Newbie....need clarification please with fps at DVinfo.net

Joven OHara · December 14th, 2004, 05:21 PM

Hello-
Just got myself a canon xl1s ntsc. Somewhat confused with fps. Reading from the forum...is 25 fps the frame mode and 60I the normal movie mode?
Also...perhaps somebody can direct me where I can get good info on aperture/iris/AE shift/exposue/shutter speed.
Took some video last night (test shots) and video had a strobo effect on it when subject starts moving.

1. I had the cam on a tripod with the stabilizer on. (Mistake)

2. Shutter I believe was set at 1/30. (Mistake?) I had a monitor attached and did not notice it until playback.

3. Shot was in my living room which was dark so I put one omni light (diffused/umbrella). Cam was about 7 feet away from subject but playback was still a bit dark. Any help and guidance is really appreciated.

I know that this forum is helpful since I've been reading postings for the past few months. Thank you all!!

Rob Lohman · December 15th, 2004, 05:10 AM

Welcome aboard DVInfo.net Joven!

Strobing is usually the cause of two things. Progressive (frame)
mode and low shutter speeds. You had both.

1. indeed a mistake

2. most people shoot at 1/60th shutter in frame mode (30p)

3. this is something you need to learn. The best way is to have the camera in manual mode and see which does what. I mainly trust my zebra stripes to know how well I'm doing exposure wise. Otherwise a good broadcast monitor might be required (you will also learn overtime how the viewfinder is biased on your camera)

Since you have the NTSC version your camera's frame mode is
30p (half of 60i) and not 25p (that is for the PAL version!).

Actually, to be precise your camera does 30p dropframe and 60i
dropframe. Which means, it does 29.97 frames per second (fps)
in progressive (which we call 30p) and 59.94 FIELDS per second
in interlaced. If you don't know, a field is half a frame.

A basic explenation on the options:

1. aperture = iris: the opening of the lens, this will change how much light enters the lens

2. exposure = shutter speed: how long the camera views a frame that is sent in by the lens. In 1/30th it only takes 1/30th of a second to record the image. The higher the number after the slash
(/) the less blurred/stuttery the image will be and the more light you will need. The lower the number the more blured (motion blur) the image will be and the less light you will need

3. AE shift is used in a semi-automatic/manual mode to control if the camera should favor a darker or lighter scene

4. Gain: the amount the signal should be amplified by the camera (the higher the more noise will be introduced). Keep it (if you can) at -3 or 0 db

5. ND filter: a sunglass for your lens, cuts the incoming light (which you will usually use on a sunny bright day outside for example)

I hope this will get you started. In the end there is nothing better
then to just expirement and see which does what!

Joven OHara · December 15th, 2004, 04:55 PM

Thank you for the info. I will be messing with my camcorder now.......he,he,he.

Again...thank you very much!

Joven

Les Wilson · December 15th, 2004, 06:45 PM

Hi Joven. Welcome to the XL1s world. I'm sure this isn't a factor for you but just in case....when I bought my XL1s used, the prior owner had set a custom whitebalance. SOmehow on my first shoot, I didn't notice I'd put White balance on Custom and all my footage was blue. So, one thing to try when setting up and you can't get what you want is to put it in automatic mode and see if the camera can get you close.

December 14th, 2004, 05:21 PM	#1
Joven OHara Regular Crew Join Date: Dec 2004 Location: Fremont,CA. USA Posts: 50	Newbie....need clarification please with fps Hello- Just got myself a canon xl1s ntsc. Somewhat confused with fps. Reading from the forum...is 25 fps the frame mode and 60I the normal movie mode? Also...perhaps somebody can direct me where I can get good info on aperture/iris/AE shift/exposue/shutter speed. Took some video last night (test shots) and video had a strobo effect on it when subject starts moving. 1. I had the cam on a tripod with the stabilizer on. (Mistake) 2. Shutter I believe was set at 1/30. (Mistake?) I had a monitor attached and did not notice it until playback. 3. Shot was in my living room which was dark so I put one omni light (diffused/umbrella). Cam was about 7 feet away from subject but playback was still a bit dark. Any help and guidance is really appreciated. I know that this forum is helpful since I've been reading postings for the past few months. Thank you all!! __________________ To be.....or not to be

December 15th, 2004, 05:10 AM	#2
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Welcome aboard DVInfo.net Joven! Strobing is usually the cause of two things. Progressive (frame) mode and low shutter speeds. You had both. 1. indeed a mistake 2. most people shoot at 1/60th shutter in frame mode (30p) 3. this is something you need to learn. The best way is to have the camera in manual mode and see which does what. I mainly trust my zebra stripes to know how well I'm doing exposure wise. Otherwise a good broadcast monitor might be required (you will also learn overtime how the viewfinder is biased on your camera) Since you have the NTSC version your camera's frame mode is 30p (half of 60i) and not 25p (that is for the PAL version!). Actually, to be precise your camera does 30p dropframe and 60i dropframe. Which means, it does 29.97 frames per second (fps) in progressive (which we call 30p) and 59.94 FIELDS per second in interlaced. If you don't know, a field is half a frame. A basic explenation on the options: 1. aperture = iris: the opening of the lens, this will change how much light enters the lens 2. exposure = shutter speed: how long the camera views a frame that is sent in by the lens. In 1/30th it only takes 1/30th of a second to record the image. The higher the number after the slash (/) the less blurred/stuttery the image will be and the more light you will need. The lower the number the more blured (motion blur) the image will be and the less light you will need 3. AE shift is used in a semi-automatic/manual mode to control if the camera should favor a darker or lighter scene 4. Gain: the amount the signal should be amplified by the camera (the higher the more noise will be introduced). Keep it (if you can) at -3 or 0 db 5. ND filter: a sunglass for your lens, cuts the incoming light (which you will usually use on a sunny bright day outside for example) I hope this will get you started. In the end there is nothing better then to just expirement and see which does what! __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

December 15th, 2004, 04:55 PM	#3
Joven OHara Regular Crew Join Date: Dec 2004 Location: Fremont,CA. USA Posts: 50	Re: Newbie Thank you for the info. I will be messing with my camcorder now.......he,he,he. Again...thank you very much! Joven __________________ To be.....or not to be

December 15th, 2004, 06:45 PM	#4
Les Wilson Inner Circle Join Date: Jan 2004 Location: Boca Raton, FL Posts: 3,014	Hi Joven. Welcome to the XL1s world. I'm sure this isn't a factor for you but just in case....when I bought my XL1s used, the prior owner had set a custom whitebalance. SOmehow on my first shoot, I didn't notice I'd put White balance on Custom and all my footage was blue. So, one thing to try when setting up and you can't get what you want is to put it in automatic mode and see if the camera can get you close.