Going mad with exposure

[Joel Brock]

Purchased brand new pd170 few months ago. Have done two three shoots absolutely happy with cam and picture. However did an interview shoot the other day set up the lights, cam on tripod, zoomed in as per usual to subjects face, focused and then in manual mode pressed iris to get a numeric reading on the lcd, then adjusted the gain zoomed out and began filming.

When I got back and watched on TV noticed that the exposure was shifting through my wide medium closeup. On close-up I had perfect exposure, but on the wide's highlights on the face were overexposed. I told myself I must have left gain on auto or something as when I played the tapes back and put data code display mode on the gain number was shifting. Anyway hours of colour correcting later I managed to save the interview.

Went to my next shoot determined to not leave gain on auto, set up another location zoomed in set manual exposure (4.1 or something like that on the screen) zoomed out and the image went totally dark. This was crazy!! Turned the cam off, checked gain etc, manual selector was in correct position etc, even pressed the factory reset button on the side of cam. Still the cam was auto exposing the shots. The only thing I noticed was when I flicked it to full auto the exposure changed far greater for the same shots. So what it seemed to be doing was like 'bracketing' the exposure as the shot changed. I was tearing my hair out at this point.

I started thinking gain might be a percentage increase of light available but to be honest I thought the cam was broken. Please excuse my lack of full knowledge with the cam (still learning it) but I thought when you set exposure it kept it fixed and any gain setting increased the image globally

So I’m so confused, is my new camera broke?? Or am I doing something wrong. Please can anyone advise????. Shutter was on auto (default) but I thought the shutter only adjusted in relation to iris and so the pic always stayed the same.

Read the manual - useless.. I don't understand what the AE Shift button is or the custom preset button is hence I pressed factory reset in case I had inadvertently pressed them but still no joy.

Am I missing something in the exposure operation? or should I call Sony.

Please help if you can, many thanks

[Boyd Ostroff]

Originally Posted by Joel Brock

Am I missing something in the exposure operation?

It sounds like you've just discovered what many of us learn the hard way.... the PD-170 (and every fixed lens camcorder) has different maximum f-stops at the wide and telephoto ends of the zoom. So zoomed all the way in (72mm) it's an f2.4 lens but zoomed out (6mm) it's a f1.6 lens. From your description I'm not real clear on what your methodology was, but this phenomenon would cause the wide shots to be overexposed and the closeups to be correct if you used the widest available opening in each shot.

Turn data code on and play back the tape. That should give you a good idea of what was going on with exposure.

[Joel Brock]

Thanks Boyd for your response, really appreciate you taking the time to read and offer your advice !

But im not sure this is it. The cam wasn't doing this on the first two shoots, and the procedure for exposure I have used on other cams all the time. Its not so much a case as from one end of the focal lense to the other but in a room with controlled light the cam changed exposure every 'slight' change of shot. It was just weird. when you zoomed in on someones face the whole picture was changing and getting brighter/darker when it should have stayed the same.

[Boyd Ostroff]

That is odd. Try playing the tape and looking at the data code as I suggested. If things are getting brighter and darker but the lens opening isn't changing then it might be a problem with the camera...

[Craig Seeman]

Just to cover the bases, exposure, gain, shutter speed should all be in manual. Also turn off Auto Shutter internally on the menu.

[Marcus Marchesseault]

I'll betcha a gazillion dubloons that it was auto-shutter. That has happened to me before and it briefly drove my crazier than my normal level of mania. It is not intuitive on the PD170 how to shut it off, and I can't remember at the moment since it is not my camera and I can't check. I don't think a motion camera should ever default to auto-shutter.

[Sheila Ward]

I'm glad to see this post because I had the exact same issue on a shoot this past weekend. I had no problems with my VX2100, which was setup right beside my PD170. I checked over and over that I had everything set to manual but couldn't figure out why the exposure kept changing. This was only my second shoot with the PD170 so I kept thinking I was a dufus and could't figure out the settings. The exposure changes were too great to be the f2.4 vs f1.6 issue I believe.

I'm going to go through all the settings again. Like you Joel, I was about ready to send my camera in for repair. If you find the magic setting let me know and if I find it I will do the same.

[Sheila Ward]

OK, finally got it. It was the auto gain. I read the section of the manual on manual settings several times, and then it finally registered. For the gain to be in manual mode, it has to be showing on the display (like shutter speed, white balance and exposure). So if you don't see that little 0db (or whatever the setting) on the screen, he's having a field day adjusting your settings.

I wasn't used to that on the VX2100, since gain is tied to exposure.

Someday I'll own a camera with only manual buttons with ON/OFF switches. :-)

Hope this helps you out too Joel.

[Marcus Marchesseault]

Auto-gain? Crap. I forgot about that evil little (expletive deleted). Yeah, like that's the best way to regulate exposure? Ever? It's absolutely the best way to RUIN video. Let's see, how often would I want ND1 F5.6, 60shutter, and 18DB OF GAIN?! Bueller?

