Need help choosing a telephoto lens

Question

I have a Canon kit, which comprises of 4 lenses:

1. a 17-40 mm f4
2. a 50mm f1.8
3. a 100mm 2.8 Macro, and
4. a 70-300mm IS USM (non L)

I am looking for a telephoto/supertelephoto to replace #4 above.

I am looking at the 70-200 f2.8L IS II and 100-400 4.5-5.6L IS II. Now these two are definitely not cheap, there are non IS versions which are nearly half price. And then irrespective of the IS/non-IS feature, I see the 4/4.5-5.6L lenses are comparatively cheaper than the 2.8L ones.

I also plan to get a 2xIII extender.

Now what I am not sure about is how much a 2.8 vs 4/4.5 (or 5.6 at 400mm) will differ in output. Given that I will hardly be shooting without a tripod at night, do I really need a 2.8 for mid day (well lit conditions) usage? I don't think there will be any visible/perceivable difference in the DOF at larger focal lengths (please correct me if I am wrong).

If there anything else I need to look at before I make a decision on which one to go for? It's a one-time purchase, meaning I plan to make a purchase which will last me more than few years, and hence not shying from spending on a quality Canon lens. I just need to be sure (and well informed) on what I am putting the money on.

I have a Canon 5D Mk III (full frame).

The existing lens (70-300) is very very old (nearly 8 years). All the pictures I take using this existing telephoto I have, are extremely grainy (not sure why). Also the auto-focus seems to have slowed down (not sure if this is actually a possibility). I need a better telephoto lens (or kit - lens + extender whichever fits the budget) which is sharper and more durable.

Any advice is greatly appreciated.

Answer 1

I also plan to get a 2xIII extender

For most Canon bodies, a 2X teleconverter will only be practical with f/2.8 lenses. It's how aperture works.

f-number = focal_length/aperture_diameter

therefore:

aperture_diameter = focal_length/f-number

Which is why we write an aperture setting as f/f-number: e.g., f/2.8.

When you use a 2X teleconverter, you're doubling the focal length, but the maximum aperture diameter remains the same. So you're adding two stops to the maximum aperture of the lens.

An f/2.8 lens becomes an f/5.6 lens. An f/5.6 lens becomes an f/11 lens.

Most Canon dSLR bodies stop autofocusing when the maximum aperture of a lens hits f/8. Some stop when the maximum aperture hits f/11. If you plan on using this new telephoto lens with autofocus, and you don't have a 1-series or dual pixel sensor in the body, then you can only use a Canon 2X extender with an f/2.8 (or faster) lens.

You could use a non-reporting 3rd-party extender, but the optical quality is likely to be less than that of the Canon MkIII extenders. And the AF performance will take a hit. I use a non-reporting Tamron 1.4x extender on the EF 400mm f/5.6L USM prime. It considerably reduces AF accuracy and causes a bit of "chatter" in the lens as it hunts for AF lock on my 50D.

See also: How to enable Canon AF with teleconverter?

Answer 2

I am looking at the 70-200 f2.8L IS II, 100-400 4.5-5.6L IS II.

The biggest difference between those lenses is not the aperture but the focal range. Presumably, you don't really need a super-telephoto lens if you're considering replacing a 70-300mm lens with a 70-200mm lens. And if you don't care about having f/2.8, one has to wonder why you're not looking at one of Canon's 70-200mm f/4 L lenses, as there are IS and non-IS versions available, both significantly less expensive and a lot lighter than the 70-200 f/2.8 L IS II.

Now what I am not sure about is how much a 2.8 vs 4/4.5 (or 5.6 at 400mm) will defer in output. Given that I will hardly be shooting without a tripod at night, do I really need a 2.8 for mid day (well lit conditions) usage? I don't think there will be any visible/perceivable difference in the DOF at larger focal lengths (please correct me if I am wrong).

2 stops faster is 2 stops faster, no matter what time it is. Getting a good shot with a long lens means using short exposures. Image stabilization is great, but it's not magic. So, think of the difference between f/5.6 and f/2.8 as the difference between shooting at 1/200s vs. 1/800s shutter speed, or the difference between shooting at ISO 1600 vs. ISO 400. Or a combination of the above. Gathering more light gives you more options.

Two full stops of aperture will definitely make a difference in depth of field; whether it's a difference you care about will depend on what you're shooting. If your subject is a kid on the far side of a soccer field, you're not looking for a lot of bokeh, but the extra reach of a 400mm lens can be very helpful. But you could use that same lens at 100mm to take a portrait of that same kid after the game, when the subject is much closer to the camera, and f/2.8 can give you a nice blurred background that you won't get at f/4.5.

Answer 3

The existing lens is very very old (nearly 8 years).

That's not a sensible reason to get a new lens.

Some of the best (and favorite) lenses are well over 30 years old.

Never mind the age, does it do it's job ?

All the pictures I take using this exisitng telephoto I have are extremely grainy (not sure why).

Well this ought to be the question you try to answer before getting another lens.

If you don't know why this happens, how can you possibly know if it will affect photos from your new lens.

It would suggest you're using very high ISO (something you ought to be conscious of when shooting). This would also suggest a possible reason for focusing problems : low light. AF systems need light to work effectively. If you stop down (shoot at high F-numbers) this can make this issue worse.

With reference to landscape shooting (all you mention), note that high ISO is generally not required and can typically use a long exposure period while using base ISO (which maximizes dynamic range and minimizes the effect of noise).

Also the auto-focus seems to have slowed down (not sure if this is actually a possibility).

