Nailing the Exposure (2 of 3)

Today we'll be discussing the second of three variables, ISO.

ISO goes back to the film days when different films had different ASA/ISO speeds. You could buy a film with an ASA/ISO rating of 16, 50, 100, 400, 3200, etc. You could "Push" the speed of your film while sacrificing image quality. ISO back then referred to the sensitivity of the film to light and in today's digital world refers to the sensitivity of the image sensor to light.

A higher ISO speed/setting means more sensitive to light (brighter image, all other variables held constant) and a lower ISO implies less sensitivity to light (darker image, all other variables held constant)
You can test this out my setting your camera to Manual mode and setting any aperture/shutter speed. As you increase your ISO you'll notice that your exposure becomes brighter. Of course, as with the other two variables (aperture and shutter speed) ISO has both its pros and cons.

ISO is the first variable that I change whenever I enter my shooting environment. Using ISO 800-3200 when I'm indoors with artificial light and ISO 100-400 when I'm outdoors with plenty of sunlight. I think it's pretty self explanatory why, but if you haven't caught on… Use a lower ISO when there's plenty of light, because you'll be able to maintain a good aperture/shutter speed at pretty much any ISO and a higher ISO when you have poor lighting conditions, because you want your sensor to be more sensitive to light in order to obtain a better aperture and shutter speed.

Pros of ISO
As mentioned earlier, ISO is the first variable that I set. A higher ISO allows me to increase my shutter speed or aperture than a lower ISO would allow. Think about darker environments when you need a 1" shutter speed to get a good exposure at ISO 100. Definitely not hand holdable and if you're caught without a tripod, good luck with the shot! But by increasing ISO to 1600 or so you can maybe squeeze off a 1/15 shutter speed that is handholdable with good technique.
I know you're thinking now, so why can't I just use any ISO that I want and always have a faster shutter speed or stop down my aperture? Well, here come the cons.

Cons of ISO
If we could shoot at any ISO we wanted with no trade off to image quality, all photographer would rejoice and there would be no need for new cameras with better high ISO capabilities and we'd all be a happy bunch. The biggest trade off of higher ISOs is image quality and noise. As you increase your ISO, your image quality will go down and you'll start to see noise or graininess in your photos [especially in shadows and dark spots]. Newer cameras are getting better and better at having better image quality at higher ISOs and that is one of the biggest upgrades that newer, more expensive cameras give over the older cameras [high ISO, low noise]
Although, noise can be decreased by ensuring that you "nail your exposure" (what we're trying to accomplish here). Because perfectly exposed images tend to have less noise than underexposed/overexposed images.

Quick summary:
Low ISO, GOOD; High ISO, BAD [in terms of image quality]
Low ISO, darker & less sensitive; High ISO, brighter & more sensitive [to light]
ISO 100-400 outdoors (100 on sunny days, 400 when cloudier or closer to sunrise/sunset)
ISO 800-3200?6400?12800?25600? indoors (unless you have a D3, D3x, D700, or 5dMk2 I wouldn't suggest shooting over ISO 3200 :] )

A quick example:
This image was taken at ISO 800

ISO 1600

ISO 3200

ISO 6400

Get it now? :) Next time we'll be covering the third and final variable to exposure, shutter speed.

Gear Changes

You may notice that I've shifted quite a bit of my gear around. Thought I'd do a small rewrite of my first post about my gear.

Changes that have been made in the past few months:
Sold D200 body for D90 body
Trying to sell Tamron 17-50 f/2.8, replaced by Nikon 17-55 f/2.8 AF-S
Sold Nikon 80-200 f/2.8 AF-S for Nikon 70-200 f/2.8 AF-S VR
Bought Nikon 55mm f/3.5 AI'S

Sell Nikon D200 body for Nikon D90 body.
Back in August, Nikon released the new D90. The first ever dSLR to offer HD video recording capability. I remember a year ago when I told myself, man I wish my camera could take video like a point and shoot. Fast forward a year and here we are with my new D90 that can record at 24fps @ 720p HD resolution!!! It was a big decision to make between the D90 and the D200. The D90 adopted the same sensor from the Nikon D300 (Nikon's current professional DX body) and has a lot better low-noise, high ISO performance. I feel that the files are usable up to ISO 3200 with less sacrifice to image quality. It may be important to note that the video capability was definitely a perk, but not the main reason for buying the camera. One big sacrifice I made with the D90 is build quality. The D90 is built well, but definitely not 'like a rock' like the D200 is. Because of the switch, I also converted back to SD cards from CF. I also had my MB-D80 battery grip from my D80 lying around (wouldn't sell on forums) and it just so ended being compatible with the D90 so another plus!

