Understanding Exposure (by Calvin)
A fellow G35 owner and photographer did an excellent write up on our forum and I thought to share this with the aspiring photographers, or people that just want to understand a little more about how their camera works (even in auto mode behind the scenes).. Understanding these simple rules will help you to get more consistent shots from your DSLR, or non-auto programmable modes on your point and shoot.. Thanks for this Calvin.. Great job..
Understanding Exposure (G35Driver Edition)
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I've seen quite a few new members in this section, so I figured I'd throw this together to help get people started.
Two Ways to Control Light (ignoring ISO for now)
1) The shutter controls the duration of the exposure. A fast shutter speed (1/250 of a second) allows less light to reach the sensor than a slow shutter speed (1/4 of a second). The decision to use a fast or slow shutter speed depends upon the subject matter (i.e. if you're trying to freeze motion, use a fast shutter speed).
It should be noted that your camera will often display shutter speeds as whole numbers, even though they represent fractions of a second. For example, if you're camera displays 250, it is actually 1/250 of a second.
2) The aperture controls the intensity of light reaching the sensor. A small aperture (f/22) allows less light to reach the sensor than a large aperture (f/2). The decision to use a small or large aperture depends on the available light for exposure and the decision to use a great or small depth of field.
Shutter Speeds (in whole stops)
1 | 2 | 4 | 8 | 16 | 30 | 60 | 125 | 250 | 500 | 1000
slow shutter < more light fast shutter > less light
*Note: Cameras typically show shutter speeds in between full stops, too. For example, my camera has 640 and 800 between 500 and 1000.Aperture Values (in whole stops)
1.4 | 2 | 2.8 | 4 | 5.6 | 8 | 11 | 16 | 22
large aperture > more light
small aperture < less light
*Note: Cameras typically show aperture values in between full stops, too. For example, my camera has f/3.2 and f/3.5 between f/2.8 and f/4.Opening up & Stopping down
A stop is equal to one unit of exposure; it is equal to halving or doubling an exposure.
1/60 of a second allows twice as much light to reach the sensor as 1/125 of a second - this is one stop. Going from 1/125 to 1/60 is opening up one stop.
1/500 of a second allows half as much light to reach the sensor as 1/250 of a second - this is one stop. Going from 1/250to 1/500 is stopping down one stop.
f/5.6 allows twice as much light to enter the camera as f/8 - this is one stop. Going from f/8 to f/5.6 is opening up one stop.
f/16 allows half as much light to enter the camera as f/11 - this is one stop. Going from f/11 to f/16 is stopping down one stop.
Opening up one stop will double the amount of light reaching the sensor.
Stopping down one stop will halve the amount of light reaching the sensor.Law of Reciprocity
Exposure = Intensity * Time
Recall that aperture controls the intensity of light and shutter speed controls the duration of the exposure.Let's say that f/16 * 1/250 gives you a correct exposure. Any change in aperture or shutter speed will give you an incorrect exposure. If you change the aperture to f/11 and keep the shutter at /125, then the resulting image will be overexposed by one stop. The Law of Reciprocity says you need to reciprocate by changing the shutter speed to 1/500 (one stop) to compensate. Remember that going from f/16 to f/11 you are opening up one stop (more light), so you need to go from stop down from 1/250 to 1/500 (one stop). This will maintain the balance and keep the correct exposure.
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So let's say I'm getting a correct exposure at f/4 * 1/125 (remember, the table and your camera will show this as just 125, without the 1/___).
What would my aperture be if I wanted to open up two stops? And what shutter speed would I need to use to compensate for this change in aperture while maintaining a correct exposure?
Photo Challenge Week 1 (G35Driver.com) – Bottle(s)
The theme for the week of the G35Driver.com weekly photo challenge was Bottle(s). I decided to take this opportunity to really think out what image I wanted to portray. What size bottle? Color? Shape? A bottle can be simple and elegant, colorful and elaborate.. Did I want to capture more functionality or art?
Well of course I had plenty of questions in my head but then it came to me. I wanted to take a commercial shot. Like really try and make it look like it was for a magazine spread. I even took the time to make a product box. This gave me the opportunity to really experiment with my flashes off camera.
After tampering with the flashes position, I finally settled on a traditional 1 flash highlighting the background, and my main flash overhead to highlight the product. This gave me that really clean, high-pass, vibrant look that I was after.
I placed the subject to the left of the frame as if it were going to have typography on the right side of the "ad". I also added a bit of allure and mood by splashing some water on the bottle and letting it pool at the foot of the bottle. This was added to give the viewer someting interesting to think about througout the journey down the bottle. The reflection was due to plastic laid down at the bottom of the product box.
I'd say for my first product box shot, this turned out pretty well and exactly how I intended..
Canon 7D
Tamron 28-75
ISO200
F10
50mm
1/200
canon 430EX II (1/8)
canon 550EX (1/4)
onboard flash (-1) exposure comp
Checklist For Purchasing A Lens
I've been asked the question "What do you check for when buying a lens?" or "Is this a good lens?" more than once, and the question came up again today when a friend was buying a used lens.. So, I thought I'd share what I check for when buying a lens, new or old. Of course some of the items on the list are for zoom lenses only, but most can be attributed to lenses in general, zoom or prime.
1. Bring your camera body with you so that you can test the focus of the lens.
2. Inspect for dust and scratches on the lens surface and body. Chips and knicks aren't good especially if you plan to sell the lens as well one day. And of course you don't want dust and scratches in your shots, that will just increase post production time later.
