Thread: Lighting Question ?

Ok Lads,

This question is doing my head in.... how do you stop the horizontal bars in your images when shooting under florescent lighting? From what I can grasp then it's something to do with shutter speed ? The Nikon D90 suffers real bad from this.... however I do understand that florescent lighting does change it's wave lengths, but when I see other video guys that appear to shoot under florescent lighting conditions and NOT get the horizontal banding bars in their videos is forcing me to ask this question....

How do you stop the horizontal bars in your images when shooting under florescent lighting?

Gaz
www.strober.co.uk
www.strobegun.co.uk

PS: I hope i've posted this in the right section

Not sure about set up in a Nikon, but find shutter options and set to variable, you can then scan the frequences till you find the flicker free range

Zero's right. One thing I don't know with the D90 is, when shooting video are you stuck with just auto settings if that is the case then turn off the florescent lights and find a different light source.

The D90 shoots video at 24 frames per second. Your fluorescents are blinking 50 (Europe) or 60 (USA) times a second.

You can see the problem. Some times your Nikon will capture the whole "blink", some times it won't.

@ Zero @ Midnight Blue @ Rambrandt Rob… thanks for the posting lads….. I’m learning stuff here that I just did not know….. @ zero so camera can scan the lights wave lengths ( I did not know that, but I do know the Nikon D90 can’t do that, instead I have to work around with and “Exposure Lock” on it.).

@ Midnight Blue trust me I’m looking into my own video lighting for video making, I only really own flash guns / speedlites for my still cameras.

@ Rambrandt Rob thanks for that mate, so the light is “linking then” again I did not know that but it makes 100% sense thanks for sharing mate!!

Cheers guys

Strober
www.strober.co.uk
www.strobegun.co.uk

Strober, there are a few terms you need to get your head around.

The wavelength of light is its colour. What you're having problems with is flicker. All fluorescents work by having a pulse of electricity excite electrons in a tube and making them glow. In the UK this happens 50 times a second. The electricty pulses, the chemicals in the tube glow, the phase changes and, during this the tube stops glowing. It happens so fast that our eyes don't register it, however the camera does.

If a video camera is shooting at 25 frames per second, it has enough time to get two "flashes" or "blinks" of the fluorescent onto the frame. If it is filming at 24 frames, sometimes it will get 2 flashes, sometimes three. A CMOS chip "scans" the scene ( a bit like a fax machine scans a document, but a lot faster) in a completely different way and what can happen here is that sometimes you get two blinks, sometimes one, sometimes none.

So, the solution is either to get "flicker free" tubes (They aren't actually flicker free but flicker so fast that each scan or frame gets dozens of blinks and the odd one or two difference isn't noticeable) with a special ballast, to switch the tubes off and use a light source such as tungsten which doesn't flicker, or to adjust your camera such that it is "in sync" with the flashing. As none of us here have a D90 you'll have to dig deep into the instruction manual to see how they recommend doing it.

@ Rambrandt Rob: I have just read your excellent post and I will be re-reading that again, as a fact I think that I will print that out and post it on my studio wall as to me it is a great source of information and one that I should learn off by heart.

Now with regards to the Nikon D90 then it is "NOT" a good DSLR for making videos whatsoever. But in contrast it is a "VERY GOOD" DSLR for making stills

In the video mode you can only control Aperture / Expsure Value and that is basically all you can do... oh and don't forget to lock exspousre value. For real I was really gutted when I found out how poor of a performer that the D90 is for making videos. But again in contrast as soon as I seen it's performance with regards to making stills then I was "over the moon" and as strange as it sounds then I really love the D90. For video making on DSLR's then I see that I need something like a Canon 7D which allows you to control Shutter Speed, Aperture and ISO etc....

But Rambrandt Rob trust me your post has NOT been in vain as I'm going to soak up all that golden bit of information that you have just giving me

Regards

Strober
www.strober.co.uk
www.strobegun.co.uk

I am a Nikon fan but it is with a heavy heart that I have to confess that, when it comes to video DSLR cameras... Canons are better.

(Oh boy, does it hurt to write that, having used Nikons for over 30 years now)

As for stills... Yeah, you can't beat a Nikon!

I 100% agree.... I've shot nothing else but Nikon (apart from my very first camera Fujifilm S5600).... but when it comes to Videos then Canons are the bees knees...... It hurts me too mate but hey lets not be Nikon Purists here, instead lets me real

Originally Posted by Rembrandt Rob

I am a Nikon fan but it is with a heavy heart that I have to confess that, when it comes to video DSLR cameras... Canons are better.

(Oh boy, does it hurt to write that, having used Nikons for over 30 years now)

As for stills... Yeah, you can't beat a Nikon!

Whilst the flashing occurs at 50htz, I am not sure how about the duration of the flashes of these bulbs or the rate they increase or decrease in light. Can I assume the likelyhood of a recorded frame containing any part of a 'flash' can be minimised by using the highest possible shutter speed?