LENS TEST: Zeiss Super Speed (MK3) VS Zeiss ZF SLR's (Shot on RED)

[Ryan E. Walters]

INTRODUCTION
On May 12, 2008 I met up with fellow cinematographer, and RED owner Hunter Richards (www.hunterhampton.com) and we headed over to Lyon Films (www.lyonfilms.com) where we met with directors Devon Lyon and Kevin Curry. Later, we were joined by Owen Stephens, SOC & inventor of the Pampalite (www.pampalite.com) who got in on the action, and showed us his great line up of florescent lights. The purpose of this get together was two fold, first Hunter updated everyone on the developments that had been made on the RED camera as well as demonstrated the workflow and post process of using the RED in a production environment. Secondly, Devon & I used this opportunity to test out two sets of lenses. Both of us wanted to see how big of a difference there actually is in-between a lens designed for cinema use and for SLR use. The RED can mount both PL lenses and Nikon SLR lenses with a simple change of the lens mount. My cinematography has taken me around the world, and being able to use small, lightweight lenses on a camera capable of shooting raw 4K intrigues me. If the SLR lenses are able to perform at the levels needed for the RED, this would enable me to have a smaller profile and a lighter load to carry when traveling. Scheduled to begin production in the first quarter of 2009, the documentary Walking Through Worlds (www.walkingthroughworlds.com) will take director Joel McEwen and I to remote locations in Asia, and being able to use the SLR lenses on the RED may enable us to get the images we need for the production while keeping down the form factor and weight.

For the last two years I have been using a set of Zeiss ZF SLR lenses and various 35mm adapters on projects that have smaller budgets, but still want the cinematic look of film. For the projects that can afford it, I have been renting the cinema lenses. Having used both styles of lenses I have seen the mechanical differences between the two, and now with this opportunity with the RED I had a chance to see how big of a difference, if any, there is in the image quality of each set of lenses.

To highlight the potential differences between the lens sets I settled on the following tests: sharpness, color, breathing, vignetting, and the mechanics. To keep the results consistent I decided to shoot both charts as well as a real world test. Charts are helpful for consistency and measurements, where as the real world test will show you what you actually get. The cinema glass used for this test was a set of Zeiss Superspeed Lenses (MKIII) with a T-stop of 1.3 and the SLR lenses were the Zeiss ZF lenses with a T-stop of 1.4. To keep as many of the variables out of the equation as possible, the footage was all processed through RED Alert using the same settings. See the picture below for the settings used. The only change made to the real world footage was a change to 709 Gamma in the Output LUT.



All of the still frames have been left unprocessed and have not been graded, while the sample footage has been graded using the same settings in each set of clips in Color. You can download the Color project files, as well as the sample images and footage at my web site, by going to the resource page: www.ryanewalters.com. In the download you will find this review in PDF form as well as the setup notes for the tests which details out the various settings used, and lighting setups. So lets take a look at what the tests yielded. (I should also mention that the RED we were using was having problems with its CF drive, which ended up corrupting some of the files. We checked the files on site in the camera to see that they recorded ok, but there were a couple that although seemed fine in camera, RED Alert was not able to process them. So there are a couple of missing frames. The people at RED ended up overnighting a replacement drive for Hunter, which was great customer service for him, but too late for this test.)

DOWNLOADS: (Right click - Save As Please)
Just the RESULTS PDF (4MB)
Just the SETUP PDF (3MB)
Just the QuickTime Movie (9MB)
ALL PDFs MOVs, & STILLS (102MB)

EDIT: If for some reason these links are not working, please check my blog at my web site: www.ryanewalters.com - I have all of the same information, pictures, and downloads available there.

[Ryan E. Walters]

The first test I performed was using a resolution chart that I had made at my local Kinkos using their high quality black and white laser printer. While the chart may not be “the standard” chart for testing resolution, it does meet my needs of helping me to see overall sharpness as well as edge to edge sharpness. This test was done at both wide open and at T4 on all of the lenses. I have organized the resulting images into the charts below. (These images have been compressed, for the best viewing experience, download the full frame stills.)

The first thing I noticed when processing the resolution chart, is that both the cinema and the SLR lenses felt soft when they were wide open (T1.3 & T1.4). This is true of any lens, as lenses tend to perform best when they are stopped down about 2 – 3 stops, so this was not much of a surprise to me. However, what was a surprise to me, was that while filming the charts, it felt like the SLR lenses were sharper then the set of cinema lenses that were used. When I processed the footage, I was able to confirm that the SLR lenses were a little sharper then the cinema lenses. This was most apparent in the corners of the image, especially in the wide-open tests. The blown up portions of the charts above comes from the lower left corner of the charts. While the difference is not night and day, the SLR lenses do feel sharper to me. The SLR lenses are more then adequate to resolve enough detail to be used on the RED, and further more, they feel a little sharper then their cinema counter part.

[Ryan E. Walters]

Now on to the next test- is there any vignetting in the image? For this test I flipped the chart around and but a black cross in the center of the white card, and then filled the frame with the card. From the charts below, you can see that I did a better job at keeping the cross at relatively the same size with the cinema lenses, then I did with the SLR lenses. I did not see any vignetting in either set of lenses.

[Ryan E. Walters]

The next test I lined up was to see how well each set of lenses are matched to each other. If there is a color shift between the lenses this can make it more difficult to match shots when editing- especially when the shift if dramatic. So having a matched set of lenses is key in keeping the image consistent. For this test, Hunter brought along his Macbeth Color Chart, which provided a great sampling of colors to shoot. After processing the clips with RED Alert, I opened them up in Color, and then used the Geometry room to isolate just the color chart in each clip. After reviewing the files, I was again surprised to find that the SLR lenses are as well matched to each other as the cinema lenses are. In fact, both sets of lenses are so extremely well matched that the SLR lenses could be intermixed with the cinema lenses and there will be no noticeable difference in the color rendition.

