Ring Light Problem/Question...

Hi Folks,

I have been dipping my toes in photography on and off for a few years now, but never really got any where for various reasons, but mainly due to a lack of artistic talent on my behalf!

Fast forward to today, and I wish to photograph some small archiological objects and coins, to forward to a local museum. I suppose you could think of it as close up photography but not true macro.

I already have a Canon 50D and a copy stand and don't really want to sink a huge amount of further money into the project..

For lighting, I would like to use lights as opposed to flash so I can easily see shadows etc as I set up.

Initial tests showed that with my limited range of lenses, the best results sharpness wise, were with a 50mm prime and a 35mm extension tube..

For lighting, somebody at the museum suggested a cheap lens mounted LED ring light off a certain auction site..

The battery operated light arrived, and although a bit cheap and tacky, it actually seemed to work fairly well untill I tried to use the live view function on my 50D to help me manually focus.

At this point, I got black bars scrolling across the image on the screen, although they don't appear in the subsequent picture..

I have done a quick Google search and learnt that led lights cycle ect and sort of understand that aspect....

My question is would I have the same issue if I switched to more expensive, better quality "branded" purpose designed LED ring lights or do they have circuitry to counter this problem?

Any other suggestions for a basic table top lighting solution?


Thanks in advance,

Peter

Can you get your shutter speed and f stop where you want it with a continuous source, how much flash experience do you have? Personally, I'd be going with a flash and diffuser.

The issue might simply be the frequency of the LEDs being energized, creating a 'beat' pattern with the LCD refresh rate.

That might have no effect at all on the image being captured by the sensor. Best would be to shoot shots with varied shutter speeds to detect what issues exist (if any) in image capture, before worrying about image display on the LCD.

windpig wrote in post #19118466
Can you get your shutter speed and f stop where you want it with a continuous source, how much flash experience do you have? Personally, I'd be going with a flash and diffuser.

First, thanks for the reply.. I have no real experience with using flash like this, and using lights and reflectors seemed "easier" and was what the museum staff recomended..I should add these people are not photography experts or enthusiasts, just staff using photography as part of their job.....

I am basically trying to produce flat evenly lit almost shadowless pictures of an object, with no artistic licence allowed...if I can get to grips with this, I may venture into using flash for my own pictures of these items, but that will be a bit further down the road.

Regards

Peter

Wilt wrote in post #19118467
The issue might simply be the frequency of the LEDs being energized, creating a 'beat' pattern with the LCD refresh rate.

I am pretty sure that's the issue, but it only shows when viewing the screen in the live-view mode and my initial tests pics were fine in that respect..As such,
the issue is really only an "annoyance", but I am curious if there is a way around it...

Regards

Peter

No, the 'beat' is the interaction of the refresh rate of the LED vs. the refresh rate of the LCD. You have no control of either. The only solution might be to get a different brand/model of ring light. But unless you have specs on the frequency of the current light vs. the frequency of the new light, it is a shot in the dark as to whether the new unit fixes the annoyance.

The other option is to dispense with any LED source, and go with a conventional xenon flash tube ring light...but it will not illuminate the scene for focusing.

Thanks for that...I think I shall just perseiver...

The "style" of photo I am trying to emulate can be seen here: https://finds.org.uk …rtefacts/record​/id/799769 and just looking for simple lighting set up to achieve this....

Thanks again,

Peter

Since the ring light is 'pulsing', you really need to keep in mind to use a compatible shutter speed...probably X-sync speed or slower.

If you use a faster-that-X-sync speed, the shutter curtains form a somewhat narrow slit. And then the issue is the pulsation as the slit moves across the sensor will be captured and noticeable on the final result!

It might be valuable to enable the antiflicker mode of your camera, if there is one.

Wilt wrote in post #19118487
Since the ring light is 'pulsing', you really need to keep in mind to use a compatible shutter speed...probably X-sync speed or slower.

If you use a faster-that-X-sync speed, the shutter curtains form a somewhat narrow slit. And then the issue is the pulsation as the slit moves across the sensor will be captured and noticeable on the final result!

In the initial test pics, I was using fairly slow shutter speeds to allow me to stop down and maximize my depth of field...It sounds like this was probably why the banding never appeared on the pics themselves...

Regards,

Peter

It might be a very valuable exercise to do the following series, to get a better understanding of your equipment interactions...

• Shutter speed at X-sync or slower, antiflicker Off
  
• Shutter speed faster than X-sync, antiflicker Off
  
• Shutter speed at X-sync or slower, antiflicker On
  
• Shutter speed faster than X-sync, antiflicker Ofn
  

I don't think I have antiflicker on the 50D, but I will try shooting at various speeds to see what the threshold is....

Regards,

Peter

The threshold of difference WILL be at the X-sync speed! The change in shutter opening from fully open vs. travelling slit.
The second factor may be the exposure duration being more than one cycle of the LED.

Would it be possible to tether the 50D to a laptop & see if the problem exists viewing on a different screen? A bit more set-up involved but a lot of photography is done this way

I can't help with the topic of tethering...have never bothered to do so with a dSLR, as my studio days are long gone.