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Cheers

Rusty

Focus Stacking - When too much DOF is never enough.

NOTE: I am in the process of moving this blog to our new web site. Because this blog will be removed in the near future, please share or link to the new location. Thanks

http://www.australianlight.com.au/blog/post/focus_stacking/

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Sometimes it can be difficult to create the Depth Of Field (DOF) that is required to complete our image.

This can happen for a variety of reasons, such as….

* A long focal length (FL) is required to achieve the desired composition.
* A macro lens is being used for a tiny subject.
* A low light situation dictates that a wider, open aperture be used to achieve correct exposure.

Thankfully there is a way that we can have limitless DOF when required... a technique known as "Focus Stacking".

Focus Stacking allows the photographer to take multiple images, each with their own unique focus point or distance and seamlessly blend them into one "fully focused" or "near fully focused" image as required.

Naturally this technique is limited to static subjects, as large amounts of movement will not blend across multiple frames, but thankfully our subjects are quite often static and this allows the use of this rather cool technique.

To give an example…

Recently I was out in the sunflower fields near Killarney in Queensland. Sunflower fields can be quite difficult to photograph at times, as good vantage points from public access areas are elusive.

Shooting wide angles will quite often bring in unwanted foreground objects, while shooting long lenses will limit the DOF.

Gaining permission to enter the fields is an option, but sunflowers grow to around 1.8m tall and this makes getting a view difficult without ladders or a naturally elevated terrain.

After much zooming around the countryside looking for a decent vantage point, I came across an area where I could just sneak a look over the field from public ground. This view still required that I reverse my Landcruiser onto a dirt mound and that I shoot from a standing position on the rear tail gate.

Unfortunately the wide view was not acceptable, as I could not get my vehicle close enough to allow the flowers to fill the foreground area of my frame, so shooting a longer lens and focal length was my only option. This longer focal length meant that my DOF was now limited and to maximise it by using a very small aperture could introduce unwanted softness due to diffraction.

Wanting to avoid this diffraction and maintain maximum image quality by shooting at my lens' sweet spot of f11, led me to shoot multiple focus distances and then stack.

The following two image crops display the limited DOF and how neither pulled enough of the image into sharpness for it to be acceptable…..





I understand that some may like the limited DOF, but I was after a lot more than displayed in these.

In the end I shot a total of six images, each at their own unique focus distance. While doing this, I was extremely careful to maintain a consistent view by using a tripod and standing very still on the vehicle tailgate.

These six images where then stacked and blended within a focus stacking program, to produce one combined image with greater DOF….



This is a crop from the above image that clearly displays the increased DOF….



Focus stacking of simple subjects can be conducted manually in image editing programs such as Photoshop, but this image was far to complex with all those flowers, so the dedicated stacking program "Helicon Focus" was used.

I am quite sure that there are other focus stacking applications available, so I will leave you to Google for one that is right for you.

Like it has done for me, I hope that focus stacking will open a whole new world of images for some readers. Focus stacking can make it incredibly easy to produce images that would simply not be possible with traditional methods of DOF control.

In my opinion, focus stacking is another must have technique for the photographer's toolbox.

Cheers

Rusty
AustralianLight - Landscape Photography

Tags: helicon focus stacking dof depth of field aperture

The Focal Length and Perspective Myth

NOTE: I am in the process of moving this blog to our new web site. Because this blog will be removed in the near future, please share or link to the new location. Thanks

http://www.australianlight.com.au/blog/post/myth_busting_focal_length_and_perspective/

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It's a common myth that changing the camera lens focal length, changes the perspective within an image. This is indeed a myth, as true perspective results from viewer's location and nothing else.

The location of the viewer dictates the spatial relationship between the viewer and their surrounding objects. This location also dictates the spatial relationship between those surrounding objects themselves "as viewed from the viewer's location". It is the combination of these spatial relationships that creates what we perceive as perspective.

This may sound a little confusing, so lets look at this diagram…



In this diagram, the camera ( A ) is focused on a single person ( B ), while a group of people ( C ) are in the background. The red lines indicate the Field Of View (FoV) of a wide angle lens, while the green lines indicate the FoV of a longer telephoto lens.

