Author Topic: Questions and Answers on IR  (Read 93484 times)

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Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #60 on: June 25, 2009, 05:31:18 PM »
Hi there J.
I wrote a tutorial about IR See Here if there is anything that is still unclear, just ask.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #61 on: June 29, 2009, 09:05:26 PM »
Hello.
I have the A350, and when I tried IR photos, I get the same red pictures, and I don't know how to edited pictures to have a better results, like yours.
How you doing?

(So sorry, I don't speak English very well)

Sorry for the slow response.  Rob's tutorial is a great start.  On that particular photo I used the Sony IDC software and set the white balance using the "Set Gray Point" option on the brighter tree.  After that I just adjusted the contrast and saturation a little until I liked how it looked.

Offline groovyone

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Re: Questions and Answers on IR
« Reply #62 on: July 05, 2009, 08:09:31 PM »
I have been working on my IR workflow and panoramic stitching, so I figured why not combine them!  These stitches gave me the equivallent of 20-24MP, so close to having a converted A900!

Did some quick editing with Photoshop Elements 5.  Orange is close to how it comes out with my custom WB, and the Blue is just kind of cool:

2x3 stitch with the camera horizontal:


2x3 stitch with the camera vertical:


4 shots, horizontal pan with the camera vertical:


I am definately enjoying the modified camera.

Offline groovyone

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Re: Questions and Answers on IR
« Reply #63 on: July 13, 2009, 03:38:34 PM »
Advantage, modified camera:



I also discovered the 16-35Z seems to have a hotspot.

Offline groovyone

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Re: Questions and Answers on IR
« Reply #64 on: July 29, 2009, 07:11:30 PM »
Well, I shot 362 IR photos in Colorado this past week and made a few quick observations on the lenses.

The 16-35 Zeiss is terrible for IR.  Very bad hotspot and a funky tint to them right out of the camera.  They are a lot harder to work with then the 24-70Z.  The 135 Zeiss has the same blueish tint, but not the hotspots.  I found that I was even getting some bad hotspots with my 24-70Z but couldn't get them consistently to figure out why.  I tried the 24-70Zwith many different settings and with and without a UV filter and could not pin it down.

24-70Z with hotspot, very mild historgram adjustment in IDC:


16-35Z, odd tint and hotspot


16-35Z, odd tint and hotspot is a little less obvious because of the clouds


135Z with odd tint


All are with the exact same custom WB.  I need to play with the 135Z shots in Photoshop some to see what I can do with them.


« Last Edit: July 29, 2009, 07:37:07 PM by groovyone »

Offline groovyone

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Re: Questions and Answers on IR
« Reply #65 on: July 29, 2009, 07:14:12 PM »
24-70Z, back to the sun, wicked hotspot
« Last Edit: July 29, 2009, 07:35:30 PM by groovyone »

Offline groovyone

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Re: Questions and Answers on IR
« Reply #66 on: July 29, 2009, 07:22:48 PM »
Now the good:

One of my favs, modified A100, no photoshop and very very mild histogram adjustment in IDC and the similar shot with the A900:

Offline groovyone

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Re: Questions and Answers on IR
« Reply #67 on: August 13, 2009, 05:34:00 PM »
I have been testing the 16-80Z on the midified camera, and so far it looks like it does have hotspot issues too.  I shot some more today with a few different tests, so I'll see how it goes.

Offline pcabot

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Infrared Photography using A700 and R72 : cannot get false color result
« Reply #68 on: September 08, 2009, 01:42:39 PM »
Hi,

I read the tutorial on infrared written by minolta.mad (which is very good, thanks!) , but I can't seem to be able to obtain proper false color results.

I use an a700 with SAL16105 lens (which by the way does not seem to produce any hotspot, which is great), along with a UV filter and the Hoya R72 Infrared filter stack together. I took a lot of infrared pictures, but I cannot get the false color result I want. May be it is my setup or my post production skills.

Here is a raw file that I took, using manual mode, focus to infinity, ISO400, f8 and 20sec exposure (if I recall properly):
http://philippecabot.com/infrared1.arw   (~15Mo)

Here is the result that I get by importing the file in Photoshop and switching channels (with a few adjustments):
http://philippecabot.com/infrared1.jpg   (~800Kb)

I am not getting the "white trees" and "colored" sky result that I see on other pictures.


I have a few questions:
1. How can I get the false colors look ? Is this a capture problem, or a post production problem ? Can someone check the attached ARW file attached and tell me if it is possible to achieve it with that file ?

