John E Clark

Just to confuse the issue... I've noticed that some TVs take control of things and 'fill out' a 16:9 screen with 4:3 material. I noticed this when watching TV in a hotel and some oldie goldie TV show came on and it was filled out to 16:9... I then got the TV menu, and noted that it was set to 'always 16:9' mode, rather than letting the program select the appropriate aspect ratio.

Since I don't watch Cable/Broadcast TV unless while on travel... I don't usually have this problem, as my TV for playing DVD/BDs is setup correctly... and long ago, I moved to buying tapes and then DVDs that preserved the original film format via letter boxing, or now in the modern age of HD displays, pillboxing as required for 4:3 material.

Im new and excited to learn everything I can about cameras and have been looking into them for about 1 year now but still haven't been able to understand the difference between a CMOS sensor or an MOS sensor. I know there are different sizes and all but if some one could write out the different sizes and ratios of them that would be ver helpful.

 

Please help!

 

 

Thanks

J

At a very primitive level, Complimentary Metal Oxide Semiconductor, CMOS, vs Metal Oxide Semiconductor, MOS.

From a brief search, Panasonic annouced several years ago that they had produced a high sensitivity "MOS" imaging device, which according to the hype produced lower noise sensor than 'ordinary' CMOS devices, and better competed with Charge Coupled Devices, CCDs.

I tend to look at cameras in terms of packaging, price, and how much money I have in my pocket. Then having made a choice that I have to live with for several years... testing it in a variety conditions to learn what it will produce.

I almost never worry about the underlying sensor technology beyond that.

Here's a URL on the differences between CCDs and CMOS sensors.

http://www.teledynedalsa.com/imaging/knowledge-center/appnotes/ccd-vs-cmos/

My guess is two flash heads with 10 inch reflectors pointed into umbrellas for 'bounce' and soft flooding of light.

The Wife use to do that a lot, until we got a large 4x4 softbox which she would place right over the camera. She tended to use 400 Ws at about f/5.6 or f/8.

The biggest problem I've had with moving to 'moving pictures' is that with flash one can dump an awful lot of light into the shot... fairly easily... not so easy with continuous lights...

I appreciate the replies guys..

 

I just found out that Panasonic doesn't have a retailer here in the Philippines (causing them to become super overpriced). So I I just have to wait a couple of months to be the GH4 and GH4 become available. Luckily, my school let's you borrow the a camera and lights.

There are a number of 'low end' Canons that I have seen people use, there's the Rebel T2i/550D or the newer T3i/600D type which may have more retailers in your area.

The main thing is to shoot... and from what I've seen of these low end Canons, you could produce something you wouldn't be embarrased to show anyone...

When I started shooting 4x5 stills I could only afford a 50 year old camera, and lens of equal vintage, that was 40 years ago... I still have the lens... The camera... well, it ough to have been put in a museum... but as it is, I sold it to someone else when I upgraded to a new Cambo, even that was years ago...

I'd recommend going for a GH-2/GH-3, or even a GH-1 at about $200-500, with basic lens like the 14-140mm zoom that is part of the GH standard packages, and then get lights, and accessories. And then shoot the hell out of that equipment over the next year.

Sure, you can spend $1700 or more on the GH-4, or a Canon 5DMKIII (popular with some set of people)... but for that same amount, you can get a camera that will do for the next year, and lights that you can learn to use effectively.

An 'incident' meter measures the amount of light falling on the scene. A reflectance meter measures the amount of light being 'reflected' from a surface in the scene.

Meters are 'calibrated' to give an exposure indication which yield a certain 'density' in Film film. While the method of determining the ISO for a digital camera is different, the general goal is to have the esposure result in known levels.

One can determine one's own 'exposure index', by using a grey card, a calibrated step wedge or similar to find an 'personal' ISO value.

For reflectance meters:

In practice, one has to take in to account the approximate reflectiveness of objects in the scene. Black 'paper', 'dark' wood, etc, may be 5-10% reflective, or less depending... caucasian skin tone may be 30% reflective... a blank white sheet of paper 80-90%, etc.

