Opticron HR66 and Telephotoadapter 40215

“What lens would you recommend for starting out in bird photography?” I get asked this question all the time, and I still don’t really know the answer. Top lenses are extremely expensive, smaller zoom lenses don’t have the power, and until a manufacturer develops a 500mm f5.6 lens that retails at around £800, I think I will struggle with the definitive reply.

But for the casual bird photographer who already owns a digital SLR and a telescope there is an alternative – using that scope as a powerful telephoto lens. I tested Opticron’s HR66 GA ED model (optically reviewed in Birdwatch 195: 50) with the company’s Telephotoadapter 40215 and came up with some interesting results.

The first thing to note is that this is not an auto-focus lens; once the camera is attached via the photo adapter and T-mount (a T-mount enables independent manufacturers to fit their lens or scope to most makes of camera), all AF camera functions are lost and only manual focus is possible. The telescope becomes the equivalent of an 800 mm f12 lens when used on a full frame digital camera or a film body. Add to this the magnification factor of many digital bodies, such as my D300’s 1.5x, and the focal length is effectively increased to a 1200 mm f12 lens.

But power and high magnification come with problems, such as camera shake, so users might have to upgrade to a sturdier tripod. Using a high ISO setting of at least 400 is recommended, as this means a faster shutter speed can be used, further reducing any shake. The aperture is fixed at f12. I say aperture, but in effect there is no aperture ring or dial, so all exposure adjustments are via the shutter dial.

When looking through the ‘lens’ it provides a relatively dark image compared to a prime telephoto, and focusing is critical at such high magnification, but with practice and patience good results are possible. I was surprised at how quickly I adjusted to manually focusing again and memories came flooding back of trying to focus on fast-flying birds with an old 600 mm lens – lots of wasted film in those days, but not in this digital age.

I tested this set-up on both dull and sunny days using ISO 400-800 settings, and although there were lots of blurred images (there always are) there were plenty of decent ones, including some good flight shots. I was pleasantly surprised when viewing the images; there was a good level of sharpness, better than I had expected, and the colour and contrast were also good. My usual adjustments in Photoshop were made, involving only minor work with Levels, Shadows and Highlights and Unsharp Mask.

Just a couple of final points: don’t expect the same quality image as a prime telephoto lens: it just isn’t going to happen. This is a compromise to enable those semi-interested birders to be able to take decent photos relatively cheaply. And although I use an angled scope for birding, I found that a straight model was easier for photography, but that is down to personal choice.