1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Digital IR cameras

Discussion in 'General Equipment Chat & Advice' started by beejaybee, Dec 2, 2007.

  1. beejaybee

    beejaybee Marvin

    Whilst browsing the net (for astronomical stuff) I came across a reference to Canon and Fuji DSLRs modified for infra-red use . Since most of these can be used with a front filter for normal use as well, some people may be interested.

    There is a UK retailer for the modified 350D and 400D cameras here .

    Perhaps AP might run a test on one of these sometime?
     
  2. Rhys

    Rhys Sasquatch

    There's a way of converting them to be IR as well.

    Lifepixel

    Wouldn't want to do it myself though unless I had an old unused body or I wanted to specialise in IR.
     
  3. beejaybee

    beejaybee Marvin

    And even then the source I found might be useful for "front filters".
     
  4. Rhys

    Rhys Sasquatch

    Would a front filter work for IR if there is a filter on the sensor there to block IR?
     
  5. beejaybee

    beejaybee Marvin

    Obviously not... the point about the front filter is that it allows a modified camera to be used for "normal" photography without having to pull the camera apart to replace the IR blocking filter. Saves having to have a hugely expensive screw-in filter mounted on each lens (if available, which they aren't for some lenses). Quite apart from the specialised applications mentioned on the site I quoted at the top of the thread.
     
  6. Hotblack

    Hotblack Dead Horse Flogger

    Some or the earlier Nikon DSLRs (D50 and earlier) are quite good at IR effect using a custom white balance and a Hoya R72 (or equivalent) filter. Cameras after the D50 have much improved IR filtration at the sensor.

    I can't comment on Canon.
     
  7. beejaybee

    beejaybee Marvin

    I enquired at SCS Astro, the modified 40D will be stocked from January, don't know the price yet.
     
  8. aquatarkus

    aquatarkus Member

    Someone just might be interested to know that the Sigma SD14 dslr is capable of shooting IR sraight out of the box, just remove the dust cover infront of the sensor and away you go.
    Have a look on the Sigma forum on DPreview and this thread on that forum http://forums.dpreview.com/forums/read.asp?forum=1027&message=25885570
    hope this is of interest to someone
     
  9. beejaybee

    beejaybee Marvin

    The "dust cover" is probably the IR blocking filter! Also it has optical thickness, unless you replace it with a plain glass slip the focal plane will be moved forward by about 1/3 of the thickness of the missing "cover" and you may have difficulty reaching infinity focus with some lenses.

    Having said that, for all I know (nothing), it may be easier to remove the IR blocking filter from a Sigma SD14 than from most other makes and models. All the same I'd be surprised if you weren't trashing your warranty by doing so. The modified cameras available through retail channels carry a warranty from Hutech, who do the modification.
     
  10. aquatarkus

    aquatarkus Member

    Really suggest you have a look at the Sigma SD14 website http://www.sigma-sd14.com/feature/index.html the Dust protector is designed to be removed for cleaning it comes out by pressing a small button, it is also the IR filter, it is not anything to do with focusing etc, and as for trashing your warranty thats the best bit of misinformation if heard for quite a while. so yes have to agree with you you do know nothing

    aquatarkus
     
  11. beejaybee

    beejaybee Marvin

    If that's the case then clearly there is no issue with warranty. But unless the dust protector is infinitely thin or is made from a material with a refractive index of 1.0 (and I never heard of one) then removing it will change the optical distance between the mount flange and the focal plane. You might not notice this if your lenses have sufficient travel past "infinity" to be able to compensate, but if you focus using the distance scale (as is almost inevitable when using a "black" IR filter) you may still fall foul of this.

    Thanks for enlightening me.
     
  12. aquatarkus

    aquatarkus Member

    sorry not going to get into an argument with you but you obviously haven't looked at the Sigma SD14 website or ever seen the SD14. why would removing the sensors dust protector effect the optical distance between the mounting flange and the focal plane.
    Go on have a look at the SD14 site and understand, or is it that you think the dust protector is attached to the sensor or the lens mount?
    Have a look at the Sigma forum on DPreview you might just learn somthing

    aquatarkus
     
  13. beejaybee

    beejaybee Marvin

    No, I haven't seen a SD14. And the web site requires Flash, which I will not have on my computer as I believe the Adobe binary version creates serious security loopholes. There is an open source version under development but it doesn't work well enough to be useful yet.

    If there is a piece of glass or other transparent material in the optical path, it refracts (shortens the wavelength of) the light passing through it The wavelength of the light is restored when it leaves the material, as is its direction if the material is flat - simple lenses work by having surfaces which are not parallel to each other! Light passing at right angles through a flat plate of material of thickness "X" effectively travels a distance of "X" times the refractive index. The refractive index for most optical glass and plastic is somewhere close to 1.5 i.e. the optical thickness of the plate is about 1.5 times its thickness.

    Put a 1mm thick plate between the lens and the sensor and you need to move the lens forward about 0.5mm to compensate. Conversely, if there should be one there and you remove it, you need to move the lens back about 0.5mm; the only way you can do that it to focus "past infinity". Not all lenses will let you do that. That is why the modified Canon and Fuji cameras have a clear (transparent to IR) replacement "front filter" of the same optical thickness.

    This is a straightforward piece of optics, not related to the Sigma or any other camera.
     
