Panasonic Lumix DMC G3 Camera

[colinbm]

Thanks Andrea

I don't know about the 'hot spot', but these filters are small & the light is then spread out over the sensor, perhaps not evenly ?

These are full sensor size, but greatly compressed for here.

If you would like, I could send these to you via Drop Box to run them through RD please ?

Cheers

Col

[Andrea B.]

Yes, do!! And thank you!!!

I'm very curious about the raws for these shots. I don't expect vast differences between the raws and the WB versions.

 

By 'hotspot', I was referring to the vignetting effect from the small diameter filters. I may make charts from the center of the frames and exclude the edges?

 

I will post the RD results to this thread this evening when I'm back at the desk. Right now the daily chore list is calling my name. :D

[Andrea B.]

Here are the Raw Digger versions of Col's filter test fotos.

 

In Raw Digger I use these preferences (and others):

• 2x2 = demosaics the Bayer array
  
• Gamma 2.2 = applies the curve lift to match human vision (without this setting the foto would be very dark).
  Does not affect the histogram.
  
• Autoscale = applies brightness (without this setting the foto would be very dark).
  Does not affect the histogram.
  
• Subtract Black = subtract the dark frame, auto.
  
• Overexposure = auto @ .1%. This is very liberal.
  

Raw Digger creates 16-bit TIFs for export. To display here I use Photo Mechanic to create JPGs from those TIFs with the application of the typical sRGB profile. This is an unfortunate requirement of digital online display. :D As there is no detail, I have saved the JPGs at a medium-high quality of 70 in Photo Mechanic to reduce file size.

 

All fotos were made @ISO-6400 with 1/125" exposure time.

 

The bare sensor. Raw Digger says this is 100% over-exposed, so I'm not sure how meaningful it is?

 

386nm. Blue-Violet or Blue, it seems. No surprise there what with being so close to the 400nm area.

RD shows exposure right on the money.

 

370nm. Orange-ish.

RD shows exposure right on the money.

 

350nm. Yellow.

RD complains that the blue channel is underexposed by 51%.

I think this has nothing to do with Col's settings, but rather with the fact that there is no sensitivity to blue from this sensor or from the Bayer array when 'seeing' around 350nm??

 

340nm. Green.

Again RD complains that the blue channel is underexposed by 49%.

Same reasoning as preceding -- there is no sensitivity to blue from this sensor or from the Bayer array when 'seeing' around 340nm??

[Andrea B.]

To make these Raw Digger histograms I decided to sample a large square from the brightest area of each foto and avoid the vignetting caused by small filters. Seems reasonable, yes? The sample size was 2359 x 2059px

 

The x-axis uses an exposure scale in EVs. EV0 is determined by the camera range. The y-axis is linear. The two green channels are averaged. For good comparisons, I set the same range on both the x-axis and y-axis.

Colour samples were made in Photoshop Elements with the 5x5 dropper on a random bright area of the TIF. Please don't take the sample colour data as gospel because that is no longer raw data. It was just to help with the interpretation of the colours we are seeing.

 

386nm.

5x5 sample: 258° hue, 24% saturation, 44% brightness, (93, 85, 112).

At full sat & brightness, 258° would probably be called Indigo or Violet. Not sure which.

 

370nm.

The foto is not overexposed, but the red channel has saturated, hitting the wall at 2 EVs over the GH3's EV0.

I did not set the x-axis range large enough in the originally presented histogram so my original statement about red channel saturation was erroneous. The histogram has been replaced with a correct one showing that the red channel has not reached saturation.

5x5 sample: 35° hue, 43% saturation, 70% brightness, (180, 142, 101).

At full sat & brightness, 35° is Orange.

 

350nm.

5x5 sample: 47°, 87% saturation, 52% brightness, (133, 107, 17).

At full sat & brightness, 47° is Orange-Yellow.

 

340nm.

Clearly green leads the red by approximately 1 EV along the x-axis, so it is no surprise that the above foto is green.

5x5 sample: 79° 81% saturation, 37% brightness, (71,95,18).

At full sat & brightness, 79° is Lime Green.

[Andrea B.]

Colin, thank you for supplying the RW2s from your G3 for this Raw Digger experiment !!!

