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Telephoto Zoom lenses and Teleconverters

by Bob Atkins; created 1997

OK, so you want to be cheap. You want one lens to do everything and you don't want to spend a lot of money. Sounds like you need a telephoto zoom and a set of 1.4x and 2x teleconverters, right?

Wrong! Wrong for a number of reasons:

  • Telephoto zooms are not sharp at their long end. That applies to almost every such zoom ever built. It certainly aplies to the 100-500, 28-300, 80-400, 100-400, 200-400, 135-400, 170-500 and all such similar lenses selling for $200-600 or so. Some of the 100-300 zooms aren't too bad, but they're still not great. Most serious nature photographers wouldn't be very happy with the long end performance of most telephoto zooms over 300mm without at teleconverter, never mind with one!
  • Zooms are usually not well matched to TCs
  • If you take a lens that isn't very sharp to start with and add a 1.4x TC which it isn't well matched to, the results will not be good.
  • If you add a 2x TC, the results will be even worse.

Note these statements apply mainly to the long end of zooms. At the short end they are often quite sharp. However there isn't much point in sticking a TC on a zoom unless you are at the long end, since at shorter focal lengths you might as well use the zoom without the TC (it will be sharper and probably faster!).

Exceptions - The Nikon 200-400/4 is an exception. It is very sharp, works well with TCs and will cost you $5000-$10000 on the used market if you can find one. The Canon 70-200/2.8L is reputed to work quite well with a 1.4x TC and still be usable with a 2x TC. It's a $1400 lens to start with and the TCs are $300-$400 each. However, even after spending over $2000, the results will not be as good as those obtained from a good (e.g. Canon) 300/4 or 400/5.6 APO lens. They should be as good as, or even better than, a cheap 3rd party lens though. Will they be good enough?- see below. There may be other exceptions, but if you are looking for a cheap way to get a telephoto zoom, they don't matter to you. They won't be cheap! The new Canon 100-400/4.5-5.6L IS USM looks like a great telephoto zoom too, but at $1600 it's still not cheap. It may be the best option for Canon users though.

So are the results of an x-300 or x-400 or x-500 zoom and a TC "good enough"? The answer depends on what you want. If you want 3x5 prints, the answer is yes. If you want 20x30 prints the answer is no. If you want to post small images on the web, the answer is yes. If you want to sell your work the answer is no. Clearly there are grey areas. How about 5x7 prints, or 8x10? It all depends on exactly which zoom and exactly which TC (no, nobody can tell you exactly how good your combination is likely to be!), plus exactly what your standards are (and nobody but you know those either).

Well then, are the results of the long zooms "good enough" without a TC? Yes, no and maybe. Yes for a lot of amateurs who don't demand the ultimate in sharpness and for who the convenience of a zoom outweighs the increased sharpness of a 400/5.6 APO prime, or those who will be shooting mostly at the sort end of the zoom range. No for serious shooters who intend to market their work or who are critical of image quality and will be shooting at the long end of the zoom range. Maybe for those who fall between these two camps. Remember that you don't get something for nothing, and since these zooms are priced about the same as a 3rd party 400mm f5.6 APO prime, the something you don't get is image quality as good as a 3rd party 400/5.6 APO prime. You pay for the convenience of a zoom in image quality (unless you get the Nikon 200-400/4, in which case you pay for it in hard cash!).

The "cheap" answer to getting a longer lens is to buy something like the Sigma 400/5.6 APO Macro. A decent lens at a reasonable price and you can probably put a 1.4x TC on it and still get acceptable results. Putting teleconverters on low cost telephoto zooms is not something most serious nature photographers will be happy with for long, if at all. If you are not serious, you can try a 1.4x TC on a zoom. The 3rd party TC aren't that expensive and you will probably find other uses for it anyway!

If, after all this you still want a long zoom, which is the best? Well, there isn't that much to chose between them. I'd make sure it had a tripod support built in though (some models don't!). I'd probably pick one that went to 400mm at f5.6. The longer zooms tend to be slower and image quality drops off as you go longer. Maybe the Sigma 135-400 would be a good one to look at.

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Ryszard Stasinski , November 19, 1997; 06:59 A.M.

Images taken with my Sigma 75-300 f4-5.6 APO at 300mm with and without Vivitar 1.4 TC (EOS mount) have been indistinguishable, except for slight colour shift. Moreover, the TC has even corrected a little bit the lens sharpness at the image edge! At times the lens was claimed to be the best consumer-grade zoom, esp. for its 300mm end.

Stephen Vaughan , December 29, 1997; 12:38 P.M.

I have shot the Canon EF70-200f2.8 with the Canon EF2x teleconverter and the Canon EF400f5.6 in side by side comparisons on Velvia and was unable to see any difference with a Schneider Loupe. I am not saying there is no difference but if there is it is minimal.

Bob Atkins , January 13, 1998; 04:36 P.M.