Nikon 17-55 f/2.8 AF-S over Tamron 17-50 f/2.8. Don't get me wrong, the Tamron is a true performer!!! The Nikon is slightly sharper and has slightly better color rendition, but it's fair to say these lenses are optically close. The big perk was in build quality. The Nikon feels sturdy and tough. I would not fear damaging the lens. Ultimately the reason why I switched was because I found the 17-55 at such a steal that it was worth the $300 difference to upgrade.

Nikon 70-200 f/2.8 AF-S VR for 80-200 f/2.8 AF-S. Will never look back to the 80-200 AF-S. I thought that that lens was sharp… the 70-200 will blow it away by a mile! This baby is razor sharp at 2.8 and only gets better by stopping down. The addition of VR is incredibly helpful as well; especially with recording videos. Also found this lens at a great price and was able to sell my 80-200 so I jumped on it.

Nikon 55mm f/3.5 AI'S. Cheapo, old-school, manual focus lens. This lens is just FUN! The ability to use it as a 1:2 macro lens and practicing my manual focusing skills are a definite plus. This lens actually does not meter on my D90 so I need to guess and chimp for my exposure. It's fun to try and guess what settings to use and see how my exposures are. Definitely a learning lens. Also is great on my N90s film camera.

That's all for now, stay tuned for part 2 and 3 of Nailing the Exposure: Shutter Speed and ISO.

Nailing the Exposure (1 of 3)

As mentioned before, there are three key components to exposure. Aperture, ISO, and shutter speed.

Aperture is the size of the opening (allowing more or less light in to the sensor)
ISO is the sensitivity of the sensor to light
Shutter speed is how long the shutter remains open (mirror up, mirror down *CLICK*)

A typical analogy is that of a hose. Aperture is the size of the opening of the hose, ISO is the quality of the hose and shutter speed is how long the hose is left open to let water in/out.

Each variable works together in creating the exposure, but each has its pros and cons. In this post, we're going to focus on aperture.

Aperture
Aperture, as mentioned before, is the size of the opening. This variable is typically measured in f/ stops and is limited by the lens that you use. A smaller f/ number, means a larger opening. Counter-intuitive, I know. Each lens has its own "maximum aperture" which is the smallest f/ number that it can be stopped down to. The lower the f/ number, the more expensive the lens typically is.
There are two types of lenses: fixed aperture and variable aperture. Fixed aperture lenses have one f/ number and remain at that f/ number throughout the zoom range. Variable aperture lenses are found typically on lower-end zooms / kit lenses. These have a maximum aperture that changes as the focal length/zoom changes. (e.g. a 18-55 f/3.5-5.6 lens will have a maximum aperture of f/3.5 at 18mm and f/5.6 at 55mm. The max aperture at 19-54mm will be somewhere within 3.5-5.6)

Enough about the technical stuff. Let's get to the nitty gritty.
Aperture affects how much light comes in and depth of field.
A bigger aperture (smaller f/ number) allows more light to enter. Allowing you to use a faster shutter to capture an image. Therefore, bigger aperture = brighter, smaller aperture = darker.
Which raises the question, "Why would I ever want to lower my aperture? Don't I want a lot of light?" leading us to the next effect that aperture has on the image: depth of field.
Depth of field refers to the "depth" of your image. Ever see portraits where eyes are in focus and ears are out of focus? The blur is caused by a large aperture (small f/ number). A larger aperture will reduce your depth of field (make more shallow). f/1.2-f/2.8 will give you great subject isolation, but are difficult to use at times because a slight error will cause your image to be out of focus, because the depth of field (dof) is so thin/shallow. For group shots, you'll typically want to use an aperture of f/4 or lower to make sure everybody's in focus and for landscapes you'll want to use f/8-f/11 to ensure that EVERYTHING remains in focus.