So if one assumes that a meter is calibrated to an 18% grey card... then if one takes reflective readings of those items listed above, one would be off by one or two stops.

Hence one needs to 'adjust', usually mentally, for such surfaces.

Incident meters:

Since the incident meter reads only how much light is falling on the surface, the exposure the meter indicates, has to be interpreted in the sense of 'if there were an 18% grey card in the scene". However, one does not have to adjust based on the reflectivities of the objects...

Spotmeter:

A 'spot meter' is a form of reflectance meter which has a narrow area of sensing the light, and usually allows the photographer to obtain readings at a distance, and over a 'small' area, as most non-spot reflectance meters read a 30 degree angle, which can include other objects, which have different reflectivities. For example a black cardboard square sitting beside a white cardboard square. The wide angle of the ordinary reflectance meter would yield an average of 'black reflectance + white reflectants'... whereas a spot meter would yield two exposure readings for each of the squares.

Sure you can move close to the subject, but if one is too close, then one's own shadow may figure into the reading and skew the results... or if one is taking reading on a person's face... one can not realistically get 'close enough', or at an angle that matches the camera's view... and so a spot-meter would allow one to take such a reading off a small area.

I see, I didn't know that an angle from which you meter a card can play a role, thanks. What I am puzzled about: as far as I understand, if I metered the card from an ideal angle, getting a potentially more accurate reading, and then returned to the angle I originally shot the picture from, I would still get the same "exposure relationship" between the stump and the card, and I would have the same dillema when inspecting the picture Photoshop - either the card would have a wrong RGB value, or the stump would seem to dark (or both).

Part of the 'art' of metering includes assessing what the camera 'will see', and what values will be recorded.

While the surface of the grey card is theoretically 'lambertian', that is 'equal reflectance at all viewed angles'... in practice real materials do not have equal reflectance in the 180 degress that one can view that surface. The more one meters at 90 deg to the surface plane, the better...

As for 'why use a grey card when the camera could be calibrated for some other criteria'... well, the use of the grey card, and other calibration test targets, is simple so you the photographer can 'know' what the camera will record, given the subject reflectivities of the scene you are shooting.

With a step wedge, one can 'see' how the low and high values fall in the test image, which will give you the idea of how similar values will fall in your scene.

Since for DSLRs the 'curves' that the camera produces are not particularlly well documented, one has to reverse engineer them by shooting test targets and then analyzing them.

For Digital Film I'd recommend using the IRE scale rather than photoshop and 'pixel' values.

Premiere is the NLE I use, and it has a wave form monitor display to allow me to evaluate the test targets.

I've tuned out of Final Cut, but the Pro version had such a monitor. Don't know what Final Cut X has, but I'm sure there's a plugin. I think Vegas, at least some versions, have such as well.

(I also use a image analysis package called Image-J, which allows me to compute various statistics like noise from an image or a series of images... but who normally goes that far...).

Hey everyone,

 

I am an aspiring filmmaker, primarily interested in screenwriting and directing, but since I have a plan to shoot the first couple of shorts on my own, I am also trying to teach myself the basics of cinematography.

 

I am afraid the following question is probably really thrivial, but I haven't found an answer just googling for it.

 

18% gray cards have a RGB value of 119, 119, 119, so when you make a picture with correctly exposed gray card in it, the resulting pixels that form the card should have approximately the same values, right?

 

The first picture below is the photo as I shot it. To me it seems too dark, but when I inspected the pixels of the gray card, the RGB reading indicated that the gray card and therefore the top of the stump was actually overexposed (157,159,159). I had to lower the exposure by 0.85 to get the values of approximately 119. The end result (second picture) really seems way too dark to me.

 

 

 

I am asking because I am not sure if I am really understanding how exposing using a gray card works. So far I have always just used it in combination with spot meter and been satisfied with results, but I have never fixed exposure in post based on the card in the picture. Am I doing it right (and the stump should look so dark when correctly exposed), or have I misunderstood something?

 

Thanks a lot for any respones.

