Archive for the ‘Photo Tech’ Category
Lunar Photography – getting the correct exposure
"Man in the Moon" taken during a partial lunar eclipse
Next Full Moon – March 29, 2010
I recently had a customer ask me the best way to photograph the moon. It seems that they never could see any detail in the moon (overexposed) and the overall image was dark. First, the moon is much brighter and takes up a small portion of the image – the camera meter gets fooled since it sees all the darkness and sets an exposure that washes out the moon. Second the variation between light and dark values is beyond what your camera is capable of capturing in a single shot. We’ll talk about a fix to this problem later on . . . a little trick that involves using an imaging program like Photoshop Elements.
To capture the full “Man in the Moon” effect is easy to do by setting your camera manually to expose for the moon. We set the camera manually because your camera’s metering system usually gets fooled. Setting your camera manually eliminates this exposure error – the moon is always lit with the same intensity with the exception of solar eclipses.
For the complete “Man in the Moon” look, we suggest the following exposure – ISO 100 -1/125th second @ f/11When the moon is not full it is also very easy to get your exposure. Since a half moon is half as bright you just need to open your lens up by one more stop which lets twice a much light in – ISO 100 – 1/125th second @f/8. Using the same convention a 1/4 moon would require 4x as much light as the full moon or 2 stops more light and a setting of 1/125th second @ f/5.6. A tripod is always a great option for the sharpest shots especially when using a telephoto lens.
A Black Cat exposure guide (pictured above) is a great tool that lists manual exposure settings for more than 100 scenes. Just choose your scene – line up the scene code to your ISO and just set your camera to one of the displayed f-stop and shutter speed combinations. The Black Cat Exposure Guide is a must for anyone into time exposure and existing light photography. We stock the Black Cat Exposure Guide in Westwood & Englewood.
Getting both the moon and your scence exposed correctly in the same image is easily accomplished by compositing a properly exposed image of the moon with a properly exposed night scene in a program like Photoshop Elements.
Questions – Stop by, email or give us a call. Comments? Let us know if you liked this post. What other things you would like tutorials about?
How to get white snow – Winter shooting tips
Why are my snow pictures dull grey?
Here’s the first in some winter picture taking tips that we are putting together. A common complaint we hear when people bring their winter pictures in is – “my pictures look dull,” “the snow looks grey, not white.” Read on for the short and the long answer.
The picture you see is the one above with white snow . . .
The more technical answer
This is all caused by a camera’s meter system which is designed to see “18% grey” ( the solid gray image to the left ). Essentially anytime you take a picture that is predominantly white or black the camera will make the wrong exposure. Since the cameras meter can only see grey, an “average scene”, we only need to make adjustments when our scene is predominantly white or black. Luckily 98% of what most of us shoot are scenes with average lighting values and need no adjustment.Using histograms to further understand
A histogram is just a map of the tonal values in our image from black (left most point) to white (right most point) with the height representing how much of the image is at a particular level of brightness. Your histogram will look the same in camera and when you open that image up in your imaging program.
^Black Middle^Grey White^
In the grey snow example above our histogram has a good deal of room before the white point on the right so the image represented by this histogram is a shade of grey not white. By overexposing one stop ( +/- +1.0) the camera automatically adjusts and allows 1 extra stop or twice the amount of light. As you can see from the histogram below we still have a small amount of room before the white point (this room indicates we have not blown out our highlights. If this histogram started all the way to the right and did not build to a peak, this would indicate over exposure and blown out highlights. The fix would be to reduce the exposure compensation from +1.0 to +0.7 and check again. The peak will move to the left each time you reduce your exposure. More on histograms in an upcoming tutorial.
Please let us know what you think of this tutorial and let us know what else is causing a challenge in your photography.
Phones with cameras and cameras with phones and so on and so on…
I’ve had a lot of customers stop by the shop recently and ask if we can print photos that they’d taken with their cell phone. It’s definitely a do-able process, though it’s not easy.
First and foremost, your image quality is going to be sloppy at best. The imaging sensor in cell phone cameras is small – smaller than any pocket sized digital camera. Even at 4×6 it’s going to be an extremely pixelated photo. Cell phone images are generally meant for sending in phone messages or uploading to the net.
If you aboslutely need to print an image from your cell phone, check to see if your phone will accept a memory card. Most modern, mid-to-high end cell phones will take some type of removeable flash memory. If that’s the case, get the images copied over to the memory card and we can pop it into one of our photo kiosks and make some prints that way. Nice and simple.
If your camera doesn’t take a memory card, your next best option is to get it onto your computer and email it to the store. Getting it to your computer is the hard part – you need to make sure you have the correct cables and/or wireless connection. Some phones and computers are able to connect to one another via Bluetooth, which is a quick and easy way of transferring files.
Memory Cards – Speeds, Sizes, etc.
Memory cards are now coming in absurdly large sizes. Compact flash cards are available up to 64gb capacity and SD cards come as large as 32gb. Unless you’re doing high-def video, a memory card of that size is total overkill. Instead of getting one large memory card, I suggest multiple smaller cards. Don’t bring one 8gb SD card with you on vacation – instead bring either 2 4gb card or 4 2gb cards. The more the merrier. Imagine taking 1000 images during your once-in-a-lifetime Italy vacation and losing or damaging your 8gb card? Doesn’t sound like a good time to me.
When purchasing a new memory card, keep your eyes open for the read/write speed of the memory card itself. Many of the cheaper memory cards are 15 or 20x read/write speed. A memory card of that speed will greatly increase the time between taking photos on a digital camera – a VERY common complaint amongst consumers. Make sure you get a card that’s at least 60x speed. Again, with this one, the more the merrier. Faster cards = more money, but it’s worth the price.
Do JPEG’s break down?
Numerous cameras nowadays have the option to either create images in a JPEG format or an uncompressed format, such as RAW or TIFF. I’ve been asked many times to suggest the best format for image files. In a way it’s a lot like choosing a camera – it all depends on what you’re going to do with it.
Yes, over time JPEG files will break down, but only if you open the file, edit it, and re-save it again as a JPEG. Simply opening a JPEG file will not cause it to lose information. JPEG files are considered lossy files – the computer will discard what it deems useless or unnecessary information.
On the other hand, uncompressed files do not lose information, no matter how much work you do to it. They’re much larger files but can retain all of it’s original information. There is a slight difference in the initial image quality when shooting in RAW – there will be more information retained in the highlights and shadows and a slight boost in your color information.
RAW files require additional software (as well as additional editing time) in order to be printed. Always keep that in mind when shooting in RAW. If you shoot 300 images from your summer vacation in RAW be prepared to convert every single one of those files to JPEG before then can be printed.
Do you like to print on your own? Do you want to get knee deep in the photo editing process? Then an uncompressed format is right for you.
Not much of a computer person? Would you prefer sending your images to get printed at a lab? Then JPEG is for you.
Both JPEG and RAW work for me. It all depends on the occasion.
