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I am primarily a landscape photographer but also photograph the endangered Sierra Nevada Bighorn Sheep. I have only photographed the sheep at closer distances on two occasions. Generally it takes binoculars or a spotting scope to find them and they are beyond the range of any native A7R2 lens. I have tried several adapted lenses including the Canon 100-400, Canon 400 5.6, Sony 70-400 and the Canon version of the Tamron 150-600. I have learned a few things along the way and can tell you that none of these lenses are suitable for backpacking in the high Sierra where these sheep live. I can also say that none have worked for me. I think the prime reason is that the apertures of these lenses are simply not wide enough for the Sony autofocus to be dependable or accurate. I have rarely had sharp results.
I recently rented a Canon 300 2.8 and discovered that the results were often sharp and the autofocus worked well. I set the camera for Contrast Detection not Phase Detection as Brian Smith recommended in his article on Canon Lenses and adapters for the A7R2. The problem with the Canon 2.8 is that it is way too heavy and too short a range without teleconverters/extenders added too. And we all know how teleconverters degrade the quality of the light and photos.
I finally realized that the crucial issue for Sony and adapted lenses is the need for a large aperture lens. That is why I rented the often dismissed Canon 400 f/4 IS USM version I. The lens has an undeserved reputation for not being sharp. It is sharp. Because it uses diffractive optics, the lens is shorter and lighter than even the 300 2.8. It is not considered an “L” lens but it is a sturdy well-built lens.
Someone reminded me lately that the A7 cameras have a “Clear Zoom” feature that is a kind of middle ground quality between digital and optical zoom. By using this feature, I am able to double the 400mm to 800mm. How does this stand up to scrutiny? I think quite well especially when compared to the quality of a 400mm lens with a 2x extender where one would absolutely lose autofocus and IQ.
I found that autofocus was good in auto mode. However when I set the camera mode dial to “auto” the camera set the iso to 100-200, f4 or f4.5 and 1/400. Using this lens wide open is difficult when shooting things close up since the zone of focus is too limited. Photographing hummingbirds at about 15 feet is a good example of this. What worked for me was to set the lens to manual focus, to set the mode dial to aperture priority, set auto iso and 1/400 for shutter speed. In manual mode, I also used “focus zoom” which helps fine tune the focus.
I rented the lens from lensrental.com and was so excited about the results I was getting; I offered them a purchase price for this lens before I had to ship it back. They have a policy of allowing renters to buy the lenses they rent. We negotiated and I bought the lens. I know, I have had honeymoon periods before and written about the other lenses I mentioned. This lens is expensive even as used older model but it gives me hope that the next time you see bighorn sheep photographs they will be stunning.
If you are only a landscape photographer, Sony has all the e-mount lenses you need. If you also photograph wildlife, maybe this lens is your solution. It is not a “bird in flight” lens but it is sharp, dependable and has a longer reach.
400mm Book At 15 Feet
I took this photograph yesterday (02-26-17) using a rented 1.4 extender (560mm)
I don't have the best vision but it seems plenty sharp to me.
And here is a crop of my Sierra Nevada Bighorn Sheep located via a spotting scope. They are sharp and probably a half mile away. This photo is with a rented 1.4 extender. F8, 1/1000, ISO 2,000. There are two mature rams in the group of four rams. This time of year they drop down on the eastern Sierra Nevada slopes to get out of the snow. This has been a difficult winter for them with snowpack at 200% of normal and the endangered sheep total has been diminished by mountain lion predation because they are more vulnerable at low altitudes.