Digital Zoom – A boon for the no-so-affluent

Edit: This is a backdated post, backdated by about 4 years, to the time when I bought my first camera and took my first few steps into photography.

1) Digital Zoom should not be used.
2) Digital zoom spoils image quality.
3) A camera should not be judged by the amount of digital zoom that it offers.

These are the claims and instructions that one will find all over the internet, preached by professional photographers and enterprises. Is this real or just a myth?

I have been bitten by the digital photography bug and bought my first digital camera one year back with the same points in mind. I have refrained from using digital zoom as much as possible. What are my views on the points mentioned above?

Digital Zoom is not evil. Yes, the 3rd point makes a lot of sense. As much as possible don’t judge a camera by the amount of digital zoom. Compare with respect to optical zoom and then use digital zoom as the comparison when zoom is the main criteria for purchase. If you find a camera with 4x optical zoom, no doubt prefer it over one with 3x optical zoom. But when you have two cameras with 3x optical zoom and one has 4x digital zoom and the other 6x digital zoom, then without a question of doubt the 6x is the one that will find its way into my pocket. The reason? Lets see what is digital zoom and why people are against it.

Digital zoom is not a true zoom. Why? Optical zoom uses a combination of lenses to magnify the subject and duplicate the image in question over the entire area of the sensor. Whereas in digital zoom, the image is taken with the maximum possible optical zoom and then a small area is cropped from this and enlarged to fit the full frame size. (The megapixel size of the original image) i.e Suppose you have an image of full frame size 2560x1920 and you use 4x digital zoom. Now the 4 time magnified part of the full image will be 2560/4 x 1920/4 = 640 x 480. So a portion of the image that is sized 640x480 is cropped and enlarged to 2560x1920. What this means is that lots of extra pixel information is added to the image and even with the best resizing/re-sampling algorithm, some detail is lost and the picture will look jagged and bad. So what the advantage of digital zoom?

The advantage lies in the use of digital zoom. Consider a huge white background with a small dark object in the center. The dark object is not necessarily black but is in fact (say) dark blue with dark green and brown spots. Suppose, this image at full optical zoom still doesn’t enlarge the image to full frame and covers only about 1/10th of the frame. Now the camera metering ‘sees’ a lot of white and assumes this as only a black object. When you see your final picture the details on the small object is lost, maybe not completely, but at least it doesn’t reproduce the vividness of the actual colors. This is because the dynamic range of cameras is smaller than what the eye can see and to accommodate the amount of white information a little compensation is made with regards to the smaller objects. The sensor doesn’t know that the object is the most important part of the scene and compromises a little with its detail. This problem can be alleviated a little using spot metering which will meter only on the center portion of the frame so that the object is marked as the important part of the picture and some colors are now reproduced correctly. But what if the object is so small that even spot metering is not enough? In this case digital zoom comes to the rescue.

When I zoom completely into the object, there are the following advantages.
1) I am able to see the point of interest more clearly and can frame it better in the viewfinder/LCD.
2) Since the object occupies a larger portion of the viewfinder, the camera can meter it better and can help reproduce much of the dynamic range.

The result? A much better reproduced picture. But it will be distorted because it is blow up. So what? Resize it back to the smaller size from which it was cropped. In the above example it is 640x480. Now downsizing also causes losses and some may argue that again the point of digital zoom was lost, but it is not so. Downsizing is much less lossy than expanding. Moreover, take the image in RAW mode and use the same re-sampling/resizing algorithm to downsize the zoomed image as the algorithm that was used to expand it. This causes very low pixel loss and the best part is that you have a well metered and reproduced image. So what if you can take only a small print? At least you have a print of that interesting object that you can show off to your friends with a similarly specified cam and lesser digital zoom.

