Use the KATAPULT service through photoheight.com to do all of your measuring from anywhere, anytime.
The distance rule is to prevent errors due to parallax. It has nothing to do with the camera, and cannot be simply fixed with math. When you stand under a pole and shoot it with a wide-angle lens, bolts look like a vertical line instead of a point.
We've found the minimum distance needed for consistent measurements is to match the pole height. If the pole is 40' tall, stand at least 40' away.
The biggest advantage of our recommended DSLR setup may be the zoom range. With the 28-135mm lens (Canon EF 28-135mm f/3.5-5.6 IS USM), if the pole fits in the photo, you're far enough away. This simplifies field training a great deal.
Target placement determines how high you can accurately measure. A rough rule of thumb is 2.5-3x the height difference between the lowest and highest targets on the height stick. We worked closely with a power company who specified a goal of +/-3" accuracy at 50' high. With a 17' stick and 5 targets (14' between top and bottom targets) our heights have checked out well.
We recommend the Crain/Seco SVR-17 (model #98021). If you already own a 25' SVR, the top 4 sections work just as well.
The 17' model is around $150 if you need to purchase one.
The nice thing about the SVR line is the inset rod face. It prevents the adhesive targets from scraping off when the stick is collapsed.
If adhesive targets won't work well for your application, contact us. We've experimented with quite a few targets; our engineers are happy to offer advice.
Supported rugged compacts:
Where to buy:
Supported DSLR lenses:
Comparison and Notes:
DSLRs take clearer photos, are easier to use in bright sunlight, shoot faster, and have much better low-light performance. Field crews report less per-pole time and at least an extra hour of useable light each day. The batteries are much larger and usually last all day. When measuring, the extra clarity makes it easier to see bolt details, drop wires, etc. along with better target identification accuracy.
We expect to calibrate additional lenses and cameras over time. In general, DSLR lenses can be calibrated, while rugged compact cameras are unpredictable. For example: the Pentax WG-2 calibrated flawlessly, while the Canon D20 proved unuseable. Contact us with any questions; we're happy to share what we've learned.