Posts Tagged ‘RAW’

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Battle of the VariNDs: What’s the Best Variable ND?

Friday, June 14th, 2013

UPDATE: DO NOT UNDER ANY CIRCUMSTANCES BUY THE GENUSTECH ECLIPSE FADER FROM THE GENUS WEBSITE (more info below)

(Caution: this blog post contains serious camera geekery. If that’s your thing, read on!)

Pros have long known that Neutral Density filters are really important for shooting video on DSLR cameras (because they let us open up the lens to nice wide apertures and get that nice shallow depth of field). The most convenient way to use ND filters on DSLRs is the “VariND,” or variable ND filter, whose filtration can be adjusted with a simple twist of the filter ring. The problem with variable NDs though is that up until now they’ve usually been quite soft and tend to degrade image quality. Recently though a number of companies have released new models of VariND filters designed to address the softness. I am a stickler for tack-sharp imagery, so when I heard good things about a couple of the new VariNDs, I wanted to test them, to see which one was the new king of sharpness. After a thorough testing process I had a winner, but it was NOT a result I expected.

The two new variable ND filters that have come out recently that I had heard good things about were the Genustech Eclipse and the Tiffen Variable ND. Take a look at the video below for my intro to my testing.

Here’s what the test shots looked like:

©2013 Chris Conti Photography. All Rights Reserved.

If you’re interested in doing tests like this yourself, you can download the full-resolution test chart that I used here (it’s also handy for testing focus, adjusting autofocus microadjust, etc!).

I originally planned to stop both lenses down to f/11 for the tests to make sure that I eliminated as much softness coming from the lens as possible, so that I could really isolate softness being introduced by the filters. After conducting all the tests at f/11 though and inspecting the RAW files on my editing machine, I have to say I was completely blown away with the results: I couldn’t see almost ANY softness introduced by EITHER filter even at maximum filtration strength!

Even though the lens aperture shouldn’t matter in terms of the filter sharpness, I decided at that point that since I would likely be using these filters at wide apertures, I might as well test them at wide apertures. So then I opened the lenses up to f/2.8 and ran through all the test shots again. Again, the results were astonishing. Take a look at the 1:1 crops of the center of the resolution charts below:

©2013 Chris Conti Photography. All Rights Reserved.

Remember, these are 1:1 (i.e., full size) crops of a 21 megapixel frame! Both the Genus and the Tiffen were set at maximum ND filtration (or close to it), and compared to the shot with no filter, there is almost no perceptible softness. The jagged lines of the resolution chart are due to the resolution of the laser printer I used to print the chart (which was printed at 300dpi!). While neither of the filters introduced any significant softness, they both added about 20 points of green tint (thankfully though, that is very easily correctable either in the camera via custom white balance or in post). Also, while the image above is of the 200mm test, the results on the 24mm test were the same: nearly zero perceptible softness.

So Were the Two Filters Equal? NO.

Even though both filters were amazingly sharp (gone are the days of soft VariNDs! Hooray!), they were NOT equals. The Tiffen Variable ND was the clear winner. Here’s why:

As I said in the video, as a result of their opposing-polarizer design, ANY VariND filter is going to get the cross-type pattern of doom eventually. Here is what the pattern looks like, if you’re not already familiar with it:

The cross of doom. ©2013 Chris Conti Photography. All Rights Reserved.

The difference between the Genus and the Tiffen was that the Genus started displaying the cross pattern above substantially earlier in its filtration range (in other words, had less usable range) than the Tiffen. Compared to the Genus, the Tiffen had an extra stop or two of usable range before it too started showing the cross pattern. It is a subjective judgement how much cross-pattern darkening is acceptable before the image becomes unusable, but using the same lighting and camera settings, it was clear that the Tiffen had substantially more range (I’d estimate about two stops) before it started exhibiting the same level of the pattern above as the Genus.

The Tiffen Variable ND Wins

So the test concluded that both the Genus and the Tiffen were tack-sharp filters. Congratulations to both manufacturers for achieving that. The Tiffen filter though is the hands-down winner. In the end, there were plenty of reasons why: In addition to the added usable ND range, the Tiffen was both ergonomically superior (the build quality is better; the rotating ring is very nicely dampened and almost feels fluid whereas the Genus rotates somewhat loosely) AND less expensive ($150 vs. $165 for the Genus). The Tiffen is also easily available at Amazon, whereas the Genus is harder to get: the company distributes its products in the United States only through a small handful of distributors (and my local distributor, Rule Boston Camera, told me they couldn’t even get the Eclipse), and I ended up ordering it directly from the company in Australia.

So there you have it. It seems, for the time being at least, the Tiffen Variable ND is the sharpest, best variable ND filter you can buy… and it’s not even very expensive. Well done, Tiffen.

