Canon EF 28mm F2.8 (Hàng chính hãng)

Introduction

The Canon EF 28mm f/2.8 completes the local tests of the classic Canon wide angle fix-focals. The lens was first released in 1987 so it is as old as the EOS system itself. On APS-C DSLRs the field-of-view is equivalent to 45mm so it can almost be considered as a standard lens here.

The lens is a rather simple being with just 5 elements in 5 groups including one molded aspherical element. The aperture mechanism features 5 blades. With a min. focus distance of 0.3m the max. object magnification is about 1:8. It´s really a miniature lens with a size of just 67x42mm and a weight of 185g. The filter size is 52mm.

The build quality of the lens is quite decent with good quality plastics. The inner lens tube extends a little when focusing towards closer distances but the front element does not rotate - using a polarizer is therefore no problem. The focus ring operation isn't all that impressive - typical for many Canon lenses of that era it feels a little scratchy. Thanks to the small number of elements the AF is very fast despite its conventional micro motor.

Distortions

The lens showed a slight to moderate degree of barrel distortions (~1%). Not stellar for a fix-focal lens but still pretty decent in absolute terms.

The chart above has a real-world size of about 120x80cm.

Vignetting

On an APS-C DSLR the full frame EF 28mm f/2.8 enjoys the usual sweet spot but the effect isn't all that pronounced regarding vignetting which is relatively high at 0.8EV at max. aperture. However, from f/4 and up the issue is quite negligible.

MTF (resolution)

The resolution figures in the lab where somewhat puzzling so I repeated the tests several times in order to verify the findings. The center performance reaches its excellentpeak at max. aperture and deteriorates towards medium aperture - a highly unusual characteristic which is unprecedented so far for a large aperture wide-angle lens. The border performance behaves a little more conventional with good results at f/2.8 increasing to very goodfigures at medium aperture settings. So despite the rather unusual MTF curve the performance is on a pretty high level.

The resolution chart has been revised to take field curvature into account.

Below is a simplified summary of the formal MTF findings. The chart shows in line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about it you may check out the correspondingImatest Explanations.

Chromatic Aberrations (CAs)

CAs (visible as color shadows at harsh contrast transitions) can reach an average CA pixel width of significantly more than 1 pixel at the image borders - a weak performance here especially for a fix-focal lens. CAs can be reduced and usually even eliminated via imaging tools but such a lens should definitely perform better than that.

Sample Shots

Ok, finally here're some sample shots taken with the EOS 350D (converted RAWs). Click on a thumbnail to view the original file (opens in a separate window). Please note that the full-size images are supplied in JPEG2000 format. You should be able to display the images in most modern imaging applications such as Photoshop. This is a measurement to limit the bandwidth which is a scarce resource.

If you prefer to watch the full-size samples in your Internet Explorer browser you may try theJPEG2000 ActiveX Control (Windows) plug-in. I've checked out a few plug-ins for Mozilla/Opera but haven't really found a good one. Firefox will open IE if you install the ActiveX Control above.

Make Canon Model Canon EOS 350D DIGITAL ISO Speed 400 Focal Length 28.0mm Exposure Data: f/11.0 @ 1/125s Size 2312x3472	Make Canon Model Canon EOS 350D DIGITAL ISO Speed 400 Focal Length 28.0mm Exposure Data: f/11.0 @ 1/125s Size 2312x3472
Make Canon Model Canon EOS 350D DIGITAL ISO Speed 400 Focal Length 28.0mm Exposure Data: f/9.0 @ 1/160s Size 2312x3472	Make Canon Model Canon EOS 350D DIGITAL ISO Speed 400 Focal Length 28.0mm Exposure Data: f/2.8 @ 1/1600s Size 3472x2312

Verdict

The Canon EF 28mm f/2.8 may not be the most attractive lens on the market but it is still interesting nonetheless. It is very affordable in combination with a pretty impressive optical performance (except CAs) and quite decent mechanics. However, it faces pretty stiff competition from the Sigma AF 30mm f/1.4 EX DC HSM which is a little better in the center but worse at the borders. The Canon is much cheaper though.