FX7 ISO (ASA) Rating? at DVinfo.net

Steve Henry · February 1st, 2009, 11:24 PM

I'd like to use my external incident light meter with my new FX7 sometimes. Does anyone know the effective "film" speed rating of the camera? At 60fps it seems to be around 320ISO? And I guess if I ran it at 30fps, it would "double" the ISO? Thanks.

Graham Hickling · February 2nd, 2009, 12:41 AM

Steve, the 60 and 30 you are refering to both shutter speeds (i.e. 1/30sec and 1/60) not 'frames per second' which is the meaning of 'fps'.

Adjusting the shutter speed does not change the frames per second, which will be 29.97 in both cases (in the US).

To answer your question, yes, changing from 60 to 30 will double the ISO .... provided gain is being held constant.

Steve Henry · February 2nd, 2009, 02:51 AM

Graham, oops, I had FPS on the brain. Yes, I meant shutter speed. My main question was about ISO so I can set the ISO on my incident meter and see how that works with the FX7. Thanks.

Brian Tori · February 2nd, 2009, 11:02 AM

I do not know the speed of that camera but have rated several others and can describe to you a quick and easy method to obtain it:

1. Obtain 18% grey card from local camera store
2. Position it about 4-5ft. from camera lens and zoom to fill screen
3. Light card with a soft, even light source
4. Put camera on auto iris and let it find f-stop it likes
5. Set meter to 1/60 shutter and hold at card postion in same light
6. Take reading and move ISO up or down until f-stop on meter matches f-stop on camera.

If you use ND filters you will need to compensate for the stop loss after taking reading.

Enjoy better pictures.

Steve Henry · February 2nd, 2009, 11:50 AM

OK, I'll try that and then compensate for ND, gain, aperture/iris and shutter. Gulp, maybe I'll just watch the zebra and histogram :)

February 1st, 2009, 11:24 PM	#1
Steve Henry New Boot Join Date: Jan 2009 Location: Long Beach, CA Posts: 14	FX7 ISO (ASA) Rating? I'd like to use my external incident light meter with my new FX7 sometimes. Does anyone know the effective "film" speed rating of the camera? At 60fps it seems to be around 320ISO? And I guess if I ran it at 30fps, it would "double" the ISO? Thanks.

February 2nd, 2009, 12:41 AM	#2
Graham Hickling Trustee Join Date: May 2004 Location: Knoxville, Tennessee Posts: 1,669	Steve, the 60 and 30 you are refering to both shutter speeds (i.e. 1/30sec and 1/60) not 'frames per second' which is the meaning of 'fps'. Adjusting the shutter speed does not change the frames per second, which will be 29.97 in both cases (in the US). To answer your question, yes, changing from 60 to 30 will double the ISO .... provided gain is being held constant.

February 2nd, 2009, 02:51 AM	#3
Steve Henry New Boot Join Date: Jan 2009 Location: Long Beach, CA Posts: 14	Graham, oops, I had FPS on the brain. Yes, I meant shutter speed. My main question was about ISO so I can set the ISO on my incident meter and see how that works with the FX7. Thanks.

February 2nd, 2009, 11:02 AM	#4
Brian Tori Major Player Join Date: Nov 2004 Location: Detroit, MI Posts: 408	I do not know the speed of that camera but have rated several others and can describe to you a quick and easy method to obtain it: 1. Obtain 18% grey card from local camera store 2. Position it about 4-5ft. from camera lens and zoom to fill screen 3. Light card with a soft, even light source 4. Put camera on auto iris and let it find f-stop it likes 5. Set meter to 1/60 shutter and hold at card postion in same light 6. Take reading and move ISO up or down until f-stop on meter matches f-stop on camera. If you use ND filters you will need to compensate for the stop loss after taking reading. Enjoy better pictures.

February 2nd, 2009, 11:50 AM	#5
Steve Henry New Boot Join Date: Jan 2009 Location: Long Beach, CA Posts: 14	OK, I'll try that and then compensate for ND, gain, aperture/iris and shutter. Gulp, maybe I'll just watch the zebra and histogram :)