Some manufacturers recommend that a 18% grey card should fall at about 30-50% IRE. Because camera models have different gammas, and there is sufficient bit depth, the resulting image after post processing, etc. can be placed such that the image reads well.

I've been tending to set my GH-1 to place the 18% grey card at 50% IRE. I've not tested my D600 sufficiently to come to some determination about it in this regard.

It may also be that I prefer slightly 'lighter' values.

Hello.....does anyone know the required amperage for a 1965 Arri 16 BLEQ motor? 12V for sure but what should be the amperage on DC power supply to gain enough power for the motor?

 

Cheers!

 

 

From the manual for the SR2 found here http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCEQFjAA&url=http%3A%2F%2Fwww.towson.edu%2Femf%2Fdocs%2Farri_sr2_manual.pdf&ei=Pk2jU_zZHtD8oATCjIDICw&usg=AFQjCNFmfWWhB4LmTEb5YWgmTRH3mK6KdQ&sig2=0UDb704YG0VKa10FksQziQ&bvm=bv.69411363,d.cGU&cad=rja

There is mention of a 12 V 1.2 Ah battery, which leads me to believe the amount of current required is less than or equal 1 A while in operation.

There's mention that the ARRI 16 BLEQ is similar in power requirements to the SR2...

But I really do think you need to contact someone who services older ARRI equipment, and see if they can assist in correctly identifying things for you.

In the other thread you have on this topic, I think you need a schematic of the wiring for the cable that has some apparent damage.

These days people are sort of wyrd about copying 'copyrighted' service manuals, despite the equipment being long out of production, and even if the original manufacturer is out of business (ARRI is not... so perhaps there's some way to get archival service manuals...).

But if someone can get you the schematics, it may help you in understanding and fixing the problem.

Dupped post for some strange reason... no post delete option.

Unfortunately, it is almost impossible to find GH1 and GH2 here in the Philippines. The GH3 is around $1900 with 14-140mm. I am yet to find a GH3 body only. But I am guessing it is around $1400. So I narrowed down my choices to GH3 and GH4. My question is: is it worth the money if I go GH4 instead of GH3?

If it's a matter of 'wait' a bit, and get the GH-4, I'd go with the GH-4. I've been impressed with my GH-1, and the GH-2-4, have improved on the design from the reports of others.

Panasonic even was 'forced' to show the GH series at NAB, National Association of Broadcasters, in some sense, due to the number of 'pros' and 'semipros' using the camera. Canon of course has had their DSLR line at NAB for years...

I've not hacked my GH-1, mainly due to my 'fear' of bricking my unit. I think these days the hacks are stable, and others have been pretty successful in their use.

Also, when I hear the Canon 5DMKII/III I also hear 'Magic Lantern' firmware package, which 'improves' the camera from what Canon produces.

I have a Nikon D600 that I bought the Wife, but I've not tested it as much for such things as 'effective' ISO settings, or how good the video measures up even to compare with my GH-1. The Wife only shoots stills, and can use 'raw' image files, so moving pictures is not really a big issue for her.

Philosophically I don't worry about 'full 35mm still frame' vs MFT, APS-C, DX sized sensors... 'shallow DoF' is not my fetish... on the contrary, I tend more to deep focus.

The idea is sound. In the "good old days" Kodak used to make their cine stocks available on 35mm rolls for DPs to use in testing (source: "Every Frame a Rembrandt" -Andrew Laszlo). I don't know the Konica well, but if you can set it for 1/50th of a second, and meter for that (use a tripod. It won't come out well hand held) you should have a good idea of what the finished project looks like.

 

I heard (possibly apocryphally) that Matthew Libatique did something similar when filming Black Swan. He'd test lighting by shooting a still on a DSLR, so he'd know he's got (close) to what he'd get when he shot on S16.

While not a DP, i shot a few rolls of whatever the then current popular motion picture stock with my 35mm still camera in the early 70's. I didn't like the look, and as I recall there was an issue with processing motion picture film, due to the 'black' backing.

