Leaf Credo WS
Good to Know Facts
The new Leaf Credo WS backs are available in 80 and 60 megapixels and in both Mamiya and V mounts. They
deliver the renowned image quality of the standard Leaf Credo back but extend their capability by enabling you to
capture a wider light spectrum.
This document covers the basic guidelines for using Credo WS backs.
Spectrum and Wavelengths — Basic Numbers (approximate, in nanometers)
380-740 nm: Visible light
740 -1,400 nm: Near Infrared (NIR)
350-380 nm Ultraviolet
Most digital cameras and sensors are designed to emulate and record what the human eye sees and thus
incorporates an IR+UV cut filter that prevents Infrared and Ultraviolet light from being recorded. Typically, the
sensitivity of the sensor can be described using the Quantum Efficiency vs Wavelength chart (see Image 1). The
green section represents what a standard Credo back records.
Image 1: QE vs. Wavelength Standard Credo
On Leaf Credo WS backs, we have replaced the IR+UV cut filter with a “plain” glass filter, which allows the sensor to
record from 380 nm to about 1,100 nm:
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Image 2: QE Vs Wavelength Credo WS
And this is what a Leaf Credo WS back records when using a 720 nm pass filter:
Filters
External filters can be utilized to selectively block specific wavelengths and let other wavelengths be recorded.
These are offered by companies such as B+W, Heliopan, Hoya and Lee and can be purchased from pro camera
resellers and online retailers. They are often labeled according to the specific wavelength for example, 720, 780,
830, 950 or 72, 78, 83 etc.
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Image 3: Leaf Credo 60 WS and a set of ø 72 mm filters. The darker ones are IR pass filters.
The majority of the current Mamiya lenses use a ø 72 mm filter. We recommend that you check your lenses before
ordering filters. If you buy ø 72 mm filters and you have lenses with a smaller thread you can use an adapter or
stepdown ring. However if your lenses are larger then you can consider using larger filters or looking for a universal
filter holder and using square filters.
Image 4: Lee filter holder and adapter rings © Lee Filters
We carry a standard ø 72 mm IR+UV cut filter which you can order from your Mamiya Leaf dealer (Part No. 70720).
It will allow you to capture “normal” colors with your Leaf Credo WS back.
Below is a comparison of using a Leaf Credo WS with a standard IR+UV cut filter and without. The image on the left
was taken with a standard IR+UV cut filter and the one on the right without any filters.
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Image 5: Using a standard IR+UV cut filter
Image 6: Without any filter
Applications
The most common application for a wide-spectrum camera is landscape photography, where using different filters,
such as red, orange or yellow creates false colors and a “dreamy” look.
Image 7: Using an R695 filter
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Image 8: Using an R720 filter
There are some scientific applications where high nm IR pass filters are being used and help detecting certain types
of diseases in vegetation.
Another application is art conservation, where certain types of pigments can be detected in old masters’ paintings
and their origins can be traced.
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Image 9: Using a 950nm filter to reveal hidden layers in paintings (right)
Focusing
The change in wavelength results in a shift of the focus plane. This means that when you use IR pass filters you have
to adjust by focusing a bit closer to compensate for the focus shift.
Infrared light creates a slightly different plane of sharpness compared to visible light, so when shooting with a 720
nm filter, you should always manually correct focus. Instead of using the white mark on the lens' focus scale, use the
red mark, which is found on most Mamiya lenses.
Image 10: Red IR focusing mark on Mamiya Sekor 80mm /f2.8 LS D lens
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Live View
The Live View function on Leaf Credo backs helps you to adjust focus accurately, whether you are shooting tethered
in the studio or out on location. When shooting under bright sunlight conditions, many Leaf Credo users find neutral
density filters to be helpful in cutting some of the light when framing or focusing in Live View. In the case of the Leaf
Credo Ws, the dark IR pass filters serves as neutral density filters and helps focusing in bright sunlight.
Exposure
By using IR pass filters, you are essentially blocking longer wavelengths from being recorded; as a result the red
channel can be overexposed. To properly set exposure when shooting with a Leaf Credo WS back, it is important to
pay attention to what the histogram says and compensate by using a smaller aperture, lower ISO, higher shutter
speed or adjust the EV compensation on the body.
If you use other filters (e.g. blue) you should follow the same practice. The high dynamic range of the back allows
you to recover shadow detail if necessary.
Image 11: An Overexposed Red Channel
Image 12: Properly Exposed Histogram
On the back’s LCD you can use the full screen mode of the histogram to view the separate channels:
Image 13: Full Screen View of the Histogram on the LCD
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Differentiating between a WS back and a standard Credo back
The glass filter that covers the sensor on WS backs has a different color compared to the one on a standard Credo
back, which has a slight blue-green tint to it.
Image 13: Physical difference between the Credo WS and the standard Credo
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