Getting Started

Why buy a dSLR you ask? Digital SLRs provide the high quality photos that [film] SLRs provided long ago with the capability to instantly review images and have them on your computer easily without having to develop and scan film. dSLRs are still a bit behind the superb quality that film has, but with newer full-frame cameras like the Nikon D3, D700, Canon 5d mk II, 1D mk III - film-like quality is almost attainable.

dSLRs provide several advantages over standard point and shoots.

• Complete control over your camera. The ability to set shutter speed, ISO, aperture, and color balance. This insures that you get the best image possible [technically speaking]
  
• Higher FPS [frames per second]. Love to make flip books? Take action shots? Here's where FPS is handy.
  
• High quality images. A common misconception is that the more megapixels the camera has, the better quality the image will be. In fact, it is the sensor that determines the image quality. Megapixels simply determine the pixel density. dSLRs use larger sensors than standard P&S [point and shoot] cameras yielding greater quality images.
  
• Interchangeable lenses. I have a different lens for every occasion. The fisheye for ultrawides and fun, a zoom for a nice walk-around lens. My 85mm f/1.4D for portraits. Each lens plays its part as a brush does for a painter.
  

Once you decide to get your dSLR there are a few things to know.

There are four modes that you should typically shoot in. P, A/Av, S, and M. These stand for Program, Aperture priority, Shutter priority, and Manual respectively.

Beginners, please skip the AUTO mode of consumer dSLRS and feel free to set your camera straight to P. The camera will adjust everything but the ISO.

Aperture priority is where you set the aperture and ISO and the camera will automatically adjust the shutter speed.

Shutter priority is just the opposite. You set the shutter speed and ISO and the aperture is automatically chosen for you.

Manual mode is where all three variables are set manually and the exposure is completely in your hands.

Metering

There are traditionally three types of metering: Matrix, Center-weighted, and Spot.

Matrix metering pulls information from the whole scenes and attempts to expose the image according to the entire scene.

Center-weighted metering exposes the image for the central area of the image.

Spot metering will meter for the center of the frame and nothing else.

White Balance

Auto white balance may be a good place to start. Advanced users can venture into shooting a grey-card to preset white balance or tweaking the white balance through menus. One last alternative that I highly prefer is setting white balance on the Kelvin scale.

The Kelvin goes from 2,500K - 10,000K (2,500 being cooler and 10,000 warmer) Tungsten lighting tends to be around 2,800K. Fluorescent 4,000K, and Daylight 5,700K.

That's all for me for tonight. Until next time!

Random Shoots

Have had a lot of random shoots lately. A lot of small group pictures and a random shoot with Limee.

I've recently upgraded to the Nikon 17-55 AF-S f/2.8 from my Tamron 17-50 f/2.8 and I am loving it.

Coming soon: Writing a beginner's guide to exposure (ISO, Shutter Speed, Aperture) am hoping to shift this blog into a semi-beginner's guide to dSLRs and photography.

Here are some of the pics from my recent shoots.

Turkey Run State Park, Indiana with Small Group




Photoshoot with Limee

Fall is here

Been extremely busy with school, church, job search, studying for actuarial exams, etc.

I wish I had a lot to shoot, but I don't

Here's a couple from a short walk I did with my new 55mm f/3.5 AI's Micro lens.

Manually exposed with manual focus.

And fall comes

D90!

Pics of my D90 unboxing

September 8

John 15:5 I am the vine; you are the branches. If a man remains in me and I in him, he will bear much fruit; apart from me you can do nothing.

September 7

My normal view

Roommate, Brian Cho, from behind

September 5

Coffee House!

Mikey explains the game to the freshmen

September 4

Cookies!

Made these for small group

Day #2

Already missed a day because of vacation. Currently studying for my first exam (can you believe I already have an exam?!) Will try and take a picture later and post it up

Current participants:

• Danny Kim
  
• Peter Kim
  
• Steven Lee
  
• Daniel Kang
  

  I'll be shooting with my D200 and 50 f/1.8D, but hope to have my pre-ordered D90 later this month!
  

