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DPChallenge Forums >> Hardware and Software >> Canon 180mm Macro and 1.4x extender?
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 02/18/2007 04:13:29 PM · #1
I am running into conflicting info about using the 1.4x extender on the 180mm Macro.

1) Will it have any AF ability on a 5D body? I've seen "no", "yes, but not at less than 0.8m", and "yes".

2) I saw one site state that with the extender the 180mm Macro lost its ability to focus to infinity. Anybody know anything about this?

Lookin for answers...
 02/18/2007 04:30:19 PM · #2
Were they talking about Extension Tubes, or Tele-extenders?

With extension tubes, you'll definitely lose the ability to focus to infinity. Extension tubes have no glass in them. They simply move the lens further from the focal plane which allows you to focus closer and, all important in macro photography, gain a larger image magnification.

With tele-extenders, the reason you would lose AF ability is if the original lens, plus the extender, does not let in enough light to focus (generally f/5.6). So putting a 2x extender on a 2.8 lens works, because the largest aperture becomes 5.6. But put that same extender on a f/4 lens and you'll lose auto focus. However, a 1.4x on an f/4 lens still works because the final aperture is once again f/5.6.
02/18/2007 04:33:58 PM · #3
Originally posted by dwterry:
Were they talking about Extension Tubes, or Tele-extenders?

With extension tubes, you'll definitely lose the ability to focus to infinity. Extension tubes have no glass in them. They simply move the lens further from the focal plane which allows you to focus closer and, all important in macro photography, gain a larger image magnification.

With tele-extenders, the reason you would lose AF ability is if the original lens, plus the extender, does not let in enough light to focus (generally f/5.6). So putting a 2x extender on a 2.8 lens works, because the largest aperture becomes 5.6. But put that same extender on a f/4 lens and you'll lose auto focus. However, a 1.4x on an f/4 lens still works because the final aperture is once again f/5.6.


Yes, I'm talking about the tele-extenders. the 180mm is a f/3.5, so 1 stop on the 1.4 would be less that f/5.6 I guess.

What about the infinity focus issue on the tele-extender?
 02/18/2007 04:37:14 PM · #4
Originally posted by DrAchoo:
What about the infinity focus issue on the tele-extender?


I tend to doubt that it's a problem... maybe something specific about that lens and tele-extender combination???
 02/18/2007 04:43:41 PM · #5
Go here and check the compatability chart for yourself. Will tell you if it will work as you want or not.

//www.bhphotovideo.com/bnh/controller/home?O=278&A=details&Q=&sku=220456&is=USA&addedTroughType=categoryNavigation
 02/18/2007 04:50:51 PM · #6
Just to double-check... (and beat on a potentially dead horse)

So your real purpose for using the 1.4x is to take pictures of something farther away than your 180mm on-its-own will reach, right?

I ask because, if your purpose is greater magnification (which is what most people with a macro lens are concerned about), then the extension tube is what you want.

Tele-extenders will soften your image (i.e. the clarity of your 'L' lens will be reduced). But if an extender is the only way to "get the shot", then by all means, use it.

Extension tubes, having no glass, have no impact on the "quality" of your image. All they do is allow you to focus closer, thereby magnifying the image.
02/18/2007 09:08:05 PM · #7
Right, what I'm hoping to do is allow the 180mm lens to act as a telephoto lens until I buy something on that end later.

Right now I'm thinking about buying one of the following:

180mm f/3.5L Macro
70-200 f/2.8L
100-400 f/4.5-5.6L

naturally all those are some serious coin so I don't think I'd be able to buy another for a year or so. My thinking is that I could start with the macro and get the 1.4x tele-extender which would also give me a 252mm f/5.0(?) lens to have in the meantime.

Is there an error in that logic?

EDIT: Thanks for the chart link. It says this about the 1.4x tele-extender and the 180mm lens: "The autofocusing range is from 0.8m/2.6ft. to infinity."

Message edited by author 2007-02-18 21:09:56.
 02/18/2007 09:16:57 PM · #8
Doesn't surprise me that the AF range stops short of full magnification. At closest focus, you'll be at 1.4:1 magnification, which is getting into territory where AF is useless anyhow. Given the reputation of the 180/3.5, I'd guess that the pairing will work well, but I'm pretty sure that the AF performance will be rather slow. If you're not planning on tracking fast-moving subjects regularly, you're prolly OK.
 02/18/2007 09:19:54 PM · #9
Ya, I've heard of the slowness of the AF, although I'm starting to understand that's a product of it being a macro lens and that the longer they are, the slower the AF.

As far as using it for a telephoto, it would be a stopgap measure anyway until I can either get the 70-200 (which would work well with the 1.4x extender too), or the 100-400.
 02/18/2007 09:22:55 PM · #10
I'd love to know how the 180/3.5 does for astro work. The 100/2.8 really is not that great, oddly enough. It produces stunning results on an APPS-C cam, but there's significant light fall-off and some coma & chromatic issues in the corners wide open on FF. I suspect the 180 is significantly better.
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