 

*********************

 

I've made up this colour bar of the fully saturated, fully bright colours loosely associated with the preceding fotos. I don't know how meaningful this really is because we don't really see our UV fotos with this level of saturation and brightness. But seen like this, we better recognize the tinted colours in the preceding fotos.

 

Colours associated with the G3 filter test.

[colinbm]

Thanks very much Andrea for doing this very scientific digestion of the G3's UV output colours.

Cheers

Col

[Andrea B.]

I was checking the work and realized I had an error in one of the histograms. I did not set the EV scale along the x-axis to be large enough. So the 370nm histogram is erroneously showing a saturation of the red channel. I will replace the histograms and correct that error. The histograms for the other 3 filters are OK.

[colinbm]

Thanks for that Andrea

Col

[Andrea B.]

OK, looks good now.

I enlarged the x-axis range to show more both above and below EV0.

 

Note that the pixel counts (y-axis values) are binned (1/64 EV) so the histograms have a "comb" appearance.

[colinbm]

Thanks Andrea

It will take me a while to understand the deeper meaning of all this, but it is helpful to see it all displayed here thanks.

Cheers

Col

[Andrea B.]

There may not be a deeper meaning! :D But it might help clarify how some of our cameras and filters record UV and IR data.

 

There has been a lot of nonsense written about that over the years. Now we can produce some accurate data and see for ourselves. Note that it was possible to do this before Raw Digger, but RD is the first easy app I've found for such analysis. It will - eventually - be instructive to see how non-Bayer sensors record UV data. For example, the Fuji X-Trans array is non-Bayer. (I haven't yet seen a conversion of this camera.) And your Sigma cam.

 

There is also a lot of smoke & mirrors with respect to white balance and false colours.

 

[[And I hate to bring up that touchy subject about correlating false colours to UV wavelengths but one would have to look at raw data for that - not massaged, colour profiled, edited frames. With the raw data, you would have some chance at seeing how far you could get with such a correlation. However, the Bayer dyes were chosen for their capability to help mimic human vision in a digital sensor, not "UV vison". So I think the false colour to UV wavelength is doomed to failure for that reason and for a few more reasons besides. But we've talked about that ad infinitum elsewhere.]]

[colinbm]

It will be interesting to see how the next non-Bayer, Ricoh-Pentax K-3 II, "Pixel Shift Resolution" mode, works out for UV too.

http://www.imaging-resource.com/PRODS/pentax-k3-ii/pentax-k3-iiTECH2.HTM

Col

[Alex H]

It will be interesting to see how the next non-Bayer, Ricoh-Pentax K-3 II, "Pixel Shift Resolution" mode, works out for UV too.

http://www.imaging-r...-k3-iiTECH2.HTM

Col

 

Where do you see that it is "non-Bayer"?

[colinbm]

The Fuji X-Trans is still a CFA, but a different layout to the Bayer CFA.

The Pentax K-3 II is still a CFA, but a different layout to the Bayer CFA, in that it is moveable, above the pixel well, to give a full RGB reading at each pixel well.

Col

[Alex H]

OK, thanks.

[colinbm]

I had found the Wollensak 1"/25mm f1.9 lens, nice & wide & with a close focus of just under 2' or 600mm, all very useful.

But sometimes I want to get closer up, & fill the frame with a flower, for example.

Today I was experimenting with increasing the macro focus of this lens.

These three examples of the Hibiscus flower of about 6" or 150mm diameter, show the lens on the Panasonic G3, with...........

1/ no spacers between the lens mount.

2/ C/CS 5mm spacer between the lens mount.

3/ a 2mm spacer between the lens mount.

 

 

1/ Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with no spacers between the lens mount.

 

 

 

2/ Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with C/CS 5mm spacer between the lens mount.

 

 

 

3/ Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with a 2mm spacer between the lens mount.

 

Cheers

Col

[colinbm]

Some more testing today with the Panasonic G3, this time with some different UV lighting.

The G3 with a BaaderU2 filter was CWB in daylight.

Four snaps were taken of the Hibiscus Flower in daylight & mixed with other UV lighting.......

 

1/ Daylight & on camera flash.