The good news is that Sony seem to be wising up. The FX1 (and presumably the Z1 to an even greater degree) has mostly individual buttons, knobs, or switches for different functions. Even better, is that many of those are assignable. The problem with all this choice is that there are a lot of buttons, knobs, and switches that you must learn how to use. Of course, to anyone that has used the camera for at least a day or two will find them a godsend. They, at least for me, are also much more intuitive.

[Boyd Ostroff]

I have a VX-2000, a PDX-10 and an HVR-Z1. I really do like the individual manual controls on the Z1, but with just a few caveats. First, it's still like the VX/PD in the respect that if you don't see something displayed in the viewfinder then it's in auto mode, even with the slider set to the middle (manual position). First time I filmed a test I couldn't understand why the manual iris wasn't responding. Then playing back with data code I saw the shutter speed was changing as I adjusted the iris!

The Z1 has a gain switch with 3 settings which you can program in the menu. This is probably great for many applications, but I find it a little problematic shooting performances where the light levels can vary a lot. On the VX and PD as you turn the iris wheel after you get to the full open position you can add gain in 3db increments. On the Z1 you're stuck with either auto gain (which I haven't tried) or the 3 position switch. Now you're going to want to put the first level at 0db, so it really only allows you 2 other levels which isn't enough for performances. Oh well, nothing's perfect I guess :-)

[Joel Brock]

Thanks Boyd, Craig, Marcus & Sheila. (really appreciate your help)

First of all Marcus - if it was autoshutter then how unhelpful is this setting!

Sheila, thanks for letting me know Im not the only one. I know it wasn't gain as I had it set on the lcd but it seems it was the crappy shutter that wasn't set!!! So Im getting somewhere. Other cameras don't do this so its been so confusing.

So can some one clarify if I 'TURN OFF AUTOSHUTTER' in the menu do I need to always have shutter speed selected and displaying in the LCD all the time, along with iris and gain or with auto shutter turned off does it remember your settings ie 50 (for pal) Because all 3 take up so much screen space ?

Also noticed on one of my shots with the exposure problems I had white balance selected on the screen to the indoor bulb icon. I was shooting in a room with fluroescent lights/ Arri 650's and daylight but on one interview the shot gentley fades backwards and forwards from a white tone to a orange tone in a rythmic style (ie not the sun) So can someone explain this? I thought having the bulb set locked it to 3,200K as the manual says - or did I need to do custom white balance. Sorry for asking a new question but I went with the exposure question first because it was more scary

thank you Joel

[Boyd Ostroff]

The general rule with the 150/170/2000/2100 is that unless a parameter is showing in the viewfinder, IT'S ON AUTO. Yeah, I also hate how much screen space this stuff occupies, and it's a nice feature on the Z1 that you can make it all go away.

The white balance thing is puzzling. Same thing applies there, if you don't see one of the WB icons then it's on auto. There have been numerous reports of white balance drifting when in custom mode, but don't recall reading about problems in tungsten mode (with the light bulb icon showing).

One final time... PLAY THE TAPE AND LOOK AT THE DATA CODE. This should be your first step troubleshooting these issues.

[Joel Brock]

Hey Boyd, I did mention in the first post that I checked the data code on playback. Yes the light bulb icon was showing and yes it shows on the data code whilst in playback with datacode display on. I got this right at least :-) but the colour was still shifting.

I hope you can now understand why I was so confused with these two problems and think new cam is playing up.

So i take it from your post to my other question shutter speed always needs to be displayed not just set it once and turn off auto shutter.

Thanks Boyd

[Boyd Ostroff]

Oops, sorry I missed that in your first post. Yes, IMO if something doesn't show in the viewfinder it's running on auto - or at least its current value is unknown. I believe there has been some controversy on this stuff before though, and to add to the confusion the VX and PD series behave slightly differently due to firmware I guess.

For example, on my VX-2000 if I set the iris with the wheel, then press the shutter speed button and change it (or even just look to see what it's set to) then the iris will automatically be set to a new value. But that will cause the current shutter speed to be displayed on the LCD, and pushing the shutter button again will let you resume manual iris control at the speed you selected. I gather the PD-150 and 170 don't behave quite this way, however the PDX-10 does.

Gets confusing, especially with Sony's odd arrangement of similar looking buttons. I don't know how many times I've messed up white balance by accidently pushing the that button when I really just wanted to check audio levels! :-0

[Jeff Toogood]

I had this happen to me a few weeks ago. Was doing an interview against a white background. I could not figure why the camera was wanting to be WIDE open with 12 db of gain to get proper exposure!!
I got two takes into the interview when I noticed the white background brightness changing in the monitor. And THEN it clued it!! Auto Shutter!!!
*****!!!!!
Would have been a disaster had I not figured this out.
After I was able to get proper exposure at F5.6 with 0db of gain.