Infrared, Just Started.

[chris_arnet]

Allright, my first two IR photos. Hoya R72 on a Canon 50mm f/1.8, Mounted on a Canon 20D. I know that the 50mm prime gives me limited creative ability, but I didn't wanna drop $250 on a filter before I had infrared basics down. I've been noticing alot of image quality loss too. Any pointers or suggestions? For Image quality loss or just IR in general.

Any help appreciated, Thanks.


Chris

 

[Sideburns]

I'm not sure, but part of the quality loss could be focus, and part is the long exposure noise. How long were these?

 

[chris_arnet]

I focused carefully and then screwed the filter on. Exposeres were anywhere from 10 to 25 seconds, I bracketed like crazy and don't remember. Still, it shouldn't make the fallen pavillion that soft though...

 

[Cero21]

Your quality loss could be attributed to the loss of the 1 blue and 2 green sensors for every 1 red sensor on your camera. Therefore shooting IR cuts your total megapixel count to 1/4 what it was. Hope that makes sense.

 

[Sideburns]

The reason I say your focus could be off...depending on how dark the filter is, the focus point changes.

 

[chris_arnet]

So i now have a 2.05 magapixel camera?

 

[Cero21]

effectively

 

[chris_arnet]

well, that sucks.

 

[shorty6049]

The IR filter , (Hoya R72 i'm assuming) WILL change your focus point a little. Thats why some lenses have a little "r" or a red dot on the focus scale to show you where you'd need to line up your focus for IR work. I always just focus in and out taking shots each time until its sharp. (i shoot at a very high iso so the exposures are like 2 seconds each) then i set it back to like 100 ISO, and shoot the final image. that usually works pretty good. also, i've heard that cameras focus with IR light anyway, so you SHOULD just be able to frame the shot, then put the filter on and focus with it on and it'll still work, but i find that its always still a little off....

 

[shorty6049]

i hope you dont mind, (if you do let me know and i'll remove it) but i played around with your first image a little (cleaned it up and did a channel swap)

 

[chris_arnet]

i love that dude. i have elements, so i cant channel swap.

i do frame without the filter. and focus, but its always OOF after i take the pic. And my 20Ds LCD screen is small, so everything always looks nice and sharp.

 

[Alpha]

First, never judge your shot by the LCD unless you're looking at the histogram.

Second, adjust the focusing to compensate for the aberration. If your lens doesn't have an IR guide mark, then do the math. There are lots of resources on the web that will instruct you on IR focusing.

 

[shorty6049]

cant you magnify your LCD image to check the focus though? thats what i always do

 

[Garbz]

Just autofocus through the filter. Autofocus mechanisms don't have a low-pass filter infront of them so every autofocus I've seen has worked right through the R72 filter.

Your quality loss could be attributed to the loss of the 1 blue and 2 green sensors for every 1 red sensor on your camera. Therefore shooting IR cuts your total megapixel count to 1/4 what it was. Hope that makes sense.

Since there is significant portions of red and yellow in the picture it's safe to assume the blue pixels were the only one not being used. 7.5mpx would still be used for light purposes, and I certainly have not had any issues with sharpness using a Hoya R72 which wasn't my own fault (forgetting to focus, moving the camera etc.)

 

[el_shorty]

What tripod do you use? Using a cheap low quality tripod at those long exposure times will give you soft images.