URSA Mini 4.6 Pro Lens Suggestions

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Cody Sinclair

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URSA Mini 4.6 Pro Lens Suggestions

PostTue Apr 18, 2017 9:44 am

Hey everyone.

So I've spent likely far to much time attempting to research/find the exact answers that I'm looking for across the internet, and so it just now dawned upon me to register here and get feedback from people with experience. With that said, I apologize in advance if this is a common question or is otherwise something that I could have found with some digging through the forum. I also will apologize in advance if I use incorrect grammar, if I end up repeating myself, or if I otherwise start rambling—I haven't slept in almost 40 hours now so needles to say Im about to crash once I finish typing this :D

I'm currently in the middle of pre-production for a short film a buddy and I are making. I'm not a novice when it comes to filming/operating a camera, but this short film is special as for this project I wish/am able to dip my toe into the realm of a professional, cinematic camera—something that I have yet to do. I have had experience with professional grade cameras before such as the Red One (yeah, it's been awhile) and the related workflow for handling the larger files, I just have yet to use one to film a short film. Obviously having registered here the camera I will be using for this project is a Blackmagic camera, specifically I will be using the URSA Mini Pro 4.6k. My concern is with selecting appropriate lenses, which is why I am here right now. Regrettably, I only have the most basic understanding of lenses and their functions (Focal Length, Aperture, ISO, etc). My knowledge is extensive enough to know how to use these functions, but my current issue is more technical and beyond my understanding.

My problem is I do not know what camera lenses work best with the camera and the specific format I wish to film in. To try and explain this as simply as I can in my current mindset: I know that I would like to shoot in the camera's 4.6k 2.4:1 format. Now in my extensive research and attempt at learning as much as I could about sensors and how they interact with lenses, the concern that kept popping up was crop factor. I am confused on how that relationship works with this particular camera and further if this even applies to the 2.4:1 format, as (how I imagine it) unlike true anamorphic, the 2.4:1 format is essentially the exact same sensor/frame as the 4.6k format only in 2.4:1 the camera simply doesn't capture the spaces in the frame where the black bars are. Or to put it in other words—the only difference to my understanding between filming in 2.4:1 and filming in 4.6k and then adding black bars in post is that 2.4:1 saves data when recording.

Just some extra information: currently I am only able to rent the camera and any lenses from Borrowlenses (or other places, but I am most familiar with them) if that helps give an idea of how limited(?) my selection of lenses is. Also, I prefer to work with prime lenses but its not something I will refuse to reconsider. Ok, Im starting to lose myself here, please bear with me.

My underlining question(s) is will lenses be cropped while filming in the 2.4:1 format? Will they be cropped if I simply film in 4.6k and then add the bars in post? If there is simply no way around cropped lenses with this camera, then can anyone recommend lenses while also specifying what the adjusted focal length is? OR if there are lenses that wont be cropped in either the 4.6k or the 2.4:1 format could you list those instead? Before all my confusion, research, and more confusion I was eyeing the Rokinon Xeen prime lenses—so hey, if anyone knows if those lenses are cropped or not that sure would potentially save a lot of trouble for me.

To those who read through this, you have my thanks. To those who actually can offer advice/suggestions you have my gratitude. I have no idea if what I wrote makes sense to any of you, I'm at the point now where I may as well be drunk. I just wanted to type this now before I forget when I awake, and hopefully by then there will be some responses ;)
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rick.lang

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URSA Mini 4.6 Pro Lens Suggestions

PostTue Apr 18, 2017 10:24 pm

Cody, rise and shine! Your message made a lot of sense for someone who has been awake 40 hours. Now promise your mom you won't pull that stunt too often as it's not really healthy. Been there, done that!

The 4.6K sensor at 25.344mm is a little wider than a traditional Super 35 film gate at 24.9mm. But focal lengths of the lens choices would be the same. The Xeen primes cover 'full frame' 135 film format with a 36mm horizontal width. But the 4.6K sensor (or 4.6K 2.4:1 raw window) is a 1.42x 'crop' of that 135 film format. A 50mm lens on 135 film gives you a normal angle of view 39.6 degrees, but on the 4.6K sensor you would need to use a 35mm lens to match that angle. Roughly 50mm/1.42= 35mm.

For medium close, an 85mm lens on 135 film with horizontal angle of view of 24 degrees would be matched by a 50/60mm lens on the 4.6K sensor. On the telephoto end, 120/135mm lens on 135 film with 17 degree AOV would be matched by the 85mm lens on the 4.6K sensor. At the wide end, a 24mm lens on 135 film with 73 degree AOV would be roughly matched with an 18mm lens on the 4.6K sensor.

Hope that makes sense. Once you rent a set of Xeens, you'll see what they do on the URSA Mini Pro and you'll be fine.

If you're not wanting to rent a complete set of Xeens, just remember to pick lenses suited to the production. You may find 18mm is as wide as you want to be and 85mm as long as you need. If you'll be in tight quarters, Xeen has a 14mm now I believe. For longer shots, the 135mm Xeen on the 4.6K sensor will be almost like a 200mm lens on 135 film.


