Infrared question: Will the Canon 16-35/2.8 cause a hotspot if the hot mirror has been removed?

[rayn]

I'm thinking of taking the plunge and removing the hot mirror on a Canon 20D (wish me

luck). But I only want to do it if I can use my trusty Canon 16-35/2.8L lens with it. This is

the lens I use for landscapes with a normal (unmodified) 20D and I'd like to avoid carrying

a separate lens for IR if possible.

 

Now I know this lens will cause a hotspot on an unmodified 20D, but I think the hotspot

has something to do with reflections off the hot mirror. So does anyone have a digital

body modified for infrared and a 16-35/2.8 that can comment from direct experience?

[scott_ferris]

Hi Ray,

 

In the interests of expanding my knowledge, what are you talking about? What is a hot

mirror? And why don't you just simulate IR in Photoshop rather than go to such measures?

 

Take care, Scott.

[bobatkins]

Sorry I don't.

 

But my understanding is that the hotspot seen in IR images with some lenses does disappear on the 300D and 10D if the hot mirror is removed. I haven't heard of hotspotting with any lens with the modified cameras - but that doesn't mean it can't happen I guess.

 

Good luck with the mod. You're braver than I am (or richer...)

[Brad_]

Good luck and please report back after you do the mod. I'd like to do the same thing to a

300D.

[scott_ferris]

Hi all,

 

Well thanks to the internet and Google in particular I am now the worlds foremost expert

on Hot Mirrors! ;0) Ha Ha.

 

Anyway Ray as Bob says you are a braver man than most and by the looks of it a trailblazer

in your commitment to IR photography with the 20D.

 

Take care and good luck, Scott.

[barmijo]

Ray,

 

Are there instructions somewhere for removing the hot mirror?

[rayn]

There are some for the D70 <a href="http://www.lifepixel.com/IR.htm">here.</a>

 

<p>If you know of any for the 20D, I'd sure like to see them. I might just have to make a

tutorial myself for this, provided I am successful.

 

<p>I thought I'd just go slowly and carefully and not go beyond anything I couldn't undo.

If it

looks like it's too risky, I'll just abort and put it back together. I know the 10D cannot be

converted because the hot mirror is soldered to the sensor. It cannot simply be

unscrewed like the D70. However, the digital rebel can be converted so I'm hoping the

20D is more like that. I won't know until I open it up.

[chip l.]

Here is a site that offers the service on some Canon models (not the 20D):

 

http://www.irdigital.net/

 

The reason that 300D is so expensive compared to other conversions and why the 20D is

not offered - according to posts on other sites from the guy that does the work - is that

the filter is harder to remove on the 300D and too hard on the 20D.

[hugh_crawford1]

The "hot" in hotspot and the "hot" in hot mirror are two different things. For hotspot, think of internal reflection, flare, or something that looks like vignetting. For hot mirror think of something that reflects heat. So I don't think that the two are related other than having the word "hot" in them.

 

Scary do it yourself instructions for the 300d are here

 

http://ghonis2.ho8.com/rebelmod.html