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Archive for June, 2012

This is the third and final installment of the 50mm lens review, comparing image quality shot at F3.5 (or smaller for zooms).

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The first set shows 100% crops of the centre section.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F5.6, 1/1600s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F4.5, 1/3200s

3. Nikkor 50mm/1.8 – ISO 320, F3.5, 1/6400s

4. Sigma 50mm/1.4 – ISO 320, F3.5, 1/6400s

The image quality in the centre of the image seems quite good for all four lenses even at wider apertures.
It seems that Nikon 50mm/1.8 is the sharpest (look at the lettering at lifebuoy). Sigma image is slightly lighter with more details
in the shadows despite being exposed exactly as the Nikon 50mm/1.8.

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The second set shows 100% crops of the left edge.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F5.6, 1/1600s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F4.5, 1/3200s

3. Nikkor 50mm/1.8 – ISO 320, F3.5, 1/6400s

4. Sigma 50mm/1.4 – ISO 320, F3.5, 1/6400s

CONCLUSION:
The two primes demonstrate clearly their higher quality on the outside edges, and Sigma 50/1.4 is visibly sharper than Nikon 50mm/1.8. The shadow details are also much clearer for this lens.

If you use the 18-55mm kit lens or the 18-70mm Nikon lens, position your main subject in the middle, and the background is not too important or in the far distance, you won’t notice any problems. However, if you are shooting a landscape scene and want it to be sharp from edge to edge, with the above zoom lenses you will incurr significant penalty on the outside perimeter of the image. In that scenario, the prime lenses will do a much better job.

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As we have seen in the Part I, when we shoot at F8 and position the main subject in the centre, most lenses perform quite well.
In this installment, we’ll look at the left and right edges, exposed at F8.

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The first set shows 100% crops of the left edge.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F8, 1/1250s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F8, 1/1000s

3a. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s

3b. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s
Exposure adjusted (lightened) to match with the Sigma exposure (1/1000s)

4. Sigma 50mm/1.4 – ISO 320, F8, 1/1000s

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The second set shows 100% crops of the right edge.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F8, 1/1250s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F8, 1/1000s

3a. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s

3b. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s
Exposure adjusted (lightened) to match with the Sigma exposure (1/1000s)

4. Sigma 50mm/1.4 – ISO 320, F8, 1/1000s

The two zooms performed again very similarly, and show significant detail deterioration even at F8 aperture. The inexpensive 18-55mm kit lens was perhaps slightly better than the 18-70mm lens. The tested kit lens was newer than the tested 18-70mm zoom which may explain the difference in image quality.

The 50mm/1.8 Nikkor was visibly sharper than both zooms, and the contrast seems also better.
Sigma 50mm/1.4 renders the shadow details even better. Too bad, the camera metered 1/1600s for Nikon 50/1.8 lens and 1/1000s for Sigma 50/1.4, because that makes the 3a picture darker, so I tried to compensate for it by adjusting the curves and lightening the Nikon 50/1.8 shot (picture 3b).
Interestingly, Sigma lens exhibited some light pink patches on the white ship.

CONCLUSION:
The two primes demonstrate clearly their higher quality on the outside edges.
If you use the 18-55mm kit lens or the 18-70mm Nikon lens, position your main subject in the middle, and the background is not too important or in the far distance, you won’t notice any problems. However, if you are shooting a landcape scene and want it to be sharp from edge to edge, when using the above zoom lenses you’ll incurr significant penalty on the outside perimeter of the image. In that scenario, the prime lenses will do a much better job.

In the Part III, we’ll look how these lenses perform at the wider apertures.

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In case, you were wondering about the differences in image quality between a 17-55mm kit lens and a 50mm prime lens, this post examines those differences. I compared four lenses – two primes and two short zooms – Nikkor 50mm/1.8, Sigma 50mm/1.4, standard Nikkor kit lens 18-55/3.5-5.6G VR DX, and Nikkor 18-70/3.5-4.5G DX.

The experiment took place on a sunny day at the picturesque Gravenhurst Wharf, the shooting mode was set to Aperture Priority, and the aperture was set to F8. The testing was done on a 12MP D300 camera in RAW mode, camera mounted on a Manfrotto tripod. As you can see, each lens has a different sensitivity (or D300 metered slightly differently), there is a difference in colour rendering, and the calculated shutter speed varied between 1/1000s and 1/1600s. The pictures are not manipulated or sharpened in any way. To see enlarged images, click on the image you want to inspect in more detail.

In hindsight, I should have selected manual mode, and exposed all lenses in the same way, but it was interesting to observe that the camera metered differently with each lens.

The first set shows uncropped, scaled-down images. You can’t see the details, but you will notice slight differences in hue, contrast, and saturation.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F8, 1/1250s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F8, 1/1000s

3. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s

4. Sigma 50mm/1.4 – ISO 320, F8, 1/1000s

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The second set shows 100% crops of the center section.

