Math and Magnification
April 20, 2018 ~ After a pitiful, non-productive trip to Quintana Neotropical Bird Sanctuary last Friday for more itty bitty flitty birds, we took a break and headed out to familiar places for long-legged waders and shorebirds. Oh, there were birds at the sanctuary, but the light was not to our liking and it was crowded. Maybe later we will try again.
Parked on the shoulder of the cutoff road under the Intracoastal Canal bridge, Bill Maroldo was working on a Great Blue Heron on his side and I had a nice Little Blue Heron perched on a post on my side. We had some sea fog along the coast so the light was nice and there were no crabbers to disturb the birds. Bill suggested I might like to use his Nikon 1.7x teleconverter instead of my 1.4x on my long lens.
You can already see where this is going, I bet.
And... I didn't move, same set up out the window of the truck at the same perched bird. And the above image is also a 7MP crop from the original 36MP image. With the 1.7x teleconverter on the same lens and camera... the focal length is now 850 mm.
Go ahead, embiggen and compare. And I can't see any degradation in the image quality looking at them side-by-side. What do you think?
Now, back to our discussion. A teleconverter is a small secondary lens that fits between your camera and your long lens. They are made in 1.4x, 1.7x and 2x magnifications and have pros and cons.
On the plus side, you can get more "reach" from an existing lens for a smaller price than a buying a longer lens. A 1.4x on a 300 mm lens will give you 420 mm. A 1.7x on a 300 mm equals 510 mm, and a 2x on the 300 mm doubles the focal length to 600 mm. And adding the teleconverter to increase your focal length won't add much weight at all.
Of course, there are many negatives. Not all lenses will work with a teleconverter, you will absolutely lose a stop or more (it lets in less light) and focusing can be slower. Sometimes the autofocus will not work at all with a particular lens. And since it is magnifying only in the center, the surrounding areas and edges may not be as sharp. Here is a great in-depth article What is a Teleconverter? if you want to know more. Believe me, there are serious negatives or everyone would be using them and no one would buy those high-dollar big lenses. Here is another article on pros and cons of teleconverters
Short story is they generally work best with prime lenses not zooms, a teleconverter by the same mfg as your camera/lens will work better than a 3rd party item and most sizes over 1.4x are not satisfactory. And your lens has to be really fast to start with (like a f/2.8 or f/4) since you will lose stops. Do a lot of research first if you want to go down that road. The teleconverter magnifies the flaws in your lens as well as the subject.
Except this Nikon 1.7x has great reviews. Bill bought it to use with his Nikon 300 mm f/4 PF for BIFs and has been pleased with the results. Here is some more info if you are interested in that combination.
No more side-by-sides but this is a pretty good test of image quality. The little Tricolored Heron was just off Crab Rd and I shot this out the truck window. He was RIGHT there and this is not cropped. Seriously. I did later change to f/8 because he was so close, but he had moved a bit by then and those shots didn't have as much curved neck. He was fishing and it was a challenge to keep him in the frame. Because 850 mm is a lot of magnification :-)
I was kinda liking this new toy.
Mom Killdeer and her eggs
Nikon D810 with NIKKOR 500mm f/4E VR + Nikon 1.7x TC ~ 1/1000 sec f/8.0 ISO 1000; braced in window
Down one of the side roads at Surfside we saw a couple of Killdeers. One was sitting on the gravel and sure enough, she was on a nest! It is just a scrape in the ground and I bet she wasn't 15 feet from the road. This is a panorama shot; I took one of her head and shoulders, the lowered the lens slightly to get her body and the eggs. Then with the magic of Photoshop I merged the two images.
We made a mental note to go back next time and see if there are tiny babies running all over the parking lot.
We didn't find any songbirds at Kingfisher Corner because there were trucks and fishermen. No Long-billed Curlews in the lawns. Heading out of Surfside Bill spied a Merlin on a wire. He pulled over and I got out to go to the back of the truck with my bean bag support. And the 850 mm reach brought him in a bit closer than my usual 700 mm. This is a substantial 6.7 MP crop out of 36 MP, but it looks sharp.
