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eris

GH4, Bolex 16/32 1.5x, Speedbooster and Focal Lengths

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Just in case anyone was curious.  I've been doing some experiments with the Bolex 16/32 1.5x and the MD to Micro 4/3 Speedbooster on the GH4.

Mostly I just wanted to verify the possible angles of view and vignetting that might occur because I'm trying to approximate the rough lens selection that Tarantino uses on his productions.  From research on the web Tarantino likes to use 50mm, 40mm and occasionally 28mm when shooting anamorphic (eg: on Django).  Occasionally he'll also use longer lenses when appropriate.  This is for super35.

I did some calculations and using lenses widely available for taking lenses (and ones I happen to have on hand), I decided that given the GH4 UHD crop factor (2.4x) that if I used a 50mm, a 35mm and a 28mm that would bring me close to the effective super 35mm equivalents area of views of 58mm, 40mm and 35mm.  During experiments this is what I found with the Bolex.

50mm Rokkor f1.4 speed boosted becomes a 58mm f1.0 with no vignettting

35mm Rokkor f1.8 speed boosted becomes a 40mm f1.3 with no vignetting

28mm Rokkor f2.8 speed booster becomes a 33.5mm f2.0 with a little horizontal vignetting.  Since a 1.5x de-squeeze on the Bolex yields a 2.67:1 ratio you can use a small crop and still fit within standard 2.39:1 anamorphic cinemascope.

I could go down to Tarantino's 28mm anamorphic equivalent, but a couple things make that unattractive:

1) 33.5mm is plenty wide for anamorphic already.  Close subjects feel *very* close even at 33.5mm anamorphic perhaps because of the already widescreen view.

2) You would have to use a 24mm lens to achieve an S35 28mm equivalent and I know that would create heavy vignetting that would ruin the shot.

3) You can't use floating lens designs for anamorphic taking lenses because their filter rings also rotate and obviously that would make the anamorphic rotate.  Not a pleasant sensation.  Also all Rokkors below 28mm are floating lens designs except the 24mm Variable Field Curvature and that one usually goes for about $800.

Nuff said.

I'll post some footage samples when it warms up.

Also really looking forward to the anamorphic and vLog updates to the GH4.  I could break out my 2x Sankor 16D which has beautiful blue flares and shoot some night scenes.

eris

 

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Proctor: Glad you're getting good results also.  That Bolex isn't cheap but it's pin sharp for an anamorphic.  Since it's a 40 year old lens I also sent it in for calibration .  That made it even sharper.  What's another $300 for calibration when you've already spent $2000 for the lens and diopters.

You're right.  I think 28mm is as far as I dare go since even that requires a small, but acceptable crop to achieve 2.39:1 aspect ratio.

Do you have any sample shots on Vimeo or anything?

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Proctor: One other thing.  At 35mm and below the lenses are beginning to "see into" the distortion area of the Bolex.  Straight horizontal lines at the bottom of the frame have a slight curvature in the center.  This is the area of older anamorphics that might have what are called the "mumps".  Since I know my MC Rokkors are nearly distortion free in these areas I think it's a non-linearity at the very edge of the Bolex.  I haven't checked, but I have every reason to believe that the distortion increases slightly with the 28mm lens.

 

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Eris

You are right. When you start hitting the very far edges of the Bolex, it starts to distort. Not a problem locked down, but distracting otherwise, and pain ugly on pans.

I use my 16/32 with a set of FDs and I love the look. Quite simply the best rendering anamorphic I've seen and used, even ISCO. So much resolving power and a natural low contrast effect that can help a lot of digital artifacts. 

I'd be interested to know where you got your lens calibrated. 

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You are right. When you start hitting the very far edges of the Bolex, it starts to distort. Not a problem locked down, but distracting otherwise, and pain ugly on pans.


 

​Yes.  Well I guess you can have everything.  If I knew what kind of distortion it was it might be possible to correct for it.  Simple barrel distortion possibly?

I use my 16/32 with a set of FDs and I love the look. Quite simply the best rendering anamorphic I've seen and used, even ISCO. So much resolving power and a natural low contrast effect that can help a lot of digital artifacts. 