Disclaimer: There are many many more considerations that you have to consider before comparing digital zoom and it also depends on the users preference. Some may prefer the feel of one camera and that may be a deciding factor. Some may like the twistable screen of a cam and weigh that over the higher digital zoom of another. The bottom line is that keep digital zoom out of the mind till every other required feature is found and still further narrowing of choice is required.
Of course when you have the money then you would buy a camera with larger optical zoom or bigger lenses in the case of SLRs. But not all are so fortunate like the pro photographers and monetarily blessed to afford such large lenses and ultra zoom cameras. In this case I would say there is no other choice than to go for digital zoom.
Zooming is also a foolish option when you can get closer to the subject. Move in as much as possible and then use optical zoom to get a shot, if that is also not good enough then go digital.

Inspiration: I was out birding this morning and there was a huge lake with a small bird sitting on a stick in the middle of the lack which was inaccessible to me. I was on the periphery and almost on the verge of falling over. I had a 400mm lens and spot metering on, but even this was not enough for a good shot. The water reflections and the dark coloring of the bird were both counter-productive to a good shot and I had to zoom in digitally. The shot was much better than the completely optically zoomed shot since I now had only the bird in focus and it was well metered because the bird filled almost 2/3rd of my frame. As I came back home I thought well and hard about how useful digital zoom was to my trip and then decided to write down this article.

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Moon Photography

The moon is one of the most interesting subjects to photograph. Each day brings to you a new face of the moon and a new way to look at it and photograph it. The moon has so many features on it, and a good photograph will bring out all those surface features on the moon leaving you very happy and pleased with the results.

However, photographing the moon is not very straight forward and easy as it looks. A scene with the moon can be so deceptive that most cameras that don’t have the correct settings set manually, will never be able to capture the moon and all its detail.

The first thing about moon photography is to understand the scene. Usually the moon will be in a dark background and will be the only clearly visible object in the sky. When you take a photograph, the camera sees most of the object as black and will try to overexpose to try and get the back in detail. It doesn’t realize that you are trying to photograph the moon and not the night sky. This is where you come in and do a few adjustments on the camera.

If you leave aside the night sky, then you will realize that the moon is an incredibly bright object in the night sky. You have to approach moon photography just like you approach day time photography. However, moon photography, thankfully, is not one thing that required the use of a lot of manual settings. It is of course an option to go manual on the moon, but it is just not necessary provided you have the right features on your camera.

Zoom: The first thing to look for is optical zoom. The longer the zoom you have, the more details on the moon you can capture and the more impressed you will be with your photograph.

Metering: The next thing is to check out whether you have ‘spot metering’ function. Using a spot metering mode ensure that you have metered for the moon and not for the night sky. This will ensure that a fairly high shutter speed is used, prevent blur due to hand shakes, and also that the moon is not over-exposed and too bright.

Focus: This is a tricky part. Most non-SLRs use contrast detection. If you have a good zoom and you are trying to focus bang in the center of the moon, you will not go anywhere. You have to focus at the edges of the moon. The black and white contract is the best and your camera will pick up that very accurately.

Once you have all these, it just required a steady hand and you can start shooting. You can produce some amazingly sharp results if you use a tripod.

Tips: Full moon are the brightest and the easiest to photograph handheld. Half moon and crescents are the most interesting to photograph since you can see so many features of the moon along the illuminated edges as compared to a full moon.

Some photo of the moon from Flickr available for distribution under Creative Commons license.

 

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Photos of a Solar Eclipse – That’s How

In the previous two posts here and here, I wrote about how one should go about photographing a solar eclipse. I wrote about all the precautions and settings that one should take before going out and photographing an eclipse. It was time to practice what I wrote and I set out yesterday to photograph the eclipse over Bangalore. Below is a picture of the eclipse.

See a couple of other photos from the eclipse at my gallery

Taking photos of the eclipse is quite a strain in itself. It is a very tough job avoiding seeing the eclipse directly and still trying  to take its photographs. However, the instructions that I wrote about hold true and that is how I approached this task. More than anything, it is very important to not underestimate the brightness of the sun. Even at 85% coverage the sun was so bright that a photo without filters could not be had.

