GH4 GH4 4K crops....

wwjd said:
not a cine lens on GH4, but close to the REAL lable on the side: what is the FOV of a 35mm on full frame/s35/etc? just trying to match that.
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Full Frame and S35 are different Fields of View. The markings on the lens are the same, but their effect based on the medium you're using will be different. Full Frame is more traditional to still photography, or if you're trying to emulate something shot with the 5D or a Full Frame RED. Using a speed booster will help you achieve a very similar field of view to what those focal lengths will do with S35. If you're trying to train your eye as a DP/Director (which is what it sounds like you're aiming for), then I would suggest focusing on the S35 equivalent. Unless you're shooting with a full frame sensor, teaching yourself to see in the "true" focal length field of view is pretty pointless. Figure out what each of your lenses look like when used with motion picture film, use a speed booster with the GH4 to achieve that same field of view, and you'll be set. Another suggestion I would have is to pick up a cheap director's viewfinder and pay attention to the S35 markings on that. Use that, and not your camera to scout/frame up shots, and it'll be a great way to train your brain to know what a given lens's field of view will be.

I think I understand what it is you're after (you want to be able to pick up an 85mm lens and have it's field of view actually be 85mm), but again, unless you're shooting stills or using a FF sensor, there's no need. You just need to know what an 85mm will look like on your camera.

Hope this helps :)

-DES
 
DES, Bingo! Exactly what I am after. So I have the speedbooster .64xl, not the .71 one. Which one matches the s35 like you are talking about? I also have the Mitakon .72 booster. How CLOSE does it match, and I how do I calculate that? Knowing some sensors are different sized than others, sounds like I am after the s35 sized movie camera
 
wwjd said:
DES, Bingo! Exactly what I am after. So I have the speedbooster .64xl, not the .71 one. Which one matches the s35 like you are talking about? I also have the Mitakon .72 booster. How CLOSE does it match, and I how do I calculate that? Knowing some sensors are different sized than others, sounds like I am after the s35 sized movie camera
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The 0.64x magnification of the Speed Booster XL was chosen (by me) to work well on the GH4 to make its ~15.39mm horizontal dimension in Cinema 4k mode effectively match the ~24mm horizontal dimension found in most S35 cameras. This is of course not an exact thing since the last thing sensor/camera makers seem interested in these days is standardizing on sensor sizes. For example, most Sony S35 cameras (FS5, FS7, F5, F55, etc.) have a 23.62mm wide sensor. The Canon C100, C300, and C500 have a 24.6mm wide sensor. The Alexa 2k is 23.661mm wide, and the Amira 2k is 23.76mm wide. And forget about RED - they are all over the place!

But even though the situation seems chaotic in detail, on average a "super-35" sensor is right around 24mm wide. So, for example, when you put your Speed Booster XL on a 50mm lens and then shoot with a GH4 in Cine 4k, then it will appear as though you are shooting with a 50mm lens on a super-35 camera. Of course, in reality the lens being used on the GH4 in this case has a true focal length of 50x0.64=32mm.
 
wwjd said:
DES, Bingo! Exactly what I am after. So I have the speedbooster .64xl, not the .71 one. Which one matches the s35 like you are talking about? I also have the Mitakon .72 booster. How CLOSE does it match, and I how do I calculate that? Knowing some sensors are different sized than others, sounds like I am after the s35 sized movie camera
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None and both. The amount of variation is pretty small and like I said before there are variations of s35mm sensors. So both adapters get you in the range but none will get you exact. For almost every situation getting you in the range is good enough and there is really no such thing as getting exact. Even lenses have variations so even if you could calculate an exact situation where a lens should on paper match another lens with a focal reducer the chances are those lenses have variations on what 50mm actually means and might be off by 1mm.

again we are talking a 50mm difference of 32mm vs 35.5mm between the two adapters. a 25mm lens has a difference of 16mm vs 17.75mm which is an even smaller difference. Not a huge amount of difference there and both more or less get you within that s35mm range. Think of s35mm more or less about a 1.5 crop vs a 1.0 crop or 2.0 crop. Any focal reducer will get you in that 1.5 crop range give or take a very small variation. That small variation doesn't really mean very much for most shooting situations.
 
Thanks for the input guys! Much appreciated. Definitely settling on the fuzzy logic, over some precise numbers - which I can't even dial in on my lenses if I tried... they are like 4 empty spaces tween numbers on the lens, so I am just doing ball-parking guestimates on where to set it. It will be close enough.