3. Check for fungus or debris on the ring edges of the lens. Lens fungs is a BAD thing, you don't want to deal with that. I wouldn't advise buying a fungus infected lens regardless of the price. It only gets worse. Check out the length one photographer goes to avoid fungus.
4. Shake the lens, to make sure there are no loose elements, you should hear NO rattles (if you do, the lens has most likely been dropped or the person has used the lens a LOT zooming in and out) The damage done is normally the lens won't shoot as pin point as it did when it was newer because one of the elements isn't perfectly aligned anymore and the light isn't directed properly.
5. Check for loose switches as well.
6. Make sure the zoom ring and focus ring move smoothly throughout the focal length, and there are no areas where it "catches" or is hard to turn.
7. Hold the lens straight up, zoom at various focal lengths and ensure the weight of the lens doesn't close the lens back down a lot (this is called zoom creep, in cheaper lenses, this is common and unavoidable, it's just the build quality you get with cheaper lenses.) You can also do this holding the lens straight down. Open it slightly, and see if gravity opens the lens all the way or if it stays at the focal length you opened it to.
Then put the lens on your camera:
8. Check for is back focus or front focus issues.
(You'll have to use your LCD on the back of your camera for this)
Focus on something and then check the results in the LCD. If the lens focuses on the thing you expected it to, you're good. If it focuses on something in the foreground, you have front focus issues, if on something in the rear, back focus issues.
9. Focus on something far away and see how fast the lens autofocuses, then do the same for something close up. Do this at the short and long ends of the lens and ensure it's to your liking. In some photography, such as sports, you'll want a fast autofocus, and if the lens isn't quick, you could potentially lose a lot of shots. Also listen to the sound of the focus motor, is it too loud? You don't want to be obtrusive if shooting at a wedding with a loud focus motor.
10. Then I'd shoot at F4 to see how sharp the image is (that's normally the sweet spot for most lenses) It should be pretty sharp all the way to the edges
BONUS TIP: Ask for the box, and any warranty cards for the lens. Ask if there was a lens hood and make sure you get both lens caps (front and rear).
Hopefully this list will come in handy for you.. These are the things that I check for when I'm purchasing a lens. Don't let a slightly used lens scare you. You can easily determine if a lens is "LNIB" (Like New In Box) or "slightly used" as advertised by following this simple checklist. Don't be naive and think a new lens is perfect either.. Sometimes lenses can come defective from the factory, so don't be bashful, use this list on new lenses as well..
World’s Largest Image – Dresden
In order to truly appreciate this, you must read what it took to produce this 106 GIG (that's the file size, most images shot w/ a digital SLR are 2-4 MEGS) image..
That Robot took pictures of a Dresden panorama for 172 minutes straight, resulting in 1,665 photos. Each photo carried 21.4 Megapixels of data [by default, EOS-5D gives out 21Mpixel image i.e. 5616 x 3744 pixels - but A.F.B. media GmbH used almost all of 22Mpixels thanks to Full-Frame sensor, Ed.]. End result was 102 GB of images, stitched together on a heavy-duty quad-socket workstation packing 16 processing cores and 48 GB of memory. For this daunting task, it took 92 hours of full 100% CPU load across all cores but the result of this is a staggering image in majestic 297.500 x 87.500 pixel resolution - 26 Gigapixel.
Then check out the resulting image.. It's simply amazing.. Click on the squares below the main image and look at the depth of detail you gain as it zooms.
Tony/Yash Car Shoot – North Dallas
Met up with my friend Yash from the G35Driver forums. We are both passionate about photography and the emotion that it provokes. We're also really into our cars and frequently use our modified Gs as subjects. We shot at a few locations in the Uptown location and Deep Ellum.
It was an experience to say the least. During the shoot, we attracted several onlookers one of which was a van driving down the street and slowed down to observe. Unfortunately, the driver of a new C-Class Benz wasn't paying attention and rear-ended the van. At another location, we were greeted by the publishers of a local teen magazine and asked some information about us to feature us in their next issue.? They took some snaps of our cars as well.
Canon 20D/ISO 200/ Canon 18-55 f3.5-5.6/ Canon 430 EX II flash
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Halloween ‘09
Well, Halloween is among us.. This is time for some of us to either put our masks on, or take them off.
Our family has a yearly tradition of going to the "Boo on Ballard" event, which allows small local businesses to hand out candy to kids as well as promote their companies.. The kids love it and it provides a safe and organized environment for kids of the community.
We had a blast as usual and Anthony (Darth Vader) and Aric (Snake-Eyes) had a couple of friends join in on the fun, of the Dawkins family, Aleena (Daphne) and Amaya (Scooby-Do).
Canon 20D (ISOs 200 and 800) / Tamron 28-75mm f2.8 lens/?Canon 430EX II external flash
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Anthony’s Fall Show
Went to Tibbals Elementary today at 7pm to be treated to watch 160 Kindergarteners sing in unison. Actually, it was very VERY good. (Not just because my son was in it). I was expecting to hear at least ONE bad note, but I was amazed that the whole show went without a hitch. The kids remembered their lines and all. There were several brave 5-6 year olds that had multipart rhyme speaking parts that lead us on a journey through the "Colors of Fall". They discussed, Red, Green, Blue, Yellow, Orange, and Purple, then put them all together for a RAINBOW. It was a lot of those kids' first time in front of an audience and they did EXCELLENT. My Dad came out to see the festivities and was amazed. He shot the whole event on our HD camera and I covered w/ the 20D of course.
Canon 20D (ISO 800) / Canon 75-300mm f4-5.6 III
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