GR User Forum

The spot for all Ricoh GR camera users

Register for free, meet other Ricoh GR users, share your images, help others, have fun!

Tell your friends about us!

Best way of focusing infra-red?

Colman

New Member
I was out playing with my new IR filter today, having half an hour to kill while I was in the city on a sunny day (the joys of compact cameras!), and of course, like an idiot, I set the focus manually to infinity resulting in quite soft images, having completely forgotten the issue of focus shift. Would the AF have sorted it out, or does anyone know which way to shift the focus point?
 
There was a good discussion about infrared and AF. But it was related to GX100 passive focus problem.

viewtopic.php?f=4&t=731&p=3014&hilit=infrared#p3014

According of Bertalan's post, the Multi AF with covered passive detection system (CCD based AF) should help with this issue. As there is no passive AF on GRD2, you don't need to cover anything. Just try the Spot or Multi AF.
 
Right: that'll teach me to try and out-smart the camera! Anyone know if the focus point is before infinity? I assume it is?

Anyway, the pictures turned out ok in the end, if a bit soft before processing:

web.jpg
 
The infra-red infinity point seems to vary a lot between lenses depending on focal length. For the wide angle lens of the Ricoh cameras I think it is around 1-2 m, certainly less than the 2.5m snap focus point anyhow. On a long focal length lens it would be much further away.
 
Actually on my GX100 to get infinity in focus, you need to set the manual focus to under 1meter. I put a piece of tape over the focus window(on the GX100 anyways) and use multi or spot focus. It works fine except that in dark conditions(overcast in a forest) it sometimes has trouble getting focus lock.Just make sure theres a good edge for it to focus on.There are examples on my flickr page, the early ones are blurry (Backus series) because that was before I found the cover-the-focus-window trick(thanks Hiro!)
http://www.flickr.com/photos/bertreimer
 
Dear ALL

I have a GRII with adaptor ring and IR filter, yet cannot get anywhere near your quality....is the trick to shoot in black and white as well?

I am a total noob when it comes to IR, and all my shots are coming out red.....just a tip or three would be most helpful...


treesmall.jpg
 
This is quite normal Addy. All you need to do now is to convert the image to grayscale. The best way to do this is using a channel mixer (usual tool in most image editors). But any B&W conversion tool should work fine.
 
With infrared your shutterspeeds are going to be quite long so use a tripod. I always shoot IR in RAW then convert to jpeg with a RAW editor. I use RawTherapee, which is free, and works great. Just open your RAW file in RawTherapee and play with the white balance first to get an idea of what you can all get out it color wise. If you want blue sky, open the channel mixer and invert the red and blue(under RED change red from 100% to 0% and blue from 0% to 100%, then do the same to BLUE). Hope this helps. I use a converted D40 for IR now, but maybe I'll do a couple comparison shots(I use a GX100)
 
A couple samples

Just a few quick shots I did this morning. Things are just starting to turn green around here so its not quite IR time yet(for me anyways). My favourite thing about IR is how it turns the foliage white.
Anyways, this first one was shot RAW, then in RawTherapee; WB=Auto,Exp.=+0.5,Contrast=+20

RawTherapee;WB=Auto,Exp.=+0.25,Contrast=+20,Color Boost=-100,Black=6100

Nikon D40(IR converted) RawTherapee;WB=Auto,Exp=+1.00,Contrast=+20,Color Boost=-100
 

Attachments

  • EXIF
    R 001rt1sm.jpg
    387.7 KB · Views: 827
  • EXIF
    R 006rt2sm.jpg
    139.3 KB · Views: 826
  • EXIF
    N 004rt1sm.jpg
    127 KB · Views: 815
Great thanks guys, you have got me going again, was getting to me, the postings of the exif data very useful....

adrian
 
Back
Top