Nikon D90

I'm seriously considering picking up the new Nikon D90 that was announced this morning. I've been itching to jump for the D700, but the price has held me back. I'm looking forward to both low-noise high ISO performance and playing with the video seems fun too.

Heading out to Las Vegas this weekend and I'll be making my final decision then. Let me know if any of you see the D90 for sale anywhere (I'd prefer Amazon, B&H, or Adorama so I don't need to pay $80 in tax).

Keep on the look out for Vegas photos and my final decision on the camera :)

BTW: I've started posting via MS One Note because I randomly stumbled upon it.
So far so good.

September Prime Challenge

I know it's been a long while since I've posted, but I've been busy with moving, driving up and down from Champaign to Chicago, and attending various retreats.

Been shooting a bit lately.
Pics from Evanston Beach, Indiana Dunes, Botanic Gardens, Chicago, and a few randoms.

For the month of September, Peter Kim, Steven Lee, and I are doing a ONE PRIME challenge.

The rules are as follows:
Can only use ONE prime for the entire month (My weapon of choice is the 50mm f/1.8D)
Must take at least one picture a day and post.
The goal is to learn how to think differently by being stuck with only a prime.
The only time a different lens is allowed is for gigs/events.
As an additional stipulation, I am also manual focusing only on my D40.

If you want to join me, leave a comment with your blog and we can keep each other accountable.

DIY Flash Gel Filters

This summer I acquired a lot more strobes and my lighting kit as well. Been trying to and meaning to experiment a lot with it.

One of the first things I did was to go out and make my own gels/filters and figure out a way to mount them.

Gels are handy for many different things. You can use Tungsten/Fluorescent (Orange/Green) gels to change your flash's color to match the ambient and to set your camera's WB accordingly.

Beyond that, I ordered these nice little gel samples from B&H and they gave me about 40981 different colors. They're having a hard time keeping them in stock though. I'd suggest signing up for e-mail alerts to increase your chances.

Without further adieu...

Materials Required:

• Name tag holders
• A knife, scissors, Xacto, box cutter, etc.
• Gels!!!
• Velcro
• Common sense

Now on with it.

1. Cut the name tag holder to a size that will fit over your flash head

2. Add velcro to the ends of the cut out piece and to your flash head.
I used the soft end on the tags and the hooked ends on the flash head

3. Insert Gel into the nifty little holder you made and place on flash

4. Enjoy!

Here are just a few samples:

Danny Kim and Nancy Hwang eSession

I met Danny my freshman year at the U of I. He was my co-leader my freshman year and the craziest person I know. From singing crazy songs, to giving rides to drug dealers, this guy is the real deal :). I met Nancy earlier this year when I ninja'd the proposal. I had a great time shooting for them at Northwestern and Evanston (first eSession!).

Best wishes to the both of you on your upcoming marriage!

Weekend Shoots

I'm currently at home in Chicago to do a couple of shoots.
Shot with Danny and Nancy who are set to get married on August 9th!
Hit up Northwestern campus and Evanston beach and had tons of fun.

Today I'm heading up to the Botanic Gardens and shooting for my sister and her sorority sisters. Should be interesting.

Will definitely post some pics up when I'm back on campus.

Look forward to a post on DIY flash gel/filters and practical uses (as seen on Strobist)

Have a great weekend!

The Circular Polarizer

When starting photography I heard all this chitter chatter about filters, all these different types, sizes, pros, cons, etc.
There were UV, skylight, CPL's (the topic of today's post), ND, color, etc.

I started out using UV filters for protection, but then now I simply resort to lens hoods to protect my front element. If I'm caught in a sandstorm, maybe I'll throw on my UV filter.

The circular polarizing filter (CPL) is an incredibly useful tool to have handy in a kit.

It can cut reflections in glass and water, give skies a deep blue look, and also serve as a faux ND filter and cut a stop of light if conditions are too bright.

Here are just a few samples of what a CPL can do.













All of these were shot at similar settings with the only difference being a turn of the CPL filter