grain without gain? FX1

[Sho Wada]

Hi

I have bought an used FX1 as a sub camera recently and have used a couple days ago with V1J as a main camera.
I was capturing and noticed that on FX1 without gain has a lot of grain.
I have searched about FX1 and found out that FX1 is supposed to be a better camera than V1J in low light shoot.

Here is the images of FX1 at F8 or so and V1J at F4 or so.

www.yamatofilms.com/videos/FX1.tif
www.yamatofilms.com/videos/V1J.tif

Did I do something wrong on the FX1 settings?

I appreciate any advices.

Thanks
Sho

[Perrone Ford]

These images don't help us.

1. We can see that you are not at the same distance so we cannot compare the images.
2. We do not know if frame rate and shutter speed is the same.
3. You tell us the iris is is 2 f-stops different.

In order to get a proper comparison, you need to shoot the same scene, from the same distance, with the same camera settings. That might allow for a comparison.

[Sho Wada]

Thanks for your quick reply.

I know those images aren't good enough for a comparison, but those are only images I have for now.

1. Two camera is at almost a same position. They were on tripods side by side. V1J for close up and FX1 for wide shot.
2. Frame rate and shutter speed were the same on both cameras.
3. I can't remember the exact iris but gain wasn't used on both cameras.


One thing I just noticed playing with the FX1.

-set to GAIN OFF, f-stop at 6.2
www.yamatofilms.com/videos/P1000211.JPG

-set to GAIN at 3db, f-stop at 6.2
www.yamatofilms.com/videos/P1000212.JPG

-set to GAIN at 15db, f-stop at 6.2
www.yamatofilms.com/videos/P1000213.JPG

When I push Gain it uses Gain at 3db and it gets darker than the Gain switch off.
According to this, it seems GAIN switch OFF is using GAIN at 18db.
Is that right?

Took those pics with my digital camera so that you could see the setting on LCD.

[Perrone Ford]

Is the camera in automatic mode? The ONLY way these exposures could do this, is if the shutter speed is getting shorter as you add gain.

Can you set the camera to manual mode? Then set at:

1080i 60 frames per second
set shutter to 1/60
then fix iris to get proper exposure
Set gain to 0


If you do this for both cameras then we should be able to get a good comparison. It seems the camera is in automatic mode and is making adjustments for you that you don't want. Why it is giving an iris of 6.2 I don't know. Iris should be F2 or some other small number.

[Chris Barcellos]

I have an FX1. To assure that camera is not adding gain, you need to:

1. Set Auto Lock button to middle selection, which unlocks gain auto exposure features.

2. Select Menu, Gain set up. Set the three levels of gain you might use. I have mine set at 0, 6, 12.

3. Exit out of menu.

4. Push the gain button. You should see a reading in the viewfinder giving the gain setting. With the gain selector switch, you can cycle through L, M, H settings of gain.

IF you aren't actually selecting a gain setting like that, the camera will automatically add it !

[Perrone Ford]

Thanks Chris. It was obvious gain was being added since +15 looked nearly the same as gain off!

[Sho Wada]

Thank you all for advices!!

I have been using V1J and the way to control gain is completely different on FX1.
And that made me misunderstood the way to control gain on FX1.

On V1J, once you set the main control switch to Manual from Auto, the shutter speed, gain, iris, all of them are controllable and all of them will be Manual. However on FX1, you switch the main control switch to Manual from Auto, you still have to push gain, shutter sped, iris, each button to control manually, otherwise they are still Auto.

So I thought switching main control switch to Manual makes gain 0 but it was still Auto and was using gain at 18db. That is why there were a lot of grain and the f-stop was way higher than the V1J.

Thanks again.
Sho