Yes.  Canon FD is usually the preferred taking lens.  I thought about going either with the FD or Nikon speed booster and came to the conclusion that I wanted anti-reflective coating, but an absolute minimum of it so as not to kill the flares.  I've used the MC Rokkor 58mm f1.2 with my Sankor 16D and it retained the 16D's gorgeous flares.  The MC Rokkors usually had a single layer of quality anti-reflective coating where (from my research) both the FD and Nikons were using mutiple layers very early on.  The MC Rokkors solve a complex set of requirements: (1) have a speed booster available for micro 4/3 (2) have very high optical and mechanical quality (3) have a single good anti-reflective layer (4) have a bayonet mount instead of a screw mount (don't want things unscrewing) (5) mount to my MC Rokkor 58mm f1.2 bokeh monster :)

Note for those following this path: Even though the speed booster is supposedly for Minolta "MD" mount, the mount is actually called the SR mount and in fact mounting the MD series (right after the MC series) can be troublesome because a number of the MDs have protrusions that prevent it attaching properly.

I'd be interested to know where you got your lens calibrated. 

I send all of my anamorphic calibration (Bolex, Sankor) work to Bernie O'Dougherty at Super16 in New York.  He's the man and very cool.
His email domain is "super16inc.com" and his user name is "bernie" so I think you can figure out his email address.  You can also just go to super16inc.com on the web and get all the latest info.  He might be on vacation right now.

 

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Interesting update to this discussion.   I was analyzing the distortion on my Bolex mated to the 35mm Rokkor and when everything is aligned correctly the distortion on the Bolex (not the Rokkor) appears to be barrel.  It's not severe and it appears that even super high end Hawks ($40,000 derivatives of Lomos) have barrel distortion at 35mm that looks almost identical to mine.

Here's a test of both a Hawk and I believe a Panavision (C-Series) at 35mm.   I think the degree of barrel distortion on the Bolex is similar to the C-Series lens.

 

 

 

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How are you guys connecting your Moeller 16/32 to the taking lens?

I have one of these anamorphics and read on an ebay auction to just use a 52mm (Nikkor taking lens) to 39mm step-down ring. It does work but the Moeller will rotate easily as it doesn't tighten up at exact the spot I need it to, so it is a little loose.

Also, any idea for a rear lens cap for this expensive piece of glass? I need one...

Many thanks!

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The Redstan adapter screws don't touch the Bolex at all.  It's a 2 piece adapter with an inner/outer ring. The inner ring screws into the Bolex directly and the outer ring screws into the taking lens, both with the possible assistance of step rings.  You then loosen the alignment screws and turn the Bolex and inner ring until it's properly aligned.  Then you tighten the set screws in the outer ring which prevents the inner ring and Bolex from moving.

Do not just use step rings.  Considering the amount of cash you probably paid for the Bolex, the additional amount of cash for a good RedStan adapter is negligible.

 

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Thanks Eris & Cineman1!

 

I actually bought my Moeller 7 years ago before this craze, actually for my Bolex Super16mm RX-5 as a nice to have item. It was ca. $500 at the time. I am actually on a budget today

 

OK I will have to look for a res stan clamp. Any good alternatives? Vid-Mid-Atlantic makes one and there are some on ebay...

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Eris

You are right. When you start hitting the very far edges of the Bolex, it starts to distort. Not a problem locked down, but distracting otherwise, and pain ugly on pans.

I use my 16/32 with a set of FDs and I love the look. Quite simply the best rendering anamorphic I've seen and used, even ISCO. So much resolving power and a natural low contrast effect that can help a lot of digital artifacts. 

I'd be interested to know where you got your lens calibrated. 

​Itimjim: Have you tried applying distortion correction to your footage?  I know it can be done in Premiere, but the thing I noticed is that after distortion correction it will probably slightly warp the borders which means that you'll have to crop the footage to remove it.  After un-distorting and cropping you may find that you're at the same effective angle of view as a non-distorting 50mm taking lens.  There's no free lunch.

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Thanks Eris & Cineman1!

 

I actually bought my Moeller 7 years ago before this craze, actually for my Bolex Super16mm RX-5 as a nice to have item. It was ca. $500 at the time. I am actually on a budget today

 

OK I will have to look for a res stan clamp. Any good alternatives? Vid-Mid-Atlantic makes one and there are some on ebay...

​Cfreak: I like the guys at vid atlantic, but their anamorphic adapters are pretty cheap.  I got one free with my Sankor.  The set screws tighten directly into the lens barrel and it scratches it.  Since they have no alignment inner/outer rings it doesn't screw onto the lens and it's really a PITA to align on camera (and off for that matter).

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