The EF 70-300 DO IS USM
lens is very attractive with its focal range and small size, the associated drawback linked to its extension is a somewhat harder zoom ring that softens with time; also take notice of its black color, excellent Image Stabilizer
, quick USM autofocus
with FTM (Full Time Manual is very useful with shalow depth of field at the long end), virtually no chromatic aberration, low distortion and a non rotating front element when adjusting a polarizing filter
It gives excellent results with my favorite subjects: details, architecture, low light, and even portraits. I like its "bokeh" (definition), but some seem disturbed by onion ring shaped out of focus specular highlights that I never managed to get... From what I have seen, it's more interesting than bothering, especially on an uncropped image with a strong subject. It should be even less noticeable on a full frame camera.
Nevertheless, it has a tendancy to flare with strong front lighting. Flare appears when stray light is being scattered by lens elements and sensor micro-lenses. This results in brighter shadows and therefore a slightly diminished contrast that should not be confused with lack of resolution.
Below, you will find some tips to very efficiently workaround this specific characteristic when necessary. Those who take the trouble will be gratified with very good sharpness in all circumstances (most recent pictures were shot with the 5D Mark II).
The true drawback of this lens remains of course the very modest max aperture, that's why I bought the EF 135 f/2 L as a complement... Nevertheless, with the EOS 5D Mark IV and it's excellent high ISO performance, the drawback is somewhat mitigated.
No UV filter
Even a multi-coated UV filter will aggravate flare. On the other hand, the provided lens hood is simply unavoidable; and in view of its size, the front lens is sufficiently protected to simply forget about a UV filter.
Roll your mouse over this image to see the effect of removing a multi-coated UV filter in flare conditions. Here is the complete article.
If the image is not under-exposed, a reasonable (< 1.5 EV) contrast recovery through "Shadows" adjustment in Photoshop Camera RAW is very clean. Indeed, eye sensitivity is non linear as opposed to sensor sensitivity: higlights are coded with excess details that can be recovered by darkening in post-processing. In extreme conditions, overexposing just before saturation (to the right of the histogram) gives you even more information to recover; your image is therefore too bright and needs exposure compensation in your RAW converter. See this Adobe document
for more details.
Roll your mouse over this image to see the effect of Black Point adjustment. Both images were similarly sharpened.
Incidentally, when shooting digital, a very contrasted lens is not always desirable as the sensor response is linear as opposed to film which compresses extreme shadows and highlights in a nice "S" curve. My 17-40 L has very contrasted UD glass, and sometimes gives me hardly usable RAW files with saturated highlights and poorly detailed shadows...
Image sharpness is a subtle subjective mix of global contrast, resolution and micro-contrast. Despite a good resolution, the EF 70-300 DO IS USM lens sometimes lacks micro-contrast. As opposed to resolution, micro-contrast can easily and effectively be compensated with the Photoshop USM filter that I use in two steps:
- First, local contrast enhancement with a small amount 10% to 30%, large radius 20.0 to 50.0 pixels, and 0 threshold (or small < 5).
- Then, a classical sharpening technique after resizing with a high amount 90% to 300%, small radius 0.3 to 1.5 pixels and small threshold 1 to 8.
Roll your mouse over the crop to see the effect of such local contrast enhancement.
If you are not too keen on tweeking USM filter parameters, it seems that PhotoKit Sharpener is a great solution : automation + creativity...
In case of important flare due to front lighting, as soon as the histogram shows too little contrast for a reasonable black point recovery (> 1.5 EV for instance), I expand the hood with an A5 (6 x 8 inches) black card fixed with a rubber band. It very efficiently shades unwanted stray lightrays from entering the lens.
Roll your mouse over the 100% crop to see the effect of such a hood extension. These images were taken with a tripod, at 300 mm, were corrected for black point and were sharpened similarly.
Nevertheless, on a bright hazy day, long distance shots will not be contrasted enough, and the hood extension will not be of much help. This is the compromise I readily accept with this lens, taking into account all its other qualities.
As opposed to what I have read, the polarizing filter works perfectly well with the 70-300 DO. And the lens' non rotating front element facilitates its adjustment.
Roll your mouse over this crop to see the benefit of a polarizer on this mid-day shot; both images were post-processed similarly.
300mm wide open
As most zooms, wide open at f/5.6 and its longest focal length (see besides), the DO is slightly soft but perfectly usable
. Keep in mind that you are looking - your nose on the screen - at a 100% crop of an image that would be 60 x 90 cm (24 x 36 inches). At close focusing distances, depth of field
is of about 5 mm (1/5 inch)! Focusing is then really critical and it is easy to believe in lack of sharpness...
Rolling your mouse over the image, the aperture will be stopped down by 1/3 EV at f/6.3. The result is then already very good. Both images were post-processed similarly.
I do use this lens at its widest aperture and I never hesitate below 250 mm, particularly for some portraits. As focusing remains rather critical, I use either AI-servo choosing a focusing point locked on the subject's eye, or FTM (Full Time Manual focusing).
Stiff zoom ring
Even though the zoom ring softens with time, dilatation may render it too stiff during very warm days. In this case, simply use it as a push-pull zoom holding it by the hood. Roll your mouse over the image for an illustration.
Tripod and Stabilizer
The EF 70-300 DO third generation Image Stabilizer has a specific tripod mode to help absorb vibrations. To activate it, you need to depress the shutter release halfway, standing still for a full second before fully triggering (time needed by the lens to detect the tripod) => this must be done with a remote release.
This image was taken at 140 mm, f/7.1, 4 s. Rolling your mouse over it will show a 100% crop; IS really helps with this light tripod (SLIK U2000)!
Full Frame Vignetting
Considering the same field of vue and print size, this lens is sharper on a full frame sensor compared to APS-C, as the apparent blur artefacts are reduced. Chromatic aberration and distorsion remain very low. However, vignetting becomes very visible and requires being corrected, especially at 300 mm and large apertures. In JPEG or under DPP, this can be done automatically. Under Photoshop CameraRAW, it is a simple adjustment.
Roll your mouse on the image to see this 300 mm f/5.6 image corrected (shot with Canon EOS 5D Mark II).