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Long Lens Selection

Table of Content

Introduction

Overview  

Independent Options

Usage

Handling

MTF Performance

Conclusions

Introduction

This page is focused on looking at the Canon options for achieving longer focal lengths. The investigation is limited to Canon’s own lenses for quality and compatibility reasons, although third party possibilities are mentioned.

The main constraint in this study is cost. Long lenses of any quality are expensive, possibly very expensive.

Typical applications for these lenses would be sport and wildlife and possibly some specialist landscape work.

Generally for wildlife work in particular the lenses need to be as long and fast as possible so only prime lenses are studied.

Canon produce teleconverters that are specially matched to their L-series telephoto lenses including MTF data for each combination in their Eyes of EOS III book. See this information for background on MTF data. An EXEL Spreadsheet is used to produce the plots and this is downloadable here.

In this study lenses of about £1000 are considered affordable but two slightly more expensive lenses of over £3000 are also looked at.

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Overview

This section tabulates various lens information in a convenient way.

The following two tables list the basic information regarding the lenses and teleconverters, the two expensive lenses are highlighted in red.  

Some of the lenses have image stabilization. Some have IS mode 2 (for panning) and some are tripod compatible (this seems to just mean they turn themselves off so perhaps is not too important). The Canon literature seems to suggest that IS has benefits with monopods (See test here) also but it is not clear if all lenses have a stable IS control loop for monopods.

Y? Canon data is contradictory.  

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Independent Options

The Sigma 300mm f2.8 EX APO HSM is a cheaper option fast long lens that has at least one positive review and has matched teleconverters available. Some say that Sigma lenses sometimes have compatibility issues with new Canon bodies. Also Sigma do not publish MTF data so an objective comparison of even manufactures data is not available.

The Tamron SP 150-600mm Di VC USD has the following maximum apertures vs focal length:

Usage

The following table lists the basic effective lens performance with and without teleconverters.

Where the converted maximum aperture falls below f5.6 autofocus will no longer be possible on Canon bodies such as the 20D, these are marked in green. Some Canon professional bodies may provide autofocus down to f8. 

The stopped down columns refer to the less that maximum aperture MTF trace in the Canon MTF plots. Thus listed is the converted stopped down aperture that Canon quote in the plots; the effective set aperture on the lens (this converted aperture will appear in the viewfinder); and by how many stops from maximum aperture this trace is.

The closest focus is assumed to be unchanged by the teleconverter (should be a safe assumption), so the maximum magnification for the lens is then multiplied by the conversion factor.

So ignoring the unconverted 200mm focal length which falls in the range for general photography, the possible focal lengths are 280-300, 400-420, 560-600 and 800 mm.

It is worth noting that none of these solutions would provide autofocus for 800 mm with a non-pro body and the only options for autofocus in the 560-600 mm range are using one of the expensive lenses.

Retention of autofocus is a major factor for most applications of these lenses, however autofocus accuracy and speed can be expected to be degraded by the use of converters.

A point also worth noting is that the 300mm f4 has the highest magnification, this almost becomes a macro lens with a 2X converter.

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Handling

Length and mass will also dictate handling largely, even on a tripod.

Clearly these lenses should be used on a sturdy tripod with a heavy duty head if at all possible. However, many of the lenses include image stabilisation which in conjunction with the low noise performance of the current DSLR cameras tempts handheld use.

Only the 200mm f2.8 and the 400mm f5.6 lack image stabilisation, although in good light the 200mm could be used without converters and perhaps with the 1.4X and masses up to about 1Kg even with converters.

Of the remaining lenses this leaves only the lower cost EF 300mm f4L IS USM as handholdable mostly due to mass of 1.2 to 1.5 Kg depending on teleconverter fitting. Even so, when a 600g+ body is added the total mass will quite a load and could not be held ready to use for any length of time.

The two higher cost lenses mass 1.9 to 2.8 Kg and would be quite a weight to lift.

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MTF Performance

In this section the relative MTF performance is compared using the MTF Samples Spreadsheet (download here).

The plots presented here are maximum aperture; and are averages of the meridonal and saggital directions at 10 and 30 lp/mm; mostly because the user will always be struggling for maximum shutter speed to freeze motion.

NB: The MTF data for the 300mm f4 without converter is different on the web and in the Eyes of EOS book, here the book’s data is used.

Each plot pair covers 10 lp/mm (contrast) and 30 lp/mm (detail) respectively.

280-300 mm Solutions

400-420 mm Solutions

560-600 mm Solutions

800 mm Solutions  

Back to MTF Performance Start

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Conclusions

The comments made in this section are with regards to the current non-pro bodies (20D et al)

EF 200mm f2.8L II USM

Light enough to be used handheld but no IS. Autofocus available for all teleconverter combinations but performance is not so good with converters.

EF 300mm IS f2.8L USM

Very good MTF performance, with autofocus available to 600mm. Too heavy to handhold despite IS. Expensive.

EF 300mm f4L IS USM

Good MTF performance with autofocus to 420mm. Light enough to handhold and has IS.

EF 400mm f4 DO IS USM

Good MTF performance and autofocus to 560mm. Too heavy to handhold despite IS. Expensive.

EF 400mm f5.6L USM

Good MTF performance but no autofocus with converters. Just about holdable but no IS.

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Last Updated 17/08/2014

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