Well, I've shot prime Canon "L" glass with the Canon APO TCs and I even see a difference there, a significant difference with the 2x and a detectable difference with the 1.4x.

I've never seen results I'd call good from a zoom with a TC. People's standards vary. Maybe mine are too high!

Max Grogan , January 16, 1998; 11:09 A.M.

I have used the Tokina (MF) 100-300 f4 ATX lens for six years and find it to be the best of this range.It is SHARP w/ great CONTRAST. Images are indistinguishable from Nikkor 400mm f3.5 at the 300mm end. Works very well w/ Nikon TC-16A.

Best $$ value on market in my opinion.

Bob Atkins , January 28, 1998; 07:10 P.M.

Here's a well presented comment from John Song which he posted on the nature Q&A forum. It addresses the issue of image quality even using one of the best APO zooms around.

"I've tested 70-200 F/2.8 w/ 1.4X and 2X and I find the result not satisfying for my purpose(birds). 70-200 w 1.4X gives pretty satisfiable image but it still is not close to Canon and Nikon 300 F/4(and too short for birds). I've tried on both Tamron 1.4X and Canon 1.4X, the center is about the same but the corners on Canon 1.4X is much sharper. I find 70-200 f/2.8 and Canon 1.4X quite acceptable for most of my work(newspaper). 2X was quite soft though. It is still acceptable for newspaper use, but I won't use it to work on my portfolio prints or slides(or magazine). If you don't want to print anything bigger than 8X10, it might be accpetable"

Paulo Bizarro , September 08, 1998; 11:20 A.M.

Canon are introducing a new L zoom this coming Photokina. It's the 100-400 4.5-5.6 IS L USM. It takes the TCs. According to the available web photos, it is a push and pull type zoom, and it is white.

It is also probably expensive... However, if image quality is not too bad, it might be a good option for the non-pro nature photographer like me, which only ocasionally needs to go longer than 300mm (even for that I use my 135 f/2 with the 2x TC, or the 180 macro with the 2x TC too).

Raymond Robertson , October 08, 1998; 08:35 A.M.

I wonder if there are some basic misconceptions about the purpose of teleconverters. I thought of buying one myself recently in order to get better close-ups of some parrots nesting in a box I fixed to a nearby tree. My reasoning was that by using a 2X teleconverter with my 300mm Tamron zoom, I would effectively be getting a slightly inferior and much slower 600mm zoom which would nevertheless give me a better overall result provided I was able to keep the camera rock steady. It seemed logical that if I could enlarge the image on the negative 4 times (twice the width and twice the height) then it would need less enlarging at the printing stage resulting in a sharper picture. However, after reading the comments on this web page and pondering upon the subject, I've arrived at the conclusion that it makes little difference whether the enlargement is done prior to exposure (by using a teleconverter) or after exposure using an enlarger in a darkroom (or in my case, the computer), provided that your enlarger lens is of equivalent quality to the teleconverter, or in my case, provided the quality of my slide and negative scanner is of equivalent quality to the teleconverter. So, the question remains, "What is the use of a teleconverter?" Well, I can think of a few, and I stand to be corrected on these points. If you're lucky enough to own a really high quality lens that outperforms the film with regard to resolution (which wouldn't be too difficult in low contrast situations), then enlarging the image as it appears on the negative 4 times by using a high quality converter (you might call it "pre-exposure" enlargement) would enable the film to accommodate the full resolution capabilities of your high quality lens. Another use would be for people who don't do any enlargement, who are satisfied with postcard size prints. A teleconverter can be a sort of partial substitute for a darkroom enlarger. (Enlarge the image before it hits the negative, sort of!) In my situation, where a Nikon LS2000 scanner is a substitute for an enlarger, I wonder if scanning an image 4 times the size but containing essentially the same information as the image without the teleconverter, might produce a better result bearing in mind that consumer grade scanners are unlikely to extract all information from the image. The larger image would contain 4 times the number of pixels after scanning. Maybe someone more knowledgeable than me might like to comment on this.

Marc Alberts , March 31, 1999; 05:45 P.M.

Bob, in the opening you mentioned the issue of a "well matched" lens and teleconverter combination. I have been contemplating buying one of the new Nikon 80-200 AFS lenses and the 2x teleconverter. Why not just get a 400? Price is the obvious answer, but it also has to do with the sports photography that I do, where having no ability to back away when the subjects are running towards me forces me into the 150-400/500 type of camp. I have tested the combination just in the shop, and the focus speed seems exceptional. The question is: is this indeed a well-matched combination where I would get results much better than I would with the third party lenses mentioned above? Or would I be better off just renting the 400 lens when I need it, and not have the flexibility? In other words, what kind of quality loss could I expect with the Nikon TC-20E and the 80-200 AFS combinations compared to the 400 AF?

Marc Alberts

T A , October 12, 1999; 09:09 A.M.

