SciBlogs

Archive July 2012

#Macro photography- don’t forget the light Brendan Moyle Jul 30

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I think one of the major benefits of spending a lot of years peering down a microscope, is that you develop a deep appreciation for how important lighting is. In order to see details, you don't just use a good microscope. You also spend a lot of time playing with different angles and levels of light. That's why you have light sources above and below the slide, and also fibre-optic lights on goose-neck lamps. Having the highest quality microscope in the world, means nothing of you can't work with light.

The same principle carries over to macro-photography. I've noticed a lot of people who start up with macro photography who think it's all about the lens. So they're willing to spend a lot of money on a top-grade lens, and then there's nothing left over for macro-flashes. The thing is, having light sources you can use to bring up relief on the subject matters a great deal.

This orbweb spider below is one of my favourite shots


One of the reasons is the lighting. I've got a green card set up behind the spider to reflect light back on it, and it's been hit with two flash sources. This is a spider I've photographed in the dead of night, in NZ bush. There is no other lighting here other than the sources I carried in. There's no streetlights, and the forest canopy is preventing moon or star-light from impacting on the picture. So by using light from different directions the spider ends up having shape and detail.

One of the reasons I went with Sony in my early DSLR days was because I saw the potential in this system for macro photography. The camera bodies had stabilisation, which gave hand-held macro shots a helping boost. The other factor was the weak AA filters used on the Sony sensors. This gave a notorious level of noise to images at high ISOs, but more detail in photos at low ISOs. Given I shoot macro at low ISOs, this suited me just fine.

Weaknesses however remained. Whilst Minolta had an excellent 200/4 long macro lens, Sony never resumed production of this lens- nor brought in a replacement. That left the macro lineup as a 50mm, and 100mm and later a 30mm. The gap at the long macro can be offset by using 3rd party lenses, but I really wanted to see a 200/4 back in offer.

The second weakness was lighting. Again Minolta had a ringflash in production prior to the Sony acquisition. This has been replaced with a ring-light instead- which suffers the problem of not actually being a flash and of very limited use for macro photography. The only other option was the Sony HVL-24. This is another Minolta rebadge of a specialist macro lens.

Up to now however, I've always baulked at paying the retail price for this unit. In the mean time I've been using a Sigma EM-140 ringflash. This wasn't available when I first got into macro-photography again, and it's actually a good unit. Nonetheless, you're still restricted by a ring-flash. It's difficult to make meaningful adjustments to the direction the light comes from.

Well, I've now bought a 2nd hand copy of the Sony HVL-24. This solved my issue with the retail price new :) And hopefully, I can offer some thoughts on its value after some use.






Size Matters: Manual focus with the NEX camera Brendan Moyle Jul 24

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Part III: The Art of Manual Focus

The Nex system has, possibly not by intent, become an excellent manual focusing system also. This means many lenses from the manual focus era (yes, there was a time before cameras developed autofocus functions where everything had to be focused by hand) have a new lease of life.

The reason manual-focus has become much more popular is a feature called focus-peaking. This was added to the first models in the Nex system by firmware and is now standard. What this does is show you what is in focus in your frame by colouring it. You even get a choice of colours (I use red). As part of the manual focus, you can magnify the view by either 7x or 14x. This allows for both accurate and straightforward manual focusing. In the past with film cameras, manual focusing was always associated with a level of frustration. That frustration has been replaced by enjoyment. The NEX-system doesn’t just give you the option of manual focus, it takes that concept to give you almost an entirely new way to take pictures.

The red areas (peaked) in the screen reveal what will be in sharp focus in the final shot


If you want to use lenses that are not E-Mount, you will need to use an adapter. If you already have Sony or Minolta AF lenses one such option is the LA-EA1. This preserves aperture controls (so you can adjust the f-stop) and if you have an SSM or SAM lens, it will also give you autofocus. Nonetheless, the autofocus speed is not exemplary (the camera is still stuck with contrast detection). A more expensive option is the LA-EA2 which is bulkier and adds the phase-detection autofocus via an translucent mirror mechanism. This makes it a lot better at autofocus, but if your main intention is to use the camera for manual focus, it is a very expensive option.

The LA-EA1


Side-view: the tripod mount is useful to balance the camera and take the weight off the camera body


NEX-5 with LA-EA1 Adapter and 70-200/2.8 G SSM lens


The effect of this adapter can be illustrated with these snap-shots.

