if filter on 645D

[leeonmaui]

Aloha,

Has anybody messed around with the built in IF filter in the special menu/function on the 645D?

[theguywitha645d]

IF filter??

[leeonmaui]

Hmm,

In the  custom effects menu , in the filter effects window, scrolling through the filter effects choices I came across "infrared filter" which kind of excited me as I have some screw on filters which I use but due to the really long exposures need a tricky to use.
I was out shooting yesterday and thought I would give the Filter effect a try, shooting a few shots, and reviewing the play back, I saw something that was monotone and might contain elements of IF effects.
Upon returning and opening the files in bridge, the images just opened as regular color images.

has anybody used this filter, if so wtf?

[theguywitha645d]

You mean the IR filter--not IF.

No. From what I understand it is a monochrome image using only red channel, which is not IR, and maybe some processing/exposure control to give the high-key look of IR. I use a IR filter on my 645D for IR. It is really the only way to do it.

This is not a RAW, but a jpg format effect only.

[leeonmaui]

Aloha,

I started thinking this was another feature for JPG only on The D not that is that big a deal, I use screw on filters as well, hard to find calm days to shoot here, and the wind really degrades my long exposure...

it's a little annoying that a few cool features on this camera are JPG only; HDR, extended bracketing, now this...

Anyway thanks for the comeback.
 

[ondebanks]

No. From what I understand it is a monochrome image using only red channel, which is not IR, and maybe some processing/exposure control to give the high-key look of IR. [snip] This is not a RAW, but a jpg format effect only.

If that's all that setting does, one could do the same thing on the RAW file, in the software of your choice.

I use screw on filters as well, hard to find calm days to shoot here, and the wind really degrades my long exposure...

How long do your IR-filtered exposures typically need to be? The KAF-40000, like all Kodak MF CCDs, has inherently high IR response, but it all comes down to how aggressive Pentax made the IR-blocking filter in the camera.

I pop the IR-blocking filter off my Kodak DCS 645M back sometimes, and shoot with a 780nm IR Cokin P style filter - the marvellous thing is that the IR sensitivity is so high that the "sunny 16" exposure rule works; I can freeze motion, and I can even shoot handheld when a tripod isn't practical (although the viewfinder is of course completely opaque, but I get a high hit rate of successful guessimated aims by sliding the filter out of the way in the P holder to compose, then sliding it back to take the shot).

In other words, the DCS 645 an ISO 100 back at longer than 780nm; whereas cameras with a fixed IR-blocking filter are under ISO 1 !

Ray

[theguywitha645d]

Ray, you need exposures of a minute or more with the 645D and an IR cut on filter at about f/5.6 - f/11 and an ISO of 400.

[leeonmaui]

Aloha,

Seems my exposure times were less then a minute by far when using the screw on filter I have, I even think I kept my ISO down at 200, I'd have to check on my files at home though. Still way too blurry for any kind of print to be done when shooting in our normal 15 kts tradewind conditions.

I might try the JPG filter effect, whats the trade off, raw blurry or JPG clear, but if its just blocking of a channel, your right it could be done post shot.
I haven't found any compositions around that really strike me as crying out for IR so not that worried, it's pretty neat to play around with it though.

[ondebanks]

Ray, you need exposures of a minute or more with the 645D and an IR cut on filter at about f/5.6 - f/11 and an ISO of 400.

Nice shot. Wow, 1 minute+|f/8-ish|ISO 400 implies very low transmission indeed.

Here's one of mine. 1/90 second (handheld), ISO 100, f/16 [55-110 AF zoom].

It was a blustery day, and the winds which created those dunes were pushing those massive shower clouds in off the sea at a fair clip, while the dune grass was moving a lot. This shot would not have worked with a camera/back where you cannot remove the IR-blocking filter.

Rau

[theguywitha645d]

Aloha,

Seems my exposure times were less then a minute by far when using the screw on filter I have, I even think I kept my ISO down at 200, I'd have to check on my files at home though. Still way too blurry for any kind of print to be done when shooting in our normal 15 kts tradewind conditions.

I might try the JPG filter effect, whats the trade off, raw blurry or JPG clear, but if its just blocking of a channel, your right it could be done post shot.
I haven't found any compositions around that really strike me as crying out for IR so not that worried, it's pretty neat to play around with it though.

I am using a B+W 093 IR filter and so it could have a very different response to the one you are using. Also, I imagine Hawaii gets a little more IR than Maine.

If you use the filter, use the long exposures to your advantage.

