Canon wildlife lens?

[Daniel Browning]

Are you saying telescopes do worse close up because they are optimized to image at infinity, or that they'll do worse even when taking pictures of far away stuff?

Thanks for the reply, Jon. I could be wrong; I haven't done much evaluation of refractors, but I have read a lot of comparisons on Cloudy Nights. I was thinking of up close performance. Sometimes, lenses are even better than telescopes at infinity, but not always.

For far away stuff , it is hard to imagine the 400mm f/5.6 doing better across a 36mm field than, say, a takahashi fsq or "baby q". Am I wrong?

I think the baby q ($3k) will be better at infinity. When I said "Twice the price" that was probably too much exaggeration.

Have you done or do you know of someone who has done these comparisons?

I just read about them every once and a while on Cloudy Nights, but I don't have any links. There was a thread a while back where I said there was no way that a photographic lens could match a telescope (at similar price ranges), because of like two dozen reasons:


<span class="post"]Fast f/numbers are needed, which I understand are more difficult than slow f/numbers.
The flange focal distance is fixed.
(Usually) larger image circles needed
Bokeh
Color balance compared to other lenses in the line.
Length is usually less important in telescopes.
Telescopes are not often handheld, so weight tolerances are lower.
Volume matters more in photographic lenses which must pack for travel.
The lens must focus, and have good travel, control, smoothness, sensitivity
Design for close focus distances and performance at those distances as well as infinity.
Focus shift at various focal ratios is less tolerated than in a telescope.
Lots of mechanical design issues such as aperture diaphram
Compensation for cosine^4 falloff, which I don't think is a big deal in telescopes.
Filter size (very few photo lenses allow rear filters)
Teleconverter compatibility
Aperture Activation Variance
Auto focus motor speed and accuracy
Image Stabilization
Noise from I.S. and Autofocus
Electronic communication with the camrea
Continuously variable aperture ring
Resistance to shock, vibration, impact (IMHO)
Focus marks
Manufacturing delivery schedule, marketability, cost, etc.


I was certain that with so many factors in favor of telescopes that there was no way a lens could be better at infinity. But many people responded to correct me, saying that there is one all-encompassing and overriding advantage: economies of scale.

[Daniel Browning]

Daniel, any suggestions for either the Sigma and Tamron?

A used Sigma 300mm f/2.8+2X would do better than the zooms. Sometimes a used Sigma 500mm f/4.5 will come around for $2,900, but that's over budget. I thought Tamron had some nice old prime teles, but I don't see them.

Like you've said, I wish Canon would fill the gap. A 500/5.6 might be the ticket?

Yeah. I'd prefer an 1100mm f/11 IS with optional 2X wide converter (which would turn it into a slightly soft 550mm f/5.6). Only problem is that 35mm 2X wide converters are encumbered by patent issues for the next few years, no thanks to Kodak. It would be the ideal hand-held birding lens.

[ShutterbugJohan]

Daniel, any suggestions for either the Sigma and Tamron?

A used Sigma 300mm f/2.8+2X would do better than the zooms. Sometimes a used Sigma 500mm f/4.5 will come around for $2,900, but that's over budget. I thought Tamron had some nice old prime teles, but I don't see them.

I'm positive that they had an old 300/2.8.

Only problem is that 35mm 2X wide converters are encumbered by patent issues for the next few years, no thanks to Kodak.

How do they work? I've never heard of such a thing. []

[Daniel Browning]

How do they work?

It's the same thing as a focal reducer (or field flattener), which are used all the time in astrophotography, except with a few extra elements to preserve the backfocus distance.

They're like the inverse of a teleconverter. They mount between the lens and camera, but instead of making the focal length longer and f-number slower, they make the focal length shorter and f-number faster. They need about 7 elements, same as a good TC, but thicker, and it needs to be matched specifically for a single lens.

It would be ideal for wildlife because most of the time we'll want super long focal lengths (e.g. 1100mm) with the highest quality possible. An 1100mm f/11 L IS with no TC would provide that quality (and even allow another 1.4X TC), and for those rare times when it's too long or you need autofocus, you pop on the wide converter to get 550mm f/5.6, though the quality is lower.

One example is the Oly 35-100 f/2.0, which is actually just a typical 70-200 f/2.8 lens with a wide converter permanently attached: that's why it's over two times heavier than a 35-100 f/2 should be. It should have turned out as a 35-100 f/1.4, but they left it at f/2 for some reason (I heard that if you press the lens release, it opens to f/1.6 but vignettes terribly -- perhaps that's why).

Unfortunately, I don't think we'll see any until the Kodak patent expires.

[ShutterbugJohan]

Interesting. Thanks, Daniel.

[tancanon58]

100-400 f4.5L IS (new $1600)


100 2.8L IS (new $1050)