IAI CFPH common mistakes
IAI CFPH · Understand the traps and how to avoid them.
Setting exposure by eye on the camera's rear LCD and judging focus from the thumbnail, then discovering at review that highlights are clipped or critical detail is soft.
The LCD is small, brightness-adjustable, and easily washed out by ambient light at a scene, so it flatters both exposure and sharpness; candidates trained on casual photography carry this habit into evidence work where the histogram and 100% zoom are the only reliable checks.
What to do instead
Adopt a fixed capture routine: shoot RAW, verify the histogram (no clipped highlights on the subject), zoom to 100% on the LCD to confirm focus on the plane of interest, and bracket exposure where lighting is uncontrolled. Practise the routine until it is automatic before exam day.
Failing to photograph an item in three states (in situ, with scale, and after repositioning or removal) and omitting an overall-to-midrange-to-close-up sequence.
Candidates think of a photograph as a picture of an object rather than a record of its context and relationship to the scene; once an item is moved, the original context is gone forever, and the omission is invisible until someone tries to reconstruct the scene.
What to do instead
Memorise and rehearse a scene protocol: overall views establishing the location, midrange views showing relationships, close-ups with and without a scale, and documentation of every item before and after any handling. Write the sequence on a card and follow it at every practice scene.
Placing an ABFO-style scale arbitrarily, at an angle, or partially outside the frame, and photographing a wound or impression without the scale in the same plane as the feature.
The scale looks like an afterthought rather than a measuring instrument; candidates do not realise that scale placement, plane alignment, and camera-axis perpendicularity determine whether the image can support later measurement at all.
What to do instead
Learn the geometry: scale in the same plane as the feature, camera axis perpendicular to that plane, scale filling a meaningful portion of the frame and fully visible. Practise on curved and irregular surfaces, and always take one frame with and one without the scale.
Leaving the camera on auto white balance, auto ISO, or program mode and letting the camera choose settings that vary frame to frame.
Auto modes produce acceptable-looking images, so the failure is silent; candidates do not connect inconsistent colour and noise across a series with the difficulty of later comparison, enhancement, or testimony about what the camera did.
What to do instead
Shoot in manual or a controlled semi-manual mode, fix ISO and white balance for a series, and record the settings. Include a colour reference in the first frame of each lighting condition so colour can be normalised later.
Using on-camera flash for every subject, producing hot foregrounds, hard shadows, and specular glare on reflective evidence such as glass, wet surfaces, or metallic items.
Direct flash is the simplest way to get light and candidates default to it under time pressure; they underestimate how glare can erase the very detail (serial numbers, toolmarks, latent prints on curved surfaces) the photograph is meant to preserve.
What to do instead
Learn off-camera and diffused lighting, and the technique of lighting at an angle to the surface rather than along the camera axis. For reflective subjects, use bounce, diffusion, or a light tent, and take multiple frames with varied light positions rather than one flashed frame.
Altering, rotating, cropping, or 'enhancing' an original image and then presenting the derivative as the record, without preserving the untouched original.
Candidates treat digital files like prints and assume editing is harmless if the result looks better; they do not appreciate that forensic images may be challenged as evidence and that provenance and continuity of the original file are the foundation of admissibility.
What to do instead
Treat the original file as immutable: copy, hash, and store it before any processing. Do all work on working copies, keep a documented edit log, and be able to produce the unaltered original. Practise explaining the workflow in plain language as if testifying.
Photographing footwear, tyre, or toolmark impressions with oblique light from the wrong angle or distance, or without a scale and orientation reference, so the impression is flat, shadowed, or unmeasurable.
Candidates do not realise that impression detail is revealed by grazing light at a low angle and that the light-to-surface angle, not sheer brightness, controls contrast; they also forget orientation markers that let a later examiner align the image.
What to do instead
Practise oblique lighting at several low angles and distances, comparing results, and always include a scale and a directional/orientation indicator in the frame. Take a series at different light angles rather than a single exposure, and record which frame used which angle.
Shooting a night or low-light scene hand-held at a slow shutter speed, or pushing ISO so far that noise destroys fine detail, instead of stabilising the camera and adding light deliberately.
Candidates prioritise getting any image over getting a usable one, and camera or phone stabilisation masks blur on the small screen; noise and motion blur only become obvious at full size or under enlargement for court.
What to do instead
Use a tripod or stable support, mirror lock-up or a remote/timer release where available, and add light in a controlled, documented way rather than relying on high ISO. Test the acceptable ISO limit of the equipment you use and stay within it.
Failing to document metadata, camera settings, lighting, distance, and the identity of the photographer, so the image cannot be tied to a time, place, and method.
Candidates see the photograph as the deliverable and the surrounding record as bureaucracy; in practice an image without a chain-of-custody and method record is far weaker evidence, and memory of the details fades quickly.
What to do instead
Build a capture log into every session: date, time, location, photographer, equipment, settings, lighting, distances, and any scale used. Verify that device clocks and metadata are correct, and keep the log with the image files.
Assuming the camera's automatic focus selected the intended subject, especially in close-up or low-contrast scenes, and not verifying the focus point before releasing the shutter.
Modern autofocus is fast and usually right, so candidates stop checking; in macro work and on low-contrast evidence the depth of field is razor thin and the camera may lock onto the background or the scale instead of the feature.
What to do instead
Use a single, manually selected focus point, focus on the critical plane, and confirm at 100% magnification. In close-up work, stop down for adequate depth of field, use focus stacking or a focus rail where appropriate, and take extra frames rather than trusting one.