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There is something quietly satisfying about testing new equipment in a place you already know well. The variables reduce to one. You know the light, the rhythms of the location, the way the stone takes shadow in the afternoon. What you do not yet know is how one small addition to the kit — in this case a yellow filter threaded onto the 75mm lens of the Bronica ETRSi — will shift the outcome.

I picked up a Pig Iron Yellow Y2 Pro filter on eBay for less than the cost of a decent lunch, largely out of curiosity. Yellow filters are the mildest of the contrast-enhancement filters available for black and white film work, and I had been meaning to test one properly at Calleva for some time. The Roman walls there offer exactly the kind of subject — open sky, stone texture, tree lines, shifting light — that should show filter effects clearly without making the experiment feel contrived.

Yellow Filter Photography — The Basics

The contrast filter family — yellow, orange and red, each progressively stronger in effect. Yellow is the gentlest starting point: it shifts the tonality without announcing itself.

A yellow filter works by absorbing a proportion of blue light before it reaches the film. Blue sky records as a lighter tone on panchromatic black and white film than it would appear to the eye, because film tends to be more sensitive to blue wavelengths than human vision is. By reducing the blue light that reaches the emulsion, a yellow filter darkens the sky slightly in the final negative, which in turn increases the apparent contrast between sky and cloud.

The effect is described as mild for good reason. Unlike an orange filter — which produces a more pronounced sky darkening and stronger overall contrast — or a red filter, which dramatically darkens blue tones and increases contrast to the point of drama, a yellow filter simply nudges the tonal balance in a more pleasing direction. The image still looks like a photograph of the scene. It just looks like a slightly better one.

In practical terms, a yellow filter offers four things in black and white film work: a slight darkening of blue sky, better definition of clouds against that sky, improved tonal separation in midtones where foliage and stone might otherwise compress together, and a very gentle overall contrast lift. None of these effects is dramatic individually. Together, they produce an image that feels more resolved — more confident in its light and form — without appearing manipulated.

Camera, Film and Filter

The Zenza Bronica ETRSi with 75mm lens is my standard medium format setup for location work at Calleva. The 75mm on the ETRSi gives a field of view roughly equivalent to a short normal lens — wide enough to include context and sky without introducing distortion, and long enough to compress the ancient tree lines against the wall in a way that suits the subject. Medium format negatives also give the filter effect room to breathe; the tonal benefits of a yellow filter are easier to read in a large negative than in 35mm.

Film choice was Kentmere Pan 100 — a classic-looking ISO 100 stock at an affordable price point. At box speed with a 1.5-stop filter compensation, I was shooting at effectively ISO 32 in some of the darker areas of the wall, which meant careful metering and a tripod for the slower exposures. ISO 100 film is also a good choice for filter testing because its finer grain structure makes tonal changes easier to read than they would be on a faster, grainier stock.

Development was in Rodinal at 1+25 dilution for 9 minutes — a slightly more concentrated dilution than my usual 1+50, which gives marginally more shadow density at the cost of slightly more pronounced grain. Rodinal’s high-acutance character suits stone and texture subjects well; the edge contrast it produces in fine detail reinforces the tonal benefits introduced by the filter.

Yellow Filter Photography in the Field

The Roman wall at Calleva Atrebatum — Kentmere Pan 100, Pig Iron Yellow filter, Bronica ETRSi. The sky has just enough depth to hold its own against the treeline without the effect reading as obviously filtered.

Tonal separation between treeline and sky — one of the areas where the yellow filter earns its place. Without filtration, overcast or hazy sky and spring foliage can compress into a similar tone; the filter gently distinguishes them.

The first thing I noticed when metering was the filter factor. The Pig Iron Y2 requires approximately 1.5 stops of exposure compensation — straightforward with a handheld meter and a willingness to adjust, but worth remembering if you are accustomed to working without filters. TTL metering through the lens reads through the filter automatically, so the compensation happens without conscious intervention; with a separate meter it needs to be applied manually.

Composing and focusing through the filter presented no issues. Yellow is the mildest filter colour in terms of viewfinder dimming — the tint is barely perceptible through the ground glass, which meant the usual medium format experience of slow, deliberate framing remained unchanged. Darker filters — red in particular — can dim the viewfinder enough to make accurate focus more difficult. Yellow causes none of that.

Stone texture and earthwork — the modest contrast lift from the yellow filter suits the ancient, weathered character of the walls. Nothing is overdone; the image looks like the scene, just more clearly itself.

Open sky over the wall — the modest darkening of the blue tone gives the sky some presence without the dramatic effect that an orange or red filter would produce.

Path and treeline — spring foliage along the wall benefits from the modest green/yellow transmission of the filter, which lifts leaf tones slightly and prevents the foliage from becoming a flat dark mass against the sky.

Pig Iron Photographic Filters

The Pig Iron Y2 Pro that I tested is part of a broader range of filters available through eBay UK and Amazon, covering everything from standard contrast filters to variable ND and infrared. Build quality on the yellow filter was solid — smooth threading, no rattling glass, and no unexpected colour casts. For a budget-priced filter, it behaved exactly as a filter should: invisibly, except for the effect it was purchased to produce.

For anyone new to filter use, the yellow is the sensible starting point — affordable, forgiving, and genuinely useful without requiring significant adjustment to your working method. Once you are comfortable with what yellow does, an orange filter is the natural next step; the effect is more pronounced and better suited to scenes where you want the sky to really hold its own against the land.

Is a Yellow Filter Worth It?

Yes — and the bar for entry is low enough that there is little reason not to try one. The Pig Iron Y2 Pro costs less than a roll of film and takes up almost no space in a field kit. At Calleva, it did exactly what it is supposed to do: the skies had slightly more depth, the treeline separated more distinctly from the sky tone, and the stone textures held their character with a little more clarity than a straight unfiltered exposure would have produced.

What it did not do was transform the scene or make it look different in kind — which is precisely what makes a yellow filter the right starting point for anyone new to filter use in black and white film work. Learn what a mild effect looks and feels like in the field before reaching for something stronger. The yellow filter teaches you to read the relationship between sky and land in tonal terms, which is the foundation for understanding what orange and red filters do at progressively greater levels of intervention.

For the film and camera used here, the Kentmere Pan review covers the film stock in detail, and the Bronica ETRSi review covers the camera. For a broader look at how film choices affect the outcome in black and white work, the guide to choosing the right film and the film grain guide cover the variables in detail.