Teleconverter question

Started Feb 26, 2014 | Discussions thread
Bob GB Senior Member • Posts: 1,730
Re: Teleconverter question

billslatteryjr wrote:

OK say one usually lands up cropping away 1/4-1/2 of a bird, insect, animal... photo. Now they use a 1.4 teleconverter that causes a 5%-10% loss in sharpness. But that same shot now gets a lot less cropped away. Wouldn't one get a better photo using the teleconverter as long as the shutter speed stays fast enough for the subject?

There is no simple answer to this question. The lens, sensor, magnification of the image and post processing form a complicated transfer function producing the end image.

Adding a TC to a lens is similar to magnifying the image formed by the lens in this case by a factor of 1.4. Doing so, you reduce the resulting sharpness (resolution) of the lens by the same factor (1.4) which is a reduction of 29%. The TC itself is also a lens with its own aberrations which will be added to those coming from the main lens.

If this reduced sharpness (by 29%) still is better than the sensor in your camera you are probably in good shape. But as others have pointed out you also lose 1 f/stop demanding either more ISO or a longer exposure time. I would say using one of the exotic long lenses this is probably the case. If you add a TC to a zoom lens the 29% reduction of resolving power would perhaps make the lens fall below the D800 sensor.

However, the impact on the image might be a little different comparing a sensor limited picture to a lens limited picture. It is really up to your preference. I strongly suggest you try it out with the lens in question.

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