(P.S.- If you want to have a look at the RAW files to see the results for yourself, I’ve put them all online. You can download them here (be aware though that it’s about a 600MB download))

UPDATE: Do NOT buy the Genus filter from the Genus website under any circumstances. Here’s why: After performing this test and finding the Genus Eclipse Fader more expensive than the Tiffen and with a smaller ND range, I went back to the Genus website where I had originally bought it to return the filter (the company’s website clearly spells out their return policy, which I had checked before purchasing the filter, which says that Genus accepts returns of items within 30 days of delivery for full refund). I couldn’t find any way on the website of initiating the return, so I emailed the customer service email address listed. After hearing nothing back for several days, I contacted the company’s Twitter account asking about how to do a return. The person in charge of the Twitter account got back to me relatively quickly saying they’d check in on it for me. After another couple of days I got a response to my original email from an individual named Mark asking why I wanted to return the filter (this itself was slightly unprofessional as any company of any size has enough experience that they simply accept returns without demanding to know the customer’s reasoning first). I cheerily responded to Mark that I had conducted the test described here and found another competing filter to be better, but that had read Genus’s returns policy on the website before I bought it in the first place. After another day Mark then angrily emailed me that if I wanted to return the filter not only would I have to ship it to an address in Hong Kong (which alone essentially prevents returns, since the cost to ship anything there is about half the cost of the filter itself), but “all costs relating to the sale” would be deducted from my refund, including Paypal fees (Genus doesn’t accept credit card payments), shipping (which I’d already paid upon purchase), an “inspection” fee and a restocking fee (note that he didn’t tell me how much any of these fees would be). I then emailed back that none of those fees were mentioned in the company’s published returns policy. At that point Mark then emailed back and said “Until we receive the unit back and have the unit checked we cannot determine whether the unit is damaged or not.” My clear interpretation from that statement was that despite the fact that the filter was in immaculate condition, when it arrived Genus was going to claim it was damaged.

From this exchange it was very clear that despite their published returns policy Genus was not accustomed to refunding customers’ purchases and were not inclined to give me my money back. So I can only recommend that readers stay far, far away from Genus’s store, either for VariND filters or for anything else.

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How To Color Balance Mixed Lighting Sources

Tuesday, March 5th, 2013

I just finished a series of four blog posts talking about the various advantages and disadvantages of different types of lighting for photo and video work (the first post, with links to the others, is here), and why I’ve decided, for the time being, to use a mixed kit of fluorescent and LED lights. This kit is great and should serve my needs very well, but there is one hurdle that needs to be overcome first: while these lights are all advertised as “full spectrum” and “daylight balanced” at 5600K, in reality they all have visibly different color temperatures, so they need to be balanced with each other in order to work well being used together to light the same scene. In this post, I’m going to give step-by-step instructions on how I took three different lights with radically different white balances and balanced them to work together beautifully.

Before: Unbalanced

Before: Yuck. When white balancing for the mini LED panel on the left, the fluorescent softbox in the center is very green and the LED 1x1 on the right is slightly magenta.

In the image above, which I designed intentionally to exaggerate the color balance differences of the three lights, I placed (from left) a miniature LED panel, a fluorescent softbox and a 1×1 LED panel next to each other and aimed them at a uniformly white ceiling. The difference is striking (and awful).

Before: Yuck

Alternately, the same image above, only this time white balanced for the fluorescent soft box in the center, the LEDs on the sides are both overly magenta and orange.

As is, it would be very difficult to use these lights in a scene together without them appearing different colors. So they need to be balanced together. How to do this? Gels! Pulling out my collection of gels, I got to work.

I keep an assortment of gels to color balance pretty much anything (from left to right): CTOs, CTBs, Plus Greens and Minus Greens each in 1/8th, 1/4 and 1/2 densities. With this assortment, no matter which way a light is off balance, I can balance it.

Gels Gels Gels!

Gels Gels Gels!

In order to balance the three different lights (from three different manufacturers!) I started with the one that is most difficult to gel: the fluorescent (this is one of the biggest weaknesses of fluorescent lights in my opinion… they’re a pain to gel). I used that as my basis and then adjusted the other lights to match it.

It is possible to simply judge the color of a light visually in comparison to others next to it, like in the photos above, and to experiment with different gel combinations to get the lights to the point where they visually look the same to the eye, but “eyeballing” it like that is extremely difficult to do accurately; I have a very good eye for color (I scored a 19 on the X-Rite Online Color Acuity test! Take the test yourself, it’s fun!), and even I can’t achieve the level of precision that I want by eyeballing it. So to measure the color balance precisely I decided to use a couple of precision instruments: my camera and computer.