I did some research across 10 different lens manufacturers, and some cinematography forums, and found these to be the most common used, and manufactured cine lenses (if anyone else is reading this and cares)
Summed in a spread sheet, these were the most popular and most made:

18mm
24mm
35mm
50mm
85mm
100mm
135mm

Actually found 21 variations of mm ranges, but like everyone saying, differences tween 1, 2, and even 5mm are not critical. Now, I can cover all those, and even more on the high side, with just 3 lenses, a variety of width/bright with two boosters, a plain adapter, and an adapter with an iris.
 
wwjd said:
Thanks for the input guys! Much appreciated. Definitely settling on the fuzzy logic, over some precise numbers - which I can't even dial in on my lenses if I tried... they are like 4 empty spaces tween numbers on the lens, so I am just doing ball-parking guestimates on where to set it. It will be close enough.

I did some research across 10 different lens manufacturers, and some cinematography forums, and found these to be the most common used, and manufactured cine lenses (if anyone else is reading this and cares)
Summed in a spread sheet, these were the most popular and most made:

18mm
24mm
35mm
50mm
85mm
100mm
135mm

Actually found 21 variations of mm ranges, but like everyone saying, differences tween 1, 2, and even 5mm are not critical. Now, I can cover all those, and even more on the high side, with just 3 lenses, a variety of width/bright with two boosters, a plain adapter, and an adapter with an iris.
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Just to throw it out there but Spielberg has always loved 28mm even back in the 35mm film days. That is hands down his favorite lens to use. 28mm is common in the cinema world but it by no means is a standard and many famous film makers have used a wide range of different focal lengths as their go to lens. Some prefer 24mm and others 35mm and some prefer oddball lens FOVs that are very difficult to find. Throw anamorphic in the mix and it gets even more complicated. It really does come down to personal taste as a film maker. You pick the FOV that works best for you and you are the most comfortable with for your filming and story telling style.

This is where cine zooms are kind of desirable. You really can attempt to dial in the exact FOV you want instead of being forced to manufacturer lens FOV increments. The Sigma 18-35 new cine version of their lens would be great to dial in many of the focal lengths film makers love to use, including the Spielberg 28mm which is harder to find these days.

http://noamkroll.com/28mm-lenses-the-secret-ingredient-for-achieving-a-film-look/
 
Cool, Thomas. 28mm was on the full list, just not popular or made by too many. Since I can't afford a set of Cine Primes, I'm using my Sigma 18-35 and 50-100 to kind of hit those MM's. I know there's a million things wrong with that idea, but it makes me feel good. :)

Personally, I prefer wider lens, and deeper depth focus, but, everything has a place.
 
brianc1959 said:
The 0.64x magnification of the Speed Booster XL was chosen (by me) to work well on the GH4 to make its ~15.39mm horizontal dimension in Cinema 4k mode effectively match the ~24mm horizontal dimension found in most S35 cameras. This is of course not an exact thing since the last thing sensor/camera makers seem interested in these days is standardizing on sensor sizes. For example, most Sony S35 cameras (FS5, FS7, F5, F55, etc.) have a 23.62mm wide sensor. The Canon C100, C300, and C500 have a 24.6mm wide sensor. The Alexa 2k is 23.661mm wide, and the Amira 2k is 23.76mm wide. And forget about RED - they are all over the place!

But even though the situation seems chaotic in detail, on average a "super-35" sensor is right around 24mm wide. So, for example, when you put your Speed Booster XL on a 50mm lens and then shoot with a GH4 in Cine 4k, then it will appear as though you are shooting with a 50mm lens on a super-35 camera. Of course, in reality the lens being used on the GH4 in this case has a true focal length of 50x0.64=32mm.
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So, I'm revisiting this and taking it all in..... updating my charts....

If the 4k is cropped and makes a 50mm into a 117mm (50 * 2.34 crop), putting .64 SB on it only brings it back to 75mm?

The Speed Booster .64xl was designed to make a 50mm nearly identical to s35 film sized FOV? So, 50mm is "50mm" on SB.64 GH4 C4K?

Still confused if my math is buggered: 50mm * 2.34(c4k crop) * .64 = 75mm. OR real 50mm / 2.34 / .64 = 33mm <- where I set lens to create real 50mm FOV on GH4 C4K?
 
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more reading: on speed booster .64xl

"When the GH4 is used in Cinema 4k video mode the horizontal full frame crop factor is reduced from 2.34x to 1.50x, thus effectively transforming the GH4 into a super-35 format 4k cine camera."

So, what they keep beating me over the head is.... 1.5 crop IS THE SAME as Super35, Alexa-ish size and there is nothing to bother converting here. Is that right? If I popped my 50mm on s35 / alexa / GH4 with .64 SB, it would be nearly identical FOV?

