Posted on Apr 21, 2020
Check out the quality of your lenses with this free lens testing chart, as mentioned in The Photography News Podcast, episode two. The digital file can also be used to set-up and test digital projectors/lenses too.
Our test chart can help you to see how sharp your lenses really are and which are your lens’s best apertures when you are shooting for ultimate image quality. Professionally produced ISO 12233 test charts are available but they are expensive. There are free test charts available if you web search for them although they are not often very large and might be subject to copyright.
We are not claiming that our test charts are scientific or as rigorous as a properly designed and printed chart, but what it does is give you a practical idea of how your lens performs at different apertures and focal lengths.
The Photography News test chart comes in two sizes for free download, A3 (42×29.7cm) and A2 (42×59.4cm). Size-apart, they are identical and both are high resolution at 300ppi.
To start, you need to make a high quality print on a lustre or a bartya gloss-type paper – it is best not to use high gloss materials because reflections and light scatter can make checking the chart a problem. Printing can be done at home with a photo quality printer or by a commercial online photo printing service.
Get the best possible results
Your print of the test chart might only be A3 or A2 but you can easily mimic a much larger test chart by moving it around, so use a wall/flat surface that is least three times the height and width of your test chart so there’s enough space to enable this. You also need room to work leaving the camera in place – until you do the next focal length.
If you prefer, for convenience, just fill the frame with the test chart and shoot it, also following the below procedure. With telephoto lenses you might not have the option of getting back far enough.
- Using a small blob of Blu tack to attach the test chart to the wall means it can be repositioned quickly. This assumes the chart has printed flat. If not, fix it to a stiff piece of card
- Position and compose with the chart occupying roughly the central third of the frame, and set up the camera with a bubble level in the hot-shoe or use the camera’s virtual spirit level and try to be straight on to the wall
- Use a firm tripod, preferably positioned on a solid floor – or if’s not solid, keep still after the exposure has ended
- Focus manually. Use live view on your DSLR, and whether your camera is mirrorless or DSLR use the focus magnifier to ensure critical focus
- Use the camera’s self-timer at 10-12secs to ensure the camera is absolutely static when the exposure is made. Use mirror lock-up if your SLR has the option, or live view to avoid any shutter vibration
- In manual focus, focus should not drift in-between shots if you take care. But check focus after each shot if you prefer
- Shoot a picture at every aperture. It’s up to you whether you use 0.3EV, 0.5EV or 1EV steps. Most camera/lens combinations record EXIF data in the file to help with your checking, but making notes is a good idea regardless
Once you have done the centre pictures, reposition the test chart into each corner of frame and if you want to, above, below, right and left. The corners are the most important. Check positioning via the monitor/viewfinder.
Have a sheet of A4 office paper with a black cross drawn on it and when you reposition the test chart replace it with this at the centre of the frame. It just means you can still check camera focus is unmoved as the chart is moved around.
Name the files with the aperture used and in the case of a zoom, the focal length. Process the files identically so you can make a value judgement and view comparisons side by side at 100%.
Click the images to see a larger view
If you haven’t listened to episodes one and two of The Photography News Podcast, you can find them on YouTube and Spotify. They’re packed with tips and advice, particularly for shooting at home during lockdown.
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