Local Pukeko, NEX-5, 70-200/2.8 G


Cow, NEX-5, 70-200/2.8 G


Now, neither the camera or the lens will have any stabilisation so having the means to stabilise the shot is handy. I use a gorillapod for SLR camera with a small Giottos ballhead.

#Dragonfly macro Brendan Moyle Jul 24

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One of the most archaic groups of insects are the Odonata.
New Zealand has its very own native giant dragonfly Uropetala carovei. It is a typical dragonfly and predates on other insects and invertebrates.

This picture was taken at Long Bay and rather than using my macro lens, I was using my 70-200/2.8 G telephoto (at 200mm).

Aerial exempler: the takapu (#gannet) Brendan Moyle Jul 23

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While many of our forest birds are either flightless or poor fliers (I mean, seriously, who else wonders how a kereru manages to stay in the air?), the sea birds can be more adept. One of the most exciting to watch is the takapu (or Australasian gannet). Auckland is fortunate enough to have a colony nearby at Muriwai and some good viewing areas.

Here's an example of the takapu in flight


Link to larger image

This photo is also available at Committed Photography


Part 2: Size Matters- the beginner’s guide to the NEX E-mount camera Brendan Moyle Jul 16

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This part of the series deals with using your E-mount camera if you have a weak background in photography.

Sony has followed Minolta’s system of defining models based on a number system. This gives the Nex-3 (entry-level), Nex-5 (amateur), Nex-7 (advanced-amateur) and scope for a Nex-9 which would correspond to a ‘professional’ camera. Minolta did the same with the first digit of each model number matching to a market-segment. The 3 meant entry-level, and the feature set improved as you went up this 3/5/7/9 scale. Rather than using the same alpha-lenses (Minolta AF or Sony alpha) for the camera, the NEX series uses the e-mount. These lenses tend to be smaller than their alpha-cousins.

The differences at the moment is that the 7 has a 24MP sensor, a proper flash hotshoe for an external flash, and improved user interface. The 3 and 5 lack a proper hotshoe* and the user interface is more cumbersome. All cameras take videos and none have in-body stabilisation. This is part of the cost of making the cameras small. Some E-mount lenses do have stabilisation in the actual lens.

So, if you’ve got a Sony Nex-camera, what sort of setups might suit a beginner? The first thing to do is install the latest firmware. This is the age of digital photography. Cameras often qualify for upgrades that add new functions or improve performance. These upgrade are free and should be taken advantage of.

Firmware & other support: Sony Asia Support

A lot of people are largely interested in cameras to take pictures of friends, family and kittens. (There is a popular theory that the internet was invented by cats precisely to circulate large volumes of cat and kitten photos). So the following basic settings might appeal.

(1) Using Scene Mode

Under menu, go the the “Shoot Mode”, find SCN (scene selection) and pick portrait. This will try to shoot in a wider aperture (small f-stop) and at a decent shutter speed. This means the image will have good detail. Under the menu item, pick quality as fine and image size as large. Under the menu term “Camera” select DMF. Under menu item “Setup” set the Peaking Level to high and the Peaking Color to whatever takes your fancy (mine is red).

What the DMF allows you to do, is to fine tune the focus manually after the camera achieves a focus lock. The peaking colour will show you what areas of the image are in focus. So if you want to make an adjustment you can.

The basic problem with portrait mode is that it won’t be any good for landscapes. For landscapes (or macro) you want a small aperture (large f-stop). The second problem is the camera’s shutter speed can drop very low in poor light. This means that you may end up with more motion blur. It’s pretty hard getting a detailed shot at 1/30 second or less. Obviously changing the scene modes are one way to solve the aperture problem. But if you want a high shutter speed to ensure neither the movement of the camera or the subject ruins the shot, try something more advanced.

(2) Using shutter priority

Under “Shoot Mode” find the ‘S’ option. Then use the scroll wheel to pick a shutter speed of say 1/100 or 1/125 second. Then go the "Brightness/Color" and find the ISO to ISOAuto. What this means is that rather than letting the shutter speed drop to levels only appropriate for stationary subjects, the camera will adjust the exposure by boosting the ISO rating instead.

Once you’re used to adjusting the shutter speed you should be to make adjustments based on experience. For action shots- especially in good light, shooting at 1/500 second will often ‘freeze’ the action. For posed shots you may want to wind it down to 1/60 second.

What is ISO about?

