Flourescent lights and leaf shutters

[Ed Sutton]

I'm not a technically mined photographer but I take a lot of photos in a venue with strip lighting. I manage to overcome the colour temperature issue (half a frame warm, half cool or some variation on this) using DSLRs by using a shutter speed of 1/100th of a sec. Yesterday I was using a Fuji X100t and didn't notice any trouble with unexpected colours no matter what shutter speed I used. Is this my imagination? Does the Fuji have some magic trick or is it the leaf shutter saving the day?

 

[Kodiak Qc]

is it the leaf shutter saving the day?

Most certainly, the leaf shutter has nothing to do in the equation
but Its speed and not its type… as any shutter is affected more
visually at 1/100 ~ 1/125 s:

• a vertically traveling curtain will display horizontal bars,
• an horizontal curtain will display verticals bars and
• a leaf will show a circular shape of the same casts.

It has more to do with the speed of the flickering cycle (50Hz) of
the fluorescent light.

 

[Ed Sutton]

That's what I thought. Maybe I was just lucky!

 

[StewartR]

It has more to do with the speed of the flickering cycle (50Hz) of the fluorescent light.

It has *everything* to do with the 50Hz frequency.

 

[HoppyUK]

It has everything to do with both the leaf shutter and the flickering.

With a focal plane shutter, at faster speeds you'll get a change of colour and brightness* over the frame as the shutter scans down and captures different parts of the flickering cycle. Leaf shutters are 'global' in that the whole sensor is exposed equally at the same time, so at fast speeds you could still get changes in colour and brightness from shot to shot, but each individual frame would be affected equally all over.

In both cases, the you'll get more accurate and consistent results at longer shutter speeds.

*Edit: while the flickering cycle is fixed at 50Hz, what happens to the light within that 1/50sec can vary quite a lot with different fluorescent tubes. Some have quite marked changes to both colour and brightness, others much less so.

 

[Ed Sutton]

Thanks Richard.

I'm guessing that auto WB has compensated for frame to frame variation. Handy to know I have a tool which I can use faster than 1/100th sec.

 

[HoppyUK]

Thanks Richard.

I'm guessing that auto WB has compensated for frame to frame variation. Handy to know I have a tool which I can use faster than 1/100th sec.

Possibly. You may not have seen my edit above, but fluorescent tubes can vary a lot. In my kitchen for example, the main ceiling strip is a fairly constant yellow/green at all times, but the under-cupboard lights change noticeably from green to pink at different moments in the cycle. To the naked eye, they both look much the same overall colour

 

[Ed Sutton]

I missed the edit. So long as the colour is consistent across the frame I'm happy. It was having an orange top and a blue bottom to the pictures which drove me mad until I twigged what was going on with the DSLR.