Author Topic: Questions and Answers on IR  (Read 85268 times)

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Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #30 on: February 24, 2009, 05:02:56 PM »
I am lucky in that the lens i use for infrared has an adjusted focus mark for IR See under focussing, hereon it.
Its best to use 'Hypefocal distance' if your lens doesn't have any IR marks. There is an exact calculation for a given length in mm, for how far your lens will need to be adjusted for IR. I have always found it simpler to use the 'hyperfocal distance' method. For an explanation of the method and focal distance calculations see here


Hope this helps


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #31 on: March 10, 2009, 01:35:17 PM »
Well, I got the A900 out for some good IR attempts.....and it is no good at IR!  I used the same settings range that I used successfully with my A700, but this thing must have a much stronger IR filter on it.  The shots just came out red instead of red + IR like normal for the R72.  No IR 'pop' to them at all, even with shots in the 20-30 second range.  Even with a lot of help from photoshop, the IR effect is not there.

I did get an IR modded F828 to play with, and it did quite well, but I am not used to editing photos from an actual modified camera yet.  Need some more practice there.  I may have found a place that modifies Sony's even though they are not on the website list.  Too bad I did not grab an A300 when they were on sale cheap at Circuit City!

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #32 on: March 10, 2009, 04:36:50 PM »
Did you try much longer shutter speeds, say 60-70 secs and what did the historgram look like with the 30 sec pics ???
Was it the same lens that you used peviously, with the other camera, as i have found that different lenses can sometimes give different results.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #33 on: March 10, 2009, 07:37:48 PM »
I did not try even longer speeds due to the fact I was trying it at lunch.  I hope to experiment more this weekend.  At first I thought maybe the Zeiss coatings on the 24-70Z may be causing more difficulty, but I used the 16-80Z in the A700 and also tried the STF on the A900.

My plan for the next round is higher ISO to see if I can get a reasonable result and go from there.  I'll have to check the histograms tonight against the A700 ones and see.

Offline groovyone

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Re: Questions and Answers on IR
« Reply #34 on: March 10, 2009, 07:41:14 PM »
Here are some shots to compare, all straight from their respective camera with daylight WB:

IR modded Sony DSC-F828:


Standard A700 + R72 on 16-80Z:
ISO 200, 30 Sec, f/5.6


Edited in IDC:


Standard A900 + R72 on 24-70Z:
ISO 200, 30 sec, f/5.6


ISO 200, 20 sec, f/5.6


Maybe I just need higher ISOs to increase the sensor sensativity to IR too.  I should have taken a better range of settings than I did, but I was doing it on a work break with a setup I know worked with the A700.  Either way, it is more resistance to IR light than the A700. (yes, it was windy)
« Last Edit: March 10, 2009, 09:22:40 PM by groovyone »

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #35 on: March 10, 2009, 08:28:29 PM »
Very strange, it looks like they are close to being overexposed.
Upping the ISO probably wont have much effect other than shortening the exposure time to get the same effect.
Will be interested to see how you get on, as i am planning to get an A900 at some point.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #36 on: March 10, 2009, 09:24:56 PM »
Yeah, that was my thought too since it just seems to become a big red blur.  I fixed the A700 in camera shot and you can see the huge difference.

Offline groovyone

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Re: Questions and Answers on IR
« Reply #37 on: May 20, 2009, 04:26:24 PM »
Well, after a lot of looking I have a reputable place to convert an A-mount camera.  Now I am just trying to get my hands on an A350 body.  I was hoping the new A380 announcement would lead to a price drop, but it hasn't yet.

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #38 on: May 20, 2009, 04:53:59 PM »
Well, after a lot of looking I have a reputable place to convert an A-mount camera.

Could you let me have the details or perhaps post them on here ???
Would be much appreciated.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #39 on: May 20, 2009, 09:28:43 PM »
I sent you the details in a PM.  I haven't done the conversion yet and want to make sure they do a good job before I recommend them, but I have little doubt they will do it well.

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #40 on: May 20, 2009, 09:54:28 PM »
Thanks for that, let us know how you get on.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #41 on: May 28, 2009, 05:46:59 PM »
I have an A100 on its way to me.  I should have it on its way for IR conversion by next weekend and I will post results as soon as I have them.

I do have to say, this is your fault, Rob. Your guide got me to start playing with IR on my A700 and it has been all downhill since.  A big thank you from me, and a not so big "thanks a lot" from my wife.  hahah
« Last Edit: May 28, 2009, 05:49:03 PM by groovyone »

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #42 on: May 28, 2009, 05:58:33 PM »
OOPs :roll:

Cant wait to see the results.


Rob

Offline groovyone

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Re: Questions and Answers on IR
« Reply #43 on: June 01, 2009, 04:01:37 PM »
My A100 has shipped out to be modified.  I did shoot some quick and dirty IR shots yesterday before boxing it up and tried again with the A900.  The A900 is TERRIBLE for IR.  Even with 30s exposures I get no signs of IR at all.

Unmodified A100, in camera, Daylight WB, ISO 100, 30s, f/8 and then with quick WB/Hist adjusments:



Unmodified A100, in camera, Custom WB, ISO 100, 30s, f/8 and then with quick WB/Hist adjusments:


« Last Edit: June 02, 2009, 02:50:06 PM by groovyone »

Offline Rob aka [minolta mad]

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Re: Questions and Answers on IR
« Reply #44 on: June 01, 2009, 07:28:30 PM »
Which lens are you using for the images above, it looks like there is a touch of a hotspot to the first 4 ???

Rob

P.s Have modified your post as there is a max of five images per post