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02-12-2013, 02:46 AM   #1
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UV-IR cut filters - Whats-up-with-it ?

I have been researching into UV-IR cut filters which screw onto the front of your lens.

Does anybody on this forum use UV-IR cut filters ? What are the uses and pitfalls to using UV-IR cut filters ? Are certain manufacturers producing better filters than others ?

What I've researched so far seems promising in that they can improve the image quality for outdoor photographs.

Ephotozine has an article about a Hoya branded UV-IR cut filter. In the article, they suggest taking a photo of your TV remote while pressing one of the buttons on it to see if your camera can see the IR LED on the remote. Well, my K-5 can indeed see the IR light, which means a certain amount of IR light is going through the low pass filter at the image sensor.

Hoya UV & IR Cut Filter review

So has anybody out there had any experience with UV-IR cut filters on their Pentax K-5 ? Any help would be apreciated

02-12-2013, 05:45 AM   #2
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QuoteOriginally posted by zoolander Quote
What I've researched so far seems promising in that they can improve the image quality for outdoor photographs.
Unless you are using a IR modified camera a filter like this is pretty useless.I will point out there is already a UV-IR cover glass used on digital camera sensors. The amounts of IR /UV light that do get through this built in filter is a trivial concern for photographers*.

IR cut filters aren't really necessary for DSLR cameras, the IR sensitivity is pretty abysmal. I use the Hoya R72 and RM90 IR filters and even under the heat of the midday Australian sun my exposure times are around 25 seconds at f/11 - normal daylight exposure would normally be 1/125th at f/11 @ ISO 100

As things are the need for UV filtration is negligible, the type of silicon used in digital camera sensors isn't really all that sensitive to it. In fact the borosilicate glass used in lenses attenuate UV frequencies quite a bit, and don't forget about the coatings used on camera lenses which will reduce it further.

If you want to get the most out of your lenses and keep the money rather than spend it on a superfluous filter, a lens hood will improve image quality more than a UV/IR cut filter can.

*The weak UV/IR cut filter on the Leica M8 got Leica in hot water with many of its fans - thankfully Leica owned up to it and provided a solution.

Last edited by Digitalis; 02-12-2013 at 05:56 AM.
02-13-2013, 05:33 AM   #3
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QuoteOriginally posted by Digitalis Quote
Unless you are using a IR modified camera a filter like this is pretty useless.I will point out there is already a UV-IR cover glass used on digital camera sensors. The amounts of IR /UV light that do get through this built in filter is a trivial concern for photographers*.

IR cut filters aren't really necessary for DSLR cameras, the IR sensitivity is pretty abysmal. I use the Hoya R72 and RM90 IR filters and even under the heat of the midday Australian sun my exposure times are around 25 seconds at f/11 - normal daylight exposure would normally be 1/125th at f/11 @ ISO 100
I was aware that the low pass filter in front of the sensor was a combination UV-IR cut and an anti-aliasing filter. But the IR cut is not a true IR cut filter because it alows Infrared to enter and the camera is enabled for IR photography.

Most folks online recommend that same Hoya R72, and also complain about the long exposures.

Okay, so establishing the fact that the K-5 can be used for IR photography. The information I've read online suggests using the UV-IR cut filter, because even that small amount of infrared light coming through does degrade the image quality. They show the typical pics without the filter, and with the filter sample images - like in the link above.

Can i ask you mister Digitalis, which brand/model of UV-IR cut filter have you used and can you describe exactly how it performed ?

There's some guy on YouTube (Link below) with a modified Panasonic camera without a normal low pass filter (UV-IR cut + AA), but just a clear piece of glass. He tries one UV-IR cut filter and its inferior, then puts on his own brand "Jeff Poon Filters" and voi-la, it works like a charm ! I know that this is a dramatization for the purpose of selling his filters, I'm just wondering what experiences other folks are having with them and if indeed there are inferior and useless filters out there on the market. There is no review of ANY UV-IR cut filter on Pentax Forums ....... yet.

https://www.youtube.com/watch?v=pKx38mHZ2xI

So far you've said - don't waste your money. But getting greater IQ can be desirable for most of us even if its just a smidge.

Thanks in advance
02-13-2013, 06:36 AM   #4
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QuoteOriginally posted by zoolander Quote
The information I've read online suggests using the UV-IR cut filter, because even that small amount of infrared light coming through does degrade the image quality.
No, it doesn't. The amounts of IR/UV light that do sneak through the built in filter are infinitesimal compared to the amount of visible light being recorded by the sensor.

