Dptips :. Digital Photography Tips, Tricks, and Techniques

Teleconverters, either 1.4X or 2X, are efficient tools to add focal length to the photographer’s arsenal. However, universal-type teleconverters have certain limitations in performance when used with ultra-telephoto lenses of 200mm or longer as compensation of chromatic aberration alone becomes highly critical in this focal length range. The new PRO-series teleconverters are specifically designed and optimized for use with such ultra-telephoto lenses to deliver maximum resolution, contrast and color rendition without degrading any aspect of the master lens performance.

The 1.4X teleconverter will increase the focal length of the master lens by 1.4X and make the lens one f-stop slower. The 2X doubles the focal length of the master lens and makes the lens two f-stops slower. In addition to increasing focal length, both teleconverters allow greater magnification in macro since the Minimum Object Distance (MOD) of the master lens does not change when used with the teleconverters.

The 1.4X teleconverter can be used with both AF and MF lenses. AF will be retained if the master lens is F/4.5 or faster. AF will be retained with the 2X teleconverter if the master lens is F/4.0 or faster.

Tamron SP Pro-Series Teleconverters

The SP AF PRO-series teleconverters, with a newly designed optical construction (4-group/5-element for 1.4X and 4-group/7-element for 2X), are designed to be used with lenses that are F/2.8 and of focal lengths of 90mm or greater. This would make the use of the SP teleconverters ideal for the Tamron SP90mm F/2.8 macro, 70-210mm F/2.8 and 300mm F/2.8. Relative illumination is significantly improved resulting in better overall contrast and resolution across the entire image field. In addition, chromatic aberration and astigmatism are better compensated for by virtue of the use of higher-grade glass materials and more sophisticated design techniques than used in universal-type teleconverters. When used with lenses with smaller maximum apertures (F/4 and F/5.6, for example), there will be little difference in image quality as compared with the standard Tamron teleconverters. When used with lenses wider than 90mm, the SP teleconverters can actually comprise image quality.

Tamron Standard Teleconverters

The standard Tamron teleconverters extend the focal length by a factor of 1.4 or 2 respectfully and sustain the same light loss factors as the Pro-series. Though using a teleconverter on wide-angle lenses is never really recommended, these converters can be used with lenses that are wider than 90mm and are ideal for all lenses that are not F/2.8’s.Seth