LED color temp question

[gensou.shigotonin]

Hi guys,

 

I use the two following products from China for my ghetto light box set up:

 

http://www.aliexpress.com/item/DEEP-new-generation-of-LED-light-box-softbox-80CM-professional-photography-studio-equipment-photo-shoot-props/32250977867.html

http://www.amazon.com/YONGNUO-camcorders-3200-5500K-adjustable-temperature/dp/B00COGKPLM

 

While they claimed that their color temperature is 5500k, when I process the RAW files from my camera (Sony A7M2 and RX1), the auto value is 4600/4150 respectively (and they are really the best). It is really bugging me. So my questions are:

 

1. Are the LED not color accurate at all?

2. Does the diffuser (cloth, semi opaque plastic plates insert) or the reflector (those metallic interior or matte box) affect color temperature?

3. Why the optimal color temperature to each camera seems different?

 

Please help. Thanks guys!

 

Result is here. I only calibrated my monitor recently and aside from the most recent four pictures, all color in the previous shots are off. Hard luck.

https://www.flickr.com/photos/133640171@N07/?

 

[ALwin]

Shine the lights on a sheet of white paper, adjust your camera to the same WB as the lights, take a photo of that paper and measure the WB in Photoshop.  See if it remains the same or differs.

 

The optimal WB temperature depends on the situation, not the camera.  If you take photos outdoors, indoors, at night, under tungsten lights, etc.  Also, optimal depends on what style you want.  Sometimes I may deliberately choose an "incorrect" WB to get a different look and feel.

[Omon_Ra]

5 minutes ago, gensou.shigotonin said:

 

1. Are the LED not color accurate at all?

2. Does the diffuser (cloth, semi opaque plastic plates insert) or the reflector (those metallic interior or matte box) affect color temperature?

3. Why the optimal color temperature to each camera seems different?

 

 

1. Probably not

2. Yes

3. Variations on what the sensor determines as 'white'

 

Stick to a manual white balance. You can set your white balance by color temperature (lower numbers are cooler/bluer, higher is warmer/redder) and in your case, I would start at 5500K since that is the reported temperature of the bulbs. Or you can set the sensor to a specific 'white.' Take a white board (sheet of paper if you're in a pinch) and hold it where the subject is going to be in the shot (so it's under the same lighting as the subject will be). Zoom in so the whole frame is white and hit the 'set white balance' button. That will manually set the sensor to detect that shade of white as 'white.' I personally like setting my white balance according to color temperature, as then I have a concrete number to make adjustments from; but also in controlled conditions, if I find in post I need to make white balance adjustments, it's one change for all of them in that set.

[gensou.shigotonin]

Problem reference: http://imgur.com/a/5sWT9

 

Thanks guys for your input! The problem seems to be a color cast on the object that just won't get away. I am now planning to move to tungsten light or strobe (probably with a couples of Sony or Nissin, if it is possible). I have read some articles but I am still confused.

 

I am looking at the Godox tungsten light - as I may wish to make some video in the future. The set up will be in a very confined space and I prefer soft fill light over hard light, so I will get the softbox. Can anyone with experience give me some more insight? Please help.

[ALwin]

• Set a custom white balance in the camera
• Shoot in RAW and adjust in post

These are your options, aside from buying a new set of lights.

[.spider.]

LEDs are the wrong choice if you are aiming for the most accurate color reproduction.

Tungsten light/ halogen light and so on* and a color checker is key.

 

*light sources with a continuous spectrum

[gensou.shigotonin]

4 hours ago, .spider. said:

LEDs are the wrong choice if you are aiming for the most accurate color reproduction.

Tungsten light/ halogen light and so on* and a color checker is key.

 

*light sources with a continuous spectrum

Yes, the problem is probably the continuous spectrum... I just love the sun for this...

 

4 hours ago, ALwin said:

• Set a custom white balance in the camera
• Shoot in RAW and adjust in post

These are your options, aside from buying a new set of lights.

Thanks man!

[ALwin]

41 minutes ago, gensou.shigotonin said:

snip

Don't use cheap LEDs for photography.  There are good ones, designed to be used for photo and video which cost more.  Many professionals, including myself have no problem with using HQ LED panels.

 

By the way, I only opened your link (was at work earlier) and even judging by the photos you regard as problematic, I don't see anything that cannot be fixed by shooting with a custom WB or RAW and adjusting in post.  In fact I'm looking at them on my calibrated monitor and I don't see anything that I would consider as a color casting, I only see slight changes on EV that may be perceived as color cast.

[gensou.shigotonin]

32 minutes ago, ALwin said:

Don't use cheap LEDs for photography.  There are good ones, designed to be used for photo and video which cost more.  Many professionals, including myself have no problem with using HQ LED panels.