QuoteOriginally posted by zoolander Quote
But the IR cut is not a true IR cut filter because it alows Infrared to enter and the camera is enabled for IR photography.
Due to the quantum law of forbidden transmissions, there is no such thing as a true IR cut filter. All filters from the most prominent manufacturers ( B+W, Hoya, Tiffen)allow infared light to be transmitted above 1200nm.

QuoteOriginally posted by zoolander Quote
There is no review of ANY UV-IR cut filter on Pentax Forums
The reason for that is that under normal circumstances they are completely unnecessary.

QuoteOriginally posted by zoolander Quote
But getting greater IQ can be desirable for most of us even if its just a smidge.
Let me state for the record, have been a photographer for 18 years. I work professionally as an instructor and as a commercial photographer: for commercial work In the great outdoors and in the studio I use a Leica S2, Pentax 645D and I also work with the Phase one IQ 180 80 Megapixel digital back on an Arca-swiss M line technical camera with state of the art diffraction limited lenses from Schneider and Rodenstock. The point is: if I don't need to use a UV/IR filter, neither do you.


Last edited by Digitalis; 02-13-2013 at 06:43 AM.
02-13-2013, 07:49 PM   #5
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Thanks for your reply on this Digitalis.

Have you ever used a UV-IR cut filter ?

Are your opinions above based on first hand experience with UV-IR cut filters ?

Did you look at any of the links I provided ?

You've stated that the amount of Infrared light reaching the sensor is infitesimal. Here is a quick photo of my TV remote while I'm pushing any button :



In live view it looks even worse because my TV remotes IR LED is flashing brightly. Taking the photo in the dark illustrates this even further that the K-5 lets in a MASSIVE amount of infrared light - my Sony A65 sees it even worse!

This is not an infinitesimal amount of infrared light being seen by my K-5, then why is is my TV remote is lighting up like a Christmas light ? Ephotozine has shown the same thing in their article with a video in the link I've provided above - of which I've tested for myself and it is now tested, verifiable and confirmed empirical evidence.
02-13-2013, 08:02 PM   #6
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If anybody has used and tested out UV-IR cut filters before your input would be helpful !

According to wikipedia, the human eye see's light between 390nm to 700nm - aka visible light. So as a rough guide the UV-IR cut filter is blocking UV below 390nm, and is blocking IR above 700nm.

UV-IR cut filters only work on lens with a field of view up to 60 degree's, anything above that, is a problem

There are various manufacturers making UV-IR cut filters. I did an ebay search for the 49mm size, plus I cross checked their specifications on the manufacturers websites:

Rocolax ($29 ebay)

380nm-670nm

(Generic brand) Optical UV-IR CUT filter ($28 ebay)

380nm-760nm

Baader Planetarium ($115 2” or 50mm) (not available in 49mm)

400nm-690nm

B&W ($69 ebay)

No specifications stated on website

Marumi ($69 ebay)

No specifications stated on website

Hoya ($85 ebay)

320nm-780nm (as stated in the ephotozime link)
(Hoya website states the specifications are 390nm-700nm)

Has anybody used any of the above filters ?

Thanks in advance !
02-13-2013, 08:06 PM   #7
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The review you link to says this:

QuoteQuote:
It's dificult to see much difference with the above three comparision sets because the camera is already doing a pretty good job of filtering out IR wavelength, so for cameras of this kind there's not a great advantage in paying extra for the IR Block aspect and a normal UV will suit as a lens protector.
I looked at a couple of shots when I took some shots with my K-7 and a Hoya 72, then unscrewed the filter and took a visible light shot. Shots with the Hoya 72 were 11 or 12 stops darker than the visible light shot. I don't know how much IR the Hoya 72 blocks while it's blocking visible stuff, but even if it's 3-4 stops, the IR component is way down there at the floor of the dynamic range, swamped by the visible stuff. That's in midday Colorado summer sun, when visible photography is uninteresting anyway.
02-13-2013, 08:41 PM   #8
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Thanks Just1MoreDave !

Yeah I read that part of the article. It was referring to the 3 shots above that appear to have been taken under a bridge in the deep shade facing the taller bridge. Yes it appears the UV-IR filter hasn't made a difference in those shots. But in the preceding shots (the first triple set) it appears to have sharpened the hilltop scene. In the field scene below that one it appears to have taken out some of the red and sharpened it a little in the field. But the second and third sets appear to have been taken in the late afternoon judging by the long shadows and IR light is dropping off.