  14. aquatarkus

    aquatarkus Member

    Well you gave the guys on the Sigma forum somthing to think about as you obviously know more about the SD14 than they do.
    Focus (in theory) shifts with pure IR work anyway. Look at an older lens with an IR indicator - the way you work it is you set the focal distance you like first as normal, then shift to the focus point you set to the IR mark instead which moves the focal point AWAY from infinity (by a fair distance).

    have a look here for some IR work done with the SD14 (all done with the dust / IR filter removed)

    http://www.flickr.com/photos/seng_merrill/sets/72157600724666686/

    as to Adobe Flash do you not understand computer security well enough to set it up so's not to compromise your system

    Regards
     
  15. happy2bhere

    happy2bhere New Member

    It's basic optics, and despite claims to the contrary by Sigma's ardent (and often lunatic) fans, the Sigma is not immune to the laws of physics.

    That's why some lenses with rear filters require a piece of clear glass in lieu of a filter. It changes the optical path. The SD-14 IR filter is quite thin so it probably doesn't make a huge difference with it removed. Even with the shift, some lenses that use rear filters can get away without a filter in place (and not all require it) because the lens can still focus even with a slight shift.

    And the Sigma forum at dpreview never disappoints. In the thread discussing this thread, someone said to mention that the microlenses 'act as negative-index refractive material when the IR-Cut filter is removed, or that it reverses photonic polarity.' I'm still laughing at that.

    http://forums.dpreview.com/forums/read.asp?forum=1027&message=25951134

    Anyway, for infrared work, it is less money to get a used Nikon D50 and have it modified than to get a Sigma SD-14 (which would require a bunch of new lenses too). And it's a better camera.
     
  16. beejaybee

    beejaybee Marvin

    ROFL! :D :D :D :D :D :D :D
     
  17. beejaybee

    beejaybee Marvin

    Thanks for helping me out. I wasn't aware that I'd encountered a refugee from an alternative universe where the laws of physics relating to optics are different.

    Maybe. But I've learned that the Sigma does do something that other cameras don't. That's to its advantage, in certain specialist fields like astrophotography where lenses may not be an issue (camera used at prime focus of telescope). However it's unlikely that the camera will ever catch on for scientifically orientated users so long as its advocates seem to deny the physical properties of material objects. This is unfortunate for both Sigma as a company and, in the long term, for the advocates themselves, as a struggling company is more likely to give up the fight than those who are doing reasonably well.

    Sigma make some very good lenses; the competition is helpful to users of other brands of DSLR. I'd be really sorry to see them terminally associated with the loony brigade.
     
  18. aquatarkus

    aquatarkus Member

    Unfortunatly some of the Sigma users on the DPreview forum can get a bit carried away at times but, the point still stand that the Sigma out of the box can do IR photography with no modifications apart rom removing the dust cover NONE of the other DSLRS can do that.
    Did you look at the site i linked to for the IR photos taken with the SD14 (some were also taken with the 9 and 10 as well) if you didn't or haven't bothered then think you really should as you just might be suprised.

    As to the point about the D50 being a better camera in which way? body yes very probably but image wise not in a hundred years, show me an A0 print of a D50 image that has the detail of any one of the Sigma images go on have a look at the sigma forum on pbase or is it that because its not a Nikon or Canon it can't be any good or is it a case of being to blinkered to actually see that the Foveon sensor could just be the way to go and get rid of all the bayer mush.
     
  19. happy2bhere

    happy2bhere New Member

    None? The Fuji UV/IR can do IR out of the box (and UV which the Sigma doesn't do), and it doesn't need a filter to be removed. Plus, the Sigma filter is fragile:
    http://forums.dpreview.com/forums/read.asp?forum=1027&message=25194633
    http://forums.dpreview.com/forums/read.asp?forum=1027&message=25212031
    http://forums.dpreview.com/forums/read.asp?forum=1027&message=25213943
    http://forums.dpreview.com/forums/read.asp?forum=1027&message=25214601
    http://forums.dpreview.com/forums/read.asp?forum=1027&message=24390827

    However, most cameras do require a modification for IR, and an unmodified D50 isn't too bad either.

    Many ways. The D50 is cheaper, faster buffer write times, faster and more reliable autofocus, fewer firmware bugs (no lock-ups or corrupt images), has an easier to use interface (no ridiculous FUNC button), an orientation sensor, auto-ISO, lower noise especially at higher ISO settings, more sophisticated flash system, substantially better battery life and a significantly wider selection of lenses including fast normal/tele and stabilized lenses. On the other hand, the SD-14 has depth of field preview and mirror lockup and the D50 does not. And although the SD-14 can use non-Sigma lenses with adapters, they won't autofocus and they require manual aperture control, and sometimes they even need to be disassembled so that protruding parts don't hit the dust filter. It's a good thing that filter is removable!

    There are literally millions of very sharp and detailed Bayer images printed at A0 and larger and that the 'Bayer mush' is invariably due to focusing errors, lens choice, shallow depth of field, camera shake, etc. Also, Sigma images are heavily sharpened (even 0 sharpening in SPP is actually a heavy dose of USM). And lets not forget that those huge Sigma images had a LOT of postprocessing done to avoid all of the jaggies and other artifacts.

    http://forums.dpreview.com/forums/read.asp?forum=1027&message=22514745
     

Share This Page