ISO is a measure of sensitivity to light. It’s based on traditional film. A fast film (ISO-400) would have larger grains than a slower film (ISO-100). These larger grains means the film would react faster to the light. An ISO-200 film would thus need half the exposure (shutter speed) of ISO-100 film (all other settings identical), and an ISO-400 would need quarter the exposure (shutter speed). Digital sensors achieve this a different way. As the pixel-size is fixed, the ISO-adjustment is done by amplification algorithms. So if you shoot at ISO800 instead of the base of ISO200, the camera will open the shutter for ¼ as long, then amplify the signal by 4 times. This means you have less of the original signal, and the amplification will increase ‘bad’ information as well. So it’s not a clean process. It can’t recover detail that was never recorded.



Now there’s basically two things that will affect your exposure badly. The first is if your white balance is wrong. The second is that your ISO-setting is too high or low. You don’t want to keep going through menus to change these settings as this makes for an awkward interface. If you’re shooting in portrait or landscape mode however, you may not have a choice. If you are shooting in either S, A, M or P mode, you can customise the camera to make access to these functions easier.

So you should use the custom-buttons (in the setup menu) to make it easy to change. For example, I have my Soft key B Setting assigned to White Balance. I have my soft key C setting assigned to ISO (then autofocus area and metering mode, which you can ignore for now).

The white-balance determines the temperature of the light in the scene. If you’ve ever taken a picture in a room in the evening lit by light-bulbs, you may have noticed it has an orange or red tone to it. This is because the camera is often expecting the light-temperature to be around daylight (maybe 5200 kelvin) whereas the room is really about 2500 kelvin. If you set the white-balance correctly, the warm cast disappears.

You can leave the camera on AWB (auto-white balance) but this can be fooled, especially where there are several light sources or lighting is extreme. So just using the custom button will open up a menu that lets you dial in the lighting conditions that best match your scene. If you shoot in jpeg, this is pretty important. It is less important when you shoot in Raw because this easily fixed later. You can also use a custom white-balance against a white-object- this process is explained in my youtube video.

The second thing that can go wrong is the ISO setting. Now while a low ISO is a good thing, it comes at a cost. It means the shutter has to be open longer and this means the image is more at risk from camera shake (photographer can’t hold the camera steady) or motion blur (the subject moves). While the ISOauto may be good in most cases, it might still opt for (say) more amplification tna you want. So you may want to be able to adjust these manually. Often ISO-400 will work in good light and ISo-800 indoors. If your image lacks detail, colour or has more digital noise, you might want to dial the ISO down down. I find that I’m often able to shot up to ISO 800 without too much compromise on the image quality.

So given that fine-tuning the white-balance or the ISO are likely to be something you do often, having them available to change easily without having to work through menus is very useful.

The last function you might want to make accessible via the custom-buttons is another feature called DRO. This stands for dynamic range-optimisation. If you use DRO this makes subtle changes to the exposure in different parts of the image. It’s a way of recording a bit more detail in very dark and very bright zones. This is less important for someone who uses this camera to shoot raw, but for a jpeg photographer it can help. Of course, it can also make scenes worse by inflating the amount of digital noise in dark zones, so the ability to turn it on or off or use it at differing strengths is handy.

In the next part, I discuss the fun you can have with manual focus.
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* The cameras do have a hot-shoe that you can mount the small flash that comes with the system. You can also get a proprietary flash from Sony (the HVL-F20S) for these NEX-3 and NEX-5.

A couple of recent pics from the Waitakeres Brendan Moyle Jul 14

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Two pictures of the Kite Kite Falls in the Waitakere Ranges. …

Size Matters: A look at the Sony NEX Camera system Brendan Moyle Jul 06

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Introduction

Photography has undergone some seismic shifts in the last decade. The digital camera has dealt large blows to the fortunes of many companies. Kodak is bankrupt. Minolta has vanished into the hands of Sony. Pentax and Olympus are struggling. Yet with all of that, it looks like the digital compact camera is being killed also. The camera phone has now taken off. Two of the three most popular cameras on Flickr are iPhones. Not one of the top 5 is a digital compact.

Digital compacts are going to take another hit from another new technology. This is the mirrorless camera. It produces DSLR quality photos in a compact body. Now while it might be assumed that the mirrorless camera is kind of a halfway house between a compact and a DSLR, this misses the point. The mirror-less camera is really a completely different way to take pictures. Its portability means it’s much easier to take with you (e.g. it now comes with me when I’m cycling) so you end up trying and experimenting with more kinds of photos.