It appears to be working in the first and second sets of test shots and improves image quality in the bright sun and afternoon sun.

I understand what you're saying, that the IR getting in is small, but this UV-IR cut filter seems to make a REAL difference out in the full sun (according to that reviewer). Yeah photography in full sun is not attractive, but I remember taking film pics in the full sun and getting really good images - like at sports car shows.

I think I'll definitely get one, I've read of a couple of comments from folks who rave about the UV-IR cut filter. Hopefully someone on Pentax Forums may have tried it out.

02-13-2013, 09:49 PM   #9
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QuoteOriginally posted by zoolander Quote
Have you ever used a UV-IR cut filter ?
yes, I do use a UV/IR cut filter on my Leica M8. Due to an unintentional oversight in production the Leica M8 has a weak internal UV/IR cut filter and therefore using an external one is necessary, to their credit Leica provides users with two free filters. The filters I requested are the E49 and E60mm these Leica filters cost around $170 new. There is no real improvement in image sharpness by using the UV/IR cut filter* - however by using the cut filter colour fidelity from the M8 is improved considerably by the removal if UV/IR light contamination.

QuoteOriginally posted by zoolander Quote
But in the preceding shots (the first triple set) it appears to have sharpened the hilltop scene. In the field scene below that one it appears to have taken out some of the red and sharpened it a little in the field. But the second and third sets appear to have been taken in the late afternoon judging by the long shadows and IR light is dropping off.
Actually in the afternoon light IR wavelengths are amplified by atmospheric scattering of shorter light frequencies - IR light is less effected by Rayleigh scattering because the wavelengths are so long. IR light diffracts around air particles instead of smacking straight into them like shorter wavelengths do. As the light from the sun has to penetrate more of the earth's atmosphere the light gradually becomes red-shifted.


Just to show you what IR contamination on the Leica M8 actually looks like:


This is an image of black velvet - Photographed under a Halogen hot light. Black velvet eats up light for breakfast. On the left is with the Leica M8 with UV/IR cut filter, on the right is the Leica M8 without it. Both images were taken with Identical exposure values.

QuoteOriginally posted by zoolander Quote
This is not an infinitesimal amount of infrared light being seen by my K-5, then why is is my TV remote is lighting up like a Christmas light ? Ephotozine has shown the same thing in their article with a video in the link I've provided above - of which I've tested for myself and it is now tested, verifiable and confirmed empirical evidence.
The IR LEDs used in TV remotes have an intensity that goes far beyond any natural source of IR illumination, the luminous efficiency of many IR led lights outpaces natural sources by around nearly 9~ 4 stops**. If you had actually done the proper research on UV/IR contamination and digital cameras you would know this.

*I have done a considerable about of testing with and without the UV/IR cut filter using the Leica 50mm f/1.4 ASPH Summilux-M which is arguably the sharpest 50mm lens in the world.
**the efficiency purely depends on the materials used to construct the diode, GaAs Gallium Arsenide being most common.

Last edited by Digitalis; 02-14-2013 at 12:09 AM.
02-14-2013, 06:34 AM   #10
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1.Okay so you use UV-IR cut filters for your Leica with the defective low pass filter.

2.Perhaps infrared light may become amplified during the afternoon, but the Ephotzine pics do show an improvement, though the light looked fairly dim. Perhaps they should have shot out in the full sun to really put the filter through its paces.

3. The chart below suggests that there is significant infrared radiation at sea level above 700nm. Some of the Infrared is absorbed by oxygen and water (probably in the form of water vapor), producing hills and valleys in the infrared light spectrum. It drops off and continues beyond 2500nm. Natural IR illumination goes from 700nm to beyond 2500nm.

Thats the source:

http://https://en.wikipedia.org/wiki/Sunlight

And this is the chart:

https://en.wikipedia.org/wiki/File:Solar_Spectrum.png

4. TV remotes operate roughly at 930nm-940nm, and if the K-5 can see this range, then who knows what are the specifications are for its low pass filters sensitivity. IR film was sensitive between 700nm-900nm. Either the latest IR remotes frequencies are lower, or digital camera's sensitivity is greater, I would believe that the latter is true. Or perhaps it doesn't have an IR cut in the low pass.

Here's the source:

https://en.wikipedia.org/wiki/Remote_control

Here's the chart:

https://en.wikipedia.org/wiki/File:Control-remote-spectrum.png

Yes, I am aware that a TV remotes infrared LED is more intense than natural sources. The issue is that back in the film erra (some are still in that erra, but its okay, me too), film had dye's that blocked Infrared above 700nm, and DSLR's do not block IR light above 700nm for the purpose of enabling IR photography.

