Poppy fields seem to becoming less common as farmland is used in newer ways, but stumble on a poppy field and you'll be greeted with a wonderful blanket of red or, as you move closer, some fascinating detail in the subtle petals and contrasting green and spiky stems of this symbolic flower.
A wide-angle lens of around 18mm (24mm in 35mm format) is fine for taking in the typical sweeping vista of red, but shoot on a wider lens between 10mm to 15mm and you'll achieve a much wider perspective. Shoot with a zoom and you have more flexibility - one reason why the 10-20mm type lens has become so popular.
Poppies also provide plenty of detail when you move close, so you could use the wide lens if it has a close focus facility but it's better to switch to a short telephoto so you can fill the frame with single colour.
Using a tripod will help you concentrate on composition while keeping the camera steady, but beware if it's windy no amount of camera support will keep the flower heads from swaying so faster shutter speeds are essential.
A reflector is useful if you want to try backlighting poppies. A silver one will pump back plenty of light into the shadow areas to balance the exposure.
Also consider buying a spirit level to ensure your horizon's straight as it's often harder to tell with a field full of poppies.
First thing when you stumble on a poppy field is it's probably on farm land, so respect the land. Many fields can be accessed from the road side, and tracks often run alongside. Poppy fields aren't always at the side of a layby so don't just pull over, make sure you car is not a hazard.
Movement Or No Movement?
Shoot with a fast shutter speed if there's a breeze to prevent blurred flower heads. From a distance these will be less noticeable but slight movement will spoil a close up shot. Alternatively you could go for the very abstract blurry effect and deliberately use a slow speed. A neutral density or polarising filter will help here.
To get the best landscape shots look for a slightly higher vantage point so you can shoot the field from a height. You only need a small height to ensure the field looks large and interesting.
Include a tree in the distance to break a flat horizon and give more shape to the shot.
Single Out A Poppy
If you use a wide zoom with close focus try focusing on one close up poppy head but have that as a small part of the scene and allow a background of red to fill the frame.
When photographing close up poppies look to include the green stem and make sure that you have things level so the stem looks natural, also consider backlighting as the stem has fine spikes that really stand out against rim light. Include a few heads and try to find positions that isolate the single heads from the background. Use a wide aperture and focus carefully on the main head. Placing the stem into one of the thirds gives a more pleasing composition.
Shoot at sunrise/sunset to provide an extra level of warmth. Alternatively, shoot against a blue sky with white clouds and you have a strong contrast and vibrant colours. Use a polarising filter to enhance the colours.
The colour of poppies tend to cause trouble for some camera sensors/camera processing, especially older ones, so make sure yours isn't having problems. The reds tend to block up so you lose detail. Shooting in RAW mode is better on such cameras, then you can fine tune in your RAW processing program.
A poppy is one of those flowers that looks great at all stages of its life cycle. From the early formation of a bulb with textures and spikes (backlit) to the splitting open (frontlit) to open (front or backlit) to fully open/petals beginning to drop (frontlit) to the seed head (front lit) and then the skelton (backlit - silhouette). You could even scatter seeds and do a macro pattern/texture shot.