APS-H (1.3x)

APS-H sits in a size class most photographers never encounter directly: 27.9 by 18.6mm, larger than any APS-C sensor but still meaningfully smaller than full frame, giving a 1.3x crop factor. Canon used this exact sensor size across several generations of its 1D-series professional sports and press bodies before eventually consolidating that line onto full-frame sensors — making APS-H largely a historical format on this site's reference rather than one still actively used in current camera production.

Why Canon Built a Sensor Size Specifically for This Purpose

The 1D-series existed to serve wire photographers, sports shooters and photojournalists who needed both extreme continuous shooting speed and every available millimeter of telephoto reach, in an era when full-frame sensor readout speeds hadn't yet caught up to what a smaller sensor could achieve. APS-H's 1.3x crop factor gave meaningful extra reach over full frame — a 400mm lens read as roughly a 520mm-equivalent — while staying much closer to full frame's image quality and low-light performance than a more aggressive 1.5x or 1.6x APS-C crop would have, a deliberate middle-ground engineering compromise rather than a cost-driven choice the way most crop-sensor formats are.

Depth of Field Between Two Worlds

This sensor's circle of confusion works out to roughly 0.0224mm under the diagonal/1500 convention, sitting between full frame's 0.0288mm and the APS-C figures around 0.018mm. Framing the same shot on each format — which needs a progressively shorter real focal length as the sensor shrinks — depth of field on this format lands genuinely between full frame and APS-C, exactly where the 1.3x crop factor would predict. For a sports photographer needing both reach and reasonably shallow depth of field to isolate a subject from a busy background, that middle position was a real, deliberate part of the format's appeal rather than an incidental side effect.

Why the Format Effectively Disappeared

As full-frame sensor readout speed, autofocus systems and processing power advanced enough to deliver 1D-series-level continuous shooting performance directly on a full-frame sensor, the engineering rationale for a dedicated middle-size sensor largely evaporated — Canon's later 1D X-series bodies moved to full frame while retaining the same target audience and continuous-shooting priorities the APS-H bodies were built to serve. No major manufacturer currently produces a new APS-H camera, which makes this format worth understanding mainly for anyone still shooting or researching Canon's earlier 1D, 1D Mark II and 1D Mark III bodies rather than as an active current buying consideration.

What Owning One of These Bodies Today Actually Means

A used 1D Mark II or Mark III is still a genuinely capable camera for casual shooting decades after release, but the discontinued sensor size means every equivalent-focal-length and depth-of-field comparison drawn from current online resources or forum advice needs its own APS-H-specific math rather than reusing a more commonly discussed APS-C or full-frame figure. Lens compatibility isn't a concern in the way sensor size is — these bodies use Canon's standard EF mount, so any EF lens from Canon's extensive catalog works normally, just with this format's specific 1.3x field-of-view multiplier applied rather than a more commonly quoted crop factor.

Genuine 1.3x-crop APS-H sensor figures are available directly in the DoF & Hyperfocal Calculator and the Crop-Factor & Equivalence Converter for anyone still shooting one of these discontinued professional bodies, rather than approximating from the more common 1.5x or 1.6x APS-C figures.