Friday, 31 October 2014

Basic tele lenses compared

All camera systems have a cheap tele zoom lens available. Here are two such lenses, the Lumix G 45-200mm f/4-5.6 for Micro Four Thirds, and the Nikon 1 30-110mm f/3.8-5.6 for the Nikon 1 system:


The Nikon lens is seen here in a glossy orange finish. I guess it could have been worse, it could have been pink. Yes, this lens also exists in pink!

Both lenses cover a fairly wide range of tele focal lengths, useful for daily use. The range of the lenses is illustrated in the diagram below, in 135 film equivalent terms. You can also compare the maximum aperture as a function of the field of view:



Even when extended, the Nikon lens is impressively small:


Both lenses have rubberized zoom rings, which are nice to handle. The Nikon lens does not have a focus ring at all. I don't see this as a problem. The autofocus works well anyway, and I rarely see the need to focus manually.

Specifiations


Lens
AnnouncedSept 12th, 2008Sept 21st, 2011
Equivalent focal length90-400mm81-300mm
Lens elements/groups16/1318/12
Minimum focus1m1m
Weight380g180g
Diameter70mm60mm
Length100mm61mm
Filter thread52mm40.5mm
Focus ringYesNo
Image stabilizationOpticalOptical

Image quality


To compare the image quality, I have taken the same pictures with both lenses. The images were taken with the Lumix GH4 (my review), and Nikon 1 V3, respectively. The images were taken with the cameras safely mounted on a tripod, with the self timer to avoid camera shake, and at base ISO.

Lumix 45-200mm @ 45mm f/4
Nikon 30-110mm @ 30mm f/3.8

Here are some 100% crops from the centre:


From the right side:


And finally 100% crops from the top left corner:


In the centre, both lenses perform very well. However, in the corner, the Nikon lens is clearly a lot better. It renders the corners more sharply, and also handles the high contrast between the sky and the leaves better. This situation is quite challenging to render for most lenses.

Here is another comparison at the long end of the lenses:

Lumix 45-200mm @ 200mm f/5.6
Nikon 30-110mm @ 110mm f/5.6

Now, the Lumix lens has some advantage here, as it is used at a longer reach. True, on the other hand, this is how people use these lenses: They are often used in the most extreme setting. So that is why I test them like this.

Here are 100% crops from the centre:


And from the top left corner:


In this setting, the Lumix lens appears to show more details. However, it also has slightly more magnification. The Nikon system suffers from somewhat more diffraction effects when stopped down, that is why you see more dullness at f/9.

Bokeh


At long focal lengths, the depth of focus is thinner, and you tend to get the foreground and/or the background out of focus. Hence, the nature of the out of focus rendering, the bokeh. Therefore, it is important that the bokeh does look nice, and effectively blurs the out of focus areas.

To illustrate the bokeh, here are a couple of pictures taken wide open, at the short end of the lenses. I focused on the bicycle light in the top left part of the image:

Lumix 45-200mm @ 45mm f/4
Nikon 30-110mm @ 30mm f/3.8

Here is a magnification from both lenses:


Both lenses have perfectly fine bokeh in this example. The Lumix lens does feature slightly "dirty" out of focus highlights, but it is hardly a problem.

Autofocus during video


Panasonic and Nikon are taking different approaches to autofocus. Panasonic relies entirely on contrast detection (CDAF), and the most recent model Lumix GH4 adding DFD (depth from defocus), which attempts to find out in what way the image is out of focus by analysing the bokeh.

Nikon, on the other hand, has relied on phase detection sensors on the imaging chip (PDAF). This approach leads to very fast AF performance, even with moving subjects, and while recording video. However, the performance can be sub-par in darkness.

To test the autofocus performance during video recording, I recorded two sequences with the Lumix GH4 and the Nikon 1 V3. The first sequence was recorded inside an artificially lit shopping centre while riding an escalator, to get the same movement speed in both sequences.

The second sequence was recorded in darkness while watching an approaching bus:



All of it was recorded in 1080p, 60FPS. The settings were 150mm f/5.6 for the Lumix lens, and 110mm f/5.6 for the Nikon lens.

In the first sequence, the Nikon system certainly keeps the focus up better. Even in darkness, it does retain a good focus.

Conclusion


Generally, I am more convinced by the image quality of the Nikon 30-110mm lens. It is not as long, and, hence does not provide as much details in the tele end as the Lumix 45-200mm.

With the Nikon lens, I feel more confident using it wide open at all focal lengths, and I think it handles challenging contrasts better. While, with the Lumix lens, I more often feel the need to stop it down for better image quality.

The Nikon system also keeps the focus better up while recording video, and with moving subjects. However, as the image processing improves, future Micro Four Thirds cameras may very well be able to perform as good.


Alternative lenses


For Micro Four Thirds, there are a lot of alternative lenses. If you have an Olympus camera, with built in image stabilization, you could go for the affordable and great Olympus 40-150mm f/4-5.6.

For use on Panasonic cameras, you could go for the very compact and reasonably priced Lumix G 45-150mm f/4-5.6. Another alternative is the more expensive and very good Lumix X PZ 45-175mm f/4-5.6 (my review).

From Nikon, there are not any alternative lenses in the same price range. For a bit more money, you can get the Nikon 1 10-100mm f/4-5.6. It is not as long, but with the added wide angle range, it is very flexible, and covers most focal range needs in one lens.

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