Full Spectrum vs. Dedicated IR Conversion

There has been a LOT of talk recently over the type of conversion service you choose for your dedicated IR camera system! Personally, I have used them all. I have had everything from a 590nm Goldie to an 850nm Deep IR conversion and recently, 2 Full Spectrum conversions. All are good (some more than others)!

DSLR Lightpath

If you are going to convert a DSLR camera then you should look into a specific wavelength conversion. The reason is that with a mirror/prism based DSLR you actually look through the lens. This means that if you choose a FULL  SPECTRUM conversion, you would be attempting to look through the IR filter (which is screwed into the end of the lens you are currently using) which will make focus/composition all but impossible. If you hold up a IR filter, 665nm and up they are almost impossible to see anything through!  The drawing of a DSLR optical path to the left shows the light path and problem.

OK, lets digress a little….

IR 820nm Filter

Full Spectrum conversion is one in which the anti-alias and IR blocking filters (hot mirror) are removed from in front of the sensor and replaced with a clear piece of glass. This type of conversion will let you program your camera’s Infrared wavelength with the addition (in front of the lens) of an Infrared filter to ANY wavelength you desire, including UV, Normal Color & IR!  Nice!   But…. with a DSLR you

Black & White Filters used for Infrared

have to look through the lens and IR filter to focus and compose….. So not a good choice. BUT, if you are using a P&S like the Canon G9, 10 or 11, or the new Mirror-less DSLR like the Olympus PEN family with interchangeable lenses then this would be the way to go.  There is even a factory converted full spectrum camera out there from Fuji, called the Fuji IS-1. It was designed for police CSI departments and comes with a full range of IR/UV filters to modify how it shoots! You can still find them on Ebay.

Now, a specific conversion involves the removal of the internal filters as described above but then replacing them with an IR filter of some sort (popular choices are 665nm and 720nm, but there are many more!). Since you now do not have to look through an IR filter in the optical path you can use a normal DSLR!

Micro 4/3 Mirror-less Light Path

I am currently using BOTH systems. I have a 590nm Goldie converted Canon 20D (DSLR) an Olympus PEN E-PL1 mirror-less DSLR at Full Spectrum and an Olympus PEN E-P1 at 720nm. The E-PL1 PEN is my favorite camera for IR (I have had about 10 different IR cameras so far!). I like the Full conversion due to the fact that I can change its flavor at any time simply by changing the external filter on what ever lens I am currently using! This opens up a whole world of possibilities when I am out in the field shooting.

Keep these 2 types of conversions in mind when you are deciding which camera to convert as well as what wave length to use!


15 comments on “Full Spectrum vs. Dedicated IR Conversion

  1. Why it’s so complex! Full spectrum conversion require external filters…right? But, those filters are also block a lot of light….right? Then, for some application who require higher speed it’s a disadvantage,…..right? A simple lost pro and cons of full or specific conversion….will be great 🙂

    • There are no dumb questions! A full spectrum conversion on a DSLR without a live view would kind of be a waste since you cannot see through the lens with a 720nm filter installed. Does yours have this function? If not, I would keep your DSLR the same and just pick up a Olympus E-PL1 from amazon for about $350 and have it converted!

      • pardon me to give my opinion about “A full spectrum conversion on a DSLR without a live view would kind of be a waste since you cannot see through the lens with a 720nm filter installed.” . my opinion is still not wasted. because you still can use it for infrared. i have canon 1000D full spectrum and able to use it without live view. here is the trick… try to lock focus with your IR filter not attached to the lens. the camera will focusing and metering the scene as full spectrum. than, put the IR filter in front of the lens while your finger still on half press position, than shot. it will give you the infrared image, use a smaller aperture will be a benefit

      • Your opinion is never wasted here! You are correct in your assessment of using a full spectrum conversion (my personal favorite) on a camera without a live view. Your procedure of pre focusing using AUTO FOCUS then locking it and attaching the filter will work provided you use an aperture of f/8 or higher. The reason for this is simply that Infrared light energy focuses at a different wavelength than visible. The camera will focus using some portion of the spectrum (we cannot know which it will use because we do NOT know the sensitivity of the focus system to the various spectrums) but we can safely assume that it will likely be in the normal visible spectrum as that is what it was designed for. This means that the IR portion will be slightly out of focus.

        Again not important if you use a smaller aperture giving a larger depth of field!

        Thank you for taking the time to point this out to our readers!

  2. Sorry, scrap the last question I just asked you, I see that what I was looking for is a hot-mirror filter. The only questions I actually have then are whether these filters are threaded so that other filters (like a polarizer or ND) can be put over them? And also is there any filter you’ve encountered that will allow through a spectrum of IR, not just one specific wavelength, like 700-900nm?

  3. Hi, thanks for writing this, it clarified a few things for me. I was thinking of doing a full spectrum conversion on my one and only DSLR, however, when I want to shoot in normal visible color, would I not have auto focus problems and softer images due to the fact that the IR is still getting through and (from what I’ve read) focuses differently from visible light. Is there a lens filter that just allows through 400-700nm and nothing else. I haven’t seen any on ebay and, I mean, it would be pointless for a company to make such a filter, unless for people who are doing what we’re doing.

  4. Lots of talk.. Lots of theories… Lots of views.. The question still remains.. To go Full spectrum or stick with IR? Of which I am totally at a loss. I want to go full spectrum. However, From what I have seen, the clarity of FS is so low that it confuses me. Again, from what I’ve seen. For this field.. For this biz. Where it you? What would you be using? I believe that high speed single shot is absolutely a plus. BUT, High speed IR or FS?? Please? Before I buy?

    • I like full spectrum then program the IR frequencies with external IR filters. If I was going to do just a dedicated conversion I would select 590nm or 665nm. They both give great results in Faux Color and B&W IR imaging. Look thru the blog here and take note of the filter posts and example images.

  5. This is my first time that i visit right here. I discovered so many beneficial thing in your blog site especially it’s discussion. On the a lot of feedback on your articles, I guess I am not the only one getting the satisfaction right here! keep up a good work.

  6. Question: Would using live view make a difference in the case of having a modified full spectrum DSLR with a screw on IR filter? So instead of using the optical viewfinder to see through the lens (which would be difficult for the human eye), would using live view instead work as the image doesn’t use the mirror and instead goes directly to the sensor and then gets displayed on the LCD? I’ve only got one DSLR I can have modded, so I’m trying to decide between full spectrum or IR only.

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