 

By the way, I only opened your link (was at work earlier) and even judging by the photos you regard as problematic, I don't see anything that cannot be fixed by shooting with a custom WB or RAW and adjusting in post.  In fact I'm looking at them on my calibrated monitor and I don't see anything that I would consider as a color casting, I only see slight changes on EV that may be perceived as color cast.

Thanks AL. In any case, I made the shots in a small 60cm*60cm box. I shot them in RAW and process them after. I am really having trouble tuning them to the correct color, but I want to learn (and other PS skills as well). Do you know any good way to start?

 

Thanks again.

[ALwin]

7 minutes ago, gensou.shigotonin said:

snip

What mode were you using, manual or some priority mode?

[gensou.shigotonin]

2 minutes ago, ALwin said:

What mode were you using, manual or some priority mode?

Aperture priority, Jpg + RAW at AWB. EV should be at around +1 something. Sony A7ii, RX1 and Leica X Vario.

[ALwin]

Just now, gensou.shigotonin said:

Aperture priority, Jpg + RAW at AWB. EV should be at around +1 something. Sony A7ii, RX1 and Leica X Vario.

For product photography like this in a "controlled" environment, I recommend Manual mode, RAW (you don't need to shoot RAW+JPG), set a fixed WB (to the temp of the lights) and set EV to +/- a bit as necessary, make sure everything remains the same for every shot.  This helps to keep things consistent.

 

In any other priority, there will be slight variances in WB and exposure because the clothing on your dolls differ, their colors and hues.

[gensou.shigotonin]

Thanks, will try.

 

The doll is actually 62cm tall and I definitely need to create a bigger set up. 

[ALwin]

4 minutes ago, gensou.shigotonin said:

Thanks, will try.

 

The doll is actually 62cm tall and I definitely need to create a bigger set up. 

If you create a bigger setup and will no longer be using that box, keep in mind that you may have some mixed lighting issues.  The room's lights and the lights you use for photography.

[gensou.shigotonin]

 

3 minutes ago, ALwin said:

If you create a bigger setup and will no longer be using that box, keep in mind that you may have some mixed lighting issues.  The room's lights and the lights you use for photography.

Yea. I plan to seal the windows and get tungsten lights for it.

 

That's a small price to pay for learning studio photography.

 

By the way, I am really looking forward to Sony releasing a E mount camcorder with good NR. Is the FS7 good in dim/crappy light?

[ALwin]

The FS7 is a fantastic camera, I've been using it for about half a year now and love it.  But if it's too expensive you can consider the FS5.  There are very few video cameras under $10,000 that rivals the FS7 and FS5 for what they can do.

 

The FS7 is a decent low light camera (though I recommend that lights be added if there isn't enough light, with any camera), and it is certainly way ahead of BlackMagic's URSA/Ursa Mini in handling less than ideal lighting situations.

 

I just did a live broadcast with the FS7 yesterday in a less than ideal lighting situation.

 

Be careful with tungsten lights, cheap ones can be just as bad as cheap LED panels but in a different sort of way and they will definitely run hotter and can consume a bit more power (so keep an eye on your electricity bills).

 

My recommendation for video, get higher quality LED panels, don't buy cheap eBay Chinese panels.  For photography, buy some good speedlights if you want strobes or actually invest in some nice studio strobes, but you may also need to invest in some wireless/IR triggers.

[gensou.shigotonin]

I may just get 3 of these:

 

http://www.bhphotovideo.com/c/product/483616-REG/Lowel_Rifa_Lite_eX_44_One_Light.html

 

Seems to be the best budget solution. I will indeed purchase 3 Sony HVL-F43M for the strobe, at least I could bring it around when I have to. Do you think it could work? Sorry but I am complete noob in this.  10+ years of amateur photography never taught me anything about indoor.

[.spider.]

FYI there are metrics which determine how well LED reproduce colors. 

CRI: Based on human eyes, should be at least 90 or more.

TLCI-2012(white paper EBU Tech 3355) : Based how cameras are capturing colors; a value of 90 is almost perfect. 

[ALwin]

4 minutes ago, gensou.shigotonin said:

snip

The Sony flash units should be OK. But for the tungsten lights, since I don't have experience with that particular model and it has ZERO buyer reviews, I say look for another kit that has user reviews.

 

I also recommend these Westscott LED panels, they are very good:

http://www.bhphotovideo.com/c/product/1174881-REG/westcott_7452_flex_10x_3_daylight.html

[ALwin]

12 minutes ago, gensou.shigotonin said:

10+ years of amateur photography never taught me anything about indoor.

I've been into photography for around 20 years, and nearly 10 as a professional.  You just have to explore, learn, experiment and turn it into instinctual knowledge.

 

There are great videos and articles online about lighting, mainly the ones by Scott Kelby, Joe McNally and Jerry Ghionis.  Avoid the "free" and "cheaper" channels, like FroKnowsPhoto and such.