I remained firmly in the B&W camp, and only shot a few color shoots over the course of 10 years.

hi guys,

 

can someone give a link or the name of a book where i can learn about the inverse square law specifically for cinema.

i want to learn the hole think note a simplified equasion.

 

thank you

Here is a URL that has a general description of The Law.

http://www.portraitlighting.net/inversesquare_law.htm

Here's a 'webtool' for ARRI lights in determining what amount of light is at what distance, for ARRI lights.

http://calc.arri.de/calculator

Since ARRI lights are popular cinematography lights, you can use the calculator to figure things out from imagined scene scenarios.

The problem with 'cheap' lights, is that often the manufacturer or seller has no 'data' like the ARRI lights to allow you to calculate what the light intensity is in a given setup.

Kodak color negative can handle more than 2 stops of overexposure and be pulled back -- that's only, what, about 12 printer light points? If your negative normally prints around the 30's and you had one shot that had to be printed at the mid 40's, that would work fine. I once got back a second unit shot where they accidentally used 500 ASA film when they thought they were using 50 ASA film and thus overexposed the image by a bit over 3 stops and it could be printed back down to normal, though I ended up in the high 40's with that shot. But even if you top out at 50, you could re-trim the printer if needed to print down a bit more.

Would that be the 5219 Vision 3 stock? And how is it for 'under exposure'?

It's pretty hard core calling someone a troll. Expect comeback before the end.

 

If one imagines the full tonal range of the film, 10 or 13 stops, whatever one thinks, the scene being photographed (frame) may have less range, less stops between the brightest and darkest usefull information. So this scene can be shifted up or down the scale. But it really depends on what can be quite intimate or spiritualized creative intentions, and exactly how things will look at the extreme ends of the dynamic range of the film (tonal range of the film as I put it)

 

So that's me trying to explain it. Guy or one of the working DoPs will explain it better.

There may be creative reasons for having blank black shadows, blown out highlights, or similar. Making such choices is part of the creative process.

But underneath those choices is the knowledge of what the process is capable of. If one is working with a system that has 8 stops of representation capability, and the scene has 8 stops of 'contrast'... then one has 'no latitude' for error. If one has a recording medium of 15 stops, and one has a scene with a contrast of 7 stops... one has 'a lot' of latitude'.

But there will be effects of those choices in most cases. It has been my experience with still films that 'over exposure' for Tri-X yields images that begin to have flare in the shadow areas, and that affects my perception of the quality of the image. Now... some people like flare for some situations... ok... so for those situations, the flare is part of the 'creative' effect.

I don't think 'moving picture' film behaved significantly different in this regard, and perhaps the movie film photographer did not have the ability to adjust 'easily' for over exposed highlights that I as a still photographer did (such as burning in blown highlights, dodging under exposed areas, etc...). There may have been some adjustment in the print light intensities, perhaps with the creation of a high contrast 'mask', to deal with blown highlights, or alternatively 'preflash' the film stock, so as to ad 'density' in shadow areas to lift the resulting values 'a bit'.

But all those things were bandaids on getting an image to a presentable form.

But ultimately what happens on the screen, or in the print, is how the image is evaluated, and as far as I can tell, even these days, the output range is about 7-8 stops. If one consideres 'Rec 709' at least some varients, that knocks it down to about 5 stops.

One would think that if a DSLR yielded 10 stops of dynamic range, fitting that into 5-6 stops of 'TV' would be fine dandy. But I think one of the problems is that the DSLR was 'engineered' to yield a 'ready for presentation' image, and so the engineering has already taken away a certain amount of 'choice'.

 

In the quest for uniqueness are you giving new definition to the word "latitude" ?

 

I think most color films in the 70s were shot on 100T stock (5254/47).

From the wiki on the film use of the word 'latitidue':

http://en.wikipedia.org/wiki/Exposure_latitude

---

Exposure latitude is the extent to which a light-sensitive material can be overexposed or underexposed and still achieve an acceptable result.

---

and

---

It is not to be confused with dynamic range, the range of light intensities a medium can capture simultaneously.