[theguywitha645d]

This shot would not have worked with a camera/back where you cannot remove the IR-blocking filter.

That moving cloud effect would have been awesome. Along with the luminous water. Don't knock long exposures.

Not quite ready to remove my IR cut filter from my camera, yet. Still, it gives me a chance to take a white light exposure for false color imaging--pity the moon moves so fast. Although I have found that I can get something more than a monochrome image from my IR.

[leeonmaui]

Aloha,

Yeah I would think we get lots more sun lol.

speaking of senors, have you gone in and cleaned yours yet?
I think I need to get in there and clean it, although I don't really see much in the way of dust.
I'm dreading going in there, as I used to have a 1ds 2 and that thing was a nightmare to keep clean...

what lenses do you have?
My kit;
35 FA
75A
120A
80-160FA
300A
400FA (I mount this using an arca swiss monoball and a wimberly sidekick works great!)

[theguywitha645d]

So far I have just used the dust removal function in the camera and a blower brush. I have had the camera for a little over a year. However, I really need to use a swab now.

I am using the A 35mm, D FA 55mm, A 120mm Macro, and FA 300mm f/5.6. I have an Arca Swiss P0 ball head and Manfrotto tripod which works well with the lenses.

[leeonmaui]

Aloha,

what do you think of the 55 ?

[leeonmaui]

I like the 35 well enough but was wondering if the 55 DFA might be better

[leeonmaui]

both with the 35 FA

[ondebanks]

That moving cloud effect would have been awesome. Along with the luminous water. Don't knock long exposures.

True. I should try stacking a many-stop ND filter with my IR filter in the P holder. Then I could shoot long or short.

Not quite ready to remove my IR cut filter from my camera, yet. Still, it gives me a chance to take a white light exposure for false color imaging--pity the moon moves so fast. Although I have found that I can get something more than a monochrome image from my IR.

So what you've done here is layer a regular visible-light image with an IR one? Interesting idea.

If I shoot with no filter at all, I get something like that. Things which don't reflect much IR appear almost in their natural colours, while the flora glow white. Grab-shot example below. The amount of IR and far-red coming through is something like 3 times the normal visible light flux, so when both are coming in together, I have to decrease the metered exposure by 2-3 stops.

With my IR-pass filter in place, all four RGBG pixels in each Bayer block pick up about the same quantity of IR flux - this is a great advantage for Kodak MFD sensors over Dalsa ones, which only pick up IR in the R pixel  - the GBG pixels get virtually nothing. So the Dalsa sensors lose both resolution and sensitivity (forcing even longer exposures, which we all know they're not good at!).

Out of the camera, my IR RAW files look blue-violet tinged - probably because the software is applying an R:G:B white balance ratio which compensates for the natural dominance of green in visible light. Retaining the violet-mono look is ok for some shots but is not for everything, I think (it would be like toning all of one's B&W chemical prints in something like blue or selenium + gold). So converting the output to neutral-grey B&W makes sense to me most of the time.

Ray

[theguywitha645d]

Aloha,

what do you think of the 55 ?

I like it very much. It is my most used lens. It was panned by a few at its release, but I have found it to be very sharp for landscapes and panoramas. At f/2.8, it is soft, but so are many lenses at maximum aperture and when I shoot it a f/2.8, the subject is one where it is not important.

[theguywitha645d]

So what you've done here is layer a regular visible-light image with an IR one? Interesting idea.

I convert the white light exposure to Lab and paste the grayscale IR image into the luminance channel. It is simple. I should use a ND filter in the white light to catch the motion, otherwise the white light is so sharp the registration between the color and luminance get a little strange.

Out of the camera, my IR RAW files look blue-violet tinged - probably because the software is applying an R:G:B white balance ratio which compensates for the natural dominance of green in visible light. Retaining the violet-mono look is ok for some shots but is not for everything, I think (it would be like toning all of one's B&W chemical prints in something like blue or selenium + gold). So converting the output to neutral-grey B&W makes sense to me most of the time.

Ray

My IR images are not purely monochrome. When opening the RAW, I can play with WB to separate the a difference in objects in the frame (I will post an image tonight). I am wondering if that is because the Bayer filters don't reach transparency at exactly the same wavelength and so a separation of "color" is possible because of a slight variation of reflected wavelength. I just got my IR filter and have not used it much--the image is from my garden and Maine in April is not very green.

[theguywitha645d]

Ray, this is a single IR file. The color has been brought out through processing--not possible if it were a monochrome image.