Pushmepullyou

[Tannin]

(Wasn't that an animal in the Dr Doolittle books?) But before the inevitable deluge of off-topic replies, on with the meat of my post: the Canon 100-400L f/4.5-5.6 lens and its controversial push-pull zoom mechanism.

I noticed a couple of posters in another thread saying how they considered that lens and decided against it because they didn't fancy the push-pull zoom. I've often seen simalar comments in other fora. And that prompts me to respond with my own feelings about it.

I bought the 100-400 largely for two reasons:

* I wasn't comfortable(after several years of using P&S digicams, mostly digiscoping) with the idea of a fixed length lens. Would it feel very restrictive, not being able to adjust the field of view without moving? (Something you often can't do with birds and wildlife.)
* Image stabilisation. If it wasn't for the IS, I would have gone with an f/5.6 400mm prime, and taken my chances on the first point.

On the against side, I didn't fancy the push-pull idea. It looked and sounded clumsy and needlessly awkward. But in the end, I bought the pushmepullyou despite the weirdo zoom mechanism.

Sure enough, it felt weird and awkward. The locking mechanism helped, but you needed to set it just so. Wonderful lens, but strange to use.

That initial reaction lasted about two weeks. The push-pull does take getting used to, but now that I've had the unit for a while, I love it. I wouldn't dream of swapping the push-pull zoom for a twist zoom now.

It is miles faster to operate, and simpler too. One thing I have come to mildly hate is the way that different lenses operate in different directions - twist lens A clockwise to zoom in, but twist lens B anticlockwise. I am forever twisting the wrong way when seconds matter and I'm in a hurry. (Which is nearly always with nature work.) The only lens I never twist the wrong way is the 100-400. Push to zoom in, pull to make it shorter. What could be easier?

With no zoom ring, Canon had room to make the focus ring nice and large, and there is none of that hurried fumbling for the right ring you get with twist-zoom lenses (especially short ones).

If you leave the friction ring a bit too loose, it tends to slip out to the 400mm setting. So what? Most people use a lens of this length at the 400mm setting most of the time. (Hey, we all really want a 500 or a 600 but can't afford one yet, right?) So it slips a bit if you don't tighten it, but in general, it slips the "right" way. Often I find that I've set it to 100 or 150mm for a wildflower of something similar, and by the time I am in position for the next bird, it has dropped itself back to 400 - which is exactly where I want it. And if you anticipate doing a series of shots at shorter lengths, just twist the friction ring a bit to make it stay put. After a few days' practice you will find yourself doing this without conscious thought and with one hand.

What about dust? The dust pump argument is a nonsense. A moment's thought will demonstrate that, for any given expansion ratio, a given volume of air must be moved: it doesn't matter if the lens screws out or slides out, it still has to move the same amount of air, and still has to suck in the same amount of dust. The dust question only becomes relevant when you are considering an internal zoom lens of fixed physical length - in which case it applies equally to push-pull or twist-zoom units.

Accuracy? If you often want to zoom to (e.g.) 275mm and not 278 or 269, then the pushmepullyou is probably not for you. You can set it exactly but it's a bit fiddly to do. I can't imagine ever wanting to do this with nature work, however. In the studio, sure - but who uses a 400mm f/5.6 lens in a studio? Mostly you want (e.g.) about 300mm, and 289mm or 304mm will do just fine - but you want it right now (before the bird moves, or the race car goes by). In this context, the fast push-pull is a real winner.

Summary: if you try out the trombone lens for an hour or a day, you will probably dislike it. But try it out for a month or so, get used to the difference, and you might start wondering why all lenses are not made this way.

I'm a convert.

[jseaman]

I have one of these as well and agree with almost everything you say. It is sometimes hard to give up on the dust pump notion but it is true that other zoom lenses are the same regardless of the method used for their zoom.

The only other point worth mentioning is that when you finish your shot and decide to move on - the loud clunk you get as the lens moves by itself because the clutch wasn't quite tight enough. Always makes me think there has to be a chipped piece of glass as a result!

[robski]

When I had a Sigma 135-400 I found you could push-pull that lens aswell as twist. I found myself pushing or pulling most of the time especially when a rapid zoom change was required.

I don't think it had any impact on dust levels whichever method I used.

Originally Posted by Tannin

(Wasn't that an animal in the Dr Doolittle books?)

What about dust? The dust pump argument is a nonsense. A moment's thought will demonstrate that, for any given expansion ratio, a given volume of air must be moved: it doesn't matter if the lens screws out or slides out, it still has to move the same amount of air, and still has to suck in the same amount of dust. The dust question only becomes relevant when you are considering an internal zoom lens of fixed physical length - in which case it applies equally to push-pull or twist-zoom units.

Hi Tannin

I have a different opinion, having owned two Canon 100-400 lenses over the past 18 months and they do suck in dust mainly down to poor seals. Your are correct in the movement of air theory but hold your hand at the base of the zoom when you zoom in and feel the rush of air. I nicknamed mine the dyson. In fact the seals on mine were that bad that on a recent balloon trip moisture got inside the lense, it was damp and very cold though.

Second problem is the mode 1 IS on the lens cannot keep up with a fast moving subject on the later Canon DSLR's, resulting in error 01 and camera lockup. After Canon technicians admitted this to me I decided to swap to an internal focus Sigma 100-300 EX and now my sensor is clean again. Supplemented by a nice Canon 400L f5.6 prime which again reduces dust ingestion. Canon are planning to replace this lens with a second generation IS as they have done on other L stabilised lenses.

I am glad you are happy with your choice as I am with mine.

[greypoint]

On the general notion of push/pull lenses I have an old Nikkor 80-200mm push/pull and much prefer it [I had a 100-200mm Canon that worked the same way many years ago so knew how they felt before buying the Nikkor]. I agree with Robski - I always tended to use the same method with my 135-400mm when I was trying to change length quickly. Yes - the clunk can be off putting - I try not to dangle the lens downwards!

[Tannin]

Originally Posted by Snappy

Canon are planning to replace this lens with a second generation IS as they have done on other L stabilised lenses.

Oh no! I know what will happen not too long after that - I'll want the new one. Though I have to say, I'm very happy with this one. It might be old technology - how old is the 100-400L, 8 years I think? - but it's getting some super pictures for me. I'd have gone with a prime but I wanted the IS and like most normal people couldn't afford the f/2.8 one.

If it works don't fix it ;-)

Keep the one your happy with.

If you want a prime take a look at the 400L f5.6 its very light and sharp.

http://www.worldphotographyforum.com...8&limit=recent

[Christine]

My 100-400 lens is suddenly very stiff and difficult to move up and down.should I give it a quick spray with Pledge(furniture spray) to make it easier to slide up and down,or has anyone else had this problem and used any other type of lubricant.I do not want to do any damage to the lens.

I don't think furniture spray will help, it sounds like the compression ring I would take it to a Canon service agent.

[Christine]

Thanks,Snappy,it sounds serious.Hope it is not going to cost!!!