Infared!

[paul_brenner1]

<p>I had been waiting for the t4i to buy my first digital SLR, and have not been disappointed, but discovered a minor but pleasant surprise:<br>

My understanding was that at least many SLRs had filters to block out infrared. Although I'm not a big infared person, I had enjoyed dabbling with it with my G9.<br>

Anyway, in rummaging around some lenses and filters, I found an old Canon film camera autofocus lens and an old Hoya infared filer of the same diameter. I had to try it! And the t4i apparently doesn't block out infared!<br>

Not a real biggie, but nice...<br>

<br />Paul<br>

<br /> </p>

[zml]

<p>Huh? The T4i must include a IR cut filter or you'd be a very unhappy camper.<br>

But...IR cut filters differ in their spectral characteristics and perhaps the filter on T4i is relatively weak and allows the camera sensor to receive some near-infrared radiation. <br>

A good test of IR capabilites of the camera is to put your IR filter on the flash (=block off visible light) and fire a few exposures in total darkness using the fastest lens you've got. If you get some detail (vs. a totally balck frame w/o the flash) then the camera is sensitive to some most likely "near infrared", wavelengths.</p>

[philip_wilson]

I have never tried IR on a Canon but I have always

understood that all models had a fairly strong IR filter. I can

shoot IR with my Leica M8 but it is well known that for

synthetic blacks you need an IR filter on the M8 lens

otherwise they look purple due to the fact that the sensor

has almost no IR filter. What frequency of filter do you use?

How long do your exposures have to be ( on the Leica it is

possible to handhold IR shots)

[carbon_dragon]

That Leica you're talking about is the Leica M8. I often use it without an IR Cut filter and I never get odd color rendition

(but it does happen according to what I read). So I think the idea that a less "effective" IR cut filter in the camera results in

terrible pictures is exaggerated. And the M8 does GREAT IR pictures, and you can hand hold with filters that aren't TOO

opaque.

[zml]

<p>David: You mean that when using the M8 sans the IR cut filter your images don't have a color cast?<br>

The M8 has recently been re-christianed MAGENT precisely due to this tendency...<br>

:-)</p>

[paul_brenner1]

<p>Good comments. I suspect the answer is "near infared". My filter is a $40 Hoya (not a $100 filter) which definitely is not as broad a cutoff as the more expensive filters, so I know that it DOES let in some near infared, as opposed to the more expensive filters.<br>

Anyway, I'm a happy camper...<br>

Paul</p>

[bobatkins]

<p>No cameras have filters strong enough to block ALL infrared. The problem is that most of them block most of it and just let a bit of the near IR through, so exposure times get very long or need high ISO settings. That combined with the fact that most of the response is from the red pixels (and the red pixels are only 1/4 of the total pixel count) means that image quality generally isn't very high.</p>

[paul_brenner1]

<p>Thanks Bob. Interesting extra info.<br>

Everyone may recall the "unique" quality of infared film (aside from the typical tonal effect). Fairly grainy.<br>

I always used a tripod with my G9 to keep the ISO low. Overall, the effect seems very similar to infared film.<br>

Again, infared is not a real biggie for me, but it's nice to get the look when it seems called for, without much hassle...<br>

Paul</p>

[carbon_dragon]

Michael, I can't see a color cast. Supposedly it shows up with certain types of images, like shots of certain clothing. My

shots are generally nature photographs and I don't see it. Maybe someone looking more closely, knowing what he's

looking for could see something but I don't. I do have IR Cut filters for most of the lenses but tend not to use them.

 

 

It makes sense it would be subtle. If it weren't the camera would never have been sold by Leica originally. But Leica

buyers are ... ummm... detail oriented and once the supposed color cast was in the news, it became something of a

scandal. Too bad because it makes the M8 the sort of all round camera that no other camera I know of can match. The

M9's IR cut filter is "better" and it's not so sensitive to infrared. If I ever get an M9 I'll keep the M8 for infrared.

[jaydesi]

<p>I had an old 20D converted by removal of the filter over the sensor and having a visible light blocking filter installed, which allows some red visible and all infrared through (work done by lifepixel.com, who also calibrate one lens to the sensor). This allows for sharp, handheld IR photography. It's a lot more fun than playing with long exposures, manually adjusting the focus, exposing again, etc.</p>

<div></div>

[philip_wilson]

Michael as an M8 user I expected some IR issues based on everything on the internet. While I have IR filters I often do

not use them a lot of the time (indeed on my 12mm lens I do not have one). Despite this the number of times I have had

an IR issue are very small. The only time I have ever seen the IR issue is when shooting a synthetic black material -

some of these take on a purple / maroon colour cast. The Internet is full of posts by people who have probably never

even used the camera they are commenting on. I actually love my M8 (so much so I ordered the new M) and will keep it.

The body is not perfect - it is really only good up to ISO 320 (really what Canon call ISO400) in colour and ISO640

(ISO800) in black and white. It is also takes very poor JPEGs and has a terrible AWB. Despite all this people who

actually use the camera (in RAW) generally love it and rarely see the reputed image issues that .the Internet is full of - I

probably have about 5 images with IR colour issues, no images with pink / purple edges have 2 with moire and none with

the rumored green blobs - out of over 4000 shots taken with the body. The image quality of this APS-H body with 10 MP

is as good if not better than the first Canon 5D. Obviously the lenses help but the message is don't believe all you read on

the Internet!