The center filter is a simple solution to the light fall-off problem.
It is darker in the center and gradually brighter at the edges.
Center filters always are mounted in front. They must be
screwed directly into the lens without using a step up ring, so you
one per filter size of lens.
This is because center filters are designed to be used a
certain distance from the lens.
You need to remember that it can not be seen by the film
until the lens has been stopped down at least 2 stops.
Do I need one ?
The wider the lens, the more of the full coverage of the
lens you use (ie using 5x7 with a 110mm vs using 4x5,
or using 8x10 with the 150mm vs using 4x5 with a plasmat 150/5.6 ),
or the more movements you make, the worse the effect. Most people find
that light fall-off is neglectible unless you start using a 90mm on 4x5.
Even though, few shooters would use a CF at 90mm on 4x5. On the
other hand, most find it necessary at 90mm on 5x7 or at 58mm on 4x5.
Whether you feel the need for correction is an esthetic decision.
Some people actually like the fall-off. It's less noticeable for
dark scenes than for bright scenes. It's less noticeable if your
scene has dark areas in the corners (like trees). For landscapes,
it is most noticable in skys and tends to pull the eye toward the
center. It seems to be more bothersome in interiors, particularly
For the more even image, you pay quite a price.
Not only these filters tend to be expensive, they eat at least two
f-stops and add complexity to
calculating exposures. Since they are mounted directly on the lens,
and have larger front elements (for example a 67 center filter has
an outer threading of 86mm)
they can make difficult to use of other filters without vignetting.
You could correct for the fall off in the darkroom.
Which density and brand to use ?
The filters are not matched to a
particular lens, so at least you can interchange them between
lenses if they have the same filter size.
The difference between
having a CF and not having one is quite relative (some photographers
are happy without, while some think that they are necessary), thus
you'd guess the difference between two different brands is extremely
Center filters are made by B+W/Schneider, Heliopan, Rodenstock, Hoya
Prices can vary considerably depending where you buy them.
" We stock some of the denser Heliopan CF and have sold virtually
none. You would lose so much light (3 stops) + you must stop a
lens down at least 2 stops for the filter to work that the denser
version is not too useable for most people.
Virtually every CF sold is either .40 (Rodenstock) or .45
(Heliopan and others).
I don't think you will find many people, if any, who have actually
used all 3 [B+W/Schneider, Heliopan, Rodenstocks]
on the same lens with the same film at the same time
[and can compare them].
We are in a unique position. We are the Heliopan and the
Rodenstock importer and also the Linhof importer. As such we
import the Heliopan and Rodenstock ceter filters as well as
Schneider ones for the 58 through 90mm XL lenses we sell.
An extremely knowlgeable photographer named Lief Erickson
(tragically died too early) too had this question.
So he took the Linhof Technorama 617 and the old Fuji 617 with
a Schneider, Rodenstock and heliopan center filter for a test.
He found no difference on film between them.
However that was before Rodenstock redesigned their center
No center filter is totally neutral. They tend to shift torwards
green under cetain conditions. The latest version of the
Rodenstock ones are the most neutral of all center filters. "
The main point of using a circular polarizer instead of a linear
polarizer is to ensure that autofocus and
TTL metering would work properly with your reflex camera (although
this might not always be necessary). If
you intend to use your polarizer also on a reflex camera, it's
safer to get the circular variety.
Since a LF camera has no mirror,
you can use either a linear or a circular polarizer on your LF camera. Linear
polarizers are cheaper, and some people think they are better at
removing reflections than circular polarizers.
A Kaeseman polarizer is sealed, and therefore more durable (the foil
on other polarizers tends to degrade over time). It is also said
they are better at removing reflections.
To avoid vignetting, you can use a slim polarizer (no threads for a
clip-on lens cap or an additional filter), or a
wide-angle polarizer which has a larger front element.
Many polarizers tend to have a cold color bias. It's generally better to have a
color bias than a cold color bias, hence the interest of the warm tone
In a C&D article,
Englander compared ten linear and circular polarizers.
His densitometer readings
B+W Warm (.56,.57,.57,.58)
B+W circular (.51,.55,.52,.48)
Heliopan circular (.58,.64,.58,.53)
Heliopan linear (.62,.69,.63,.57)
Heliopan Warm (.60,.60,.61,.56)
Tiffen linear (.50,.52,.49,.50)
Tiffen circular (.51,.50,.52,.47)
Hoya circular (.54,.56,.55,.53)
Hoya linear (.45,.47,.45,.43).
Tiffen Warm (.62,.58,.62,.62)
He concluded that the most neutral filter was the B+W Warm. The Tiffen
Warm is linear. Hoya has subsequently introduced a Warm polarizer
(called the Moose filter, after the so-named wildlife photographer)
in circular version, which is relatively economical.
Englender also found the
Wratten .6ND filter to match the density of the polarizers well.
This confirms the rule to use a filter factor of two stops for a
Some folks like to use them permanently for protection of the front
element of the lens, just like in 35mm. Image degradation would be
neglectible, especially considering the enlargement ratios needed
in LF. Others find that in LF, accidental damage is unlikely.
They are definitively useful at high altitudes to remove excess UV.
Step up rings
You can buy circular filters (glass) to fit your largest lens, and
a set of step-up rings to fit your other lenses. The main problem with
this approach is that step-up rings put the filter further from
the lens, which might actually increase vignetting on wide-angle
lenses. For instance, I find I get more vignetting on my 110 with
a step-up ring from 67 to 82 than with a plain 67 filter.
Filter systems (see next) work on the same principle (one set of
one ring for each lens), but are more versatile. The only advantage of
using step-up rings would be that they are cheaper than the
rings used in most filter systems.