[Ryan E. Walters]

Shooting charts is a nice was to have consistent results, but in reality charts are never shot, and they do not help you to see how a lens will perform in an actual production environment. They can help you to spot the weakness, and differences of a lens, but for me, seeing a lens in action is the only real way to determine if I like how it performs. So now it is on to the real world tests. For this next series of tests, Devon and Kevin graciously let me invade their office as they worked away on the days business at their computers. If you are interested in seeing the lighting setup notes they can be found in the Setup PDF that is included with the download of the still frames. In that same download you will also find a QuickTime file that shows the results of the breathing test done with each lens.

[Ryan E. Walters]

After processing and reviewing the results from the real world test the results confirmed what the charts had already told me. All of the lenses are well matched to each other, and in-between sets. The lenses are soft when wide open, and perform better when stopped down. And that the SLR lenses feel a little sharper then the cinema lenses I had been using. The final test that I did was to see how much each set of lenses breathed. In the QuickTime file you can see the results of this test for yourself. And while I admit I should have done a better job at getting an exact matching framing for each shot, the tests are a good sample of how each lens breaths throughout the range. From the results of the clips, as well as from playing with the lenses on set, the cinema lenses had more breathing in them then the SLR’s did- which surprised me, as I thought that the cinema lenses were going to beat them in this test. As far as performance goes, I would feel comfortable using either set of lenses on a production, with deference going towards the SLR lenses due to the increased sharpness and decreased breathing.

The results of this series of tests was very surprising to me, and it was very welcome news as well. It was great to find out that the set of SLR lenses that I have will be able to get the job done. My only hunch as to why the lenses perform as well as they do on the RED, is that the film plane on the SLR is larger then the film plane on the RED. So the SLR lenses have to be able to resolve a larger image, and due to the increased image, the breathing in the lenses is probably falling outside of most of the RED’s sensor.

So what does a good set of Zeiss Super Speed lenses costing well over $20,000 get you that a good set of Zeiss ZF SLR lenses costing just under $6,000 can’t get you? Cinema style mechanics. The last series of testing that I did related specifically to the mechanics of the lenses, and this is where the rubber meets the road and the differences really stand out. And it is these differences that will be the deal breaker for many- especially those who have been around for a while. (Detailed notes of the mechanics can be found in the Setup PDF provided in the download.)

The first major difference in is the size and weight of each set. The cinema lenses weight almost a full pound more then their SLR counterpart, and they are about twice the size as well. The second difference is the most important difference in my opinion- the SLR lenses rotate backwards. On the cinema lenses, to focus close to the lens you turn the lens counter clockwise, and for the SLR lens you turn it clockwise. The reason this is such a big issue is that an AC (Assistant Camera) has learned their trade very carefully and precisely in order to do there job well. A good AC is worth their weight in gold. Having learned their craft on cinema lenses, if they were to use an SLR lens, all of their natural reflexes will now be backwards, making their job much more complex. To further complicate the issue the third major difference between the two sets of lenses has to do with the degrees of rotation to get from one end of the lens to the other. On the cinema lenses the shortest throw was on about 300 degrees on the 35mm lens, where as on the SLR lens it was about 115 degrees. That means that there is less movement between distances on the SLR, making the AC’s job that much more challenging. The last mechanical difference is in the aperture. On the cinema lenses the aperture rolls smoothly all the way through the range, allowing for smooth transitions. On the SLR lens, there are hard stops at each half and full stop, with no smooth adjustments possible.

In the end, having a set of SLR lenses may save you a chunk of change on buying lenses, but it may end up costing you more in the long run depending on the application you are using them in. For myself, I’ll be hanging on to my SLR’s to use in applications where small form factor, and lightweight portability are needed. And then I’ll continue to rent the cinema lenses for the projects that require them. Either way I can see a need and application for both sets of lenses.

Hope this was helpful, or at least mildly amusing. :)

MECHANICS UPDATE:
(I received the following question via email, and wanted to put the answer here for all to see.)
What was the tension like / is there a large difference between the focus tension of the Zeiss SLR's and the Zeiss Cinema lenses?

There was no noticeable difference between the set of SLR's and cinema lenses that I was using. Both focused as smooth as butter, and are very well crafted lenses. When I first bought the SLR's this was the first thing that I noticed in comparison between the Nikkors I had and the Zeiss. Now this is not to say that you can't find a smooth operating Nikkor- you can. But it is less likely if you buy a used Nikkor. I didn't realize how smooth and SLR could be until I got the Zeiss. SLR lenses were not designed with a shifting focus in mind, where cinema lenses are. So having a smooth SLR lens is great for pulling focus, as you get a smooth consistent response from the lens- which may or may not be the case for that $99 Nikkor lens.

[Babu Kantamneni]

thank you

[richard peterson]

awesome! great info.

I really wish the 35mm zf shot would have made it.

[Tai Wah Lim]

Thanks Ryan for posting the test.

[Steve Murray]

The second difference is the most important difference in my opinion- the SLR lenses rotate backwards. On the cinema lenses, to focus close to the lens you turn the lens counter clockwise, and for the SLR lens you turn it clockwise. The reason this is such a big issue is that an AC (Assistant Camera) has learned their trade very carefully and precisely in order to do there job well. A good AC is worth their weight in gold. Having learned their craft on cinema lenses, if they were to use an SLR lens, all of their natural reflexes will now be backwards, making their job much more complex.

The main reason I'm using Canon FD lenses on my RED instead of Nikon.

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