82 or 65 the Televid Quandary

The big question most users have when selecting a new Leica spotting scope is,

“Which model is the best for me?” 

The Leica APO Televid is offered in body styles with either a straight through or 45º angled eyepiece design. While the former seems more intuitive for use at first (as you are always looking in the direction of your subject), the VAST majority of birding and nature consumers purchase the angled eyepiece design shown below do to the ergonomic advantages and versatility. As example, when birding in a group it is much easier for the taller participants to bow slightly at the waist to look through a lower, angled scope than to awkwardly bend to the side or stand in a crouched position to look through a straight scope set lower.

Conversely, if a straight scope is set too high, the shortest person may miss views of wildlife while the tripod is lowered, and the subject relocated. The versatility of an angled eyepiece allows users to quickly rotate the eyepiece downward without losing the subject or resetting the scope’s position. Additionally, a lower scope will invariably be steadier with less wind resistance and for the digiscoper, an angled eyepiece keeps the camera closer to the balance point, thus reducing “creep” or sagging from an unbalanced load when the extra weight of camera is attached to the eyepiece.

 

Leica APO Televid spotting scope models – 65 mm top, 82 mm bottom

The more difficult question consumers face it seems is, “Do I want the smaller & lighter 65 mm version or the slightly larger & heavier 82 mm?” Unlike some manufacturer’s spotting scopes there is no difference in magnification between the larger & smaller APO Televid models so this is not a consideration. In length there is not an enormous difference either (only ~1 inch) however, the larger 82 mm objective lens contains 3 dense and molecularly-heavy, ED glass lens elements that adds just under 1 pound in weight difference. Here is where you can simplify the decision making process, by asking yourself one simple question,

“Will an additional pound in weight mean I will carry the scope less?”

If the answer is “yes” then you may well already have your answer. You gain no real advantage from the slightly better optical performance of the 82 mm model, if you are less apt to take it into the field to use. Indeed that is the very reason optics manufacturers offer varying options of power and objective lens size in spotting scopes and binoculars, so the consumer can balance usability versus optical performance to meet their needs (one of the reasons our 8×32 Ultravid HD-Plus binoculars are so popular).

Televid exit pupils 25x_edited-1

The main difference in optical performance is in the “Exit Pupil” of the scope. Simply, the exit pupil is the diameter of the circle of light you see coming out of the eyepiece as seen above. In any optical device you begin with a circle of light equal to the size of the larger objective lens (the lens furthest from your face) so in the current Leica spotting scopes you begin with either 82 or 65 mm of light. The physics of optics and exit pupil are simple, for every power of magnification that you increase your subject, that circle of light is decreased by the same power. So in the graphic example above, the image at left shows the 82 mm scope at minimum zoom on our eyepiece, 25x magnification. Since we are increasing the size of the subject 25 times, we are also reducing that 82 mm circle of light 25x, so exit pupil of ANY 82 mm spotting scope at 25x magnification can be calculated as follows (works the same for binoculars).

82 mm objective / 25 power of magnification = 3.28 mm wide circle of light entering your eye.

65 mm objective / 25 power of magnification = 2.6 mm wide circle of light entering your eye.

Since the 65 mm objective lens assembly is ~20% smaller than the 82 mm, the exit pupil is also ~20% less as you can see in the image and formula above. Both scopes are set to the same power (25x) and you can note that as expected from the laws of physics, that indeed the 65 mm at right shows a slightly smaller circle of light coming out of the eyepiece.

Televids_edited-1

In comparing the two scopes in most daylight conditions you may find it hard if not impossible to really note a great deal of difference between the view of the 65 & 82 mm APO Televids honestly. The subject is magnified equally, the wide, eye-pleasing field-of-view is identical in both models, and the reduction in light is generally negligible in most daylight conditions.

THEONA CHECKERSPOT

THEONA CHECKERSPOT

The only tangible performance difference beyond the size and weight one can note easily in daylight is in close focus distance. The smaller 65 mm can focus below 10 feet, while the larger 82 mm minimal focus is about 3 foot  (0.9 m) further. So if studying close insects, lizards, snakes, etc. with the spotting scope or digiscoping the same, the advantage goes to 65 mm model.

White-tipped Sicklebill

You need very extreme lighting conditions (generally at or before sunrise in the morning and after sunsets at night) to really notice that 20% more light entering your eye through the 82 mm spotting scope. Here are three anecdotal examples I can think of where I could say, see, & prove that without doubt, the 82 mm outperformed the smaller 65 mm even though I know for a fact it does all the time. The White-tipped Sicklebill is a marvelous hummingbird species that occurs in southern Central and northern portions of South America. While not as colorfully spectacular as many of its brethren, it is an amazingly specialized species with a bill adapted to feed on specific Heliconian flowers that occur in the rain forests here. It is this specialty that makes it so unique and the reason I’ve always wanted to see it (much like the Wryneck is a standout amongst Woodpecker species perhaps).

