Tarmak Films ltd » tarm’akademy

some common filter factors

Tarmak Films — Tue, 27 Jul 2010 13:50:16 +0000

Here is a table with all the common filters a cinematographer is likely to come across. I have assigned I common filter factor for guidance only and would suggest you check the exact factor with the filter’s manufacturers before applying any correction.

Filter Factors (may vary slightly according to manufacturer)
where 0.3 = 1 stop and 0.6 = 2 stops, etc.

FILTER	FACTOR
85	0.2
85B	0.2
85N3	0.5
LL-D	minor
81EF	0.1
N3 or ND3	0.3
N6 or ND6	0.6
N9 or ND9	0.9
N12 or ND12	1.2
POLARIZER	0.6
B-PM 1/2	0.15
B-PM 1	0.2
B-PM 3	0.4
W-PM 1/2	minor
W-PM 1	minor
B-NET 1	0.15
B-NET 3	0.5
SEPIA 2	<0.6
812	0.1
CORAL 1/4	0.15
CORAL 1/2	0.15
CORAL 1	0.2
CORAL 2	>0.2
CORAL 4	0.3

some useful High Definition terminology

Tarmak Films — Tue, 27 Jul 2010 13:35:27 +0000

Below are some definitions of terms you will come across when dealing with HD. If you wonder what they mean here is an answer.

1080/24P
Refers to an internationally standardized High Definition production format (ITU BT 709) having a digital sampling structure of 1920 (H) x 1080 (V) and operating at 24-frames per second progressively scanned. Often used to loosely describe a system that operates at 23.976P as well.

1080/60i
Refers to a standardized High Definition production format (SMPTE 274M and ITU 709) having a digital sampling structure of 1920 (H) x 1080 (V) and operating in interlaced scan mode at 60 fields per second. Often used to loosely describe a system that operates at 59.94i as well.

1280×720
Refers to a high definition digital sampling structure of 1280 horizontally and 720 vertically. All 1280×720 images are progressively scanned (720P).

1920×1080
Refers to a digital sampling structure of 1920 horizontally and 1080 vertically. 1920×1080 images can be scanned either interlaced (1080i) or progressively (1080P).

22:11:11
Defines high definition video signals, where the luminance (Y) is sampled at 74.25 MHz and the color difference samples (R-Y,B-Y) channels are each sampled at 37.125 MHz. Note that it has become commonplace to denote HDTV Y,R-Y,B-Y also as 4:2:2. While technically incorrect, it is popularly used in a great deal of published literature.

22:22:22
Denotes a high definition system where all signals (R,G,B) are sampled at 74.25 MHz. Note that it has become commonplace to denote HDTV RGB also as 4:4:4. While technically incorrect, it is popularly used in a great deal of published literature.

Aspect Ratio (Picture)
The ratio of screen width to screen height. Can be expressed as Width by Height (Example: 16×9, 4×3) or as calculated ratio (1.33:1, 1.78:1)
Some common aspect ratios:
1.33 (4×3) Standard Television or Academy Standard
1.78 (16×9) HDTV
1.85 Academy Flat
2.35 Cinemascope

Aspect Ratio (Pixel)
The ratio of pixel width to pixel height. Standard NTSC (ITU-R 601) digital video has rectangular pixels. Computers and HDTV have square pixels.

CineAlta
Name for a line of products by Sony that are developed for the film market.

Capture Rate
Used to describe the number of times per second that a picture is taken or captured in an imaging system. In a progressive system the capture rate is equal to the frame rate. In an interlaced system, the capture rate is double the frame rate because at each capture interval, only one field (a half resolution image) is acquired. It takes two fields to make a complete frame. It is standard practice to refer to the capture rate of an image as well as how it is captured when describing it instead of the frame rate (i.e. 60i (60 captures, 30 frames per second), 30P (30 captures, 30 frames per second) and 60P (60 captures, 60 frames per second)) Also see Frame Rate, Interlace Imaging, Progressive Imaging.

