Infrared and phase detection? considering converting a 5Dc

Heya!

Since I upgraded to a 5D2 my 5Dc has seen very little use. Lately I've started considering converting it to IR but I'm wondering how well phase detection works with IR. I've read lifepixel can calibrate for IR but is it very lens specific? For anything below 35mm I can just use the distance scale on the lens but with longer focal lengths I'd really like AF since focusing through the viewfinder isn't accurate because the camera only captures IR light.

Is it ok to use phase detection with an IR converted camera or would a camera with live view be preferable? I don't feel like paying ~300€ for a used 550D which is the minimum I'd go for if I'd get a camera with live view.

I'm at the same stage as you and considering a similar conversion on my 30D. My understanding is that normal phase detection AF works fairly accurately as it obviously uses visible light via the reflex path into the viewfinder - you will see no change at all when shooting. Part of the IR conversion includes moving the sensor back slightly to compensate for the difference in the point that IR focuses, so this is effectively automatic, although not 100% reliable.

In terms of liveview, I'm not sure how the camera would convert the sensor image from IR. My 30D, like your 5D, doesn't have LV anyway. Perhaps when the US wakes, some kind soul will enlighten us.

Not much activity here, I'm leaning towards a 590nm filter and having the camera calibrated to my 85mm 1.8 so I can use it for portraits if I like. That way I could still use a 830nm filter on the lens for deep B/W photos if I wanted to. But I'm still undecided if I should go for a 665nm filter instead.

from what I've read, Lifepixel "calibrates" their conversions for a 50mm. Both conversions I've done myself (10d & 1D2) haven't involved any focussing adjustment at all. Niether are perfect, but the 1D definately doesn't like my 70-200mm f/2.8 (back focusses quite a bit)

Mostly, though I use my 16-35mm or 24-70mm and apetures around f/8 & up so the actual focus is within coeee of the dof anyway.

I'd love to someday try a liveview-capable conversion, and something with microadjust would be great...

These infrared AF "adjustments" seem to work only for one lens, or more exact on focal length when one use a zoom lens. And closing the iris is partly recommended.
As far as I know these are only AF apprioximations, not a real IR correction.

I have no more AF in my infrared camera conversion with interchangable filter. But I have no bigger problem to manual focus, cause I always use manual focus. For IR I make the IR focus correction afterwards, most of my lenses have an IR index.
I think about the same IR conversion for my 5D classic, without AF function.

Thanks for the input guys. I think I should be fine with the infrared index on my 24-105 and 100-400 in that case and shooting at narrower apertures at longer focal lenghts. I read the 85mm will exhibit hot spots from time to time but can be avoidable by adjusting the camera position. I don't want to buy another lens so I'll just have the camera calibrated for the 85mm and hope for the best. In any case I can still use my zooms. I'm planning to get the 17-40 at some point as well, which should be a good lens for IR photography.

I'd love to have live view or micro adjust as well but I don't want to invest in another crop just for IR. My 5Dc has been sitting mostly on the shelf anyway since I got the 5D2 so I might as well have it converted

Nice solution ZoneV, looks like you might get dust in between the filter and sensor easily though? I'd prefer a sealed solution and I'm not brave enough to order the filter from Life Pixel and fiddle with the camera flex cables and everything myself.

Since I'm located in Europe I'm thinking of sending the camera to Protech Photographic which is located in the UK, that way I won't have to deal with any customs BS. Seems like a reliable company and they're using the same filters as LifePixel and they also calibrate to a specific lens. The only thing is they didn't have the 590nm filter in stock for FF so it will 2-3 weeks. Still haven't ordered anything yet, I'm still negotiating with them.

I just have my second dSLR converted to IR. Based upon my use two features I considered critical for converted IR use:
1. Good magnified Live View for accurate manual focus. As you point out the viewfinder is useless as it is looking at visible light, and the focus point for IR can be quite different for some lenses. With Zooms the IR calibration can radically change with zoom position. Some older lenses have red focus marks on the barrel to give you an estimate of focus offset. Without an IR calibration (for only that lens) you are shooting blind, and have to focus bracket. Really frustrating. with the 5D you can review shots on the LCD and change focus for the next, but basically you are still shooting blind.

RGB histogram in Live View: My old 60D with an IR mod had only a luminance histogram on image review (and no live view). I found I often over exposed the red channel as the luminance channel could be quite different depending upon the composition. I would be at a total guess until I got home and downloaded the images. I used to estimate exposing the luminance channel about 2 stops low to prevent red channel over exposure. Kind of like film!

I now shoot with an IR modified 5DmkII.
Mike K

Very valid points MIke. I admit maybe I am a bit obsessed with converting a FF camera as well and thinking in my mind I will get nicer pictures compared to the convenience of a 550D with live view. So do you think I would be better off just converting a second hand crop camera? I just keep thinking the 5Dc can recover highlights a bit better but I have no idea how the red channel compares on both cameras.

I've read about blowing out the red channel, at least the 5Dc does have a RGB histogram but unfortunately the screen is pretty useless even for checking focus after the shot, due to the 50% sized jpg preview.

Xcelx wrote in post #15683804
...Nice solution ZoneV, looks like you might get dust in between the filter and sensor easily though? I'd prefer a sealed solution and I'm not brave enough to order the filter from Life Pixel and fiddle with the camera flex cables and everything myself.....

Yes, dust is the biggest issue there. But cause I always work a bit on Lightroom on images I want to publish, the dust removal is not that bad.

As soon as one want to use different focal length lenses, I would recommend manual focusing and the IR correction with the index. But one need lenses with index.

I plan / wish to convert a 5D, to get all the lenses I love on the normal 5D with same field of view. On my crop Rebel XT infrared camera I need different focal lengths, doesn´t like this. Especially the wide angle lenses are a problem.

Xcelx wrote in post #15684299
Very valid points MIke. So do you think I would be better off just converting a second hand crop camera? I just keep thinking the 5Dc can recover highlights a bit better but I have no idea how the red channel compares on both cameras.

I've read about blowing out the red channel, at least the 5Dc does have a RGB histogram but unfortunately the screen is pretty useless even for checking focus after the shot, due to the 50% sized jpg preview.

If the crop is all you can afford for a conversion then do that, assuming your lens collection will still work out. I consider the main difference between crop and FF is the difference in FOV for WA lenses. This may be even greater for IR as its mostly landscape.

For conversions I consider a good live view critical for manual focus as you don't know what lenses you will be moving to in the future. PD AF on IR will be good only for one lens at best.

The RGB histogram would be most useful on Live View (before the shot) in addition to after the shot on image review. If your red channel is blown its normally well beyond highlight recovery.
Mike K