1. Nikkor 18-55/3.5-5.6 – ISO 320, F8, 1/1250s

2. Nikkor 18-70/3.5-4.5 – ISO 320, F8, 1/1000s

3. Nikkor 50mm/1.8 – ISO 320, F8, 1/1600s

4. Sigma 50mm/1.4 – ISO 320, F8, 1/1000s

The two zooms performed very similarly, and at this aperture the inexpensive 18-55mm kit lens was even slightly better. This lens was newer than the tested 18-70mm zoom which may explain the difference in image quality. The 50mm/1.8 Nikkor was slightly sharper than the kit lens, and the contrast seems better. Sigma 50mm/1.4 is about as sharp as the Nikkor 50/1.8, but this lens metered 1/1000s as compared to 1/1250s, and consequently the exposure and the colours are slightly lighter.

CONCLUSION:
If the light is good and you can shoot at F8, even the inexpensive DX 18-55mm kit lens will perform very well.
The main advantage of the prime lenses is that they offer better colours and contrast, and you can use them also in low light. They are also more compact than the zooms.

In the Part II, we’ll look how these lenses perform at the extreme edges and different apertures.

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Heavenly Experience

The latest transit of Venus took place on June 5th, 2012. If you missed it, next occurence will take place in 105 years.

Although the afternoon was partly cloudy, the clouds cleared around the sun and the Venus appeared as expected, around 6pm EST. I’m always amazed, how exactly the astronomers can calculate these events. (But I guess, it must be more straightforward than to forecast weather for the next day).

I was lucky to get a ticket to the Dunlap Observatory in Richmond Hill. The David Dunlap Observatory is located in eastern portion of Richmond Hill, Ontario, and houses the largest telescope in Canada. The Royal Astronomical Society of Canada, Toronto Centre, operates the 74-inch reflecting telescope, but the large building with moveable dome was closed for this event.

The grounds opened at 5:30pm, and each visitor received protective sun shades. The filter on the shades looks like an aluminum foil, in effectiveness comparable to a welding shade between #10 and #14, and it is so dark, that you can’t see anything through it. If aimed squarely in the direction of the sun, one can see the sun (which when viewed this way, is surprisingly, a much smaller circle than you would think – smaller than the moon image).

Weather was great, the DDO grounds spacious, green and clean, and the volunteer astronomers very friendly and helpful. The main thing, there was lot of equipment available to observe the spectacular event.

This young couple is setting up their big gun – a 1200mm Orion telescope.

Many telescopes had cameras attached to it, and one could observe the magnified image either through the viewfinder or the back screen on the camera. This telescope was quite strong and you could see just a magnified portion of the sun. At that magnification, the sun moves very fast. The telescope had to be rotated slightly every few minutes or so to keep the Venus visible. Both celestial bodies were moving nicely in sync.

Here we have a smaller telescope, coupled with a larger camera screen, and Venus is visible as a small dark dot in the top portion of the big circle.

The next picture shows the administration building with two of the observatory telescopes built on the top.

One of the telescope on the building was connected to a camera that was feeding the images to a large computer monitor beside the building.
The transit began around 6:00pm when Venus appeared as a small dark spot in the right upper corner of the sun. You can see also some light clouds in the lower portion of the monitor.

The celestial body moved very slowly and the whole transit was supposed to last about six hours. Unfortunately, around 7:15pm the clouds moved in and put a stop to the show.

Great opportunity for a pleasant and memorable family outing and once-a-life learning experience for children. Actually, I had more fun observing the things around the telescopes than through the telescopes.

All pictures were captured with Canon T2i, and Tamron 17-50mm/2.8 DX lens.

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Not Microsoft Windows, but really pretty windows.

For a change from the everyday routine, I thought of a small project to shoot some ordinary objects but to show them in a slightly unusual way. This time, it will be windows. Each one drastically different from the others.

The first picture is a simple sky window in a long corridor. Just a plain rectangular piece of glass, reinforced every foot or so with metal bars. To take advantage of the long hall, I mounted a 17-50mm lens, dialed it to its wide end to change the shape of the window and to create a herring bone effect. I liked the soft pastel paint on the walls and ceiling, made my composition, and pressed the shutter.

Then, I positioned myself right under the sky glass, using the same wide angle lens, and took a second photo. It is, indeed, the same window, but with a drastically different effect. Almost black and white, with a magical soft light coming through the transparent panes.

OK, time for something bold.
If you want colour, nothing beats stained glass windows. A compositional problem for a guy with strong affliction for horizontal arrangements is that most really nice looking windows come in vertical shape. Luckily, I found a group of five colorful tall windows depicting the Last Supper that makes for a nice pano. Unfortunately, at that distance and resulting screen size, you can’t see the exquisite detail and colours of the individual pieces.

It bears repeating that the details, texture and colour saturation by the old masters are simply amazing. Below is just the medium pane from the second window from the left (for some reason, I’m always drawn to scenes with food on the table).

So, we had a minimalistic look, rich Italian look, now we need something haunting and mysterious. This picture was taken at dusk, just as the receeding light cast some dark shadows about the old building structure, ornate balconies, and the intricate wall details.

And for closing, I decided to add something really old and with a character. This window would have been a good candidate for some grungy HDR processing (and I happen to know some guys who would just salivate and pull out their Topaz Adjust), but I liked its simple soft and gentle appearance, and applied only a few basic tonal adjustments.

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