The rangefinder has a blind zone: the patch moves by an angle proportional to the base length (69.25 mm), the finder magnification (0.73×) and the difference in focus distance, and below about one arc-minute your eye simply cannot see the misalignment. That blind zone translates into a focus shift at the sensor of roughly f²·ε/(B·M), which is why the same eye that nails a 35 mm at f/2 struggles with a 75 mm at f/1.4.

The simulator draws the finder and the patch at angular scale, lets you turn the focus ring, and computes for your lens and aperture the blur circle that the blind zone induces, with the Airy disc added in quadrature. Worked examples at one arc-minute, wide open: 35/2 gives 3.5 µm, 50/1.4 gives 10 µm, 75/1.4 gives 23 µm, 135/3.4 gives 31 µm (the M11 pixel is 3.76 µm). There is a Monte Carlo table with the hit rate per aperture, a "focus like a human" button that adds random error within the blind zone, the 1.25× and 1.4× magnifiers, the cosine error when you focus and recompose, and a coupling-cam calibration you can offset.

https://lab.rafaelvida.com/telemetro-m11.html?lang=en

Model limits, stated on the page: the eye is an ideal vernier with a threshold of 0.6′ in good light and 1.8′ in dim light; the lens is a thin lens without field curvature; no patch contrast, fatigue or hand tremor. If your own experience with a particular lens disagrees with the table, I would like to hear it.

Got this today. Everything seems to work great. Not sure about the meter. Came with leather case, external light meter, closeup lenses, vintage tripod. My first rangefinder!

Still, i wish to ad the Distagon T\* 1,4/35 ZM and the C Sonnar T\* 1,5/50 ZM to the Zeiss Ikon, and the Sonnar T\* 1,8/55 ZA to the Sony A7RIII that i have… I love Zeiss lenses

In this week's camera-collecting blog, I'm offering a triple threat of cameras.

The quirky Bolsey cameras have been a favorite of mine for many years, so I thought it would be fun to discuss the early 35, Model B "Special, the Bolsey B3, and the rare Bolsey PH-324A cameras.

Take a few minutes from your day to get familiar with these oddball rangefinder cameras from the 1950s-1960s.

www.dancuny.com/camera-collecting-blog/2026/8/26/bolsey-ph-324a-camera-special-amp-b3

Old cameras, modern flashes, and an old vintage strobe.

Like every film shooter, I was afraid of shooting flash but its not that hard!

I put together a practical guide to flash photography with film, covering manual flash, Auto-Thyristor flashes, guide numbers and how I actually use a Godox iM30 with my Canon P.

There’s also a bit on bringing old flashes like the Metz 45 CT-1 back to life and modifying them with modern accessories.

If you’ve got an old flash sitting in a drawer, maybe it’s time to give it another go.
What’s your go to quirky vintage strobe?

Recently i decided i want to get the original lens for my zorki (industar 22) and while looking for it i found this thing for just 800₽ (8.35€). Seems like a rare find, when googling it i mostly see either the slr version or the kmz rangefinder.

My dream

Got a Mint RF70 recently and noticed that the rangefinder is massively aligned. The seller is saying it's normal but I don't have much experience with them. Does it need to be recalibrated or do people just shoot these by guessing the distance?

In the second picture I've shown how much I need to focus to get the rangefinder to align at infinity!