Only conversion would be WITHOUT the speed booster... great. More math! :D
 
don't think of it as changing the lens. Think of the SB as changing the sensor. Same thing really. Its a magnifying lens and a magnifying lens affects both sides.

All you need to know is the SB XL makes the GH4 sensor essentially larger to match s35mm sensors. To be specific DCI 4k uses about 15.34mm of the sensor width and adding the SB XL makes that sensor a 23.97mm sensor (inverse of 0.64). That happens to be a 0.99x crop factor compared to the Alexa SXT Plus shooting in 16x9 mode. That is pretty darn close to any s35mm camera. They all vary slightly and there really is no standard across s35mm cameras. The technical rule book s35mm 4-perf standard is supposed to be 24.89mm wide. The Alexa is 28.17 when using open gate (23.76mm 16x9), BMD 4k production is 21.12mm wide, Canon C100 is 24.6mm wide and RED Mysterium-X is 27.7mm wide. Technically the C100 is the closest match to the 4-perf standard with the GH4 or GH5 full sensor a very close second.

The world has greatly over complicated the concept of crop factor when it doesn't need to be. It really doesn't need to be any more complex than the width of sensor A vs the width of sensor B.

The GH5 will be almost 27mm wide with the SB XL assuming you have lenses that will not vignette. 24.3mm wide with the Ultra which again puts it right where it needs to be to match the Arri (16x9 mode) and the C100 and the s35mm 4-perf film standard. This makes the GH5 with the Ultra a darn near match to the s35mm film standard. If anybody ever actually shot on film the GH5 plus Ultra or the Canon C100 is about as close as any camera actually gets.

s35mm shooters don't think of lenses in FF terms. They think of what lenses work for them. To them a 50mm is a 50mm and acts like they expect a 50mm to act. Slap on a SB on the GH4 and a 50mm acts exactly as they are used to. DOF, FOV and in many cases sensitivity are all the same. About the only thing a SB can't do to turn a m43 camera into a s35mm camera is increase the dynamic range. Low light in some cases is actually better than RED and BMD cameras. In all reality the only thing that makes a GH4 plus a SB XL plus an external 10bit recorder plus v-log combo not a s35mm camera is the lack of raw and the slight increase in dynamic range.

With all that said like I mentioned earlier this all matters very little in the end. All that matters is that you get within that 1.5x ballpark. Everything after that is really splitting hairs. A 50mm lens acting like a 47.74mm lens on one camera or a 52.62mm lens on another camera is not really a big deal. In all three cases the image is more or less the same.

By the way I'm developing a mobile app that will handle all this stuff plus a lot of other stuff. Looking for beta testers eventually if I can ever find time outside of my regular job to get it done.
 
Excellent post Thomas. As a cinematographer first, I am very used to the standard cine lengths of 18, 25, 35, 50, 85 and know what field of view they are going to give me on a Super35 camera.

So as you say, the GH4 and GH5 with Speed Boosters are basically going to be Super35 sensors. No more conversion thinking required.

My Speed Booster never leaves my camera as I have no M43 lenses, so for all intents and purposes it's just a Panasonic body with an EF mount up front, giving me a Super35 depth of field look with standard cine focal lengths.

Cheers,

Paul :)
 
Yes, Thomas, awesome post and thanks for that! I pretty much "get it" now after reading your post and look forward to putting it into practice.

Now.... my SB stays on almost all the time also.... but what is my calculation for when it is NOT on?
IE need to know where to set the 50-100mm, without SB, to get 135mm

I get the 2.34 crop is based on m43 sensor size, and not relative to real FF or s35.... so I don't use that as multiplier, do I?

Thanks guys for helping me figure this out! :) I owe you all pizza!
 
wwjd said:
Yes, Thomas, awesome post and thanks for that! I pretty much "get it" now after reading your post and look forward to putting it into practice.

Now.... my SB stays on almost all the time also.... but what is my calculation for when it is NOT on?
IE need to know where to set the 50-100mm, without SB, to get 135mm

I get the 2.34 crop is based on m43 sensor size, and not relative to real FF or s35.... so I don't use that as multiplier, do I?

Thanks guys for helping me figure this out! :) I owe you all pizza!
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If you are shooting DCI 4k then the GH4 uses about 15.34mm of the sensor. Divide that by whatever s35mm camera you are comparing to. If you want the gold standard of s35mm 4-perf then divide 24.89 by 15.34 and that gives you the crop factor to that particular s35mm format. In this case that is 1.62x crop. Divide your lens by that amount. So a 50mm on that s35mm camera will need a 30.81mm lens on a naked GH4 shooting DCI 4k.

Edit:

If you want to also match the DOF of that s35mm camera then that 30.81mm lens should be used at f1.73 compared to 50mm at f2.8. So a 30mm f1.8 lens should be a pretty darn good match.
 
