Oben AC-1410 Tripod Review

This is a quick review of the Oben AC-1410 4-Section Aluminum Tripod with BA-0 Ball Head. While simultaneously testing a number of digital cameras from Sony, Nikon and Olympus, I realized that I need another tripod that is light, easy to use / setup and affordable. I already have a heavy duty Gitzo Systematic tripod with an Arca-Swiss ballhead that I use for my photography needs, but I found it too painful to remove the quick release plate every time I needed to mount a camera. In addition, there were situations when I wanted to use two tripods simultaneously.

Oben AC-1410 Tripod

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Sony A77 Review

Overview

This is an in-depth review of the new Sony SLT-A77 digital SLR camera that was announced together with the Sony SLT-A65 in August of 2011. I had a chance to test both cameras, along with a number of Sony / Zeiss lenses for the Sony mount, while reviewing the Nikon 1 camera system in late 2011. While I concentrate most of my gear reviews around Nikon cameras and Nikkor lenses, I got really excited about these Sony cameras after seeing the press release and decided to try them out.

Sony A77

Sony A77

I have been enjoying shooting with DSLRs for quite some time now and while I am very happy with the cameras and lenses I use, I just think that we have not been seeing major breakthroughs in new DSLR cameras. New cameras pack more resolution, faster frames per second, better video features and other bells and whistles, but nothing innovative and revolutionary that changes the way we shoot. With Sony entering the DSLR market rather late in 2006 (after acquiring Konica Minolta), it was tough to compete against the long-established Canon and Nikon cameras. Sony introduced a few DSLRs with great features at a competitive price and secured itself the #3 market share spot in DSLR sales globally, mostly with lower-end DSLR camera bodies. With a rather slow adoption rate and a limited choice of lenses and accessories available, the company quickly realized that its only way to challenge the big two was to innovate. In August of 2010, Sony announced its first “Single-Lens Translucent” (SLT) cameras – the Sony A33 and A55. While the concept of a translucent mirror is not new (in fact, Sony calls it “translucent” for marketing purposes, because it is actually supposed to be “pellicle mirror”), Sony was the first to design it to work with an electronic viewfinder. Its first SLT cameras were a success, so Sony decided to embrace the technology and take it a step further with the new Sony A77 and A65 cameras. Going forward, we will most likely not be seeing any more DSLR cameras from Sony, since its management already expressed commitment to this new breed of cameras. We should be seeing more cameras from Sony with translucent mirrors, including high-end, full-frame models.

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Best of 2011 – Landscapes (Part 2)

This is part 2 of my 2011 landscape favorites. Please note that some of the images you will be seeing in the “Best of 2011” wallpaper collection have already been posted earlier last year in various articles, but in much smaller resolution. If you are looking for technical data, like Camera type, Lens and Exposure information, you will find it in the EXIF data. Summary of cameras used for the below images: Nikon 1 V1, D5100, D7000, D700, D3s and Sony A65.

Enjoy!

Colorado Fall Colors

1) Colorado Fall Colors 1920×1200 Widescreen Wallpaper

Canyonlands

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Impact Posing Stool Review

This is a quick review of the Impact Posing Stool, used in studio environments for seating clients and models to photograph headshots or half-body portraits. When photographing subjects in a studio, especially when doing corporate photography, a simple posing stool is often required. Regular chairs have backs and arms that are problematic for half-body shots, while bar stools can be too high and inconvenient to use, so an adjustable posing stool is ideal in such situations. While there are plenty of adjustable stools available from various manufacturers, most of them are quite expensive. The Impact Posing Stool accomplishes the same task, but at a much more affordable price.

Impact Posing Stool

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Why sensor dust is more visible at small apertures

Another reader of ours, Frank Di Luzio, sent the below image that explains exactly why sensor dust is more visible at small apertures. While I have explained this phenomenon to some of our readers before (see the comment section), I have not had a chance to write a separate article with a proper illustration, demonstrating how aperture size affects the shape and size of dust particles. Thanks to our generous readers like Frank, I now do not have to do it, because the below illustration is perfect.

Dust on Sensor

In summary, when the size of aperture is large (a small F-number like f/2.8), light rays reach dust particles that are sitting on the sensor filter from different angles. Remember, although I refer to this as “sensor dust”, dust actually never touches the sensor, because there is a thick filter (actually, more like a number of filters packed together to form a single filter) that sits in front of the camera sensor. Therefore, by the time light reaches the physical sensor, it is spread out on a very large area, making dust appear as a large blob with a soft ring. When using very large apertures like f/1.4 on fast prime lenses, these blobs might be so washed out that they might be practically invisible to your eye. That’s why portrait photographers notice dust less often than landscape photographers!

