Jump to content
UltravioletPhotography

729 summary


Cadmium

Recommended Posts

Just a summery and a few reminders about the Lee 729 + KG3 2mm (Hrommagicus = Chrome Magic) stack.

https://www.leefilte...=cf&sort=number

 

First, let's start with the history:

If you want to see the origin of all this, David Twede's original examples and explanation about the 729 + KG3 stack.

David's instructions are exactly what I use when I shoot with the 729 + KG3 2mm stack.

I think it was David that invented this, as far as I know, so go there first if you want to see how it all started:

https://next-eyes.bl...tal-ir.html?m=1

 

Now a few graphs showing Lee 729.

This first one is their online example, which excludes anything above 700nm.

post-87-0-63648900-1580245842.jpg

 

This second one is the graph they include in their swatch book, it has an extended data range up to 800nm.

Everyone should get the Lee numeric swatch book, which contains hundreds of 3.5" x 1.5" polyester film filter samples, with an extended graph for each filter.

post-87-0-58344000-1580246059.jpg

 

This third one is just an overlay of the Lee 729 and Schott KG3

post-87-0-39331300-1580246148.jpg

 

This forth one has Lee 729 data entered into the Schott filter program, the line is more jerky because the data was only entered for about every 10nm from the Lee 729 graph.

post-87-0-81753400-1580246366.jpg

 

Reminder, somewhere around this site, is a spectrometer scan of Lee 729 that goes up much higher than 800nm, which Ulf made, I don't know where, maybe you can find it.

 

Now for a comparison showing the 729 stack with and without IR removed by stacking it with S8612.

(you might also try this test using Baader UV/IR-Cut filter for your visual/IR barrier (instead of the S8612 2mm), I forget how much 700nm range the Baader UV/IR-Cut filter leaks or not)

Lee 729 + Schott KG3 stack

post-87-0-95259400-1580246530.jpg

 

Lee 729 + Schott KG3 2mm + Schott S8612 2mm

NOTE: although the barn and pump house are red in real life visual, they are colorless when shot with the visual range of the 729 filter, which suppresses all visual red transmission,

thus all of the red you see on the barn and pump house with the full range of the 729 + KG3 stack is derived from IR, not from any visual red.

post-87-0-32277000-1580246620.jpg

 

Lee 729 + Schott KG3 stack (close up crop)

post-87-0-48797100-1580246662.jpg

 

Lee 729 + Schott KG3 2mm + Schott S8612 2mm (close up crop)

post-87-0-97377000-1580246754.jpg

Link to comment

The Lee 729 + Schott KG3 2mm stack is best white balanced in camera using a large gray card such as a WhiBal card.

Also, I usually have my a set to "landscape mode", and I often set my exposure bias to -0.3 step to -0.7 step when shooting with this stack on my D7000 UV/IR.

I find white balancing in Photo Ninja to be good also by clicking or sampling grays or whites, but it usually isn't much different, and often not as good as the in camera WB,

but you can play with that and see how it goes for you and your camera, it can sometimes improve results. Also, auto contrast or even auto levels in Photoshop are good to try,

but again they sometimes don't improve the results, but can do the opposite, but something you can try.

The 729 stack is what it is, and that is the whole point, and is usually the best if left alone if you have white balanced it in the camera with a gray card.

As you can see from comparing the live view to the photo below, they are the same, and personally I would not not want to alter the result of that photo.

No need to force this, don't push it, you let it become what it is, it will naturally fall into center.

 

Here are some links to 721/Hrommagicus results by Andy Broomé which I find to be good examples.

https://www.ultravio...__fromsearch__1

 

https://www.ultravio...__fromsearch__1

 

https://www.ultravio...__fromsearch__1

 

Note the live view on my camera LCD, acquired from the in camera white balance from the WhiBal card.

post-87-0-48979800-1580247094.jpg

 

Here is the resulting photo from that live view.

post-87-0-45895300-1580247126.jpg

Link to comment
  • 3 months later...
Thanks for the whole recap Cadmium. Could we please have the EXIF of the pictures ? Since 1 year or more I'm trying to get good results with this stack but for me the shutter speeds are waaay too slow to be a valuable replacement to IRChrome. But maybe it's my camera ? Or lens ? Or lens+camera ? I'm trying to understand.
Link to comment

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
×
×
  • Create New...