If it was good and necessary for film, then its good enough for digital. Granted you can swap a roll of color film and IR film, but you can't swap out your low pass filter (maybe except for a couple of models).

Why did this conversation go so far off of UV-IR filters. There's a reason why corporations and their engineers would manufacturer such a product ......unless its another digital photography scam !

Has anybody else used a UV-IR cut filter on their Pentax K-5 or other cameras.
02-14-2013, 07:51 AM   #11
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QuoteOriginally posted by Just1MoreDave Quote
the IR component is way down there at the floor of the dynamic range, swamped by the visible stuff.
Correct, Having done some tests of my own, I know this for a fact.

QuoteOriginally posted by zoolander Quote
... Ephotzine pics do show an improvement, though the light looked fairly dim. Perhaps they should have shot out in the full sun to really put the filter through its paces.
Yet ephotozine never gives any evidence to demonstrate this "improvement" All the sample photographs shown are taken under overcast conditions without a tripod with the sky completely blown out. The biggest difference I have observed by reviewing the sample images on my calibrated monitor is that the images where the UV/IR cut filter were used is there is a cyan colour cast.There is also a considerable amount of flare present in the images where the filter is used.

Ephotozone states that : "for cameras of this kind ( Olympus OM-D E-M5) there's not a great advantage in paying extra for the IR Block aspect and a normal UV will suit as a lens protector."

while I discourage the use of UV filters as protector filters - I prefer the use of lens hoods to protect the lens. The author of the test states that there is no great advantage in using the UV/IR cut filter.. I would go one step further and state that there is no advantage to using the UV/IR cut filter for everyday photography.

QuoteOriginally posted by zoolander Quote
But in the preceding shots (the first triple set) it appears to have sharpened the hilltop scene. In the field scene below that one it appears to have taken out some of the red and sharpened it a little in the field
Again, on my calibrated 27" Eizo LCD monitor I see there is no visible improvement in image quality between the shots taken with the UV/IR cut filter and without it. The lighting has changed between the images and this makes quantifying the differences much harder. The level of noise in the sample images* is visually distracting. The Author of this article clearly doesn't know how to shoot a proper test sequence. To really test for IR/UV issues with any camera the best place to do it is in the studio - where having absolute control over lighting conditions makes it easier to highlight strengths and weaknesses and test under different lighting conditions. I have done plenty of studio tests of cameras, and I have conducted tests looking for UV/IR problems with pentax DSLR cameras, and it is simply a non-issue.

QuoteOriginally posted by zoolander Quote
DSLR's do not block IR light above 700nm for the purpose of enabling IR photography.
Okay at 1/250th f/8 under direct daylight do you know how much IR light is getting through the low pass filter of a pentax K5IIs? the answer is around 0.003%**. A perfect middle grey (18%) exposure the sensor captures approximately 10,000 photons, and only 0.003% of those photons will have a wavelength around 720nm - assuming the sensor has perfect frequency response across the range of 400-720nm and light source has perfect emission spectra from 380-900nm - and using the same UV/IR cut filter the K5IIs is equipped with***.

This is a photograph taken under direct australian sunlight with my Pentax K5IIs with the FA77mm f/1.8 Limited with the Hoya R72 filter attached - take a look at the exif and note this image has been pushed +4 stops in lightroom, and you still can't see any IR....fancy that.



* most of the test images were taken at ISO 200~400 I'm surprised by the amount of noise apparent in the images - one of the reasons why I don't like 4/3rds
** I had to spend some time calculating the visible light equivalent transmission of my Hoya R72 IR filter - and it is basically a ND 16384 filter. Meaning I would need an aperture of approximately f/896 with the shutter open for 75 seconds @ ISO 100 to obtain the same exposure as 1/250th f/8 @ ISO 100.
***which is essentially impossible, All light sources have troughs and spikes in their emissions, and all sensors have metamerism.

Last edited by Digitalis; 02-14-2013 at 04:37 PM.
02-15-2013, 12:20 AM   #12
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On infrared radiation/heat:
Sorry Digitalis, but I was wrong about you being right about the late afternoon sun causing IR to become amplified. Infrared is basically heat, its heat radiation from the electromagnetic spectrum.

During the day, as the sun rises it gets hotter. In temperate zones it is usually the hottest between 10:00am and 2:00pm, and then it gets cooler after that.

