Where does one get a good focusing target to test lenses?
Focusing Target
- Thread starter DougC
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This is the link for the target I use Piston Photography.
A bit of work to print it then mount it correctly but I have found it very useful.
A bit of work to print it then mount it correctly but I have found it very useful.
Hi Doug
What is your camera - mirrorless or DSLR? What is the purpose of your testing?
For a DSLR, you may need to calibrate fine tuning so a target like the LensAlign Pro is useful. It has been discontinued and the founder - Michael Tapes has retired due to age and health issues. This item has a good test target and a diagonal scale to measure AF errors. With a mirrorless camera working with sensor based contrast detect AF, it's no longer necessary.
For testing lens corner performance, you might use something like a USAF I3A/ISO 12233 Resolution Test Chart.
I3A/ISO 12233 Resolution Test Chart | Edmund Optics
I3A/ISO 12233 Resolution Test Chart used to measure visual and limiting resolution, offers a simple method to obtain SFR data, and is available at Edmund Optics.
www.edmundoptics.com
For astigmatism and central sharpness, a Siemens Star Target like this one is probably a good idea.
Star Target | Edmund Optics
Star Targets ideal for identifying focus errors, astigmatism, and other aberrations existing in an imaging system are available at Edmund Optics.
www.edmundoptics.com
Edmund Optics is relatively expensive. You should be able to find less expensive options that you can print yourself.
Before you go too far down this path, take a look at these articles from Roger Cicala at LensRentals.
Fun with Field of Focus Part 1
I've mentioned in some other posts that our optical tools can do a lot more than just test a lens' MTF. For most of the last two years, though, testing MTF is what we've been doing. We may not seem all that busy, but we've assembled what is probably the world's largest database of current camera...
www.lensrentals.com
Fun with Field of Focus II: Copy-to-Copy Variation and Lens Testing
I mentioned in our first post in this series that one of the major reasons I was interested in looking at field curvatures was as a means of detecting lenses that are weaker on one side (or perhaps one corner). If you haven't looked at that post, you really need to before you tackle this [...]
www.lensrentals.com
Testing for a Decentered Lens: an Old Technique Gets a Makeover
What is Decentering and What Does it Do? Strictly speaking, decentering would involve one or more of the lens elements being off of the central axis of the lens. This would prevent the curved surfaces of the lens from bending the light properly. In severe cases it could result in halos or...
www.lensrentals.com
One other comment - Roger Cicala has the equipment and staff for a deep dive to test lenses, but even he has to balance the time and effort required. Some tests can take two hours or more and the cost is prohibitive on all but the most expensive lenses.