Accepting the principle that 'un-interfered with' light travels in straight lines, we can see that 'spatially' nothing has changed between the two lens focal lengths. The long lens with it's narrower FoV, simply sees a smaller section of the scene…. Person B is still the same distance from the camera, as are persons C. Plus, regardless of focal length used, the camera still sees the same relationship between person B and the partially covered person in C (as represented by the grey & magenta areas).

So there has been no "compression" of the image with the longer lens as often claimed. We are simply looking at a smaller section of the very same scene.

To demonstrate this, lets look at the following images that were taken from the same location, using different focal lengths.

Wide Angle Lens:


Telephoto Lens:


Now many people will claim that the wide angle image above demonstrates a different and much stronger perspective. However this is not the case as perspective in both images is identical.

In the following image, I have overlaid the telephoto view (lightened section) over the wide angle view and you can see that the images match perfectly.



To help see how well the images match, this is the very same image enlarged and cropped:



It must be noted that Depth Of Field (DOF) varies between the two images, but DOF is not what is in question here.

To truly change perspective and therefore the spatial relationship between ourselves and the objects around us, we must change our position. In this diagram the camera ( A ) has been moved closer to the single subject ( B).



Here you can see that the FoV for each focal length has not changed, but the viewer's relationship between ( B ) and ( C ) has changed (as represented by the grey & magenta areas) when compared to the original graphic. So by changing position, we have changed the spatial relationship or "perspective".

OK, so if the perspective did not change in the above images, why do I still think that the wide angle view shows more perspective?

Well we must remember that perspective is an illusion. It is created by the "seemingly" diminishing size of objects as they get further away and our brain interprets this diminishing size as distance and depth.

So by seeing more of a scene, we are therefore seeing more of the diminishing size relationships between the objects within that scene. This increases our spatial awareness and creates a much stronger "feeling" of perspective.

Conversely, by narrowing our FoV with a telephoto lens and seeing less of a scene, we reduce the amount of diminishing size relationships and thereby reduce our spatial awareness and our "feeling" of perspective.

Cheers

Rusty

Tags: perspective focal length diminishing size spatial awareness

The Wheat Bag Tripod - Stable Camera Support

NOTE: I am in the process of moving this blog to our new web site. Because this blog will be removed in the near future, please share or link to the new location. Thanks

http://www.australianlight.com.au/blog/post/the_wheat_bag_tripod/

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I was wandering around the city with a compact camera and no tripod, when I came across the old Regent Theatre and it's magnificently decorated interior walls and ceiling.

The theatre is dimly lit and flash is out of the question, so a long shutter speed was the only answer, but as I mentioned above, I had no tripod. (not that the management would have allowed me to use one anyway)

So I dropped into a number of chemist stores looking for a hot/cold pack that is normally used for treating injuries. At my 5th chemist I found just the one... "The Wheat Bag" at 180mm x 190mm.



This bag allows for easy and stable positioning of smaller cameras in either horizontal or vertical orientation on just about any surface. I have tested it with my compact cameras on coffee cups, chair arms, fence posts, car roof, coke cans etc., but to my surprise I have found that it easily supports a small DSLR also!

There is also a longer Wheat Bag available at 180mm x 380mm and I have used it to support my 1Ds2 (that's a big DSLR) with my 70-200/2.8 telephoto attached. The beauty of the longer Wheat Bag, is that it can be folded to provide different levels to support both camera body and lens.

Another great thing about bags like this, is that they get your camera closer to the ground than any other method and this can provide some interesting and unique viewpoints, that would otherwise be "overlooked". ;) ...pun intended.

Similar products have been around for cameras for quite some time, but when the word "photography" is attached, something strange happens to the pricing structure and we end up paying around $60 or more, while the Chemist purchased Wheat Bag comes in at a mere $15.95..... plus you can always use it as a heat/cold pack after a hard day of lugging the camera gear around.

If you are handy on the sewing machine, these would be pretty easy to make using a couple of handfuls of bean bag balls.... this would make for a lighter option also.

Cheers

Rusty

Tags: tripod tripods camera support platform

What camera should I buy?

NOTE: I am in the process of moving this blog to our new web site. Because this blog will be removed in the near future, please share or link to the new location. Thanks

http://www.australianlight.com.au/blog/post/what_camera_should_i_buy/

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It's the eternal newbie question and rightly so I would think.