When you are out taking photos of anything but a total solar eclipse, go put a few goggles, ND filters or a solar filter in front of your lens if you want to get a good shot of the eclipse. Without that you will only get a very badly overexposed image and nothing worth cheering about.

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Calibrating a Camera for a Solar Eclipse

If you think you have very little time to capture a solar eclipse and don’t want to waste much time trying to adjust the settings on your camera during the eclipse itself, then here is a handy tip to adjust your camera to approximately the same settings as you would require while photographing an eclipse.
Remember, these preset settings will not work during the total phase of an eclipse, but is valid only for the partial phases.

The simplest thing that you can do is to set up your camera by trying to photograph the regular sun during the non-eclipse period. The intensity of light at the sun will more or less be the same during the entire eclipse period except when the moon covers over 80% of the sun and of course during totality.

Point your camera at the sun with the appropriate filters and/or stained glasses protecting your lens, and set it up. Reduce the ISO to the minimum, reduce the aperture size to the minimum, and increase the shutter speed to the maximum. If the sun is still bright and shiny and your photograph is over exposing, then the only alternative that you have is to add filters in front of the lens to cut down the light.

In case the image is underexposed and you have a lot of filters piled on, then you might want to try reducing the number of filters till you get a good exposure. Once you have experimented with the filters, trying increasing the aperture size on the camera. Leave the shutter speeds as it is, since the sun and the moon will be moving and you want crisp shots. Leave the ISO at the minimum, so that you get the best grain free shots. The only thing that you can adjust safely, considering that you are focusing correctly on the sun, is the aperture. Increase the aperture size slowly till you get an image with a good exposure, giving the camera a few seconds to adjust the the exposure after each change. It is easiest if you have a histogram to work with.
In case you are able to get a good exposure of the sun the first time, or once you get a good exposure after adjustments, remember the filters and the settings so that you can use them during the eclipse. When the eclipse is nearing totality, you will notice the exposure levels reduce and you have to then compensate by increasing the aperture and the ISO slightly when required. I would still recommend you keep the shutter speeds above 1/1000th of a second. Any slower and you risk blurring the scene.

The moment you are in totality, switch to low light photography techniques, as described in the other post on how to photograph a solar eclipse.

Note: Be warned that without adequate protection, you are liable to damage your eyes. Never stare at the sun directly. If you keep your camera and lens pointed at the sun for long periods, then you are liable to damage them due to over heating. Keep the camera and lens covered and take photos intermittently.

Technorati Tags: solar,eclipse,photography,filters,eyes,goggles

How to Photograph a Solar Eclipse

Jan 15th 2010 is a special day. That is the day when some parts of the world will see the longest annular solar eclipse in the last 1000 years. The next solar eclipse that will last as long as this will only appear somewhere around the year 3034. In India, the next Total Solar Eclipse is another 25 years away.

However this time, the eclipse will be visible from Dhanushkodi and the maximum coverage will be seen from Rameshwaram in South India. In a lot of other places in India, Sri Lanka, Africa and parts of China, the eclipse will be seen as a partial eclipse. In Bangalore, the eclipse will last roughly between 11:00am and 3:15pm with the peak at around 1:15pm.

For those of you who are fortunate enough to watch this celestial event, either partially or in totality, and who have a camera in hand, this is one opportunity to not be missed. Being able to record this event will preserve the memories of this event for years to come. However, there are certain ground rules that you have to follow to photograph an eclipse.

The first and most important rule of them all is to be safe and keep your eyes protected. Never look at the sun directly, or through supposedly safe objects such as x-ray film, stained glass etc. I understand that the safest way to watch the eclipse is to project the image of the eclipse onto a wall or a cardboard by means of a pinhole camera. If you intend to do any sort of photography, do get yourself a pair of special goggles that are meant to view eclipses. Never stare at the sun too long and take just the occasional glances. Read about eye safety here.