I know finally, have the answer to the question I often get asked. That’s what camera someone should buy. The answer is a mirrorless camera. I’m pretty enthusiastic about the Sony NEX system, as it uses a larger sensor than the rival micro-4/3 (MFT) system used by Panasonic and Olympus. Your mileage may vary. There’s no such thing as ‘the best’ camera system. All have different strengths and weaknesses.

Sony Nex-5 with 18-55mm kit lens


So what are the main differences? Compared to a compact camera the biggest difference is the size of the sensor. A Sony NEX camera uses an APS-C sensor that has an area of 370mm2. Most compacts have an area of 28.5mm2 and camera phones have smaller sensors than that. This means that even at 14-16 megapixels (MP) a mirrorless camera is using pixels that are individually much larger. This means it can extract more information from the light hitting the sensor. This translates into better colours, better detail and much better low light performance. It doesn’t matter how much processing power you throw at a digital image, if there’s a not a lot of information there, you can’t do much with it. This is the main reason I’ve never bothered getting a compact before. The images just aren’t that good when you start looking closely.

The other important differences are that mirrorless cameras have interchangeable lenses, and that they allow for full manual control over the exposure and focus. Being able to use a lens that is optimal for a scene, and being able to place the focal point exactly where you want it, makes a critical difference.

Compared to an SLR camera the obvious difference is the mirror mechanism is redundant. This means the camera can be made much more compact. Because the mirror doesn’t have to flip up and down when you take a picture, it also means that you can get a high frames-per-second, and video functions are much easier to implement. In fact, because these cameras use much larger sensors than many video-cameras and you can employ high-quality SLR lenses, you can get very high quality video clips also.

The big disadvantage is that the mirror-less camera has to use contrast detection for autofocus. This isn’t a big issue for landscape shots, but makes a big difference for action shots (wildlife, sports etc). SLR cameras use phase detection which is better at predicting movement and focuses faster.

An aside on autofocus.

Phase detection: image is split and then projected onto sensor via semi-transparent points on mirror. Images are compared and measured to see if subject is correctly focused. Is better at continuous focusing and in low light conditions than contrast detection.

Contrast detection: focus is adjusted until image achieves greatest contrast. The camera cannot tell if low contrast is a result of the lens focusing in front of, or behind, the subject. This makes it less effective for moving subjects and in low light (not enough contrast). It has to do a lot more focus-hunting to find the subject.



As a result I’m not ditching my SLR kit just yet. In a recent trip I was still using 2 cameras, but this time one of them was my NEX-5. The DSLR had my 300mm prime lens and was used for the bird and wildlife photography. Whenever I wanted to take a landscape shot I used the NEX-5. It was much easier than having another DSLR with me and the larger lenses this requires.

…In the next blog piece, a beginner's guide

#Tiger woes Brendan Moyle Jul 04

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The recent Stuff news article on the dwindling kea numbers brought up the comparison with the tiger. Keas (a native parrot) have dwindled and the keen conservationists trying to avert this, point out that they get a lot less money than tigers.

Kea


This isn't really a great revelation because, well, nothing gets more money than the tiger. And sadly, tiger conservation has been one of the most conspicuous conservation failures we have. With tigers we seem doomed to repeat the mistakes of the past, largely because of the 'feel good' factor. We use reserves, trade bans and anti-poaching measures, but never try to understand how these black-markets work. Then when the policy fails- perhaps because there are all kinds of perverse effects that make these bans counter-productive- we just decide to do the same thing year after year, but with more money.

And every year, we have less and less tigers. So the blame game begins. Apparently if we decide to use a conservation strategy that makes tigers worth $US50,000 to Asian criminals, we shouldn't expect them to take advantage of it. When your basic conservation strategy to save tigers is to make Asian criminals rich if they push them to extinction, maybe we should be rethinking the whole logic being used here.

Some scenes from the Hauraki Brendan Moyle Jul 04

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So often timing matters for photography. Go out one day, and there's something that affects the picture. Perhaps the lighting isn't quite right, the wind is too strong, the air has too much heat-haze. Then some days you just find everything comes together near perfectly.


The Gulf (looking towards Rangitoto Island)


Yacht


Waiake Cliffs


The Tor

In the Waitakeres Brendan Moyle Jul 03

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The Waitakere Ranges are to the west of Auckland, and feature some of the best native forest in the region. I slipped off one sunny (but cold and wintery day) to get some shots of the area. Some of thes eare a good illustration of the benefits of having a solid and stable tripod to take photos. Note that solid and stable is in the case of tripods, a synonym for heavy :)





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