2/ Daylight & on camera flash & MTE 395nm light.

3/ Daylight & on camera flash & MTE 365nm light.

4/ Daylight & on camera flash & MTE's 365nm & 395nm.

5/ Direct Sunlight only.

 

 

1/ Daylight & on camera flash.

 

 

 

2/ Daylight & on camera flash & MTE 395nm light.

 

 

 

3/ Daylight & on camera flash & MTE 365nm light.

 

 

 

4/ Daylight & on camera flash & MTE's 365nm & 395nm.

 

 

 

5/ Direct Sunlight only.

 

Cheers

Col

[colinbm]

The same Hibiscus, this time in IR light, using the RG9 IR filter, CWB diffused through Sintered Fibrous PTFE.

1/ is the converted RAW file opened in PhotoNinja & saved without any other processing to a .jpg file.

2/ is the converted RAW file opened in PhotoNinja & post processed.

 

 

1/ is the converted RAW file opened in PhotoNinja & saved without any other processing to a .jpg file.

 

 

 

2/ is the converted RAW file opened in PhotoNinja & post processed.

 

Cheers

Col

[Andrea B.]

I'm really liking this Hibiscus flower. Such a pretty thing!! And interesting in UV/IR, too.

Nice work, Col. I really enjoyed the 395 & 365 versions above.

 

Don't let the IR go too dark in Photo Ninja when applying that Detail slider to bring out the texture. Either the Illumination slider or the Shadows slider can bring tones back up just a bit.

 

An interesting thing to me is that your MTE torch seems to cast a wide enough beam that the entire flower gets covered by the UV light? Is that correct? Because that hibiscus is a biiiiig flower. My smaller UV-Led torches do not always cover the flower, and I have had mixed results when using them to boost UV while shooting outdoors. I sometimes have wound up with a splotchy mess after trying to bring out the false colour because I was unable to completely cover the flower. I don't use these torches anymore for anything but fluorescence shots indoors. And before anyone asks, I did try "painting with light" using the UV-Led torch, but I was not always successful in creating an even illumination.

[colinbm]

Thanks Andrea

To get the wider spread of the MTE torches I have unscrewed the reflector head & just used the bare LED light. That gives a wide spread of about 120 degrees.

Col

[colinbm]

I got a chance to get another shot of a pink Hibiscus Flower today, when the Sun peeped out for a short time.

I used the UG5 plus the S8612 staked for this one.

I used the new Sintered Fiborous PTFE disc from UVIROptics, to capture a CWB through the Sintered Fiborous PTFE, using it as a diffuser.

 

 

Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with a 2mm spacer between the lens mount, UG5 plus S8612 filters stacked.

Camera settings, ISO 200, f8 at 8/10th second. Natural Sunlight only.

 

Cheers

Col

[JCDowdy]

Col,

Question on how you are using that Sintered Fibrous PTFE disc as a diffuser. I have made some DIY PTFE diffusers and find that results are better when WB on the source rather than the scene. When you CWB with your diffuser are you pointing at the scene or the source?

[colinbm]

Hi John

I have been shooting the CWB of the scene, with the Sintered Fibrous PTFE disc as a diffuser.

So I will try to shoot a CWB for the Sky, tomorrow :D

Col

[colinbm]

Woke up to a dark, cold & wet morning.......but hey, the Sun did come out :D

Raced outside & did the CWB of the blue sky, with UVIROptics PTFE on the lens as a diffuser, all good....

Here are two shots of the pink Hibiscus flower.....Sorry they are not as sharp as I would have liked, there was a breeze blowing......isn't there always a breeze blowing when you want to photograph flowers !

 

 

Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with a 2mm spacer between the lens mount, UG5 plus S8612 filters stacked.

Camera settings, ISO 200, f5.6 at 1.3 second. Natural Sunlight only.

 

 

 

Panasonic G3, with Wollensak 1"/25mm f1.9 lens, with a 2mm spacer between the lens mount, UG5 plus S8612 filters stacked.

Camera settings, ISO 200, f5.6 at 1.3 second. Natural Sunlight only.

 

Cheers

Col

[JCDowdy]

Col, are these comparing WB on scene vs WB on source or are both WB on source?