Filters and flare

They say that it's best to put on a filter on your lens to protect it. It's cheaper and more effective than having camera insurance. There have been hundreds of stories on the internet where multi-thousand dollar lenses were saved from crash/drop by putting cheap UV filters (and/or hoods). However, filters come with a price-- decreased image quality. Adding an additional glass means the lens will get flare more easily. This is especially true when shooting directly into a light source where the light source becomes a flare at the opposite side of the frame. Below is an example of a green flare, thanks to a cheap UV filter, when shooting into the moon:

Adding a filter also means decreased of light going to the camera. A cheap lens today in general will allow 90% of light source going through, and a really high end one will allow 99% going through. However, this is actually quite negligible. 10% is miniscule compared to how much aperture I can open up or how high ISO I can crank up in today's modern DSLRs. Each stop means 50% or 200% difference, so the decreased of 1% to 10% of light is a non-issue, at least for me.

Going back to the issue of image quality -- this is a real concern. Below is a wonderful HDR picture that Ping shot in Alaska with a B+W UV MRC filter. Notice the green flare to the left-bottom corner of the pictures. Personally I think it is fine as it adds some artistry to it... in fact often times people add in fake flare in Photoshop to spice up their pictures.

On the other hand, real flare can come at inopportune moments when you least want them to exist. In my past I never really cared about flare until one day, I came back from from a wedding shoot, and was horrified at a bunch of green flares on people's faces. They're shot using my amazing Sigma 50mm f/1.4 but sadly mis-paired with a really really cheap 77mm Hoya 81A filter! "Why on earth would you use a 81A filter at night" you may ask? Because I didn't have any other 77mm filter at the time, and shooting without a filter while I run around doing event photography is utterly out of the question for me.

The first example below is acceptable because the flare is not interfering with the subject. It just so happened that none of the green flare got on Jennifer, yay!


However, subsequent examples are where I really didn't want any flare to occur, but I did not realize that it was happening at the time since I was too busy shooting and I didn't have time to chimp the LCD. Moral of the story: chimping IS GOOD FOR YOU! Sometimes.
All of this of course could have been mitigated by 1) using a flash and blow away all warm natural lighting [thus rendering the color out of whack and will need to turn night pictures into black and white] 2) using a higher quality filter 3) not using a filter 4) not shooting into the light source (candles). On the other hand, I really wanted to capture the candlelight to emphasize that all these shots were made possible with nothing but natural candle-light. Most photographers will just opt for 1) because flash is a lot easier. Capturing natural candlelit subjects usually requires 1600-3200 ISO, 1/30 sec, f/1.4-2.0 (below EV2)... or pretty much at the limits of what steady photographers can hand-held AND pushing the technological limits of today's DSLRs sensors.

In short, not all filters are equal. I have compiled a list of the filters that I've been using below and some examples shots. The first row shows examples of NO FILTER. Subsequent rows show the 77mm Hoya HMC 81A, 77mm B+W 010 UV Haze MRC x1, 77mm Hoya Super HMC UV(0), 72mm Hoya HMC UV(N) and just for kicks a 77mm Hoya NDX8. The second column shows the reflection of the filter and a full-spectrum CFL light source (rated at 94 CRI) where you can look at the colors of the filters. The last 2 columns show an example of shooting into the light source, and the flare on the opposite site of the frame. Are of them were shot using a Nikkor 85mm f/1.4D (portrait lens) on a tripod:

In short, I had a very high expectation of the German made 77mm B+W 010 UV Haze MRC x1 and I was very disappointed with it. People on the internet seem to say that it is great... that it is what German engineering is about. However, my tests show that it simply blows. In fact it is *MORE* expensive than the Japanese made Hoya Super HMC, and performs as badly as the cheap Hoya [regular] HMC. Personally, I've never been impressed with the value/cost ratio of BMW cars vs. Lexus, and this test just made me feel the same about B+W vs. Hoya.

One last note. I didn't cover color range and IR/UV accuracy. I've seen tests that show that the Hoya Super HMC blocks way more IR and UV that it is suppose to thus creating color shifts, and that the B+W MRC has a much more accurate IR/UV block off points. However, without instrumentations I can't validate those tests. If color is a more important issue than flare, perhaps the B+W MRC is a better choice. Trade-offs.

