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Canon 20mm – some further thoughts

Lenses

Not perfect – you get what you pay for, I suppose.

I wrote in somewhat lukewarm terms of the underwhelming definition of the Canon 20mm lens here.

I took a more objective view of the vignetting issue by banging out four snaps on the old estate, camera and lens dutifully mounted on a tripod, at the four largest apertures:

To best assess vignetting, look at the bottom right corner. The sky is misleading as the changing azimuth angle will provide some natural vignetting with any lens this wide. You can see that at full aperture, f/2.8, the vigneting is pretty awful, but rapidly falls by f/4 with full coverage at f/5.6 and below.

So unless you want to use the Photoshop CS2 Filter->Distort->LensCorrection->Vignette->Amount, (does anyone at Adobe have the remotest iota of common sense when it comes to designing menus – who would guess it’s under ‘Distort’?) f/2.8 is simply not useable. Realistically, if it’s a low light situation, vignetting is no big deal and tends to enhance the drama of a picture. But if you want full coverage to the corners, forget it. Regard the maximum aperture as useful for focusing only.

How about definition? Well, I concluded that my first sample was just not good enough, especially after nothing but great experiences with the 15mm fisheye, the 85mm f/1.8, the 200mm f/2.8 and the 24-105mm zoom. If I can get way better definition from the fisheye after doing all that pixel stretching with ImageAlign (making the lens like a 12mm rectilinear hyper-wide) then all cannot be right with my 20mm sample which clearly has poorer definition than the fisheye. So I bit the bullet and returned the lens to B&H. Moses, of that estimable store, didn’t understand when I explained the lens sucked, but when I pulled Schlecht on him he cottoned on and was very good about it. I had a replacement (with an older serial number, strangely) in my hands in seven business days. Thank you, B&H. Was the result a quantum leap in definition? No. However, overall the ‘bite’ of the image is improved, if still not up to any of the other lenses which, frankly, easily surpass it in this regard. Vignetting in both samples at full aperture is just awful.

The right answer, I suppose, is to get a used Leica 21mm Super Angulon R and adapt it to the 5D. That lens may only be f/4 but it’s fabulous, like all Leica glass. I used one on my Leicaflex SL for years. Unfortunately, the sheer bulk of the lens, compounded by a heavy brass mount and a huge front element, not to mention a complete lack of focus or aperture and exposure automation on the 5D, rules it out. The M Elmarit will not, of course, achieve infinity focus owing to the need for a short flange-to-sensor distance mandated by the rangefinder design. Plus, it’s way overpriced.

So mediocre definition would seem to be the Achilles Heel of this optic – that or I have been an unlucky victim of poor quality control. Canon has little incentive for improving the lens, with everyone being sold on bulky, slow zooms. Shame. Still, at f/8 it’s decent and it’s dirt cheap, too, at $400. If it was much more I would return it.

You can get an idea of the relative size of the 20mm in this picture where it is side by side with the 50mm f/1.4 – it’s not too bulky.

Notice that the 72mm Canon UV filter on the 20mm lens says ‘Sharp Cut’, implying a sharp cut off prior to the infra red range of the spectrum. By contrast the 58mm filter on the 50mm lens bears no such designation. This is rather mystifying (the 77mm filter for the 24-105mm is also ‘Sharp Cut’) as the sensor in the 5D (and probably in their other DSLR offferings) has a built in IR filter – something Leica should have learned before mistakenly releasing the M8 with no IR sensor filter, only to have to issue free lens filters to all buyers as IR rays wreaked havoc with color accuracy. No biggie – Canon’s filters are inexpensive and do the job of protecting my lens’ front elements.

Update: I ended up selling the lens – too much bulk for too little performance. Read all about it here.

The woeful state of consumer digital cameras

Cameras

There is, in reality, very little choice when it comes to effective tools

A friend in England, a fine landscape photographer who has had work published by the BBC, asked for upgrade advice relating to her 4 mp digital point-and shoot. Here’s what I wrote:

“I am, believe it or not, the worst possible person to ask about the right digital camera. I used film for the past 45 years and only went digital when Canon announced the large sensor-equipped 5D. It’s outrageously expensive, overpriced, and bulky, so I would not recommend it. However, as big prints are my ‘thing’, it was the only choice.

However, one site which I do read (it’s written by an Englishman, by the way) is DPreview. Though they take advertising dollars, they are very objective and never kow-tow to manufacturers, not hesitating to trash bad gear. Unusual for commercial sites.

They have a half decent ‘camera picker’ – click on ‘Buying Guide’.

