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Lens Selection

Table of Contents

Lens Limited Resolution

Usability, Costs and Reviews

Light Gathering

EF-S Sanity Check

Introduction

This page summarizes some of my own deliberations on selecting lenses for my Canon 20D and whatever may follow it.

As such it inherently includes my own bias, for which I do not apologise, and is presented as is with no warranty, use at your own risk etc etc.

MTF Study

Read the MTF Data Overview.

20mm Region
24mm Region
28mm Region
35mm Region

50mm Region
85mm Region A 85mm Region B
100mm Region
135mm Region
200mm Region

MTF Summary

There are more issues at shorter focal lengths than at long, partly because of the more difficult design optimisations, but also because Canon has a limited range of fixed focal length lenses below 24mm. In general although the zooms looked at here are good the prime lenses have better performance as well as being smaller.

The zooms (other than the kit zoom) perform very well over the APS-C frame but show much more differentiation over the 35mm format frame coverage where the prime lenses are clearly superior.

Looking at the relative performances the only really bad (relatively) lens is the 18-55mm kit zoom. The other zooms fall into the second tier of performance being 10-20% worse than the primes.

At maximum aperture for many cases the major maximum aperture differentiation for contrast, detail and bokeh are beyond the frame of APS-C sensors.

Generally, all the large aperture primes performed well, even the 28mm f1.8 which had a lacklustre stopped down performance.

Also take a look at:

Photodo / Canon MTF Cross Validation

Contax, Nikkor and Leica R lenses vs Canon

List of Photodo Data Comparisons

Lens Limited Resolution

It is interesting to find out which lenses are limiting the image resolution, rather than the sensor being the dominant limiting factor. To work this out relies on modelling the lens spatial frequency response as a low pass filter. There are a number of problems with this, firstly the lens frequency response will be a composite of several functions and not a simple function. Secondly, Canon have only provided MTF data for two points, 10 and 30 lp/mm, this is not much to base a trend on.

So the accuracy of this analysis is limited, and at best it perhaps provides an indication of how quickly the lens MTF response decays to minimal contrast, a value of MTF=0.1 is chosen. At worst, the plots may be trying to squeeze to much data out of too little information and so be meaningless.

In these plots spatial frequencies (f) above 80 lp/mm are not plotted as this method is probably grossly inaccurate when the MTF gradient between 10 and 30 lp/mm is low.

Sensor resolution is limited to about 40 to 80 lp/mm for the EOS 20D and EOS 1Ds depending on what assumptions are made in respect if anti-alias filter losses and losses due to geometric orientation.

This is an important factor in terms of being able to get the best out of future sensor developments. Clearly sensor resolution limits are less of a problem for a larger format of a given sensor resolution.

10mm

At 10mm the only information we have is from the 10-22mm zoom, This seems to be mostly above the sensor limit.

17mm/20mm

Here some of the lenses are falling below the sensor limit as the edge of the lens is approached, the 16-35mm zoom seems to be the worst offender.

24mm

Here two zooms show up most significantly as likely to be a limiting factor, the 24-70mm and the 17-40mm.

28mm

Here again the two zooms show up as most significantly limiting, the 24-70mm and the 17-40mm and also the 28mm f1.8.

35mm

Here the most obviously limiting is the 17-40mm zoom.

50mm to 200mm

There are no studied lenses that look likely to be resolution limiting in this range.

Lens Limited Resolution Conclusions

The results of this section are somewhat suspect and should be treated with some caution.

However, it seems this is only an issue at and below 35mm with current sensor technology with the most significantly resolution limiting lenses being zooms down to 24mm focal lengths.

As around 20mm focal lengths, the prime lenses may start limiting very fine resolution at the edges of the 35mm frame.

This does not generally seem to be a major issue for APS-C sized sensors at the lens frequency response remains good up to the edge of the frame.

Note that it is also possible to use this fit method to estimate the MTF at detail resolutions higher than 30 lp/mm to scale the 35mm fine detail contrast standard to the APS-C sensor size, this would be an equivalent resolution of 48 lp/mm for a 1.6X crop factor sensor. This does not tend to provide much information over that obtained directly however, as lens performance is less well differentiated.

Usability, Costs and Reviews

Times have changed since I was last in the market for a lens system. In those days lenses were manual focus, almost exclusively via linear extension, all lenses indicted the focused distance. Also almost all (can’t think of any exceptions) included depth of field markings, even zooms as most were of the trombone style.

Things have changed, now one has to consider if these features are available or not, plus there is a variety of auto focus actuators (motors).