I've lived in the Pilbra and its plus 40 degrees for 6 months of the year - a staggeringly hot place, where its still over 30 degrees by 10:00pm.

If infrared heat becomes amplified during a sunset, it won't be by much and nowhere near as much as during the middle of the day. And 40% of sunlight is infrared radiation/heat.

I have never noticed it getting hotter at dusk. Maybe if there is cloud cover and the sun drops below the cloud cover.

I live in the sub-tropics and it gets extremely hot right before a diurnal storm. So hot that it burns you real bad, and then you know that you're in for a summer storm. After the storm the sun is milder, even if its over by noon (very strange).

On IR ingress

You've used a IR720 in your test shot above, IR starts at 700nm.

Here is a photostream of a person from flickr who uses a Marumi IR HD700:

Reflections | Flickr - Photo Sharing!

The above image is: 1/30, f/8, ISO100. The rest of their images tell a similar story.

Judging by those pics, there is a hefy amount of infrared entering our images in regular photgraphy.

Digitalis, perhaps you should have used an IR 700 to test and make your point. Do you have one to test ?

If not, then maybe someone out there has images from using a Marumi IR HD700 (or similar), that clearly shows a high transmission of IR like the above images on flickr. This might either confirm or deny my assertion, that Infrared is entering the images.

Judging by the above link to the flickr photos ....... its confirmed ! Infrared is entering DSLR images in normal photography.

Backing up my assertion is the fact that a whole host of manufacturers have created UV-IR cut filters.
02-15-2013, 01:05 AM   #13
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QuoteOriginally posted by zoolander Quote
Judging by the above link to the flickr photos ....... its confirmed ! Infrared is entering DSLR images in normal photography.
The Canon G7 (which is not a DSLR, but a high end compact digicam) that was used to make those images has clearly been been modified to see into the Infrared spectrum, and the person using that camera has use a filter to cut out visible light and record IR. The fact that you mistook this for IR contamination proves your ignorance.

QuoteOriginally posted by zoolander Quote
Digitalis, perhaps you should have used an IR 700 to test and make your point. Do you have one to test ?
The difference between 700nm and 720nm is trivial, like comparing f/1.8 to f/2. Transmission of the hoya R72 filter is 98% at 720nm, transmission falls off gradually to 90% at 1600nm

QuoteOriginally posted by zoolander Quote
Sorry Digitalis, but I was wrong about you being right about the late afternoon sun causing IR to become amplified. Infrared is basically heat, its heat radiation from the electromagnetic spectrum.
Again,the technical name for the part of the IR spectrum I was referring to is the Near Infared (NIR), we aren't actually recording heat signatures here - no ordinary DSLR can*. The NIR spectrum starts at 700nm and ends at 1500nm. True infared frequencies (emitted heat) are frequencies considerably longer than that(3-15 μm) and DSLR camera sensors are not capable of detecting those frequencies. The solar spectrum does get redshifted as the sun sets, the light from the sun travels at an angle through thicker levels of the atmosphere, the higher frequencies(Ultraviolet, Violet and Blue) in the solar spectrum are absorbed at a greater rate than longer frequencies (Yellow,Red and IR) , it is the reason why red/orange is typically a predominant colour during sunsets.

QuoteOriginally posted by zoolander Quote
Backing up my assertion is the fact that a whole host of manufacturers have created UV-IR cut filters.
The reason why these filters exist are for scientific,forensic,astronomy and military purposes but also because there are a subset of photographers who have removed the internal UV/IR cut filter from the sensor in their cameras so they can see Ultraviolet and NIR - this modification is permanent and the only way they can use their camera for visible light photography is by using a IR/UV cut filter. There is also a subset of photographers who use ND filters so dark so they have to use exposures that are so long that IR contamination is a problem ( ND filters typically do not block IR).


*If you cooled a DSLR camera sensor with liquid nitrogen it might be possible, could be a fun weekend experiment. But something tells me that doing this would completely void the camera warranty.

Last edited by Digitalis; 02-15-2013 at 04:58 PM.
02-17-2013, 01:56 AM   #14
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When I read your above comments I thought he's right, my bad. I thought maybe the Hoya IR720 had horrible transmission. On the Hoya site it shows transmission at 85% or something. I was like yep this guy is right, and I made a goof of myself, plus I've also ordered one and wasted my money.

But last night my intuition kept saying no, he's wrong. My intuition on this has been strong about infra-red getting through to the sensor. Let me explain......