Now when the lens is stopped down and aperture is significantly smaller, say at f/16, light rays coming from the lens diaphragm are perpendicular to the sensor filter. Because the angle is more or less straight, dust specks also cast direct and defined shadows on the sensor. That’s why dust shows up in images much smaller, darker and with more defined edges at small apertures.

Big thanks to Frank for sending the illustration!

Best Nikon Lenses for Wildlife Photography

What are the best Nikon lenses for wildlife photography? Our readers often ask us about lenses for nature photography and while I have already written about which Nikon lenses I consider to be the best for landscape photography, I have received numerous requests to write about lenses for wildlife photography as well. In this article, I will not only talk about which Nikon lenses I believe are the best for wildlife and nature photography, but also when I use a particular lens, along with plenty of image samples from each lens. Please keep in mind that the information I present below is a personal opinion based on my experience so far, which is subject to change. If you have a favorite lens of yours for wildlife photography that is not listed below, please feel free to add a comment on the bottom of the page with some information and links to pictures (if you have any that you would like to share).

When photographing wildlife, whether shooting bears in Alaska, or capturing birds in flight, one of the most important factors in choosing a lens is its focal length. Generally, the longer the lens (in focal length), the better. Unlike landscape and portrait photography, where you could get away with a cheap lens and still get great results, wildlife photography pretty much requires high-quality, fast-aperture telephoto optics. This obviously translates to a high price tag, with the lowest end of the spectrum averaging between $500 to $1,500, and the highest-quality / best reach lenses costing as much as $10,000+. Without a doubt, wildlife photography is a very expensive hobby to have (unless you are so good that you can sell your pictures and make good money), especially once you add up all the gear and travel costs.

1) Nikon 70-300mm f/4.5-5.6G VR

If you want to get into wildlife photography on a tight budget, the Nikon 70-300mm f/4.5-5.6G VR is the lens you want to get. It is a great buy that will get you to 300mm at under $600 USD. Its autofocus is pretty good in daylight and its versatile zoom range of 70-300mm is great for large animals and perched birds. The lens is light and compact, making it easy to carry it around when scouting for wildlife in parks and wildlife spots. It is capable of producing relatively good bokeh, especially on its longest end, although its sharpness performance also drops quite a bit at 300mm. Having VR is a definite plus when hand-holding the lens.

AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED

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Impact Multiboom Light Stand and Reflector Holder Review

This is a review of the Impact Multiboom Light Stand and Reflector Holder, used in studio environments for holding lights, reflectors, flags and other light accessories. If you do any studio work, whether it is for photographing models or your clients, it is often necessary to use light reflectors to bounce the main light for softer shadows. Other times you might find yourself in a situation when you have too much light spill and you need to block some of that light with a black card, also known as a “flag”. It is great if you have one or more assistants for these kinds of situations, because they can assist in holding reflectors and flags. But what if you work alone or need to hold multiple reflectors and flags? That’s when a boom comes in handy. I have been shopping around for a good, lightweight, portable and inexpensive boom arm + stand combo, and I think I found a perfect one for my needs.

Impact Multiboom Light Stand and Reflector Holder

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Best of 2011 – Wildlife

While looking through the 2011 photographs, I realized that I shot very few wildlife images last year. Part of it has to do with the fact that I was too busy testing equipment, but I also realized that I just did not get out locally as much as I used to in order to photograph birds and other wildlife of Colorado. A large number of great wildlife shots from Yellowstone and Glacier NP were lost during my two week trip across North-Western US as well, due to my own fault. All in all, 2011 was just not a good wildlife year for me. Hopefully I will do better in 2012. Enjoy!

Tricolored Heron

1) Tricolored Heron 1920×1200 Widescreen Wallpaper

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Why Downsampling an Image Reduces Noise

One of our readers, Mike Baker, sent the below email to me today. I thought it was a great and interesting analysis of why downsampling an an image reduces noise, so I decided to share it with you (with his permission, of course). Trying to digest this stuff makes my head spin, but it is a great read. You might need to read it several times to understand what he means, especially with all the mathematical formulas (I had to):

You recently commented about downsizing a high-resolution image to a lower-resolution in order to reduce the apparent noise. While I knew that this is an effective way to reduce noise visible in the images, I had not thought in much detail about the technical reasons why this works.

After a long evening’s thought on the subject, and running a few questions past my friend and fellow engineer, I believe I have a (reasonable, though perhaps not perfect!) handle on the subject…

If the image signal and the image noise had similar properties, averaging neighboring pixels in order to reduce the resolution would not improve the signal-to-noise ratio. However, signal and noise have different properties.

There is (in general) no relationship between the noise in neighboring pixels. Technical junkies call this “no correlation”.

Correlation is the long-term average of the product of two signals N1 x N2. If two signals have no correlation, then the mean of their product is zero.