In summer 1999 the French magazine Chasseur d'Images compared telezoom+TC against making a comparable partial enlargement of a photo taken with the zoom alone. Although they weren't happy about neither of these two options on an absolute scale, they concluded that the former option was better, if those are the only choices available to you.

John Levenbach , July 15, 2000; 08:38 P.M.

Have lens developments moved on since your comments ? Refer to the Tamron & Sigma 28-300mm f3.5-6.3 zoom lenses !

Allen Holecek , March 23, 2001; 08:24 P.M.

I have been using a 80-400 Nikon VR for about 6 months now. I am always suprprised at how sharp it is. I decided to try a TC201 since I have a hole between 400mm and 1000mm. I was concerned about vignetting more than sharpness. I have developed the first roll and was pleasently surprised that I can't detect any vignetting even at 800mm. I even shot just the sky. I shot two portraits of my wife at 400mm. One at normal 400 the other at 200 with the TC. On a 5x7 at first glance I didn't see a difference unitl I examined her necklace with a magnifieng glass. That was the only part of the picture I could detect that sharpness had been compromised. The image is still fairly good. At 800 the images are reasonably sharp. The lens is hard to manually focus since moving the ring very slightly changes quite a bit. Of course you lose the VR also. At 800mm the poor tripod mount and lack of mirror lockup on the F100 does not help me either. It is still not too bad of a combo if you have the time to set the lens up for a shot. One thing I really like is the size. I can now carry 20mm and 28 through 800mm in my bag with ease. I did not expect the TC201 to do this well with at the 400 setting. The TC301 will not physically fit the 80-400VR.

Al

mark oxley , August 30, 2001; 02:55 A.M.

I can confirm that the Canon 100-400 L IS USM is a great lens. Image quality is very sharp through the intire focal range, only slightly dropping off at 400mm @ 5.6. The Image Stabaliser function really works well, i have been able to take photos handheld at 1/60th at the 400mm end and still get very sharp results.

Image Attachment: eagleowl.jpg

Craig Lipski , March 25, 2002; 01:19 P.M.

Another point not addressed above; I can't speak to all makes and models, but the body I'm saving for, (a Canon Eos Elan 7,) will not autofocus with an aperture smaller than 5.6, thereby rendering many lenses manual focus only with the addition of a teleconverter.

Cameron Galle , March 27, 2002; 05:33 A.M.

Craig,

I'm not sure of your previous previous comment "a Canon Eos Elan 7 will not autofocus with an aperture smaller than 5.6". I bought the eye-control version of this camera (it's called EOS 30 over here) about two weeks ago and have noticed no such shortcoming.

I'm lucky enough to have a 300mm f/4? "white" canon lens on loan and have put 4 rolls of film through with it almost always set at f/4. The autofocus has been amazing... i've taken great shots (in my humble opinion) of fast flying birds with the shutter speed around 1/1000 to 1/2000th marks and the autofocus has been excellent. The only hassles I've had were on a couple of fast panning shots i've focused on the background rather than the bird, and i'm pretty sure that was because i was struggling to keep up with the birds with such a large lens (compared to previous experience) at a realatively close distance (30' or less).

But back to the TC debate...

I don't have one yet, but from what I've been told, stick to a canon TC for the Elan 7 or better body especially if you're going to have good canon lenses - the no-name TC's can't keep up with the autofocus systems.

Cheers from Down Under

Craig Lipski , May 14, 2002; 08:46 A.M.

Cameron, If I understand what you're saying, you're shooting at f4 with no problem with autofocus; That's not inconsistent with my comment, as an aperture of f4 is actually a *larger* aperture than f5.6 (The f stop number being the focal length / aperture, so a smaller f stop number is a larger aperture [If the aperture equalled the focal length, the f stop would be "1"])

Cameron Galle , June 17, 2002; 10:50 P.M.

Whoops... I knew that! It appears I had a brain freeze...

Colin Jones , July 17, 2002; 01:24 P.M.

At the end of the day it is, as has been said already, about cost,if I had unlimited funds, I would get a 400mm or longer but for most of my work, which is mainly for pleasure I would not use it enough to justify the cost. But I already own a 75-300mm USM (not the best not the worst) so if I get a x1.4 TC I would have a 75-420mm f4-f8, or a x2 (75-600 f4-f11) for approx £200. I'll never win prizes for sharpness, but L lenses or even IS lenses are out of my league. I could afford a cheapo mirror lens but then what would be the difference. The EOS 3 central focus point wil AF down to f8 so even with some TC's AF will be possible.

Hrishi Muruk , January 24, 2003; 09:45 P.M.

Craig,

I have a Elan II (the previous version of the Elan 7) and it autofocuses absolutely ok at all apertures. I have used it with three different Canon lenses 100-400mm F/4.5-5.6 L, Canon 28-135mm, 50mm f/1.8 and it works fine. Some times under really low light autofocus does not work correctly but otherwise it works great.


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