Which 1.4TC for Sigma 400 f/5.6 macro on 7D

Started Sep 16, 2017 | Discussions thread
Sharik0192 Regular Member • Posts: 232
Re: Which 1.4TC for Sigma 400 f/5.6 macro on 7D

TwoMetreBill wrote:

Have the lens but not the body yet. This setup will only be used for close work with the lens typically set to f/11-16. The converter's purpose is to increase magnification at closest focus.

As a general rule, Sigma lenses typically work best with Sigma teleconverters but:

1. Sigma has made several generations of converters, so which would be best with this lens?

2. Sometimes a Canon or Kenko converter will deliver superior results. Any thoughts?

Experience has shown that an 800mm full frame effective focal length works really well with small critters like butterflies and prairie dogs.

There are several models of old Sigma 400mm f5.6 lens. Are you talking about apo telemacro with 77mm filter thread? I used this lens in another system with and without Sigma Ex 1.4x TC (pre-DG), and must say that it performs much, much better without a TC. With TC, AF was non-existent, and you need to stop down at least one full f-stop (i.e. to f11) to get a decent sharpness, whereas the lens without a TC has a sweet spot at f6.3-7.1.

This is a very nice and special lens, I'm sure you'll enjoy it. But if you plan to use it for close-ups, consider the following: this lens has substantial focus breathing of the opposite sign to most other lenses with internal focusing. Close to minimum focus distance, its effective focal length is close to 550 mm, and effective maximum aperture is close to f8. Because of this unusual feature, you may not even need a TC.

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