What little I know is:

1 – Don’t get caught up in the ‘more megapixels’ craze. With the very small sensors in most digitals, once you have 6 or 7 mp, quality thereafter does not improve. You cannot get a quart out of a pint pot.
2 – Most digitals have zooms – only look for optical zooms. ‘Digital zooms’ merely electronically magnify the image resulting in simply horribly poor definition.
3 – Don’t buy small just for the smallness – it usually translates into cameras that are difficult to hold steadily.
4 – Look for an optical viewfinder. The LCD screen-only cameras (sadly, the majority) have screens that are very hard to see in daylight and, as you are holding the camera at arm’s length, will rob you of a steady hold afforded by a traditional v/f camera braced against the forehead. All digitals have LCD screens – few have an optical v/f.
5 – If you have ambitions to make larger prints (my standard is 18″ x 24″ but I would hardly advocate that) look for Optical Image Stabilization – motion sensors in the camera reduce the visible effects of camera shake which so take away from definition with bigger prints.
6 – Consider buying a small tripod and use the self-timer for vibration free pictures. With landscapes you are rarely in a hurry.
7 – Avoid ‘electronic’ viewfinders (a small, blurry, LCD screen you look at through the prism) found in many of the lower priced, fixed lens, SLRs. They are simply horrors to use.
8 – Forget about super telephoto zoom lenses. You don’t need them and they are of poor optical quality. Rather, with your subject matter, a really wide lens is far more important.

I ran the following parameters in the DPreview.com screen for you:

Wide lens at the short end of the zoom lens (28mm)
Image stabilization – Yes
Viewfinder – optical
Current model – yes
All other parameters – Don’t Mind

Only one camera came up!


Canon SD800IS. 28mm wide lens and a proper viewfinder, not to mention IS

This is what I would call ‘medium priced’ – $320 or so here.”

So with just a few rational parameters the choice comes down to one. How sad. When will digital camera makers start taking pictures with their mostly execrable creations and realize that what they make is not what the consumer wants? Or do they all reside in Detroit? Sure, the consumer does not know what he wants, but it’s hardly difficult to explain. Just use the came4ra you produce, and you will see just how bad it is.

Canon 5D sensor dust

Cameras, Canon 5D

Could this be the reason?

I was Googling the subject of sensor dust, which so seems to bedevil the 5D, and came across a very funny criticism by one user who may well come from eastern Europe, given the grammar. What it misses in terms of the Queen’s English it gains in clarity.

“Is vacuum pump, not camera”.

So it got me to thinking. Could the lens design have something to do with it? After all, per square inch of sensor, the 5D should gather no more or less dust than its siblings, cropped or full frame, yet the 5D seems to be a problem more often than the other models.

Part of it may be that users of the full frame sensor in the 5D are either consistently making big enlargements or pixel peeping in Photoshop just to appreciate the gorgeous definition of which this sensor is capable. Bottom line, they enlarge more, because they can, and more magnification means more dust becomes visible. On the other hand, a like-sized print from a cropped sensor camera requires a 60% greater enlargement ratio, so maybe this is not a good explanation.

Yet why is it that I can put away my 5D with 24-105mm in place – my ‘standard’ lens – only to find that sensor dust has reappeared even though the lens has not been removed?

So I took the 24-105mm off the camera and, holding the rear to my cheek, worked the manual zoom ring. Sure enough, a ‘whoosh’ of air could be felt when the ring was activated vigorously. You can gauge the stroke here with the lens set at 24mm and 105mm, respectively:


Focusing seems to generate no air rush, probably because the lens uses internal focusing. Likewise for my 85mm f/1.8 and 200mm f/2.8 lenses. By contrast, the 15mm Fisheye and the 50mm f/1.4 use traditional focusing, but the throw is so short that no detectable rush of air could be felt using the ‘cheek test’.

So let’s assume that cropped sensor Canon users for the most part avoid the 24-105 (the effective range of 38-168mm being far less useful to them than the 24-105mm on a full frame sensor). So 5D users, many of whom favor this lens, do indeed have a ‘vacuum cleaner’, or more correctly, an air pump, attached to their cameras. The only thing I cannot figure out is why 1D and 1Ds/Mark II full frame users rarely complain of this malady. Maybe they opt for the 17-40mm, 16-35mm and 70-200mm L lenses, all of which seem to have a superior reputation for dust sealing? In this regard, the 24-105mm is anything but ‘pro’ quality, though there’s no arguing with the superb optical performance.

For me the cure is probably to avoid using the 24-105mm in dusty, dry conditions, opting for fixed focal length lenses in lieu. Not very satisfactory.

Maybe someone out there has done some comparative testing of the issues and causes?

All this said, the net throughput even when sensor dust intrudes, is still exceptional, especially if a ‘roll’ needs the use of the stamp & clone feature in Aperture, which allows simultaneous removal of dust motes in the image from multiple pictures at the same time.