---

As for ISO 500... sure... the point being, that only in the last 30 years has Film film stocks gotten any amount of 'speed' to speak of.

 

I like to imagine that every film stock is as limited as reversal film. That way it FORCES my brain to think hard about nailing something. I just don;t like to allow myslef to be acknowledging lattitude.

 

Negative stocks might have lattitude for miles, yes it might be there, but if you count on it too much, that's when the drunk driving begins. That vehicle starts to move more erratically. Sooner or later you'll hit a guard-rail thinking like that.

Negative stocks did not have 'miles' of latitude, especially when one viewed the final print film to be used.

There were effects from 'overexposure', even with processing by reducing development times, which may or may not have interfered with the 'aesthetic' look of the film. Grain was in many cases objectionable. So, underexposing, and 'over developing' led to 'more grain'... aka 'noise'.

Perhaps not the same type of 'noise' now found objectionable in digital images, but definitely not something 'Hollywood' looked to present... until the 60's and the 'new wave' of realism, wherein grainy images were considered more 'real' as in 'just like newspaper reportage images of 'real' events'.

Most 'movie' films of the classic era had ASA values of 16-50. In the 50's that value began to creap up to 100-200 then in the 70's 500... Black and White movie film seems to have fossilized at 250D/200T for Double X which is still made. (I think faster B&W movie filmes may have been developed, but production has been stopped for years...).

Tri-X a popular 'highspeed' still B&W had a ASA of 400, and even then when a 35mm negative was blown up... grain was the most signficant detraction... (It was a really great film for 4x5 shooting...).

For me, I rated my Tri-X at 200, and could expect about 2 stops of 'latitiude', by compensating with reduced development times. For 'underexposure', perhaps a stop or 1.5 stops, before 'grain' started to become a problem.

I'm sure people who used Double X at the time, probably had about the same 'wiggle' room.

Color film... what me shoot color film... hell no...

Or actually...maybe just have something aiming across their faces from the side, as a very soft and generic fill that gives a lot of pop to the table surfaces and comes up to hit their faces and sort of distinghuishes whatever activity they are engaged in (in other words, rims the shapes enough, or basically fills key definitions of "them"). I just don't like how you can't see anything back there right now and it needs some creative slash of light to pick up the action.

The shot of the woman and man, are from one of several 'shoot outs' organized and presented by "Zacuto" a sales and rental house based in Chicago.

I don't recall a shot that 'constrasty', but then it has been a while since I've watched the several shootouts...

Here's a link to the shoot out I think this still came from:

http://www.zacuto.com/shootout-revenge-2012

Guy, you have made an excellent analysis of the principles of exposure. You are right on! I don't think the younger members of our craft truly study "the curve" anymore and relate it to balancing the light. That's ashame. Great post Guy.

 

G

I don't know that The Curve, and knowledge about it, realtive to Film film processing is all that beneficial.

What I'd like is better 'curves' from digital Camera manufacturers, in the DSLR category, about their sensors, relative to say the IRE display. The latter seems to be taking the place of the H-D curves of film.

In the olden days, one could get the Kodak data sheet on the film type one was going to use, then one shoot test shots, develop, and measure the resulting densities...

These days, with all the hype about 'high Dynamic Range', often it is any one's guess as to the real response curve of the camera, and further, how much 'post' modification that data can take without producing garbage.

Last NAB I went around to several major DSLR brand booths and asked the somewhat simple question of 'how does X determine the ISO values for camera Y'... only the Black Magic camera both had someone 'technically' up, at the booth... I got a range of responses to the question at the other big names ranging from... 'that guy is ill today', or 'that guy isn't at the show'... to 'that may be a question for Japan'...

In the olden days... a Kodak or Fuji rep would say... 'we use Standard X'... and if I exposed film, developed it per the Kodak data sheet I'd get 'close' to those lab results.

I did contact one of the popular rental houses, by email after the show, and the person said they have setups at their facility and I could bring in cameras or test their rental selection with some charts they have setup.

Unfortunately I don't make it to LA all that frequently during the work week...

Thank you all for your responses!

