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FD to EOS adapter j37r asks Can anyone help with a weird problem I cannot figure out? A couple of years ago I bought a Canon FD-to-EOS adapter so I could use my FD lenses on my EOS 350D. It works very well and I get really good results from the FD lenses on the digital camera. I also have an EOS 5, and when I fit the adapter to this camera and press the shutter, the camera locks up. I have to remove the adapter and then press the shutter again to release it. I get the same result from my EOS 50E. Does anyone know why the adapter works perfectly on the digital camera but not on the film ones?

Malcolm_Stewart replies i wonder if this has to do with a hidden switch in the lens mount on some EOS bodies? It's positioned at about ten o'clock when viewed from the front.

MJ_Warner replies i had to have the adapter that SRB made to enable my Pentax shift lens to be fitted to an EOS 1 body altered to circumvent this problem. If the switch is moved by a lens, the EOS body expects to get a signal back from that lens, and if it doesn't it thinks the battery is flat. To use a manual lens on an EOS body, it needs to have a cut-out at this point to prevent the switch being tripped.

j37r replies i found the switch on the body, took note of which part of the adapter engaged with it at that point, then carefully filed about 2.5mm of the flange away. I've tried the adapter with a Tokina 28-70mm FD lens and it now works perfectly.

magnesium-alloy body makes it a particularly strong compared to some other compact cameras and entry-level DSLRs. The Canon PowerShot GIO has a list price of £569 For more information visit www.canon.co.uk.

As far as using a film camera is concerned, it would obviously solve your issues concerning power, though you may find that a camera which uses AA batteries will be no lighter than your existing water. By using the linear polariser at this angle, the reflected light is filtered out and the reflections from the water are removed.

Most modern cameras use mirrors as beam splitters to split the light to the camera's focusing, metering and viewfinder systems. To do this requires non-polarised light, a certain percentage of which is sent to the different systems. Linear polarisers can reduce the amount of light that is entering the beam splitter at a particular angle, which can cause too little light to enter the autofocus (AF) system. This in turn can cause the AF system to hunt for focus. As some AF lenses turn at the front element to focus, this turns the linear polariser, which again alters the amount of light entering the AF system via the beam splitter, leaving

Nikon D70. Other batteries may be harder to obtain in the more rural parts of India.

However, if you do wish to take a small film camera with you, I would recommend the Ricoh GR1 compact camera, which is small, lightweight and has a 28mm lens. It takes CR2 batteries, so it may be worth taking a couple of spares with you. For more informauon on the Ricoh GR1 and other second-hand film cameras, see our second-hand special (AP 9 May).

the camera continuously struggling to find focus. Similarly, there may not be enough split light reaching the metering system, causing incorrect exposures.

Circular polarisers get around these problems by being constructed from two parts: a linear polariser and a quarter wave plate. The quarter wave plate converts the linear polarised light into a form that can be used correctly by a modern camera's beam splitter, so that AF and metering systems can all work as they should.

So, those wishing to use all the modern conveniences of their camera should buy a circular polarising filter. Those who have fully manual cameras or who are looking for slightly better results, should opt for a linear polariser. Richard Sibley

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merely places a uniform darkening tone over the areas without detail, ND grads enable the camera to record the highlight detail and bring out the subtle tonal variations.

There are many graduated neutral density filters available on the market and in this article I will explain the differences and how to use them, and test a selection to see which are best.

__________________the dark part of the filter covering the bright areas of the scene, it is possible to set an exposure that results in an image without any burned-out areas, and with detail in both the sky and the land For the enthusiast photographer who spends hours at work in front of a computer, this method has the added benefit of providing a solution that can be applied out in the fresh air, rather than back at the monitor.

Part of the beauty of using ND grad filters is that they are available in a range of strengths, so the system can be adapted for different scenes with more or less contrast between the brightness of the sky and land. Also, unlike applying a digital graduated filter effect that

Graduated neutral density filters are essential tools for landscape photography. Angela Nicholson explains how to use them and puts six to the test

THE highlight warning on most DSLR cameras often makes the biggest problem with landscape photography obvious. That annoying flashing of the sky in the image on the LCD screen means that all its detail has been lost and, although the land beneath may be perfectly exposed, the bright clouds above have burned out.

Fortunately, the digital photographer has several methods available to overcome this problem The most obvious is to reduce the exposure until the sky detail is visible and then brighten the underexposed areas on the computer While this can be successful in some cases, it can be tricky to get a natural result and it brings out noise in the shadows. An alternative approach is to take two or three shots with different exposures and then blend them to create a subtle high dynamic range (HDR) image. Though some HDR fans like to create flat, unnatural-looking pictures revealing detail that is invisible to the human eye, with a more delicate hand it is possible to produce a final image that resembles the original scene as we see it. However, problems arise when there is movement in the scene - swaying trees or grass, for example - as the merged images cannot exactly match-up.

Although these digital solutions can work, it is often better to use a method that has served photographers for decades and fit a graduated neutral density (ND grad)

Neutral Density

ND grads

A graduated neutral density filter, often called an ND grad, is simply a filter that is clear at one end and dark (or grey) at the other Positioning the dark part of the filter so it covers the bright section of the scene in the viewfinder enables the photographer to set an exposure that retains all the detail. An ND grad filter is often used to balance the brightness of the sky with the land in a landscape. Importantly, the dark part of the filter should be neutral so that it doesn't give the clouds a colour cast.

An ND grad shouldn't be confused with a plain neutral density filter, which doesn't have a graduation and is used to reduced the amount of light entering the camera across the whole image frame. This enables a longer shutter speed or wider aperture than the bright conditions would normally allow.

Shapes and sizes

One of the most important aspects of using an ND grad is the position of the transition (or graduation) from clear to dark, so rectangular slot-in filters are the most popular type. These allow the transition to be positioned exactly where it is needed. However, it is still possible to get circular ND grads in a variety of diameters to suit different lenses and cameras. Though the transition usually cuts across the middle of the circle, the Bedfordshire based company SRB-Griturn offers a filter-cutting service that allows the transition to be positioned anywhere within the circle.

Although it is possible to find glass filters, most ND grads today are made from a form of resin or optical plastic. This is lighter and more affordable than glass and is more likely to survive a drop that would shatter a glass filter. The downside is that resin is more prone to scratching, so the filters need to be stored with care.

Naturally, larger filters tend to be more expensive than their smaller counterparts, but having a bigger rectangular grad affords more flexibility with the positioning of the colour or density transition.

Density

Graduated neutral density filters come in different densities or strengths to enable more or less light to be cut from the covered portion of the scene. This makes it possible to balance the exposure across the image whatever the difference in brightness between the sky and the foreground of a landscape.

The density of the dark part of an ND grad varies in exposure value (EV) so the photographer knows that using a particular filter will cut out one (or more) EV of light. Most manufacturers produce a range of filters capable of cutting out one, two or three EV of light, but some, such as Lee Filters, produce grads with intermediate strengths for greater control of the exposure across the image frame.

Selecting the correct filter can be confusing as manufacturers sometimes give them different names, such as ND4 or 0.6 ND, to indicate a filter of the same density. The table below outlines the relationship between the optical density, filter factor and the number of EV that the dark part of the filter reduces the exposure by.

Optical density, filter factor and exposure adjustment

Optical density

Filter factor

Light transmitted

Exposure reduction in EV

0 1 100% 0

0 0

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