Filter systems are by far the most versatile way to use filters for a
set of different lenses. You only need to get a different adaptor ring
for each lens. You have a huge choice of filters, can
adjust them independently in rotation and translation (making this
kind of system almost mandatory if you use
graduated filters) and combine them easily. Some systems also
include a lens shade. Their main drawbacks are the bulk and set-up
time required for the system. Both factors are not a significant
aggravation in LF, hence their popularity with LF users.
A filter system has three components:
There are three
widths of holders that are usable with LF:
- A circular ring, one for each lens size. The best systems have
two types of adaptor rings,
regular rings, and wide-angle rings, which keep
the holder closer to the lens to avoid vignetting.
- A holder. The best systems have a choice of holders to accomodate
a various number and/or thickness of filters .
- A choice of rectangular filters. The rectangular shape allows the
filter to be adjusted in height (critical for graduated filters),
while the holder can be rotated. Various materials are available:
- Gels are the cheapest. Optically good, but not durable. The Kodak
Wratten filters are manufactured to very precise specs, and their
spectral response is published.
- Glass could be optically the best, but are easy to break. Tiffen,
Heliopan, and Schneider make glass filters. Schneider has MC glass
filters (a 4x5 grad is over $400).
- Polyester filters are made only by Lee (Calumet sells Lee
products under their own name). One thing to be careful with them if
you wish to combine them with the polarizer is
that they must be between the polarizer and the film. If you place
them in front of the polarizer, you'll see some interesting patterns.
- Optical resin (CR-39) is the most common, and will be discussed further.
- 83mm or 3"1/4(Cokin P)
- 100mm or 4" (Hitech, Lee/Calumet, Sinar)
- 130mm or 5" (Cokin X-Pro)
- Cokin A (3" or 75mm). Rings 36-62mm.
Just too small for most serious photographers.
- Cokin P (83mm). The most common system. Rings
48-82mm. It is by far the
cheapest (holder and rings around $10 each), so durability of the
holder is not a real concern. It will work for many
lenses, especially if you don't stack filters and saw off the outermost filter slot to reduce the
possibility of vignetting. With this modification, it works
with Nikon 20/2.8, 24-120, Canon 17-35 above 24,
110 XL in 5x7 without extreme movements.
One nice thing the Cokin system has is the ability to accept a glass polarizer
that can be rotated independently of the holder. This is important when
combining a polarizer and an ND grad. However, this polarizer will
vignette more than the holder.
The main drawback of this holder is that it is too small for some lenses.
Cokin P filters are cheap and low quality. In particular, the graduated grey is
not neutral and has a green cast. However, Hi-Tech and Singh-Ray make filters
that fit the Cokin P holder, so this is not an issue. A Hi-Tech grad
to fit the Cokin P is truly neutral, and costs only $30.
Hi-Tech also makes their holder in P size, but if
you're going to pay more than $100 for a holder, you might as well get it in 100mm.
Cokin X-pro (130mm). The largest holder. It will
fit a lens with max. 122 mm external diameter. Nobody else makes filters that
large. This system is relatively new.
The 100mm (4 inch) standard: Hitech, Lee/Calumet, Sinar
The filters are extremely similar in optical
quality, the only real difference being the holder system and the
thickness of the filter. The quality is very high.
They might be actually made at the same plant.
Hi-Tech has the best selection and the best prices (notably cheaper
than Lee) for filters. The holders are well built, however they
are heavier, bulkier, and considerably more expensive than the
Cokin. The advantage is having larger filters, and a more
Lee (100mm). The most versatile holder system as far as filter thickness
is concerned. It can use any
100mm filter. You configure your holder with a variety of slots systems
of different widths, including gel, 2mm,4mm.
The holder is $100, regular rings $40 (larger sizes are more
expensive, up to 105mm),
wide-angle rings $62 (mount the filter closer to the lens, available only up to 82mm).
Polarizer is a square
($150). To rotate it independently, you need to tandem two holders, which might
vignette wide-angle lenses.
Hi-Tech (100mm). Offers more lens attachments (in particular attachments to the
back of the lens) than Lee. The filter
thickness is 1.5mm. The Hitech may not handle all Lee filters.
The holder is $120, regular rings $25 , and wide angle rings $45, so it
comes a bit cheaper than the Lee.
Standard polarizer is a
expensive circular 105mm which fits on a front ring, which might cause vignetting.
Sinar (100mm) Filters are either 1mm or 1.25 mm thick.
The selection is limited and nobody else makes
filter that thin. You could have the edges of other manufacturer's filters
milled to fit the holder, but I don't really see why one wouldn't prefer to use
Lee or Hi-Tech in the first place. Sinar has discontinued this product line.
Singh Ray produces high quality and expensive resin filters to fit other
manufacturer's holders. Their hard-step GND has a sharper transition
than other manufacturer's equivalent. They also offer a few specialty
filters, like a reverse GND and a strip, and will consider making
custom filters. Not all their filters are listed on their web site.
fit both the Cokin P system (grad: $100, Pol: $160), and the
100mm system (grad: $150, Pol:$340). Their polarizer for the 100mm system is
a 100mm x 100mm square (like the Lee).
Wide angle lenses
Using additional filters on wide angle lenses present some unique problems,
because of the wide angle of coverage, large front element, and
necessity (for some) to have a center filter.
adapter can help and is much cheaper than custom adaptors
made by Lee. Larry Huppert is developing a
based on 100mm filters.
Rodenstock has a 2-page brochure about the use of center filters. In
the US, you
request it from email@example.com
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