Better to do full-spectrum + filters or single B&W wavelength?
This is from Life Pixel explaining different filters:
They recommend "Super Colors" for general use. But based on what some good folks here say in this thread, if you are only looking to do B&W, maybe something similar to their "Deep Black" will work better?
Do note the possibility of Astronomik clip-filters (behind the lens) as an alternative to ordering a camera with a permanent band-pass filter.
And to Vivek: What am I missing? How can removing the CFA actually reduce the sensitivity of the pixels? Does it have to do with removing the micro-lenses? Does it have to do with the camera generating the raw under the "assumption" that it is a color raw? Doesn't a program like Monochrome2DNG have some impact on that?
What bothers is that, generally speaking, removing a light absorbing medium from the system should let more photons through.
Steve: Yes, it is counterintuitive but in reality that is the case.
CFA removal enhances the UV sensitivity by several stops, increases the visible sensitivity by 1~2 stops and reduces the IR sensitivity by at least one stop.
This was clearly pointed out first (AFAIK) by Dan at maxmax. I can confirm that from my own observations with at least half a dozen sensors/cameras.
realVivek wrote:
Dave, a 49mm filter would cover FE28/2, 35/2.8 and the 55/1.8 (All fantastic for IR). 16-35 needs another filter 24-70 yet another, so on and on.
Entirely your choice.
A converted (dedicated) camera avoids all that. But you are limited to that choice of filter.
Thanks!
Seems to make to sense just to convert the camera and not have a pile of filters.
I have a spare body and the cost is not as expensive as I thought it was
Douglas Liu wrote:
This is from Life Pixel explaining different filters:
They recommend "Super Colors" for general use. But based on what some good folks here say in this thread, if you are only looking to do B&W, maybe something similar to their "Deep Black" will work better?
p.3 #11 · Is Infrared Photography a Fad (for you)?
Although there isn't much natural IR light available at night, some artificial light sources can create a lot of IR light and IMO, photographing with it creates an interesting color effect.
Here's one example:
And here's another, accidentally taken full-spectrum (i.e., without any IR filter), which shows a more subtle color effect:
Although I photograph using IR light less than 10 percent of the time, it's definitely not a fad for me!
p.3 #12 · Is Infrared Photography a Fad (for you)?
Audii-Dudii wrote:
Although there isn't much natural IR light available at night, some artificial light sources can create a lot of IR light and IMO, photographing with it creates an interesting color effect.
p.3 #13 · Is Infrared Photography a Fad (for you)?
DaveFP wrote:
What body?
Although I am in the process of trying to turn two broken A7Rs into one working IR-converted A7R, those photos were taken with a DIY-modified, full-spectrum Samsung NX500 using a Hoya R72 (720 nm) filter.
I posted them to support my general statement about the merits of photographing in IR at night.
Kolari suggests that the Sony Alpha bodies have problems with long exposure/high ISO images.
If you read the fine-print on Kolari's website, the A7 and A7R are not affected by this design quirk, only the subsequent models.
p.3 #14 · Is Infrared Photography a Fad (for you)?
Audii-Dudii wrote:
Although I am in the process of trying to turn two broken A7Rs into one working IR-converted A7R, those photos were taken with a DIY-modified, full-spectrum Samsung NX500 using a Hoya R72 (720 nm) filter.
I posted them to support my general statement about the merits of photographing in IR at night.
If you read the fine-print on Kolari's website, the A7 and A7R are not affected by this design quirk, only the subsequent models.
p.3 #15 · Is Infrared Photography a Fad (for you)?
DaveFP wrote:
What body?
Kolari suggests that the Sony Alpha bodies have problems with long exposure/high ISO images.
I did a bit more digging, it seems the potential issues with longer exposure that applies to the A7 II, A7R II, A7S II, A7R III, A9 only occurs at long exposure and very high ISO. But Life Pixel's own website says "exposure greater than 1 second", which is not that long. Here is a bit more information regarding the A7RII from Kolari Vision's website:
"This camera (A7RII) contains an internal diagnostic IR Led. This can cause light leaks when using very long exposures and high ISOs in the H-alpha and IR enabled conversions, in the range of 30 second exposures at 6,400 ISO. Can also have fine horizontal artifacts across the frame in highlighted areas in the IR enabled conversions due to the different sensitivity of some rows of pixels."
The A7RII that I bought to convert will arrive tomorrow but I would want to talk to Life Pixel to get a more direct answer before I send the camera to them. Or maybe I should start looking for an A7R!
p.3 #16 · Is Infrared Photography a Fad (for you)?
Douglas Liu wrote:
I did a bit more digging, it seems the potential issues with longer exposure that applies to the A7 II, A7R II, A7S II, A7R III, A9 only occurs at long exposure and very high ISO. But Life Pixel's own website says "exposure greater than 1 second", which is not that long. Here is a bit more information regarding the A7RII from Kolari Vision's website:
"This camera (A7RII) contains an internal diagnostic IR Led. This can cause light leaks when using very long exposures and high ISOs in the H-alpha and IR enabled conversions, in the range of 30 second exposures at 6,400 ISO. Can also have fine horizontal artifacts across the frame in highlighted areas in the IR enabled conversions due to the different sensitivity of some rows of pixels."
The A7RII that I bought to convert will arrive tomorrow but I would want to talk to Life Pixel to get a more direct answer before I send the camera to them. Or maybe I should start looking for an A7R! ...Show more →
30 seconds would be fine but 1 second a bit short. I will discuss with Kolari.
p.3 #18 · Is Infrared Photography a Fad (for you)?
realVivek wrote:
CFA removal enhances the UV sensitivity by several stops, increases the visible sensitivity by 1~2 stops and reduces the IR sensitivity by at least one stop.
I could understand the CFA dyes being opaque to UV, but the rest doesn't make sense to me.
You would think the CFA cuts out 2/3rds of the incoming [visible] light but in practice the response of the dyes overlap so it's closer to 50% or 1 stop. However the CFA lies underneath the microlenses so in order to remove it you also end up removing the microleses, which reduces sensitivity. What I've read from other people who have removed the CFA/microlenses is that losing the microlenses undoes most of the advantage gained from not having a CFA so the improvement in sensitivity is slight.
With regards to reducing IR sensitivity, it's not possible for the removal of a filter to reduce sensitivity (except in the really weird case with multiple polarizers), which means the only possibility would be that microlenses are somehow several times more effective in IR than with visible light, which seems counterintuitive for something only designed to work in the visible spectrum.
p.3 #19 · Is Infrared Photography a Fad (for you)?
I am not fond of vague quotes, conjectures and making a conclusion out of thin air. You may have to get back to those who said that the gains are slight.
A comparison of my monochrome converted RX1 (with a filter that is equivalent to the ICF on the stock camera) on the lens and a stock RX1 cleared any doubts I had.
p.3 #20 · Is Infrared Photography a Fad (for you)?
Just to sorta kinda cross-post from a thread on DPReview, I looked for the LED glow on my CFA-removed A7Rii. With a 2sec exposure at ISO100, there was no glow even with the LR exposure raised to the max +5. With a 2sec exposure at ISO800, there was no glow with the slider raised to +1, but at +5 there was quite a glow along the bottom edge of the frame. Two seconds at ISO1600 corresponds to a very, very dark scene; except for astro and landscapes by moonlight I'm not seeing much of a scenario for most of us.
On the unrelated question of removing the CFA lowering IR sensitivity, I trust Vivek's observations, but the only explanations I can imagine are both poor: removal of microlenses or, maybe a little more likely, some artifact of the different way monochrome and CFA-retained images are processed. I hope someone can shed more light on this.