P.S. For more formal results you can visit an external link here:

http://lenstip.com/113.4-article-UV_filters_test_Description_of_the_results_and_summary.html

Modular Transfer Function (MTF)

Courtesy of Norman Korman (http://www.normankoren.com/Tutorials/MTF.html)

I was going to post this long time ago but today I'm motivated to finish it because a friend asked me "I have a 15MP Canon T1i camera, should I buy a Canon 18-200mm f/3.5-5.6 IS to replace my 18-55mm version?" Well, it depends. If the lens will give flexibility when shooting kids from wide to zoom, AND it's only going to be used on the internet (1600 pixel width), AND you don't care about optical quality, then by all means get the 18-200mm lens. On the other hand, the results may be disappointing when zoomed in to 1:1 resolution or printed at 8x10 or 11x14 and above because super zoom lenses like the 18-200mm get convenience and trade-off with inferior optical quality. So if one must use the 18-200mm lens, one might as well as shoot it on a 8-10MP camera because at full 15MP, pictures will have a tendency to look "soft" and "mushy"... they will look not much better than shooting with a lower megapixel sensor and then upsize it later in Photoshop.

Let me just say that when I need convenience, I'll simply use my wife's Canon SD750 point-and-shoot, which is a superb camera to shoot casual events... kids, pets, what not. I don't usually care about optical quality for casual events. In fact I don't expect the quality of the SD750 to remotely match that of modern DSLRs+pro-lenses. On the other hand if I'm serious about something, I'll get SLR equipments but not just any SLR equipments-- pro-lenses. There's no point of buying a toy consumer 18-200mm lens when a point-and-shoot will shoot just as well. Having that said, two years ago I bought the Canon equivalent-- back then a spanking brand new Nikkor 18-200mm f/3.5-5.6 VR. I had it for about 2 months. I sold it (on eBay) after only using it for 2 months because I was very disappointed with its optical quality. In fact, eBay today is full of used 18-200mm lenses-- people are now starting to discover that super zooms don't project good quality images, and are dumping them back to the used market.

So let's assume now that optical quality is in fact of high concern, how should one determine in general whether a lens is well matched for a particular MP sensor? You compare technical specs. However unlike looking at a single MP value, lenses are a bit more complicate. Lenses are usually characterized using the Modular Transfer Function (MTF).

Originally MTF started from USAF in the 50s when the air force wanted to know how much "lines PAIRS per millimeter" (lp/mm) a lens can resolve (this is different than l/mm!). The higher details, the more information they can get from the Soviet Union using high altitude spy planes and spy cameras. In the old film days, lp/mm was used commonly because there were only a few common formats: 35mm, medium format (45, 67, etc) and it made sense to talk about lines per millimeter projected on film. Today with a plethora of digital sensor sizes, people use lw/ph or lwph (line width per picture height) in favor of the older lpmm unit. Keep in mind, the two aren't equivalent and requires calculations to get from one to another, but for the sake of simplicity, let's just agree that the higher MTF value, the more details a lens can resolve. By the way there are a bunch of good technical MTF information online. My favorite is the following URL. Is this really necessary to read? Yes, absolutely, especially if you're a pixel peeping/engineering/math type of person:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml

So going back to the question "I have a 15MP camera, should I get a 18-200mm f/3.5-5.6 IS lens to replace my 18-55mm vesion?" Unlike the camera body, we can't simply look at one single MTF value on a lens. What makes lens comparison complicated is that the center resolution will be different than the corner resolution because unlike a uniform sensor/film density, the projected optic quality isn't uniform throughout the area. To make things more complicated, lens resolution varies with aperture as well; subject to the laws of optics engineering and design, the higher the aperture, the higher resolution, and likewise the wider-open the aperture, the lower resolution. So we have two basic things to worry about now: 1) how much resolution in the different areas a lens projects 2) how much resolution using different apertures. In fact to make things even more complicated there are a bunch of other factors to consider (but we won't get into it here): contrast vs. resolution, color, chromatic aberration, vignette, distortion, and bokeh (BTW I hope I've made pixel peepers happy by mentioning all of these other issues).

