glenn nk

I'd like to offer one more piece of information about zoom lenses:

My zoom is weather sealed, and from all reports, one of the best sealed lenses (Canon 24 - 105L).

The rear element moves in and out during zooming (about 25 mm, and it's diameter is about 30 mm).

When the rear element moves away from the mirror box, the volume of the air behind the lens increases, which means that some air has to come into the camera from somewhere, otherwise a vacuum would result, and the force required to create a vacuum is enourmous.

The rear element of the lens acts as an air pump. From the point of view of fluid mechanics, it's simply unavoidable. Air must enter either the lens or the camera body. In the case of a weather sealed lens, the tendency would be for the air to enter the body.

OK, this is coming from "left field".

I was seriously considering the Canon 10 - 22, when I discovered the Canon 17 - 55 f/2.8 IS USM lens.

Take a look at Fred Miranda.com under reviews. I've stopped thinking about the 10 - 22 (I use a 1.6 crop - 30D).

It's not cheap, but the users rate it very highly.

http://www.adorama.com/CAAFC.html

I really like mine.

I think Dan Mitchell offered some good advice which it seems you are going to take - good.

On the point of selling off the film gear, keep this in mind; it is not gaining in value - it is going down in value by the day.

We had two used camera dealers in our city one year ago, only one is left and he doesn't seem to be very busy - I was in his shop on 23rd December and if you're going to be busy, it had better be two days before Christmas (where I deal on digital, the place was hopping busy).

The writing is on the wall - although many diehards won't appreciate me saying that.

I had a Canon A-1 until a week ago today - I gave the whole kit away to a student simply because it wasn't worth the effort to try and sell it (the kit included the original 50 mm lens, a Tamron 35 - 80 zoom, a Canon Speedlite (the big bracket mount type), 2X extender, black zipper case, filters, cable release, etc).

WL Man:

You mentioned having trouble using the viewfinder with the camera close to the floor - yes it is - I used to shoot wildflowers from their vantage point and some were as small as your cars.

I found the solution, although it may not fit your budget:

http://www.adorama.com/CAAFC.html

In case this link doesn't work, the site is Adorama, and the thing I'm using myself is an "angle finder". For the current cameras such as your's, it the Angle Finder C.

I wouldn't be without mine - you can put the camera right on the floor.

To Chris B:

No offence meant, but that's the dirtiest sensor picture I have ever seen - hand's down. I would suggest that it will require so-called wet cleaning.

To Rick H:

I will confess that I too use compressed gas - the gas is actually a refrigerant (bad on me - there goes the ozone). Like the camera repairman, I don't move the can and certainly don't shake it. I use gentle puffs - not full blast for sure, and I have never had any propellant on the sensor. The danger with the method is the temptation to use the full power available - this must be resisted, and I would assume any competent repairman would use restraint.

On the matter of sensor dust on new cameras, it has been stated by people with a sense of humour that, "Canon equips all new cameras with sensor dust at no extra charge".

The truth is, brand spanking new cameras will almost certainly have some spots on the sensor. Users on other forums have stated that a two day old camera from which the lens was never removed had spots.

The comment about zoom lenses moving air around is quite valid - also consider that the volume of a zoom lens changes. I've pointed this out elsewhere, but the idea was put down. I doubt that they had actually considered that zooms are air pumps, but since zooms change volume, and the metal, plastic and glass doesn't change volume, there is only one element left to change volume - the air in the lens. If it was being compressed, one couldn't operate the zoom. The rear element of my 24 - 105L lens moves a full inch over the full zoom range - it's like a piston, and it sucks air in, then pushes it out. I really don't believe the outside air is pristine all the time, but the type of dust that's floating around should not stick to tenaciously to the sensor (in part, that's why I believe in the camera wear theory).

So I would conclude that the system is not a gimmick, but it won't remove all types of dirt that gets on a sensor. As I said to someone elsewhere, windshield wipers don't take all the water off a windshield either, but they are better than nothing.

I wouldn't buy a camera because it had a dust cleaning system, but if possible I would avoid one with the system simply because it adds to the complexity of the camera, and I'm really not convinced it works. I'm not convinced it works, because on another forum, many of the requests for help cleaning a sensor are from 400D (XTi) owners.

There are other reasons:

Using a 30D, I live in a relatively humid climate (Vancouver Island on the Pacific Ocean - where I've never observed static build-up while walking on a carpet - in the colder, interior of Canada this would be common particularly in the winter).

The camera is four months old, and I've had to wet clean the sensor filter about seven or eight times. The initial attempts at removal are always by blowing - this has never provided the desired results.

There have been times when multiple swabbings were required - last night the spots finally dislodged on swabbing number five.

I no longer believe that "dust" (the stuff that floats in the air) is the problem. Consider this; whether or not the moving parts inside a camera (shutter and mirror) are lubricated or not, some wear will take place. Wear is the abrading of one part by another when they move over each other when in contact. Abrasion results in the flaking off of microscopic particles from the wearing parts. Lubricant reduces wear, but it serves to make things messier,as lubricant must be somewhat "sticky" to remain in place and be effective. Lubricant that happens to hit the sensor will not likely blow off.

Thus, I've come to believe that the "dust" we keep finding is generated inside the camera. Case in point: I have only one lens (24 - 105), it only comes off for "dust" removal!

So in chorus with the doubters, I must respectfully add my voice - perhaps it works for "real dust" which is the stuff one can see floating in a sunbeam, but for the bits of wear material generated by the camera, the system doesn't seem to be up to the task. I suspect that any 400D owner that has rigourously tested at f/22 with a clean monochromatic background has found spots.