2. My image has a very soft focus: how can I make it sharper ? I don't have a infrared focus line on my lens....

3. Is the UV and R72 filters stacked together could be the cause of the problem ?


All comments are welcome !
Thanks in advance,
Philippe

Offline Rob aka [minolta mad]

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #69 on: September 08, 2009, 07:26:58 PM »
I'll have a look at the RAW file and get back to you.
I dont use the UV and IR filters together, though i dont think that that would make too much difference.
As for the focus, you will need to use, hyperfocal distance
http://www.cambridgeincolour.com/tutorials/hyperfocal-distance.htm

Rob

Offline Rob aka [minolta mad]

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #70 on: September 08, 2009, 08:27:42 PM »
Had a look at the raw file, and i am also unable to get the channel swap to work. And as you mention, the trees arent as white as id expect.
The tree's not being white can be down to a number of things.
The time of day and and type of tree for starters, also as the leaves on the trees become older, they have less chlorophyl in them which reflects the IR light which causes them to be 'white'

I have always found that my best IR images, are taken either in the morning 9-11:00 ish and 3-5:00 ish, and i will alwyas try to make sure that the sun is behind me if possible.

Some times i have found that some days are just not good IR days, never found out why, but even with 60 seconds shutter speeds the images are just flat.
As for why the image of yours wont channel swap, i have no idea as i have never encountered this before. Though i suspect it will be due to avaliable IR light and atmospheric influences, just as some days when the isnt a cloud in the sky, but even with a polariser the sky just wont give that deep blue that you expect.

One thing that i would suggest is to find a lacation with several tree's and grass as well as a building or two, preferably on a day with the sun behind you and id imagine that you wont have any problems.
Id also use ISO 100, as opposed to 400, as this will cut down noise.


Rob

Offline pcabot

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #71 on: September 08, 2009, 09:41:49 PM »
Hi Rob,

Wow. Thanks for the detailed answer. It makes sense after all that the amount of IR radiation is linked to the current weather, and to the items in the scene. (The scene I posted above was taken at noon on a bright sunny day)

As you mentioned, I will try again (I rarely give up on photography!) and try with different scene and time of the day.
I will also look at the hyperfocal distance document that you mention.

Also, btw, how do I know if the image is properly exposed ? Just by looking at the red histogram, or all the colors histogram ?

Thanks again
Philippe

Offline groovyone

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #72 on: September 09, 2009, 04:28:03 AM »
Hi,

I read the tutorial on infrared written by minolta.mad (which is very good, thanks!) , but I can't seem to be able to obtain proper false color results.

I use an a700 with SAL16105 lens (which by the way does not seem to produce any hotspot, which is great), along with a UV filter and the Hoya R72 Infrared filter stack together. I took a lot of infrared pictures, but I cannot get the false color result I want. May be it is my setup or my post production skills.

Here is a raw file that I took, using manual mode, focus to infinity, ISO400, f8 and 20sec exposure (if I recall properly):
http://philippecabot.com/infrared1.arw   (~15Mo)

Here is the result that I get by importing the file in Photoshop and switching channels (with a few adjustments):
http://philippecabot.com/infrared1.jpg   (~800Kb)

I am not getting the "white trees" and "colored" sky result that I see on other pictures.


I have a few questions:
1. How can I get the false colors look ? Is this a capture problem, or a post production problem ? Can someone check the attached ARW file attached and tell me if it is possible to achieve it with that file ?

2. My image has a very soft focus: how can I make it sharper ? I don't have a infrared focus line on my lens....

3. Is the UV and R72 filters stacked together could be the cause of the problem ?


All comments are welcome !
Thanks in advance,
Philippe

The stacked UV filter can be an issue as many block IR to some degree.

Offline groovyone

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #73 on: September 09, 2009, 04:32:03 AM »
Here is an in camera and post edited photo:

A700 + 16-80Z + R72 Filter, f/5.6, 30s exp, ISO200, Daylight WB:


After editing in IDC, I set the WB to one of the trees that I knew was in direct sunlight:

Offline Stef.

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Re: Infrared Photography using A700 and R72 : cannot get false color result
« Reply #74 on: September 09, 2009, 05:59:15 AM »
Great shots- grovyone! Just a quick one- you do have a converted IR camera? Any reason why you shot this with a filter on the A700??? I have just sent my A100 off for IR conversion as I don't need this camera body for anything else. Which gives the better results: the converted camera or the A700 with filter???
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