Lens conundrum...

[mdwsta4]

if you're photographing indoors you may also want to consider a faster lens. otherwise, invest in a good tripod/shutter release as well.
i agree with the other post that if you primarily shoot landscapes/architecture you probably have no need for such a long telephoto, or even a telephoto at all. how about canon's 16-35 f2.8 since the 24-70 probably wouldn't be wide enough.

[RexK_Cozumel]

Wow that sucks that cannons wont focus past 5.6... I never knew that but then I have only shot with nikon. Yeah I think you will be hard pressed to find a 18-200 lens for $300. Perhaps if you were to buy a used lens you might get one for that price. The Tamron 18-250 F3.5-6.3 LD aspherical (IF) Macro lens that I have was $500 new so you might find one for $300 used maybe... Otherwise you can save a bit longer.

[mdwsta4]

what are you talking about 'canons won't focus past f5.6'?? it has nothing to do with 'canon,' 'nikon,' or any other manufacturer for that matter. it has to do with the speed of the lens. if the lens' maximum aperture is f5.6, then you won't be able to stop down any more than that. it has nothing to do with focusing.

Originally Posted by RexK_Cozumel

Wow that sucks that cannons wont focus past 5.6... I never knew that but then I have only shot with nikon. Yeah I think you will be hard pressed to find a 18-200 lens for $300. Perhaps if you were to buy a used lens you might get one for that price. The Tamron 18-250 F3.5-6.3 LD aspherical (IF) Macro lens that I have was $500 new so you might find one for $300 used maybe... Otherwise you can save a bit longer.

[RexK_Cozumel]

Issue: Autofocus does not work
Solution: The camera is unable to auto focus when the maximum working aperture falls below f/5.6.

In order to maintain autofocus capabilities, the lens must maintain at maximum working aperture of at least f/5.6 or greater.

If a 1.4x EF Extender is used on a lens that has a maximum working aperture of f/4 or greater, the camera will continue to be able to autofocus. If the same extender is used on a lens with a maximum aperture smaller than f/4, the maximum working aperture will be smaller than f/5.6, so auto focus will not be possible.

If a 2x EF Extender is used on a lens that has a maximum working aperture of f/2.8 or greater, the camera will continue to be able to autofocus. If the same extender is used on a lens with a maximum aperture smaller than f/2.8, the maximum working aperture will be smaller than f/5.6, so auto focus will not be possible.


As taken from smc1377's post on the first page of this thread.

[inkista]

Originally Posted by RexK_Cozumel

Wow that sucks that cannons wont focus past 5.6...

Not all Canons. And it's not like you can't use manual focus at that point. The 1dsII/III can AF down to max. aperture of f/8. but Nikons do the same thing--autofocus either gets very wonky or stops working at around max. aperture f/5.6 or f/8. It's just that Canon will automatically shut off the AF, while Nikon doesn't. You'll want to manually focus at that point, anyway, because you'll probably be faster and more accurate than the AF system.

And depending on the lens/teleconverter combination, you can still get things to work. I've used a Tamron 1.4x extender (doesn't report to the body) on my 400mm f/5.6L, and effectively gotten my XT to autofocus with a max. aperture of f/8.

It's just hard for an autofocus system to work without enough light to "see" by. Maximum aperture determines how much light the AF system has to work with.

To get back to the original subject of the thread, I'd say save up your pennies and get good spe******t lenses, rather than looking for a cheap all-rounder. The Zoom/Macro combination lenses are fantastic for a pinched budget, but it's neither a great telephoto nor a great macro. You'll eventually want a real 1:1 macro lens, and you'll eventually find that you want better performance at the telephoto end of the zoom range. If you just want to take architectural detail shots, then I'd say consider getting a fast prime, like the EF 200 f/2.8L. Yes, it costs as much as a EF 70-200 f/4L (non-IS), but you get an extra stop, and far better performance at 200mm, not to mention better performance with extenders. If your main interests are architecture and landscape, as everybody's been saying, then you may want to think not only about ultrawides, but also about eventually upgrading to a full-frame body (at which point, 28mm becomes plenty wide, and an ultrawide might become useless).

[Trav-man]

I appreciate everyone's input in this topic, and I have been tried the Tamron 18-200 at my local Wolf store and I am sold on the 18-200 range. It will allow me to stick with one lens, helping ensure I don't miss a shot because I have to switch lenses, and gives me the current range of the 18-55 kit lens, but allows me to take it out to 200 for those close in shots.

My new decision facing me is determining which lens to get. I know the Sigma 18-200 OS is out there but I don’t know if I really need it, or it's more of a wish list item since this is only a mild hobby of mine. I have checked reviews, and they say the Sigma has slightly better quality of images, but the Tamron is quieter and faster at AF. Does anyone have any experience with these lenses? Also, in the store at the far end of 200, the AF did work on the Rebel, so I am still a little lost on the possible issues of not focusing at f/6.3.

Does anyone have experience with Sigma's OS lenses? The guy at Wolf informed me that Tamron makes lenses for Canon, so they have some of that information, which make them work better sometimes, but I don’t think they have or are coming out with their own IS version of the 18-200 like Sigma or even Nikon has with their 18-200 VR (obviously not an option here)

Any further help or information would still be greatly appreciated.

[smc1377]

Speaking of the focusing issue past f5.6, I know I posted the knowledgebase issue previously, but then someone on my local craigslist posted a Tokina 35-300 F4.5-6.7 for sale that he had used previously on his Rebel XT.

So I wrote to him to ask him about the whole aperture issue and he wrote back saying that he had never had problems with autofocus at 300mm (f6.7) and in fact, he just put the lens back on his XT and confirmed that it has no problems focusing at max zoom.

Of course, he also offered to meet somewhere so that I could test it out on my own equipment to ensure that he wasn't lying, at least not about the XT being able to focus at those apertures.

Just thought I'd share what I have found out from someone who has a lens with a max opening less than f5.6.

Just guessing here, but you know how some lenses will report all sorts of info back to the camera and is visible in the EXIF data, and others don't report much back at all? It could be that if the lens if reporting back an aperture that is too small, that's when problems arise. And maybe on some lenses, it doesn't report anything.

Again, purely a guess.

[matthewchj]

Well, then maybe it's only canon lenses that will tell the camera to stop AF if the lens is slower than f/5.6... Maybe it's because 3rd party lenses might be wired differently.

[jdepould]

It's not that the lens is telling the camera not to focus, it's that above 5.6 there may not be enough light to focus.