Below is a table of lens information for the lenses studied. Lenses with a mass 700g and over are highlighted in orange, previous experience shows these become tiresome to use and have around the neck. Anything over 1Kg is highlighted in red.

See IMATEST and DxO Analyzer for a discussion of these lens test methods.

Make	Model	Dia mm	Length mm	Volume mm^3	Mass g	Filter Size	FE Rotation	Focusing	Reviews / Tests
CANON	EF 200mm f/2.8 L USM MK2	83.2	136.2	740481	765	72mm	AN	RFS	[1] [2] [3]
CANON	EF 135mm f/2L USM	82.5	112.0	598709	750	72mm	AN	RFS	[1] [2] [3] [4] [5]
CANON	EF 135mm f2.8 with Softfocus	69.2	98.4	370081	390	52mm	AN	RFS	[1] [2] [3]
CANON	EF 100mm f/2.8 MACRO USM	79.0	119.0	583299	600	58mm	N	IFS	[1] [2] [3] [4]
CANON	EF 85mm f/1.2L II USM	91.5	84.0	552418	1025	72mm			[1] [2] [3]
CANON	EF 85mm f/1.8 USM	75.0	71.5	315877	425	58mm	AN	RFS	[1] [2] [3]
CANON	EF 70 200 mm f/2.8 L USM	84.6	193.6	1088268	1310	77mm		IFS	[1] [2] [3] [4]
CANON	EF 70 200 mm f/2.8 L USM IS	86.2	197.0	1149663	1470	77mm		IFS	[1] [2] [3] [4]
CANON	EF 70 200 mm f/4 L USM	76.0	172.0	780271	705	67mm	N	IFS	[1] [2] [3] [4]
CANON	EF 70 200 mm f/4 L IS USM	76.0	172.0	780271	760	67mm	N	IFS	[1] [2]
CANON	EF 50mm f/1.2L USM	85.4	65.5	375186	545	72mm			[1] [2]
CANON	EF 50mm f/1.4 USM	73.8	50.5	216020	290	58mm		OLE	[1] [2] [3] [4]
CANON	EF 50mm f/1.8 II	68.2	41.0	149776	130	52mm		OLE	[1] [2] [3] [4]
CANON	EF 35mm f/2	67.4	42.5	151635	210	52mm		OLE	[1] [2] [3]
CANON	EF 35mm f/1.4L USM	83.5	77.4	423842	550	72mm	AN	RFS	[1] [2] [3] [4] [5]
CANON	EF 28mm f/1.8 USM	73.6	55.6	236549	310	58mm	AN	RFS	[1] [2] [3] [4]
CANON	EF 28mm f/2.8	67.4	42.5	151635	185	52mm		OLE	[1] [2] [3]
CANON	EF 24 70 mm f/2.8 L USM	83.2	123.5	671434	950	77mm		FFM	[1] [2] [3] [4] [5]
CANON	EF 24-105mm f/4L IS USM	83.5	107	585931	670	77mm	N	IFS	[1] [2] [3]
CANON	EF 24mm f/1.4L USM	83.5	77.4	423842	550	77mm	AN	RFS	[1] [2] [3]
CANON	EF 24mm f/2.8	67.5	48.5	173556	270	58mm	AN	RFS	[1] [2]
CANON	EF 20mm f/2.8 USM	77.5	70.6	333041	405	72mm	AN	RFS	[1] [2] [3] [4]
CANON	EF-S 18-55mm f/3.5-5.6	69.0	66.2	247540	190	58mm		OLE	[1] [2] [3] [4] [5]
CANON	EF-S 17-55mm f/2.8 IS	83.5	110.6	605645	645	77mm			[1] [2] [3]
TOKINA	17mm f/3.5 AT-X PRO (CANON AF) [1]	84.0	57.0	315881	435	77mm		Internal Floating Element	[1]
CANON	EF 17-40mm f/4L USM	83.5	96.8	530076	500	77mm	N		[1] [2] [3] [4] [5] [6]
CANON	EF 16 35 mm f/2.8 L II USM	88.5	111.6	686589	635	82mm	N	IFS	[1]
CANON	EF 16 35 mm f/2.8 L USM (Disc)	83.5	103.0	564027	600	77mm	N	IFS	[1] [2] [3] [4] [5a] [5b]
CANON	EF-S 10 22 mm f/3.5-4.5 USM	83.5	89.8	491744	385	77mm		IFS	[1] [2] [3] [4]

Make	Model	AF Actuator	FTMF	Distance Scale	DOF Scale	Zoom Control	Extends When Zoomed	Max Mag	Closest Focus M	Dec 04 Price UOS
CANON	EF 200mm f/2.8 L USM MK2