Unfortunately, most manufacturers have their own MTF values derived from theoretical/calculated results. In fact, they don't make it easy for consumers to access that information. In addition, manufacturers' MTF is a lot lower than the theoretical values due to manufacturing variations, and subject to real world conditions (heat, humidity, calibration, irreproducible lighting levels, etc). Luckily however, there are numerous MTF charts published by independent testers online. Photozone is one very good European company that publishes optical results. Let's look at the MTF for the following two lenses:

18-55mm 55-250mm	18-200mm

Go to both pages, scroll to MTF for 18mm at f/3.5. You'll see that for center MTF value (middle of projection), both lenses resolve almost the same lp/ph. Now, look at border MTF value (edge of projection), and you see while the 18-55mm resolves at 2182 lw/ph, the 18-200mm resolves at an abysmal 1703 lw/ph. Extreme corner is another story to be told. Based on this MTF, one can say that the 18-200mm lens often yields mushy looking images. "This lens at f/3.5 and 18mm isn't very sharp" is what photographers would say. You can look at other apertures and other zoom ranges and see that aperture-for-aperture, zoom-for-zoom, the cheaper 18-55mm lens usually out-performs the much more expensive 18-200mm lens! (see footnote 1)

In short, lens engineering is about trade-offs, and one of the big trade-offs is convenience vs. optical quality. I understand that the 18-200mm lens is much more convenient for shooting pets and kids. It's certainly more convenient than having to switch between 18-55mm and 55-250mm lenses. So if convenience is the primary issue at hand, the 18-200mm is a fine lens. Just don't expect crystal sharp pictures.

If on the other hand optical quality is of importance (portrait, event, wedding, poster, etc), then don't get the 18-200mm. Instead get a better lens that can also resolve just as much resolution as the sensor has. MTF is your friend.

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Footnotes:

1) One can make the argument that you can just close up the aperture to f/5.6 and beyond and both lenses will perform superbly. As good as that sounds, f/5.6 is 1.5 stop lower than f/3.5. That means the lens opening at f/5.6 is roughly 1/3 (1/(2^1.5)) than at f/3.5. Shooting f/5.6 under anything but bright day will yield a lot of disappointments.

Lynn & Ross' Wedding

Lynn and Ross are x-coworkers/friends from the Google days. They got married on August 22, 2009 in Malibu, Adamson House. What more could you ask for when you mix a beautiful day, a beautiful couple, and a beautiful location! Click www.lynnandross.com for more info.

I wanted to make sure this special couple had a good coverage throughout this once in a lifetime event and came in as a secondary/third shooter. Since we were not primary shooters, you will not see a single portrait of Lynn and Ross and no close-up of rings, shoes, etc on this web site. Enjoy!

I hope you enjoyed these pictures that Pam and I took. For other photographer's pictures, you can check out Michael+Anna's web site. They're very good, you have my endorsement!

It's all about the lenses!

I stumbled across a post on Craigslist. "High End Professional Photography Studio Sale (August 22&23) (1300 N. Wilton Pl., Los Angeles 90028)" I looked at the pictures in that post, and it brought back a lot of memories. All of the pictures here are from that Craigslist post.

Back to my story. The year was 1990. I was shopping for photographic equipments. I was armed with The Recycler (a print version of today's Craigslist/eBay-local). The rationale for shopping heavy duty photographic equipments was that they're good investments-- they would last a life time. After all, the basic photographic techniques had been the same since the early 1900s. You take a picture, develop on a canister, darkroom darkroom darkroom, print, done. It was done that way in 1900, in 1910, in 1920, 1930, 1940, 1950, 1960, 1970, 1980, and 1990 (black and white still done that way at the time). Why wouldn't it be any different in 2010, 2020, 2030? So I thought at the time.

I had an early version 1978 Pentax K1000 with a 55mm f/2 lens, and it was all I needed. The only other things I needed were darkroom equipments, and some black and white filters. I responded to a post on the Recycler. I showed up at this house in Granada Hills. This old man with white hair opened up the door. He said "oh, so you're Kevin?" He sounded a bit surprised, and I could hear the tone "Oh great, it's just a kid." He was a retired photographer selling off a bunch of old equipments, from drums, to easels, to enlarger, trays, chem bottles, camera lenses, everything. He turned out to be a nice and patient guy and explained some of the equipments that I didn't know how to use at the time. I ended up spending 4 hours looking at his arsenal of professional photo equipments. I came out with more photographic knowledge than before, more equipments, and an almost empty wallet. But I was ready to create my own photo lab, and I was excited!!! Many kids at the time just wanted to spend hundreds of dollars perfecting their Street Fighter techniques and such. I had my own darkroom... waaay cool, dude.

