Testing some of my lenses with UV...

[bsas]

So, here is an interesting test...

I used my S8612/2mm + U360/2mm stack with 4 different lenses on my camera to compare exposure but at the same time I also got very different results with the camera "auto exposure" metering and color (I used a white PTFE Film card to white balance).

 

Here is the results:

Voigtlander 58mm f1.4 (at f4): ISO 1000, 1/60s

 

 

Sony FE 28-60 kit lens (at 28mm f4): ISO 4000, 1/60s

 

Takumar 35mm f4: ISO 2000, 1/60s

 

Canon 50mm f1.8 STM (at f4): ISO 1600, 1/60s

 

So... why the color is so different?

[lukaszgryglicki]

Simple: different (sloping down) transmission deeper in UV, so different amounts of different UV wavelength pass - and because Bayered camera responds with different colors to different UV wavelengths - colors are different.

 

More buish/violet means more longwave = smaller transmission of shorter wavelengths = worse lens for UV

More redish/yellow/brown = more shortwave UV passed = better UV lens.

Green = shortest wavelengths passed = best lens (if light contains <= 340-350 nm at all).

 

More yellow/brown/red/green? should also have shorter exposure at the same f and ISO or lower ISO at the same f and exposure. In most of my accidentail UV lenses green = light leaks.

[bsas]

Nice explanation Lukas, thanks.

So, from my sample, how would you categorize the lenses from best to worse?

[Andy Perrin]

None of these look white balanced off the PTFE? If they were then then PTFE would be white/gray in the scenes. Hard to know what to make of the colors if WB is unknown. 

 

To really get an idea of the colors pre-WB you should use something like RAWDigger. Lukas is making a lot of assumptions. 

[Andrea B.]

The colors of the PTFE aren't all that different in terms of placement on the color wheel.

One of color is 292° on the color wheel. The other three colors measure 297°, 297° and 300°.

 

They appear to be more different than they actually are in the photos

because the brightness and saturation of the PTFE area in each picture is not the same. 

 

As Andy noted, the photos are not white-balanced. What happened?

 

 

[bsas]

I took all pictures using the camera "daylight" WB and later I used DxO Photolab droplet to set custom white balance on the RAW files clicking on the PTFE card... :P

[ulf]

23 minutes ago, bsas said:

I took all pictures using the camera "daylight" WB and later I used DxO Photolab droplet to set custom white balance on the RAW files clicking on the PTFE card... :P

Then the DxO Photolab cannot handle the rather big adjustment needed for these RAW-files.

When correctly done the PTFE part will be completely neutral. The images are not white balanced.

The data in the RAW-file is not dependant on the camera WB, except that it might contain a preview jpeg that the camera tried to WB.

[bsas]

1 minute ago, ulf said:

Then the DxO Photolab cannot handle the rather big adjustment needed for these RAW-files.

When correctly done the PTFE part will be completely neutral. The images are not white balanced.

The data in the RAW-file is not dependant on the camera WB, except that it might contain a preview jpeg that the camera tried to WB.

 

Aha! That makes sense... which software you guys prefer to handle UV white balance? I remember Lightroom being super limited :(

[ulf]

On my Mac I prefer the RPP64 that gives me very good control, but it has a rather odd user interface. It is a Mac-only program.

PhotoNinja is popular here, even if it has some limitations. 

I often use the free FastRawViewer for previews.

DarkTable can also handle those raw files

[ulf]

For simple images I often use FastRawViewer and then just take a local print screen.

For serious work I do FastRawViewer - RPP64 - NeatImage - Photoshop

[lukaszgryglicki]

For WB I'm using my own software... I've postem many examples in the past - actually it may be worse that existing software in many occasions, but at least I know *exactly* what's going on...

 

[Andrea B.]

Here are two tutorials for how to white balance in two free photo apps, RPP and Darktable.

After white balancing and saving the file as a TIF, you can then finish the file in any other photo software if you like.

(The RPP tutorial also contains instructions for finishing the file.)

Raw Photo Processor: Basic Conversion of a Reflected UV File [Mac Only]

Quick White Balance in Darktable

 

[Andy Perrin]

RPP has become my favorite converter lately, although I like PhotoNinja for editing and quick tests still. The issues I had with PhotoNinja before convinced me it is probably the worst choice for demosaicing (at least for the moment, since software evolves...). I like the tools and workflow, however.

