Lens Focus Calibration Tool Alignment Ruler Folding Card(pack of 6)

So, it's a piece of printed cardboard. But it's good quality and much easier than the 'standard' way of fine tuning focus - with a yardstick/metre rule or tape measure at 45% resting against a target (google it for for details if you don't want to wait for one of these). Several different places to check focus against depending on how far out your focus is when you start, and it's very, very cheap. For what it is and what it costs, it's really, really good. And I don't quite understand how anyone can review something they haven't actually used(?). Instructions are in the detailed product description on Amazon.

It's an ok wedge for lens calibration but not perfect due to not aligning fully when assembled. Good value as long as you are not expecting perfection.

Works absolutely perfect for the micro adjustments on my old DSLR’s. Also tried it with my mirrorless just out of curiosity to check they really don’t need adjustment (they don’t, it was spot on the money!).

It appears that someone has carried out a re design of this product in an attempt to save money whilst in production. The thing is, it now no longer functions as designed or suggested. Whoever carried out the re design has no idea of how this product works and has therefore created a tool that no longer functions as originally designed. I have had to adapt it so that it so that it can be used for its original purpose. It only needed a bit of tape a sharp knife and about 2 minutes of my time. In finishing I would like to suggest that whoever carried out the adaptations to this product finds another job!

I couldn’t get the rulings to show focused / unfocused to a degree I could discern a difference. I ended to checking the upright patterns for fine detail. After many tries with varying results, I wasn’t sure effort was worth it.

Yes it's made out of card as it says on the tin, therefore it is somewhat flimsy and sags very slightly on the measuring plane. I beefed it up a bit with gaffer tape. It is too small for calibrating most lenses at a reasonable distance but suits my needs for close-up photography where I am evaluating best aperture for sharpness vs focus latitude. No point complaining at this price point as you know what you are getting and it's not as if it's something you use every day.

it did the job well. Just remember lenses under 50 mm will need a bigger card. As they look tinyyyyy in the view finder. Great product

Simple but effective device to check lens calibration if your camera has fine focus control. Be sure to use spot metering when focussing on the device, and either the widest aperture or the longest focal length to minimise depth of field in order to assess back or front focussing