On 23 July 2010, my son & I were staying with our dear friends at Panama’s Canopy Lodge, when I heard rumor of a “magic branch” below the scenic waterfall upstream from the lodge on their “Canopy Adventure” property. This branch was magical (to me at least) because each night, in the last glimmer of light & long after sunset a tiny gem, the White-tipped Sicklebill, would zip in from points unknown and land on this thin twig that hung over the river and spend the night perched here. To see this beauty, I had to really ask for a lot of favors including getting special permission to stay on the property after closing, skipping the scheduled dinner at the lodge with the group, and then hiking the 3/4 mile back near dark with my then 12 year-old son.

He was toting a 65 mm and I an 82 mm APO Televid, which we had set up on that magic branch from the damp, mist-covered platform some 75 feet away. At long last and much later than we’d expected, our prize finally came in and after enjoying some marvelous views, we attempted to digiscope the bird. It was near twilight, under the shadows of mountainous ridge above, inside the dense canopy with mist in the air. The energy from the waterfall caused the tiny branch to continuously bounce up and down 2 inches or so and I was absolutely unable to capture anything but a blurred green line with the 65 mm. Happily, the 82 mm scope produced images were at least identifiable. I shot in burst mode using self timer and still only one of maybe 50 images was crisp enough to show detail. Above is that single image! Mesmerized, my son and I made our way back down the road to the lodge by flashlight where the ever friendly staff had a late meal waiting!

BT3 Asa Wright grotto

The next example of where the 82 mm outperformed the 65 mm comes from the world famous Asa Wright Nature Center & Lodge in Trinidad in July 2009. Asa Wright’s infamous “grotto” (seen behind my friend Bill Thompson III, editor of Bird Watcher’s Digest in the image above) is a very narrow crevasse of split rock with just the tiniest sliver of light entering from above which is shaded by dense tropical foliage. This near cave plays host to yet another amazingly specialized bird species, an enormous nocturnal frugivore with a wingspan of almost a meter, the Oilbird!

These birds will typically roost in caves by day and come out to search for fruit in the forests by night. Peering in to the darkness with the naked eye from a respectful distance, one could note dark lumps here and there. With the binoculars you could make out mostly bird-shaped silhouettes, but once again in the near complete lack of light of the grotto, the 82 mm spotting scope allowed me to focus on these birds perched along the lips of the jagged walls here. The image below was digiscoped through the APO Televid spotting scope with NO artificial light whatsoever and from a respectful distance to not disturb these endangered birds.

Oilbird no light_edited-1

The final example of obvious advantage 82, comes from March 2015 during the Champions of the Flyway bird race for conservation in Eilat, Israel. It was shortly after midnight on race day and I was with my team, The Leica / Cape May Bird Observatory “American Dippers”. We’d stopped at a gas station for snacks and from the parking lot added our first species of the event a fly over calling Stone Curlew. From here we moved down to the salt pans that sit just north of town. With our binoculars we could see a mass of birds in the pans from the ambient light of Eilat. Tall Greater Flamingo silhouettes were unmistakable, but the sleeping gulls in the flock (below) would require more effort.

Gulls

We had 3 APO Televid 65 mm models and a single 82 mm spotting scope and the views through the 82 meant the difference between saying “they look like gulls” and actually placing species names to these birds. The image above shows the flock digiscoped with an iPhone 5s which is notoriously bad in low light producing incredible amounts of noise (I was happy to upgrade to the 6s). Despite the horribly grainy image however, the view through the 82 mm Televid was fantastic and there was no noise pixellating the details. In this view we had mostly Black-headed Gulls & Slender-billed Gulls but even in the noisy image you can see the large black-headed, Pallas’ Gull, Baltic Gull & Heuglin’s Gull.

As we approached the end of the event almost 24 hours later we added our final species, our 168th bird species in 24 hours near 11 PM, again thanks to the additional light delivery of the 82 mm. We were scanning the Eilat waterfront behind the clubs that were pulsing out techno vibes when we spotted 3 distant gulls sitting on buoys. Again we could not make out plumage details with the 65 mm, but through the 82 mm, we could see that indeed these were the species we’d expected to see that morning but had yet to detect, the near endemic, White-eyed Gulls! This was an enormous coup because we won the Champions of the Flyway title by a single species, if we’d not had the 82 mm model we may not have been able to positively identify this bird.

2015 Leica/CMBO "American Dippers" with Champions of the Flyway staff (left to right) Doug Gochfeld, Michael O'Brien, Jonathan Meyrev (COTF), Jeff Bouton, Glen Davis, & Dan Alon (COTF).

2015 Leica/CMBO “American Dippers” with Champions of the Flyway staff (left to right) Doug Gochfeld, Michael O’Brien, Jonathan Meyrev (COTF), Jeff Bouton, Glen Davis, & Dan Alon (COTF).

Not everyone will be trying to identify birds by ambient light near midnight or in other extreme lighting conditions, and for those the Leica APO Televid 65 mm will treat you fine, but you never know when that tiny bit of extra light will allow you to identify a species or get that crisp image you want. I would never discourage anyone from getting the 65 mm for its ease of portability over extended periods, but for the person using this primarily as a lens the extra “f/stop” equivalent of the Leica APO Televid 82 mm will beget slightly quicker shutter speeds and be an advantage and be my recommendation unless the consumer has already indicated the additional pound in weight would dissuade them from using it regularly.

Merken

Merken