Canon’s 20mm f/2.8 lens

Lenses

It’s nice to have a 20mm again


Chevy. 5d, 20mm, ISO 250, 1/500, f/11, 1 stop underexposed, processed in Aperture

No question about it, I miss my 21mm Leica Asph Elmarit, though who can afford one at $3k+ today beats me. The Canon 24-105mm L zoom is wonderful, if a tad bulky and heavy, and the 15mm Fisheye + ImageAlign works out to something like 12mm! So there’s a big hole between 12 and 24mm and the inexpensive 20mm Canon lens fills it nicely.

Anyway, that’s my excuse, and I’m an ultra-wide guy by nature. The Elmarit does that to you. Now this lens, at one tenth the price, is no Elmarit, but it’s more than serviceable. Plus you don’t have to deal with the crappy (sorry, no other word to describe it) plastic Leica viewfinder which, for all its cost, gives only a very rough approximation of what you will get on film. Sorry, film only for the Leica lens if you want all of its 21mm wide on the image. That disables it for me ay any price. If you want to get flare free snaps with biting corner definition at full aperture, and you are unaware that film is dead, the price of entry to the Elmarit world is justifiable. For me, this Canon 20mm f/2.8 does fine. By f/5.6 vignetting becomes very low and the corners sharpen up nicely; frankly, they’re not so great at f/2.8. At f/5.6 an 18x print will not embarass you, provided your original is sharp and well exposed.

Yes, it has some flare spots into the sun – see above – but the image retains high contrast across the frame. All I did was bring up the shadows in this snap, using Aperture. Exposure was for the highlight on the hood. Contrast is as recorded by the camera otherwise. Works for me.

A nice lens, not all that compact, and fully automatic – lightning quick auto focus (though hardly vital with a lens this wide) and easy manual override. I bought mine from B&H in New York along with an inexpensive Canon 72mm UV filter to protect that bulging front element.

Update: After some more experience I ended up exchanging the lens for another – read here.

Canon and collimation

Lenses

An intriguing new feature in the latest pro Canon DSLR

It was a rite of passage when using my rangefinder Leica bodies – the M2 and M3. Should the rangefinder alignment go out for whatever reason, you would go outside, place the camera on a tripod, focus on infinity then remove the lens. Sighting the rangefinder, lateral out-of-alignment would be corrected by using a right angled flat bladed screwdriver on the roller cam, which is eccentrically mounted. Replace the lens, check, repeat if necessary.

Vertical alignment was even easier – with the lens in place, remove the small chrome screw next to the rangefinder window on the front and use a jeweler’s screwdriver on the slotted screw thus disclosed.

This was called ‘adjusting the rangefinder’.

Much the same your friendly Leica repair specialist would do, though for your $250 you would get a three month waiting list and the obligatory German accent should you actually be lucky enough to reach this exemplar of the mechanical arts on the phone. If lucky to get him, you could plead for the return of your body after the obligatory three month absence. Good luck.

Aaah, Leica ownership. Like owning a Jaguar. You need two. One for the garage while the other is in the shop. You also need two mechanics in case one breaks down.

So lo and behold, what does the new professional grade Canon 1D Mark III offer? Why, a modern electronic version of this same feature. I quote from the awesome (as in 720 page!) B&H Digital Photography catalog which the local fork lift operator just delivered:

“AF Micro-adjustment is another example of the flexibility of the Mark III’s AF system. If a critical photographer ever finds that his system seems to consistently focus slightly in front of or behind the intended subject, the AF Micro-adjustment (C.Fn III – 07) allows the user to adjust this in fine increments to put the sharpest plane of focus back where they’d (sic) like it to be. It even allows different adjustments for up to 20 different Canon EF lenses if necessary”

So it sounds like Canon has not only added an overall adjustment to correct for an incorrectly adjusted focus sensor, they have also made it possible to key this adjustment to your lens of choice, recognizing that manufacturing tolerances would, inevitably, result in mis-collimated lenses. So you adjust things in the camera rather than at the manufacturing stage, suggesting a very smart way of keeping the cost of lenses within reason.

Now this latest Canon camera holds no interest for me. It uses a cropped sensor, making my wide angles less wide. Even if it had a full frame sensor I would not be a buyer as I simply do not need battle toughness or 10 frames a second capability, nor the massive bulk of the fixed battery grip.

But it’s nice to know that this feature will be coming to more ordinary bodies down the road, as these things inevitably do.

For some stunning Canon publicity images from this new camera, which claims a sharper sensor than its predecessor (these are clickable BIG downloads), click here. Make sure you check out Sample Image 7 – taken on the 85mm f/1.8 – the cheapest optic used and quite superb, as I know from personal experience.