Yes, I get scared when we stop on the side of the road for birds. At least there was a shoulder and we were headed the right way this time.
At the end of Bay Rd we set up crates and tripods in the mud. In front of us were some Avocets in breeding colors but they were sleeping and never moved from behind some reeds. We watched two Black-necked Stilts, a Greater Yellowlegs, a couple of Willets and a Snowy.
The Snowy Egret was really active.
I got this on a burst of shots; no one is fast enough to get that instant with one shot. In fact, since it was all white I didn't even know he had the fish until I downloaded the day's work on my computer after we got home. This is pretty sharp even with a teleconverter; if you click to embiggen you can see half of his nictitating membrane is covering his eye.
While we tried thought-control on the Avocets to come closer (it didn't work y'all) we saw three Green Herons fly over but they landed deep in the marsh. Bill couldn't catch focus on a Caracara that flew over; I missed the whole thing.
Bill was convinced the Black-necked Stilts were going to mate right there in front of us, but I wasn't so sure. The female is just a shade lighter than the male; a dark brown instead of black. Nice to see them together for the comparison.
After chasing some Whimbrels (he got shots, I didn't) we went on to Brazoria National Wildlife Refuge. A chance to see how the 1.7x performed on some real distance and in lower light. It was getting close to 5 pm.
This female Red-winged Blackbird was flying with this dried reed when I first saw her. It looked like a yellow ribbon and I only got a couple of shots before she dropped it. It was a hard shot as the reeds kept blowing in the way. I really didn't notice any difference in the focusing speed with the 1.7x as opposed to what I am used to with the 1.4x.
It was very windy which kept the mosquitoes away, at least on the Autotour. On the way in we saw five or six Scissortailed Flycatchers AND a couple of Eastern Kingbirds flying off the barbed wire fences and back. Perfect opportunity for flight shots but even after spraying down, the mosquitoes defeated us. Must a been a low spot, they were so thick you were breathing them! No wonder there were so many birds feasting on the devils.
I saw a Pied-billed Grebe out of my window and he posed a bit. They never have seemed shy to me but others say they are. I was shocked when he brought that foot out of the water to scratch. Look at the structure! They hardly ever walk on land since the legs are so far back on their body. This is a serious adaptation for diving and swimming under water.
This was taken a short time after the female Red-winged but it was much darker in this area. Plus the bird is darker, so I dropped the shutter speed and cranked up the ISO. I used some noise reduction in ACR, but not all cameras can handle the higher ISOs. YMMV.
We found a Boat-tailed Grackle hanging on in the wind to a small bare tree. Last time we were at Brazoria this twiggy tree was full of Barn Swallows. That is one advantage to going to the same places for birds all the time. You learn the likely places for birds
Note the f/stop for the above is f/6.7. That is the widest aperture available with this 1.7x on my 500 f/4. You lose a stop-and-a-half and this late in the day with a dark bird in the high wind I needed a lot of help. He wasn't still (squawking AND moving in the wind) so I had to have as fast a shutter speed as possible and high ISOs on black birds can be problematic.
At some point late in the day I just started doing hand-held flight shots. The long lens is heavy but a little voice kept telling me to practice; the technique is the same no matter what the weight of the lens. So I was just following any bird in flight. And this strange bird was flying almost directly toward me. I thought at first it was a young night-heron; I could see all these striped on its body. I kept up with the slow wing beats until it passed. Bill had been following it as well and we both said "OMG American Bittern" at the same time.
The image is noisy. But it is still pretty danged sharp for 6:15 pm and ISO 4000 AND a 1.7x teleconverter.
So, from this experience I definitely find the 1.7x teleconverter usable. I think it is better on close subjects with my 500 f/4 than with distant. My Sony equipment that I sent off to B&H garnered almost enough monies to pay for a Nikon 300 mm f/4 PF lens and my Chase Reward points will pay for my own 1.7x teleconverter. You have to get creative about this expensive hobby after you retire. What is your experience with teleconverters? Are you using any? Do you think the image quality suffers too much? Let me know in the comments below.