It can happen, but that could be indicative of any number of issues, and not necessarily an issue with the lens.

It could be an issue with the camera's AF system, or an issue with the lens focusing motor or lens assembly, or it could be technique related (e.g. low light focusing or simply misusing the camera's AF system).

I need a better telephoto lens

Better how ?

The issues you're complaining about may have nothing to do with the lens.

Note in particular that the lenses you're discussing are heavy.

(of kit - lens+extender which ever fits the budget) which is sharper and more durable.

I'd never recommend a 2x extender. Maybe a 1.4x extender with a fast lens (and f2.8) but it's always a problem with a 2x because you loose two stops, and not only does this affect exposure, it can affect the AF system's performance. With a 1.4x you only loose one stop.

Also note that you have a 70-300 and while you're consider a 70-200, you're also considering a 100-400 and a 100-400 with a 2x extender (a 200-800 in effect !).

What's apparent is that you don't really have a clear idea about what focal lengths you actually need.

Do not get a new lens until you have clearly identified what focal lengths you need. Get a lens that covers those ranges.

As you only mention landscape shooting in comments, it's hard to see a 100-400, let alone with a 2x, being a good choice for that.

Answer 4

I am looking at the 70-200 f2.8L IS II and 100-400 4.5-5.6L IS II. Now these two are definitely not cheap, there are non IS versions which are nearly half price. And then irrespective of the IS/non-IS feature, I see the 4/4.5-5.6L lenses are comparatively cheaper than the 2.8L ones.

If you're looking for "bang for the buck" in the medium telephoto range there are some third party offerings that you probably ought to consider as well. With the advent of USB devices that enable the end user to apply firmware updates to a lens without sending it off to a service center the risk has been greatly reduced with regard to an existing third party lens not being fully compatible with newer camera models introduced after that third party lens. Sigma calls their version the 'Lens Dock'. Tamron calls theirs the 'Tap In Console'. Note that only lenses listed as compatible with these USB devices reap their benefit. Both manufacturers have been very responsive to updating firmware to deal with glitches that crop up with newer model cameras. Older models of lenses from Sigma and Tamron do not benefit from the capability of the USB docks, so be sure if you go that route that the lens you choose is compatible.

In addition to being able to update the firmware, these USB devices also allow you to fine tune your lens' AF calibration to your specific camera body in much greater detail than the 'AFMA' feature built into your Canon EOS 5D Mark III. This is increasingly important as many lenses' optical designs exceed our ability to reasonably manufacture them and their connection to our cameras to tolerances tight enough to fully leverage those designs.

The biggest remaining disadvantage to using some of these high quality third party lenses is the lack of in-camera lens correction profiles for things such as distortion, vignetting, and chromatic aberration. This would also extend to computer based raw processing if you choose to use Canon's Digital Photo Professional 4 (or any other manufacturer's in house raw converter with one of their cameras). With good telephoto lenses, though, distortion and vignetting are usually much less severe than with wider angle lenses. CA is usually very well controlled in mid-to-upper tier telephoto lenses as well.

The newest Tamron SP 70-200 f/2.8 Di VC G2 gives the EF 70-200mm f/2.8 L IS II a run for its money. When introduced it was perhaps the best telephoto zoom ever created, but seven years later everyone else is starting to catch up.

The Tamron and Sigma 150-500mm f/5-6.3 offerings have been well received in terms of the price to performance ratio.

For the price, the Sigma 120-300mm f/2.8 DG OS HSM Sports is unchallenged as a telephoto zoom with an f/2.8 maximum aperture at 300mm. (Just be sure it is the latest 'Sports' version that is 'Lens Dock' compatible.) The EF 300mm f/2.8 L IS II prime is better optically than the Sigma 120-300mm at 300mm, but at nearly twice the price it should be! The 'IS II' versions of the Canon super telephotos are some of the best mass produced lenses ever made, but they are pricey running from $6K-12K.

Although it is based on selecting a telephoto zoom for a Nikon, rather than Canon, camera Will my camera autofocus over the full range of a telephoto lens with variable aperture? has a lot of information in the answers going well beyond AF that are relevant to the question from a Canon point of view.

I also plan to get an EF 2X III extender.

Then you must also consider that the EF 70-200mm f/2.8 L IS II will become a 140-400mm f/5.6 when used with a 2X extender. The EF 100-400mm f/4.5-5.6 L IS II will become a 200-800mm f/9-11 with the same extender. In the former case most EOS cameras will still autofocus. In the latter case you will need to manually focus your lens. Most EOS cameras cannot AF with a lens slower than f/5.6, but a few of the newer top tier models will AF up to f/8, at least with the center AF point.

The EF 70-200mm f/2.8 L IS II takes the EF 2X III fairly well and still focuses fast enough to use such a combination for sports and action, but the lens is slower focusing with the extender than it is when bare. You give up a bit of image quality, but not a lot. Using the EF 2X III with the 100-400 gives up a bit more, particularly with regard to overall sharpness and CA in addition to losing any hope of using AF, and probably would not give satisfactory results.

Here's why wider maximum apertures result in better AF performance.
Here's some context regarding various 70-200mm lenses of the Canon mount.
This question addresses why maximum aperture is important to AF performance as well as illustrates how each lens model's design affects that lens' optical performance.
Two different lens models with the same focal length range and maximum aperture may be very different internal designs and have significant differences in performance. For instance, with telephoto zoom lenses focus breathing at shorter subject distances can vary widely and affect the usability of the lens for a specific purpose.