 

 

Can someone tell me what this means in practical terms? What is a simple push from one side? How do I "neg everything else?"

You need to cut down the bounce light from the 'white' walls as much as possible. You may have to put up some sort of temporary curtain across several walls in order to prevent light from either a desired light, or bounce from walls that are illuminated, onto 'back walls' behind the camera, which then in turn rebounce the light back on to your set in undesired ways.

 

Hey J.E. Clark, Jec Lark, Jecl Ark....etc, quick side bar please.

What's the name on your bith certificate, what do your friends call you, when you meet your bank manager what do you introduce youself as? Probably one of those might seem like a legitimate name on the forum. I don't know for how long, but people have been hiding semi anonymously behind nicknames or "user names" on forums on the internet. I (expletive) loath that. One or two forums do the opposite, require your real name. This forum is one of those oases of common sense that require it.

 

All in the persuit of reasonableness, logic, common sense.

 

PS. Like your little photo under your name. Is this also a reference to anonymity?

As I've said previously, if the site owner/management has an alternative that encodes my name, retains uniqueness, I'm ok with that.

But if the point of 'real names' is to avoid spamage, or other internet evils... then who are:

Tak Ada Yang Abadi

and

Odhazar Jhadeya

With attendent images that look like real people.

Whose poker spam postings are still up despite having a -2 and a -1 vote respective, since the site does not seem to have a 'report to admin/spam' option.

And while we are at it which of the 4 or 5 Gregg MacPhersons (actually google decided to rename you 'Greg', rather than 'Gregg' and list out a number of entries which presumably are not you... unless of course you are a canadian/australian singer who has taken up lawyering in Portland Oregon, and slightly altered your name for this site...

On the other hand a google search for 'jeclark2006' yields a number of references, often on the topic of filmmaking and allied activites, and further, actually yields my day job postings in completely different universes, and further even gives two images one a more 'real' image, and the one I've been using as an avatar for years... the latter being the only portrait my wife has made of me in 35 years... but I digress...

For those who don't want to 'do the math', which is tedious and if there are changes, needs to be recalculated...

For the iPhone:

http://www.davideubank.com/Good_Focus/pCAM_Film+Digital_Calculator.html

Or

https://itunes.apple.com/us/app/toland-asc-digital-assistant/id377419210?mt=8

Using the Field of View calculators you can easily get what lens length for what FoV/AoV, etc. is required for what sized object, etc. for a variety of cameras.

Well, I guess it is a personal thing because I remember watching that very movie with my wife not 6 months ago and she was very much into it. Not a single word about lighting. Then again, she has no training or awareness of lighting at all. I think it is more of a burden of knowledge thing than anything else.

For me "Escape From New York"(1981) is far to a 'stylized' film to really get worried about 'motivated' light. Sort of like getting worried about 'sounds in space', or the like...

As a film becomes more 'real world', then the motivations for the lightings become more important to replicate that 'real world'.

Instead of speaking generally, why not mention a particular film or show which you mean by this? Was it shot on film or was it bad video? I cannot recall any older films that had lighting so bad to distract from viewing but feel free to enlighten me.

Well, I have posted images from shots 'I like' that seem to have highly motivated lighting.

Here's a shot from a classic, "Notorious"(1946) which, while I've watched, and may watch it more times... I would not consider the lighting scheme to be one I'd want to emulate.

When analyzing this shot... who knows where the lighting is coming from. There are multiple shadows on Cary Grant's hands, there seems to be 'hot' lights on Grant, and just about as hot a light on Ingrid Bergman. There are shadows on the wall, that 'no ordinary' living room lighting setup would produce... etc...

jeclark2006, how is it that Tim Tyler made an exception to the real name rule for you?

jeclark is my name, perhaps not formated with spaces. And since there are about 20 milion of us with that name, 2006 makes it far more unique than a name with spaces and no 'unusual' numbers.

If the administrator/owner of the site wants me to change that, then they can suggest an alternative that is my real name with spaces, and unique enough to disallow someone from mistaking me for some other poster.