To start with, I set up a simple 18% neutral gray card on a light stand (I use this one from Amazon… it’s cheap and does the job well), along with a color chart. I lit the gray card and color chart with the fluorescent light (placing the light at an angle so that the light is illuminating the card but not reflecting glare). I then blacked out the windows in my office and shut off all the other light sources (overhead lights, computer monitors, etc.) so there was no “contamination” and I knew all the light hitting the gray card was from the light in question, and I took a still photo of the gray card and color chart with my Canon 5D Mark II camera in RAW format.

Gray Card and Color Chart

Gray card and color chart on stand for determining exact white balance of a particular light

I downloaded the photo onto my computer, and opened the file in Photoshop (you could also use Lightroom or any other application that can work with RAW files, I just happened to choose Photoshop). Using the White Balance Picker / eyedropper tool in the Adobe Camera Raw conversion screen (the same tool is in the Develop tab in Lightroom in the White Balance box), I sampled the 18% neutral gray card to set the proper white balance for the image, the values of which are then displayed in the white balance section on the right (it is a good idea to click a bunch of times in a few places on the gray card as the individual measurements will vary slightly, then average the values).

Sampling White Balance in Adobe Camera Raw

The White Balance Picker tool is the eyedropper icon near the top left. I sampled a spot on the neutral gray card, which gave me the white balance values shown in the white balance box at the top right.

Sure enough, I now saw numerically what I had seen visually on the wall: that fluorescent light was very, very green (+28 tint!). Since that is the light that was most off balance, ideally I would have gelled it to match the other lights, but since this light is so difficult to gel and the other are so much easier, I instead went the other way around and gelled the others to match this one.

With the temperature and tint white balance values for the fluorescent light in hand, I then repeated the process (blacking out the room, lighting the neutral gray card with a single light source, and shooting a photo) for each of my other lights and then found the white balance values for them as well (I found that my miniature panel has white balance values of 5100K temperature and -3 tint, and my 1×1 LED panel is 5050K temperature and +5 tint).

With that information, I then knew precisely how off balance my lights were from each other. I then added a gel to one of the lights, repeated the process of measuring the white balance values, and noted the numerical effect of a particular gel (bear in mind that as much as the gel manufacturers try to keep the color of their gels as pure as possible, a Plus Green gel will never be purely plus green…for example, my Rosco 1/4 Plus Green gels turned out to add +28 points of green tint, but also knocked off 300 degrees of temperature. But after measuring the color balance values of each light and the color effect of each gel, it was very straightforward to figure out which gels to add to each light to balance them together.

In the end, to balance my LED panels to my fluorescent lights, I needed to add 1/4 CTB and 3/8 Plus Green (one 1/4 and one 1/8) to my mini LED, and 1/8 CTB and 1/4 Plus Green to my 1×1 LED, which, while not numerically perfect, got my lights as closely balanced as possible with 1/8th-increment gels. Now I can comfortably use all of my lights in the same scene together and be confident that their colors will be balanced and visually indistinguishable.

After: I've Brought Balance to the Force

After: I've Brought Balance to the Force. While I can still see differences on this uniform white wall, in practical use these lights will never appear unbalanced.

 

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Posted in Equipment, Gear, Techniques | 6 Comments »

A Very Special Client

Monday, September 10th, 2012

Back in 2010 I was hired to shoot an executive portrait. It was a very standard assignment, but it was for a very special client: my dad.

Well, actually, my dad was the subject, but he wasn’t the client. My dad had recently retired from his position as president of Maine Medical Center, a large hospital in Portland, Maine, and the hospital was commissioning a portrait of him to hang in its Board room, along with those of all of the other past presidents. We had quite a bit of flexibility in terms of the setup of the shot; the only real requirements were that the final portrait be black and white and three-quarter length (to conform to the convention that had been in place for over a hundred years!). We talked about things that I talk about when I’m shooting any portrait (what ideas we wanted the image to convey, how to achieve them with wardrobe, location, framing, lighting, etc., shooting in a location where the subject is comfortable and relaxed, etc.). Ultimately we ended up settling on my parents’ home just outside of Portland as our location, and on the day of I drove up from Boston and did the shoot. Obviously it was a ton of fun shooting with my dad as my subject, and I was pretty happy with the final image.

Fast forward two years, and a couple of weeks ago I got a phone call from a designer saying that Maine Medical Center was putting together a tabletop history of the hospital, and wanted to use the image I shot of my dad in the book. Interestingly, the designer said that she wanted to use a color version of the (as-delivered black and white!) image (what they would have done if I had shot the image on black and white film I’m not sure). Thankfully, I had shot the image digitally and converted it to black and white after the fact, and had kept not only the final file but also the original, color RAW file (let this be a lesson kiddos, ALWAYS KEEP YOUR ORIGINALS!!!).

I did some editing to get the color version prepared for printing and sent it off to the client, and now I’m looking forward to seeing my dad in a book in a picture that I made.

Dad. ©2010 Chris Conti Photography

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