Once you have followed all safety guidelines, here are some tips that will help you take some stunning shots of an eclipse. An eclipse is meant to be captured in different ways and the techniques differ whether you are photographing a total eclipse or a partial eclipse or an annular eclipse. You first need to understand that your camera is not meant to take a photo of the sun by itself. The sun is a very bright object and most cameras cannot capture it correctly. You might be interested to reduce the intensity with which the camera captures the images by putting up a few ND filters in front of the lens. ND filters are used to cut out light and reduce exposures. Read about ND filters here. ND filters would be required when you are taking photos of the partial stage or the annular stage of an eclipse. During totality however, the way you shoot will be completely different and you have to resort to longer exposures to get those coronal streamers.

Any photograph of the eclipse where the sun is in the picture will be extremely bright and an image might not be formed correctly. Where the ND filter helps is to cut out the light and take a photo with a good exposure. If you don't have an ND filter handy, then you can make do with a dark glass. I prefer keeping a sunglass in front of the lens since I don't have an ND filter.

The important parameters to keep in mind when taking the photograph of an eclipse (except during totality) are minimum ISO, minimum Aperture, high Shutter Speed. Set these values on your camera if you have manual mode before you set out to do your photography. If your camera has a histogram function, you can adjust one of the parameters (preferably aperture) till you get a good exposure. If you do not have a camera with manual controls, then you could choose a scene mode like 'Snow photography' and let the camera do the rest. Snow photography involves a lot of light and a lot of reflection, and usually the camera does exactly what I mentioned before - reduce ISO, reduce Aperture size, and aim for the highest Shutter speeds. Remember, unlike fireworks photography, an eclipse will last a couple of minutes, even the totality phase lasts a few minutes, and you have ample time to get your setting right and get an awesome photograph.

In the case of totality the situation becomes different and it works almost like you are doing low light photography. However, in this case, I would recommend that you aim to keep shutter speeds as high as possible while adjusting all the other factors to get a good exposure. If you have Shutter Priority mode, there is nothing like it, keep the shutter at anything between 1sec to 4secs or more so that you can capture the coronal streamers. Depending on the duration for which your shutter is open, you have to reduce the ISO and the Aperture. The best photos of totality can be had when you take photographs using a tripod. While photographing totality, remember to take all the filters off, and do remember to force your flash off if you are shooting in any form of an automatic mode. You can also calibrate your camera in advance to photograph a solar eclipse.

Jan 15 2010 is the next solar eclipse and this post has been made in time for that so that you can keep your equipment ready to capture this awesome event. Happy shooting. Watch this blog for some pictures of the eclipse as long as the clouds in my city don't play truant.

Following are some images of the eclipse taken from Flickr. These images are licensed under Creative Commons and certain or all rights may be reserved.

Below are some links about this Solar Eclipse
The Hindu
Sify
Wikipedia

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We shall click again

Those of you who have been following my blogs in the past at blogs.prashu.com would remember that I used to run a photography blog. I removed this blog and many others due to lack of time and loss of enthusiasm. I just was not able to maintain so many blogs and I could not devote equal attention to all of them and had to take some of them down. As I took down the blogs, I realized that I was taking down my passion for that subject as well. If I don’t blog, then I wont learn. If I don’t learn, I lose enthusiasm for that subject. Subsequently I started losing the enthusiasm for photography.

A few days back, I decided to revive my interest in photography and started learning a few new techniques that I could try. Immediately, I felt the need to blog about it and let the world know how to try out those techniques. Well, blogging is definitely a part of my life and I can’t keep myself away from it for too long.

With that note, I decided to start afresh with a new photography blog. This blog wont be as beginner friendly as the previous blog. There are many photography blogs for beginners out there. This blog will be purely about how to take certain types of photographs that you would have seen but never knew how to capture. This blog will be mainly about photography tips and techniques. If you need more information on the basic aspects and why certain things are the way they are, feel free to drop a comment and I will respond to you there and help you would with your questions and doubts.

In the meantime, hope you enjoy Photography How Tos.

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