Even as digital photography became more prevalent in the late 90s, many professionals laughed at it. The resolution sucked. The color sucked. Everything sucked about it. Some experts estimated that it took 100 years for photography to reach the state of the art quality, and it would take at least a few more decades to do the same, digitally. But Moore's Law proved everyone to be wrong... doubling transistors every 18 months, and doubling computational power every 2 years or so... you continue this trend, and in 10 years, digital photography surpassed everyone's expectations. In less than 10 years, most of the pro photographers were already on digital (digital processing and digital capture).

When I finally parted with my darkroom equipments in 2008, I barely got back any money, after taking in consideration of shipping costs. You see these pictures of the old film equipments? They're no different than what I saw in 1990. The difference is utility-- they were useful in the 1990, and today, they're obsolete and worth very little. Hardly anyone wants to use an enlarger, let alone dealing with stinky chemicals and trays. Digital processing is not just "good enough", it is superior. With one mouse slider in Lightroom/Picasa/Photoshop, you can change contrast in 1 second. You can change the tone in 1 second. You can change the exposure in one second. You can burn and dodge in 10 seconds. A single print that may have taken masters like Ansel Adams hours to create, now takes minutes. In some instances, you can create amazing results in your digital darkroom, in seconds.

See the pictures on this post? Almost everything is worth... $0.00. They have little utility in today's world. The only things that are still worth something... are the lenses. Optics don't change like electronics. No matter what technology you're using, you need to capture light. Optical innovations isn't subject to Moore's Law. You see that old Nikkor AI 50mm f/1.4 above? It's still worth a lot. A good lens in the 70s, is still a good lens today.

It's all about the lenses!

Canon finally reversing their high megapixel trend

Today, Canon announced the Canon G11, a large sized point-and-shoot camera. The intended audience for the G-- series cameras include professionals and serious enthusiasts who use it in conjunction with their big SLR bodies. It is only 10MP. Interesting, the older Canon G10 had a whopping 14MP. It appears that Canon reversed the high-megapixel trend. What happened?

Well, remember the old post I made "High megapixel cameras preferred by lousy photographers"? For the past 3 years or so, Canon has making higher and higher megapixel cameras, esp. on small sensored point-and-shoot cameras. They have been doing so, because the laymen thinks that the higher the megapixel, the better it is. To Canon, the higher megapixels the cameras, the better they sell, so they kept going higher and higher. It is no different than a car maker enticing teenager drivers with meaningless specs like horsepower and torque. In the old days, the higher the horsepower and torque a car had, the better they sold. But then people got smarter, and realized that there was so much more that makes a car than horsepower/torque... things like comfort, mileage, ergonomics, reliability, cost of ownership, insurance rate, etc. As the car manufacturers mature, they started reversing the big horsepower trend.

IMHO, today is the day we can mark that the digital camera market is maturing. The fact that Canon reversed its high-megapixel trend, is a sign that digital camera shoppers are finally getting smarter, and more matured. They are now realizing that higher megapixel doesn't equate to a better camera. Let's take a quick look at images from the old G10. At the lowest ISO of 80, the images from the old Canon G10 (with a whopping 14MP) looks spectacular. But at the higher spectrum (1600-3200), it is completely unusable. It is grainy. It is artificial. It is ugly. As mentioned in my old blog previously, the trade-off for having high megapixel is 1) higher noise at higher ISO and 2) unusable pictures at less than ideal lighting situation. Granted, if the purpose of a camera is to use it during an ideal bright day or in a studio, a high megapixel is perfect for the job. But most people shoot in all conditions, day and night, indoors and outdoors, and most of the time in less than ideal lighting situation.

Let's take a look at a picture from a G10 (Courtesy of http://www.imaging-resource.com/):

100% crop shot at 100 ISO. It's got great tones, colors, and details:

100% crop shot at 1600 ISO. Look at the massive amount of in-camera noise reduction applied to the picture. It's very digital/artificial. It's ugly! We don't need to look at 3200 ISO even though the G10 can go up to 3200 ISO. That high ISO is marketing BS from Canon.

Not many people have had a chance to play with a G11 or look at sample pictures online, but the fact is clear-- Canon is reversing this high-megapixel non-sense. Personally, I think this is an indication that 1) the laymen are slowly recognizing that higher megapixel doesn't equate to better pictures 2) Canon is responding to the market demand, and making a camera that is more capable in less than ideal situations (vs. a high megapixel camera that sells well). In the past few years, numerous posts on photography forums indicate that people are now realizing that high megapixels means trading off resolution for image quality. Kudos to Canon for making a lower megapixel camera that shoots well, and kudos to all the buyers out there resisting buying a camera with high megapixels.

The digital camera market is maturing.