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I am looking for what the FOV would be equal to without the SB, and I think you gave me that. Like what to set my 50-100mm to, to equal what a 135mm FOV would be. Make sense? Or match nonSB 50-100 to a 50 on SB - even though that would be east to just eye ball.

Thanks again for your valuable input. More appreciated than you know :)

I'd add DOF is not for me in this, but I understand the impact. I plan to set DOF as needed for the scene. Just looking for FOV conversion. :) (Maybe that doesn't match my "imitate cine lens" idea, but I can only handle so much! hahaha)

BTW Guys, I google the CRAP out of everything before asking questions here or anywhere - must have had 10 page tabs open and read first, so I really do appreciate the people here who take time to spell things out in black and white for us!! Hard to find solid answers sometimes, even after googling and reading 10 different pages. Many havve different answers. Good old 'net
 
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wwjd said:
I am looking for what the FOV would be equal to without the SB, and I think you gave me that. Like what to set my 50-100mm to, to equal what a 135mm FOV would be. Make sense? Or match nonSB 50-100 to a 50 on SB - even though that would be east to just eye ball.

Thanks again for your valuable input. More appreciated than you know :)

I'd add DOF is not for me in this, but I understand the impact. I plan to set DOF as needed for the scene. Just looking for FOV conversion. :) (Maybe that doesn't match my "imitate cine lens" idea, but I can only handle so much! hahaha)

BTW Guys, I google the CRAP out of everything before asking questions here or anywhere - must have had 10 page tabs open and read first, so I really do appreciate the people here who take time to spell things out in black and white for us!! Hard to find solid answers sometimes, even after googling and reading 10 different pages. Many havve different answers. Good old 'net
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No problem. There is so much bad information out there and most of it way over complicates the topic to the point of sheer lunacy. When it comes to crop there are no alternative facts. It is either right or it isn't.

You mean 135mm with a SB vs using the 50-100mm without a SB, both on a GH4? That would be 135 x 0.64 = 86.5mm. Both cameras are the same so no need to worry about anything else. If the 50-100mm is used on a s35mm camera then it acts just like a 50-100m lens on that camera. The 135mm lens on the naked GH4 would be 135 / 1.62 = 83.4mm. That is something you could set the 50-100 to on the s35mm camera to match. If you are talking the Rokinon 135mm at f2.0 would equal the DOF of f3.2 83.4mm on the s35mm camera.
 
Thanks again Thomas. I don't have a 135, just the 100, but figure without the SB on, it could reach the FOV of 135-ish?

Knowing the .64 brings "crop" to 1.5-ish on GH4 C4K mode, now I am confused what the FOV would be at 100mm with no SB. I'll re-read your answers more and see if I am missing it. My wording isn't always the best in things I don't know a lot about :D
 
wwjd said:
Thanks again Thomas. I don't have a 135, just the 100, but figure without the SB on, it could reach the FOV of 135-ish?

Knowing the .64 brings "crop" to 1.5-ish on GH4 C4K mode, now I am confused what the FOV would be at 100mm with no SB. I'll re-read your answers more and see if I am missing it. My wording isn't always the best in things I don't know a lot about :D
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100mm on the naked GH4 shooting DCI would be 100mm / 1.62. That is 61mm compared to s35mm. Add a SB XL and it is 96mm again or pretty darn close to what it would be on a s35mm camera. This is compared to 4-perf s35mm.
 
Doesn't it "zoom in" more because of the less wideness the SB brings? Like, a 100mm is 100mm-ish WITH SB, then without it, it would be 150mm-ish? Taking FOV here

So, my thinking is: 100mm becomes LIKE 150-ish with no Speedbooster? Then I want to find the mm setting on the 50-100mm zoom to make its FOV like a 135mm

Sorry if I am overthinking this somehow
 
wwjd said:
Doesn't it "zoom in" more because of the less wideness the SB brings? Like, a 100mm is 100mm-ish WITH SB, then without it, it would be 150mm-ish? Taking FOV here

So, my thinking is: 100mm becomes LIKE 150-ish with no Speedbooster? Then I want to find the mm setting on the 50-100mm zoom to make its FOV like a 135mm

Sorry if I am overthinking this somehow
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We are both right. 61mm on the naked GH4 would match the 100mm on s35mm. Or you can do the reverse and say to match 100mm on the naked gh4 you need a 162mm lens on the naked s35mm.
 
so is 1.62 the magic multiplier I use? 100mm on naked gh4 = 162mm "FOV"? (I know it doesn't change the actual physical lens mm, just looking at field of view)
 
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