Does a tele-converter make an image softer?!

[mike burley]

I am using a canon 70-200 2.8L with a 2x teleconverter on a

canon 1D digital camera. I seem to notice that the images I shoot

are a little soft comapred to those I see of other photographers. I

asume they shoot with a 400mm 2.8L (I shoot mostly sports, and the

400 500 and 600 are the weapons of choice.) Does anyone have any

experience with the doubler AND one of the mentioned L series

telephoto lens? I am saving up for the 400 2.8L in hopes of a

sharper image.......Hope its worth the extra $6k. Also does the

doubler on a 200mm get the same compression as the 400?

Thanks for the help from anyone who can answer!!!<div></div>

[stephen hazelton]

A teleconverter always reduces sharpness some. When you add the teleconverter, it reduces your effective aperture to f/ 5.6, so you may be shooting at slower shutter speeds than other people. And the difference may be in how you deal with the digital files, as opposed to anything in the optics itself.

[jbq]

A teleconverter is likely to reduce sharpness, especially with a zoom. You essentially have a 140-400 f/5.6 zoom, i.e. the depth-of-field you get isn't as shallow as a 400/2.8.

 

How about a 400/4 or 400/5.6? You won't get the speed of a 400/2.8, but you'll save thousands, and both of those will be sharper than a zoom with a teleconverter.

[steve_dunn2]

<p>Look at it this way. Imagine that you have a lens that can resolve (say) 100 lines/mm, and a theoretically perfect 2x TC - i.e. one which magnifies the image 2x and causes absolutely no degradation whatsoever. Those 100 lines are now spread across 2mm, yielding a resolving power of 50 lines/mm. Your image can't help but be softer when the resolving power is cut in half. And that's with a theoretically perfect 2x TC, which of course doesn't exist in the real world; in the real world, any TC you might use will cause at least some image degradation.</p>

 

<p>I wonder if your shutter speed is high enough; remember that with your effective 400mm lens, you're magnifying camera shake (unless the camera is bolted down pretty well) and subject movement and need a higher shutter speed to compensate. The folks with the lovely 400/2.8 lenses not only benefit from superior optics (both due to the lack of TC, and because even a superb zoom like the 70-200/2.8 is inherently compromised by being a zoom) but also the extra two stops of light their lenses give them.</p>

 

<p>Apart from image quality, the image you get from a 200+2x is the same as the image you get from a 400 - same compression, perspective, whatever.</p>

 

<p>I wish I could offer you insight on how well those big guns perform with TCs but I can't afford 'em, either; my longest lens is the 300/4L IS USM (plus the 1.4x TC I bought myself for Boxing Day last month). There are a number of sites on the Web where people have commented on such things; <a href="http://www.birdsasart.com/faq_superis.html">Art Morris mentions it here</a>, for example.</p>

[chip]

Hi Mike,

 

I'm a sports shooter also, mostly motorsports, yacht racing, some field sports and the people involved in sports. The reason to use fast big glass is that you can shoot WFO and still get excellent image quality while isolating the subject. Fast lenses also give you the option to use converters and still retain AF performance and extend your shooting options by providing better flexibility in your lens quiver.

 

The EF 1.4X/1.4X II is much better than the EF 2X/2X II but this is to be expected. BUT it does not cause iamges to degrade as much as the image you've linked to. I've used the EF 1.4X and EF 2X both series on all of my own and rented lenses, EF 135 2L, EF 70-200 2.8L, EF 70-200 2.8L IS, EF 200 1.8L, EF 300 4L, EF 300 4L IS, EF 300 2.8L, EF 300 2.8L IS, EF 400 2.8L they all work great with the EF 1.4X with slightly weaker results when used with the EF 2X or EF 2X II converters. I have no problem shooting with the EF 1.4X or EF 2X II when shooting digital with my EOS 1D. For film I usually will use the EF 2X II also but usually if only if it will make the shot work best.

 

The image you've linked isn't soft due to the EF 2X, it looks out of focus. Was this image captured at f/5.6, look at the tip of the board, it's sharply in focus. Also go back and look at the RAW image file and see what the AF system was locked onto, you may have some other system problem or you may find that the camera was focused on something else.

 

HTH

[greglyon]

Both my experience AND what I've read suggests that 1.4x TCs can give results nearly as good as a lens without TC, but 2x TCs give much less acceptable results. I use a manual focus 500 f4 (birds, wildlife) and feel I get great results with a 1.4x TC on, but I rarely use a 2x anymore due to softness. It's probably a combination of all the things mentioned: Less theoretical sharpness to begin with + slower shutter speed + greater magnification (magnifies camera shake) = soft photos.

 

Save up for that glass!

[markci]

Even a theoretically perfect teleconverter will reduce sharpness considerably. It's just a magnifying device, and unsharpness is magnified to the same extent everything else is. A teleconverter cannot create detail, and it's spreading the detail that exists over a larger area.

[whayne_padden]

I have seen results from 2x TC and the 300 and 400 f/2.8Ls which were far better than I could have believed. And these were 100% crops not little jpg's. So if you are pairing Canon's TC's with high quality primes you will get excellent results. In fact some claim that a 1.4x TC makes no difference to their image quality on these lenses. Other superb lenses that work very well with TC's are 200 f/2.8L, 135 f/2L, 500&600 f/4L.

[mike burley]

Thanks for all of the great help. I think I will just have to save for the 400 2.8. I have been shooting with a fast shutter, so the unsharpness isn't that. The surfer in the iamge attatched filled about 35-40% of the original frame. Is that pushing it with my current set up? Thanks again!!!

[mike_smith2]

99% of comlpaints about soft images on this web forum are usually attributable to out of focus pictures or camera/image movement and not lens resolutuion, as has been pointed out the tip of the surf board nearest camera is relatively sharp, the surfer and rest of board is soft ie it is more likely that the image subject is out of focus, butthe high contrast is difficult to work this out - so the lens combination is not as bad as you think it is.

 

if you are considering a bigger lens bear in mind both the 600F4 and 400F2.8 are both equally massive and equally expensive, so if you need longer reach the 600 may be a better lens for you.

 

Using the super telephotos is not easy, it takes a long time to perfect the techniques required, upgrades in tripod equipment and or sturdy monopods - you need to budget at least a further $750 to $1000 for adequate support equipment - tripod, ballhead or gimbal head and lens plates - search the nature forum for many technique links and problems associated with the super telephoto lenses.

 

You may want to consider the 500F4IS lens and 1.4 teleconverter, it is half the weight of the 400 or 600 lens and relatively much more user friendly for fast action sports. I have the slightly older 4.5 non IS lens for nature photography, it is much more portable and useable, if you are walking more than half a mile down a beach to your action you will probably want to avoid the two bigger lenses.