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timbutt2

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostTue Apr 18, 2017 11:20 pm

As to your specific questions regarding shooting in 2.4:1 aspect ratio, technically yes the sensor cropping the top and bottom of the image to create the 2.4:1 ratio will kind of crop the top and bottom of the lenses as well. That's not anything specifically effecting the lenses however as it all has to do with sensor cropping.

Think about it this way. 35mm Film has been the standard in which we have shot for the last century. 4-perf film was how we shot 1.33:1 movies, and 3-perf film was how we shot 1.85 movies. 4-perf was also used for creating 2.35 aspect ratio movies by using a 2x anamorphic lens. The other manner in which 2.35:1 was creating was called Techniscope where 2-perf film was used. The thing to understand about each of these film formats is that the width remain the same on all, with the exception of anamorphic due to the squeeze.

So lets compare 3-perf vs 2-perf because that is where the comparison with the URSA Mini 4.6K sensor comes into play. Basically full 4.6K sensor is equivalent to 3-perf film, and 2.4:1 crop mode is like 2-perf film. Your spherical lenses are going act the same way on both accounts. It's only a matter of how much space you're using for the recorded frame. So with 2-perf film you'd save on film and get more minutes per magazine, and the same is able to be said about 2.4:1 mode on the 4.6K with more minutes per card. You'll find that the left and right edge of the frame remain the same in either 4.6K 16x9 and 4.6K 2.4:1, but the difference is that you lose that top and bottom pixels information.

My suggestion is to shoot 2.4:1 as much as you can, but if you need to do any kind of image stabilization or reframing then shooting 16x9 and cropping in post isn't a bad way to go. Specifically VFX shots can benefit from recording full sensor in order to get all the information possible.

Hope this information adds to wrote Rick wrote above.
"Movies are not watched. They are an encounter with a life's experience not your own." - Tim Buttner (timbutt2)

Cameras: URSA Mini 4.6K EF & Cinema Camera 2.5K EF
Computers: iMac 5K (Late 2015) & MacBook Pro Retina 15.4in (Early 2013)
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rick.lang

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostWed Apr 19, 2017 12:49 am

Thanks, Tim. I hadn't really addressed the use of the 2.4:1 option in any detail. Excellent.


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Douglas Sullivan

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostWed Apr 19, 2017 11:45 am

You might also consider keeping an eye out for Rokinon DS Cine primes. They're essentially the same glass as the Xeen as I understand it, but with a plastic housing rather than aluminum. Even so, they feel quite solid and smooth - they're still pretty heavy. They're color matched across the set; the focus and aperture gears are aligned at the same distance from the mount across the set (making for easy swaps if you're using a follow focus). I watched eBay for good prices from reputable sellers and have so far grabbed a 24mm, 50mm, and 85mm for just under $1k total. If you're in a rush, many dealers offer sets of 3-6 focal lengths ranging from $1,200-2,500ish... If you're shooting for a while, you could certainly save on rental costs. They hold their value as well, so you could sell them after you wrap if you'd like to recoup your investment.

Good luck with your film!


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rick.lang

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostWed Apr 19, 2017 5:22 pm

That's a good option, Douglas. I went from intending to order a set of Rokinon Cine DS primes to then favouring the Xeen primes when they were announced, but finally settled on purchasing the arguably optically superior SLR Magic APO 25, 50, 85mm primes for my own use.

If renting the Sony CineAlta primes are another very good option.

The Xeen range have a superior lens coating which apparently improves the contrast and clarity of the Cine DS lenses, particularly the 24mm. I've seen the comparison so if the budget allocated was a rental of Xeens as I assumed since the OP was considering Xeen, then the difference in quality may be worth the expense. In terms of ease of use, the Xeens are all matched in terms of the physical dimensions, filter or matte box considerations, and gear positions. So operationally the Xeens are more convenient to work on the camera. The differing physical dimensions of the Cine DS can still be a concern for matte box clamps and filters I believe, but they do have the gears in the same location.


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timbutt2

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostWed Apr 19, 2017 9:01 pm

Yes, the one reason I don't like using my Rokinon Cinema Lenses is because they are various sizes and thus I have to reposition my matte box. Also, the end barrels are not a great size for a matte box, so I need to use a nuns knicker to prevent reflections from light sneaking in the back.

I would suggest the XEEN's over the Cine DS any day. However, I do use the Rokinon Cine DS lenses myself. So, I'm simply pushing for using better lenses always because I know the weaknesses, but they are still fine optically. It's a matter of practicality that I would choose the XEEN's if you can.

I would love Sony CineAlta Primes. Or Cooke S4/i lenses. Or Zeiss Master Primes. Generally the great PL glass is the dream glass to use.
"Movies are not watched. They are an encounter with a life's experience not your own." - Tim Buttner (timbutt2)

Cameras: URSA Mini 4.6K EF & Cinema Camera 2.5K EF
Computers: iMac 5K (Late 2015) & MacBook Pro Retina 15.4in (Early 2013)
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rick.lang

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostWed Apr 19, 2017 11:27 pm

Tim, when you come for a visit, I'll get you using the SLR Magic APO primes and see if you add them to your list of dream glass!


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Cody Sinclair

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Re: URSA Mini 4.6 Pro Lens Suggestions

PostSat Apr 22, 2017 7:46 am

Thank you everyone for your responses! They have all been highly informative and very useful. I shall return should I need anymore advice or otherwise have further questions.

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