The signal in neighboring pixels has a high degree of correlation. If you add uncorrelated signals, then their “power” is added, meaning the combined signal is the square root of the combined power.

N_comb = sqrt(N1^2+N2^2) and for N1 = N2 = N we get N_comb = sqrt(2)*N, where N1, N2 are root-mean-square (RMS) values of the noise.

However, if signals are highly correlated, then their sum is effectively the sum of their magnitudes:

S_comb = S1+S2 and for S1=S2=S we get S_comb = 2*S

So, if we add the content of two neighboring pixels, we get:

SNR_comb = S_comb/N_comb = sqrt(2)*(S/N)

So, the signal-to-noise increases by square root of two, which is about 40%.

Now, you may say that the signal in neighboring pixels is not always 100% correlated. The correlation between the signals depends on the image content. If the image content is very smooth, the correlation is high. If the image content varies very fast, the correlation is low. Of course, noise will be more noticeable in smooth areas and the effect of resampling the image will be stronger.

Adaptive noise filters take into account the absolute signal-to-noise and the image content. They reduce the resolution more in areas that are smooth and have poor signal-to-noise and keep the original resolution in areas that have strongly varying image content and high signal-to-noise. You can think of it as a joint optimization of SNR and resolution.

Now, we also need to look into the different sources of noise:

  1. The first source of noise is dark current which is caused by electrons that accumulate in the individual pixel well, even if there are no photons entering (lens cover on). Dark current becomes dominant for very long exposures. For normal exposures the errors from trapped electrons are negligible.
  2. The second source of noise is the read-out noise. This is essentially generated by two sources: A) Noise added by the amplifier and B) Noise generated by the analog-to-digital converter. It is a fixed amount of noise that is added to each image during read-out. When you choose the ISO setting on your camera, you essentially set the read-out gain and therefore the read-out noise. The higher the ISO, the higher the read-out gain and the less read-out noise. Of course if you pick an ISO which is too high you will get signal saturation. So for low-light situations always pick an ISO that is no higher than needed to capture the image you want.
  3. The third source of noise is called “quantization noise” and is a bit harder to understand. It has to do with the fact that (in low-light conditions) we don’t sample a smooth, continuous flow of photons but rather discrete bunches of photons. The problem is, that a source of light does not produce a stream of photons that are spaced equally in time. So, if you image a low light source that sends out (on average) 100 photons per second, you may receive 90 photons for the first second, 105 for the second etc.. The average error will be on the order of the square-root of the number of photons (or electrons in the pixel sensor well). A typical sensor well contains between 20,000 and 60,000 electrons when fully charged. The maximum amount depends on the pixel size. A sensor well with 20,000 electrons has an error of approx +/-141 electrons when fully charged or +/-0.7%. A well with 60,000 electrons has an error of approx +/-245 electrons when fully charged or +/-0.4%. While we may be able to reduce dark current and read-out noise by cooling the sensor, there is essentially nothing we can do about it. If we keep on shrinking the pixels, we will have smaller and smaller electron wells and less and less electrons trapped.

    The above errors of 0.7% or 0.4% appear rather small and we would not be able to notice them. However, in low-light situations, sensor wells will be only partially filled. If we only manage to trap 1000 electrons, the error becomes 3%. If we only trap 100 electrons, the error becomes 10%.

    Notice that the term “quantization noise” has nothing to do with the signal quantization by the analog-to-digital converter. It has to do with the fact that your signal actually arrives in quantums of energy.

What do you guys think? Anyone wants to challenge Mike’s analysis? :)

Benefits of a High Resolution Sensor

As camera manufacturers are continuing the megapixel race, with Sony releasing a bunch of 24 MP APS-C (1.5 crop-factor) cameras like Sony A77, A65 and NEX-7, and Nikon planning to release a high resolution 36 MP Nikon D800, many of us photographers question the need for such a high resolution sensor. Some of us are happy while others are angry about these latest trends. Just when we thought companies like Nikon abandoned the megapixel race, instead of seeing other companies do the same, we now see Nikon back in the game with a new breed of product with a boatload of pixels. Why did Nikon all of a sudden decide to flip the game? Why does everyone seem to be going for more pixels rather than better low-light / high ISO performance? Does a high resolution sensor make sense? What are the true benefits of a high resolution sensor? In this article, I will provide my thoughts on what I think has happened with Nikon’s camera strategy, along with a few points on benefits of a high resolution sensor.

Nikon D4 Sensor

Pixel Size, Pixel Density, Sensor Size and Image Processing Pipeline

OK, this topic is rather complex if you do not know anything about pixels and sensors. Before you read any further, I highly recommend to read my “FX vs DX” article, where I specifically talk about pixel and sensor sizes and their impact on image quality.

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