Buying a new digital camera can be a very daunting thing, especially for the newcomers to photography who are still grappling with terms like 'megapixels', 'f-stop' and 'focal length'. These newbies are lucky enough to be starting out in what can be a wonderful, fulfilling and rewarding art and buying your first camera, is as exciting as buying your very first car.

Sadly though, it's like a minefield out there. The dream camera can be seen on the horizon, but to get there you need to avoid the hundreds of 'wrong camera' mines.... perhaps you may even need to cop a few long the way?

What camera should I buy? ...It's a question to which I will never give a defined answer. In fact, just like "Does my bum look big in this?", it's a question where there simply is no right answer.

Photography is a subjective art, right from the moment that you pick up a camera, until the viewer is looking at your image. What appeals to one, may not appeal to another. So here is how I don't answer the question....

What is the intended use? ...There is no need to go buy the latest and greatest 20+ megapixel DSLR, if you only intend to take happy snaps and print them at 6x4 or just keep them on the computer. Also, it would be crazy to buy that megapixel monster if your intention is to carry it in your pocket, because with a DSLR that is not going to happen!

So think about your needs and how you intend to use the camera. This should lead you towards buying a compact, a mid-sized camera or that megapixel monster.

How many megapixels? ...Again "intended use". Small prints or computer viewing of images do not need heaps of megapixels. Most cameras have reasonable resolution these days, so an 8-12 megapixel camera is readily available in compacts, mids and DSLRs. These will be more than enough to make A3 prints with good clarity.

Yes you can get higher megapixel counts, but ask yourself "Do I really need them?" In a nutshell "if you intend to print big, go big" is a good rule of thumb.

What camera is the easiest to use? ...There would be very few cameras that don't have a "full auto" mode that allows the photographer to simply point and shoot. But ease of use extends far beyond that. Think about the ergonomics (how the camera fits your hands), the use of the menu and how it is structured. Can you change quickly and easily from one shooting style to another? ...that kind of thing.

These will be quite personal and opinions will vary greatly from person to person. So "hands on" is the only way. Go to your local camera store and pick one up, shoot a few shots, delve into the menu operations and get a good feel for how the camera operates.

Which has the best image quality? ...This will vary from manufacturer to manufacturer, from camera to camera. So find your need first, then seek out image samples from cameras that meet your criteria. Online review sites such as DPReview are a great resource for images and these can be used to compare. Delve deep into the "full size" images at 100% viewing size and find what appeals to "you".

As a landscape photographer, I like lots of detail and neutral colour, but a wedding/portrait photographer may rather a little less micro-detail and a slighter warmer base tone to images. Cameras are tools and when you are driving a nail, you need a hammer. It's all about the right tool for the job.

"What lens do I need?" ...Very good question! There is no point buying a camera body, if the lens you want or need is not available for it. So now you need to think about the "system". Try to look forward, what will I need down the track, will the x,y or z manufacturer be able to meet my need? Thinking about the system and what additional equipment you need now and into the future, may well turn your head in another direction.

As a starter however, a zoom lens that offers both wide angle and moderate zoom is a great place to start. Try and avoid the massive zoom ranges, as these generally make compromises in order to achieve the extended range and these can often lead to a little less image quality. They are very convenient however, so if you are willing to trade a bit of image quality for single lens convenience, then that is your call.

My budget is only $XXXX ...Budget is the biggest killjoy. I doesn't matter if we are buying a house, a car or a camera, that darn "budget" just keeps raising its ugly head. :(

Obviously budget will be the ultimate deciding factor for many and my advice is to not overextend... on anything! Car, house, camera... whatever! If you can't afford it, then don't buy it! Buy something that is within your means, as the stress and ultimate heartache of losing it in the end should not be endured.

When thinking about your budget, think about this... "Camera bodies come and go, but good glass can last a lifetime". So if you have the extra coin, invest in the better glass, perhaps even drop down one body model to allow for that glass, as you can always update the body later.

Cameras are getting cheaper all the time and if you are a newbie, perhaps you could learn the ropes on a much smaller camera to begin with. This would also allow you time to find out more about your own needs and likes with regard to your new art.

So there is my NON-answer. Just a whole bunch of things to think about when making your decision. I may not have given you the answer you wanted hear. I may not have made your decision any easier, but I am sure that when it is made you will feel a lot more comfortable about it.

Cheers

Rusty




Tags: what camera purchase buying photographic equipment photography cameras lenses lens flash