Post by kenpossum on Apr 9, 2011 21:06:27 GMT -8
While at the Hope Airport recently, a couple of Northern Shrikes made an appearance (coinciding with the disappearance of the Mountain Bluebirds). The Shrikes were at a considerable distance and the Nikon 80-400mm (120-600mm on my N7000 body) was taxed to its' limits. f/5.6, 1/000 sec, ISO 200
I then switched to a 30 year old 500mm f/8 mirror lens (effective 750mm) to get a larger image without having to digital zoom as much. f/8, 1/500 sec, ISO 200 There was increased noise but the Shrike held together reasonably well. (It was a different Shrike, but the distances were similar.)
I then attached a 2x teleconverter to increase the focal length from 750mm to 1500mm. I was pleased with the results considering the distance involved. f/8, 1/125 sec, ISO 200
Teleconverters can work well. but they do sacrifice light. A 2x results in a loss of two stops. For that reason, many photographers prefer a 1.4x teleconverter which looses less light. As long as the bird is not moving, they can capture an image that your normal telephoto would give up on. Nevertheless, I would recommend using them only when you have to ie. your bird is very far away.
When purchasing a teleconverter for a new camera body, make sure the teleconverter is compatible with your camera body as damage may occur to your body if they are not. Strangely, some of the generic teleconverters such as Sigma and Tamron will connect with new camera bodies when the brand names (Nikon, Canon) will not. They also are less expensive than the brand names.
When you buy a teleconverter check out the specks. For example, some have five lens elements and others of the same brand will have seven. The more lenses, the higher the quality (and price). With teleconverters, always opt for quality.
NEW
Teleconverters may or may not work with your auto-focus lens, if the combined aperture is less than f/5.6. All Canons will not work less than f/5.6 but some Nikons will work at 4.5 but will be slow to focus. For that reason, the 1.4 teleconverter is often chosen as it loses only one f-stop, compared with two with the 2x.
Generally, all teleconverters will result in a loss of sharpness, but the results will depend upon the brand and individual camera model. For Nikon, for example, the N90 accepts a 1.4 x teleconverter better than the D7000. However, for most eyes, the slight decrease in sharpness will not be noticeable.
I then switched to a 30 year old 500mm f/8 mirror lens (effective 750mm) to get a larger image without having to digital zoom as much. f/8, 1/500 sec, ISO 200 There was increased noise but the Shrike held together reasonably well. (It was a different Shrike, but the distances were similar.)
I then attached a 2x teleconverter to increase the focal length from 750mm to 1500mm. I was pleased with the results considering the distance involved. f/8, 1/125 sec, ISO 200
Teleconverters can work well. but they do sacrifice light. A 2x results in a loss of two stops. For that reason, many photographers prefer a 1.4x teleconverter which looses less light. As long as the bird is not moving, they can capture an image that your normal telephoto would give up on. Nevertheless, I would recommend using them only when you have to ie. your bird is very far away.
When purchasing a teleconverter for a new camera body, make sure the teleconverter is compatible with your camera body as damage may occur to your body if they are not. Strangely, some of the generic teleconverters such as Sigma and Tamron will connect with new camera bodies when the brand names (Nikon, Canon) will not. They also are less expensive than the brand names.
When you buy a teleconverter check out the specks. For example, some have five lens elements and others of the same brand will have seven. The more lenses, the higher the quality (and price). With teleconverters, always opt for quality.
NEW
Teleconverters may or may not work with your auto-focus lens, if the combined aperture is less than f/5.6. All Canons will not work less than f/5.6 but some Nikons will work at 4.5 but will be slow to focus. For that reason, the 1.4 teleconverter is often chosen as it loses only one f-stop, compared with two with the 2x.
Generally, all teleconverters will result in a loss of sharpness, but the results will depend upon the brand and individual camera model. For Nikon, for example, the N90 accepts a 1.4 x teleconverter better than the D7000. However, for most eyes, the slight decrease in sharpness will not be noticeable.