extension ring

noun

1. photog a spacer element that can be fixed between the camera body and the lens to increase the distance between film and lens and allow closer focus than would be possible without it

Example Sentences

It features a removable clear lid so you can see how your meal is coming along, a reversible steamer plate with built-in burger formers and extension ring for high-capacity cooking.

From Salon

Like last year, LDSD's doughnut-shaped extension ring inflated as expected, adding surface area to increase the amount of friction and slow the vehicle's descent through the atmosphere.

From Reuters