[ulf]

Just to get an idea about how things can look download and try the FRW.

The trial is fully functional in 30 days and it is available for most OS.

https://www.fastrawviewer.com/

It is also well worth the money as it is rather cheap.

 

[bsas]

5 hours ago, ulf said:

Just to get an idea about how things can look download and try the FRW.

The trial is fully functional in 30 days and it is available for most OS.

https://www.fastrawviewer.com/

It is also well worth the money as it is rather cheap.

 

 

I am an old school owner of fast raw viewer. I use it to organize my stuff.

But I never used it to set white balance. Where is it???

[dabateman]

Should be under the Adjust tab at the top.

Looks to actually have many adjustments,  according to their website.  Too bad it doesn't output tiffs. But it might save this in a XMP file to open with your raw converter. 

I don't own this software. 

I use photoninja. 

 

[ulf]

9 hours ago, bsas said:

 

I am an old school owner of fast raw viewer. I use it to organize my stuff.

But I never used it to set white balance. Where is it???

On a Mac you option click in the image.

There are excellent manuals at their website that can be good to read.

9 hours ago, dabateman said:

Should be under the Adjust tab at the top.

Looks to actually have many adjustments,  according to their website.  Too bad it doesn't output tiffs. But it might save this in a XMP file to open with your raw converter. 

I don't own this software. 

I use photoninja. 

 

It might "should", but your guess is not correct. The WB is not under the adjustment tab.

Maybe you should try it. You might even like it.

This is a Preview tool for Raw files, not a full blown Raw converter, or a do it all tool like PhotoNinja.

[Andy Perrin]

The Mac lets you preview a RAW just by selecting it and hitting the spacebar. Why is a separate previewing program needed?

[ulf]

6 hours ago, Andy Perrin said:

The Mac lets you preview a RAW just by selecting it and hitting the spacebar. Why is a separate previewing program needed?

The FRW can so much more than just open and show a RAW-file.

 

It can be used for WB, working well with our odd files, even such as from a BUG5-stack.

It can zoom in to details.

It can show over and under-exposed pixels  for each cannel.

It can show the histogram.

It has tools to analyse and highlight detail contrast. 

It can be used for manipulating the preview by changing the contrast and exposure.

...

Made by the same people that created the RAW-Digger.

https://www.fastrawviewer.com/Libraw-products

IMHO, it is so useful and cheap that is should be in every serious photographers toolbox.

 

Why not download and try it. Compare it to Apples preview,

 

[dabateman]

@ulf,

But you can't export or save those edits. Any time spend in that program to see what is possible only in that program, is wasted.  That same white balance correction can't be applied later in an other raw editor. 

Why they don't cross the road to allow tiff export is beyond me, but they only want it as a preview program and not to be considered an editor. 

[ulf]

@dabateman

You can save them as lower resolution screenshots for posting on the web.

It is not waste time to find the best image of several alternative exposures, before starting the real RAW-conversion.

I use the way FRV-images look as a first indication and starting point of a possible outcome from the RAW-converter.

 

I do not always get my exposure and focus perfect as It appears you do, from what you say.

I also take several shots, especially outdoors where it is difficult to tell fi wind movement spoiled the image. I use the program to analyse and sort images and decide what to throw away.

 

I agree that it would be nice if you also had a possibility to export as a TIFF, but I do not think this Viewer is good enough for that for serious work.

I want more control, that I get in the RPP64 .

For me the PhotoNinja is not good enough either.

[dabateman]

@ulf,

No I am not that great to nail exposure and focus.

But I use the filmstip view in my raw editor to see how bad I have shot them and find the best one quickly. Then process it as I see fit.

Capture one also does blinkies to tell you what is in focus. But I don't own Capture one. They killed the side folder view option and I hate importing folders, which is why I don't use lightroom.

 

[ulf]

Maybe you should take a deeper look at FRV and it might be that you discover some features that make you continue using it, just as I did.

There are so many ways to analyse and check RAW-images that you cannot do fast in a normal RAW-converter.

Yes I know that I am biased from not having some functions in RPP64 after ditching PhotoNinja, but I have also found FRV very useful to analyse images in an efficient way.