Downconversion
The process of converting high resolution video to lower resolution video. Often done to high definition camera reels so that programs can be offlined on inexpensive standard definition editing systems before being conformed in High Definition. Also done to finished HD programs for delivery to non-HD clients

Progressive Imaging
All lines (whole frame) are captured at the same instant. Each frame represents a single moment in time. See Interlace Imaging, PsF Imaging, Frame Rate, Capture Rate

PsF Imaging
Progressive-Segmented Frame Imaging. All lines (whole frame) are captured at the same instant. Each frame represents a single moment in time. After the frame is captured, it is then separated (Segmented) into two halves. One half is the odd lines and the other is the even lines. (Now this may sound like interlace, but each frame represents only one moment in time, not two). Though transmitted similarly as an interlaced signal, if treated as a progressive signal, does not cause the same harmful artifacts that interlace scanning causes. Often image can be processed with much of the same transmission hardware that was designed for interlace. Processing hardware can also be designed to handle both Interlace and PsF (ie Switchable). See Interlace Imaging, Progressive Imaging

Y, R-Y, B-Y
Describes the luminance (Y) and color difference signals (R-Y) and (B-Y) of component video. Y is luminance information and the R-Y and B-Y signals together provide the color information. These signals, derived from the original RGB source, are used in most video systems as a bandwidth reduction technique.

LENS ANGLE to LENS FOCAL LENGTH table

Tarmak Films — Tue, 27 Jul 2010 12:16:43 +0000

Below is a very useful table that can serve as a quick reference for working out lens angles for different formats.

“NORMAL” lens (for motion pictures) is considered equal to a lens angle of 25 degrees

	Standard 16	Super 16	Video 2/3″	Video 1/2″	Super 8	Full Frame 35	Academy	Super 35	35mm SLR	Polaroid
Aspect Ratio	1.33:1	1.66:1	1.33:1	1.33:1	1.36:1	1.33:1	1.37 and 1.66:1	1.85:1	1.5:1	1.32:1
Width	9.65	11.76	8.8	6.4	5.46	24	20.96	24	36.07	95.25
Lens Angle	LENS FOCAL LENGTHS (in mm)
1	553	674	504	367	313	1375	1201	1375	2067	5457
2	276	337	252	183	156	687	600	687	1033	2728
3	184	225	168	122	104	458	400	458	689	1819
4	138	168	126	92	78	344	300	344	516	1364
5	111	135	101	73	63	275	240	275	413	1091
7	79	96	72	52	45	196	171	196	295	779
10	55	67	50	37	31	137	120	137	206	544
15	37	45	33	24	21	91	80	91	137	362
20	27	33	25	18	15	68	59	68	102	270
25	22	27	20	14	12	54	47	54	81	215
30	18	22	16	12	10	45	39	45	67	178
40	13	16	12	9	8	33	29	33	50	131
50	10	13	9	7	6	26	22	26	39	102
60	8	10	8	6	5	21	18	21	31	82
70	7	8	6	5	4	17	15	17	26	68
80	6	7	5	4	3	14	12	14	21	57
90	5	6	4	3	3	12	10	12	18	48
100	4	5	4	3	2	10	9	10	15	40

Width/(2*(TAN(Angle * 0.0174533/2)))

A little RED surprise with Ted Schilowitz presenting a Scarlet prototype

Tarmak Films — Mon, 18 Jan 2010 14:05:22 +0000

Everybody knows that RED has run into some delays regarding the delivery of the Scarlet. Its original shipment date was supposed to be early 2010 and here we are in January still awaiting an official date. According to Ted he estimates a release for late spring early summer. I would say that this could mean later this year. I believe that the RED team had to make some adjustment regarding the camera design given the amount of digital SLR camera released on the market that surprised everybody with their H264 video quality. Also notice that RED originaly sold the Scarlet’s stills photography capabilities on their website but if you visit the website now there is barely any mention of it. Go figure it out, I think that one would have to compete not only with the quality of stills Canon or Nikon deliver in their high end digital SLR’s but also with the form factor. See the video below and see if you would go out and shoot stills with it. Don’t think so. Given that the delivery for a “high-end point and shoot digital cinema” camera looks promising.

RED Scarlet Surprise Hands-on with Ted Schilowitz – Watch more Videos at Vodpod.