My first camera was a Nikon D3000, a piece of junk worthy to be thrown against a brick wall. I was only into macro photography at the time and I began noticing something. I would find a Thrips (a grasshopper type pest), and in full sun you could see with your own eyes brown markings on the side of its thorax or wing-lets, or piping lines here and there. But when you take a picture and then check to see if you captured the detail, its not there. I've always been baffled by this.

I upgraded to a Sony A65, a much better camera than the Nikon by a long shot. A similar thing was happening when I shot thrips, markings disappeared in the picture and there was a slight difference in the appearance of the Thrips. The Thrips has a slight fluorescent glow. (Sony A65 f/10 1/20th ISO 100. UV filter, auto extension tubes, kit 18-55mm) (the thrips was walking that's why he's a little blurry):

https://www.pentaxforums.com/forums/members/54618-zoolander/albums/6381-pent...ture56231.html


I found an interesting spider on a friends patio, it was about 1 inch long (leg tip to leg tip) and its head and abdomen was blue in colour. In every photo, the spiders head and abdomen came out silver. I spent a half an hour changing settings trying to capture the spiders true colour of blue, and the shot below was the best I could achieve (Sony A65 f/16, 1/60, ISO 100, UV filter, auto extension tubes, kit 18-55mm):

https://www.pentaxforums.com/forums/members/54618-zoolander/albums/6381-pent...ture56232.html

The spider to the naked eye was a nice light blue with darker blue dots on the abdomen. The picture was NOTHING like the real thing. I was baffled by this.

I googled insects and infra-red, and found the site below about how insects have infra-red (and ultraviolet) luminosity in near infra-red wavelengths. In that sites infra-red and normal shots, markings disappear in infra-red as to protect themselves from predators which can only see in infra-red.

https://edit.ethz.ch/kp.ipw.agrl/people/michaemi/Insect

So thanks to you Digitalis, I think you've help me solve something that's had me baffled for a while.

So how is the infra-red getting in ? You've done the tests on the Hoya IR720 on a k-5ii. The only thing I can think of now is that its getting in around the 700nm area. Perhaps the low pass filter does't cut off EXACTLY at 700nm. Maybe they cut off at 701nm, 702nm, 710nm or as high as 720nm and just that small amount of near infra-red radiation is taking out the markings and colouration.

I did read some comments from a guy on the Marumi IR700 flickr group, who said he prefers to use his girlfriends Nikon D3000 rather than his own D7000 because the D3000 is more sensitive to infra-red. Maybe thats why the D3000 was so horrible.

In my limited experience and opinion, its been clear to me that something is getting in, and something is wrong and weird about digital photography. Infra-red must be getting through because insects are sensitive or susceptible to infra-red luminosity, and ultraviolet luminosity. Since I always use a UV filter it would probably be the cause of infra-red.

Bottom line is: just like the UV-IR cut filters I listed (with specification and price) in a previous comment above, we can see they don't all cut at 400nm and 700nm. Some cross over into UV or into infra-red. So this is the problem with certain cameras, and I think my K-5 is letting infrared in. I haven't done any macro shots of bugs, but when the cut filter arrives I'll do a basic test. I am very confident that the UV-IR filter will do the job based on some samples I've seen.

I am now 110% certain that infrared gets, based on the missing marking and coloration.
02-17-2013, 06:17 AM   #15
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QuoteOriginally posted by zoolander Quote
I am now 110% certain that infrared gets, based on the missing marking and coloration.
I predict that your images will look no different.

As for the examples of the subject matter you are intending to photograph:

In this image the reflective body of what I take to be a golden orb spider with a missing leg is simply overexposed - a common mistake.

The missing blue markings you mention are most caused by the lighting you have used - to photograph Insect Iridescence properly you need a very broad light source, so then the light strikes the subject from as many angles as possible enabling the patrerns to be revealed, the angle of incidence equals reflection.


On your comments over the strength of the UV/IR cut filters and the precise cut off in the UV/IR spectrum on the Pentax K5 is tricky but what is most common for manufacturers to use is a 400-650nm UV/IR cut filter - nearly a decade ago it used to be that 380-700nm were considered enough but over the past several years internal UV/IR cut filter have become stronger and more efficient.

And now for your second image:

what lens did you use to capture this image?

What I think you are trying to photograph here is called thin film interference which can be affected by polarisers- again you need to use a a really broad light source angled correctly to photograph it. Remember the angle of incidence equals reflection.

Last edited by Digitalis; 02-17-2013 at 06:23 AM.
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Whats up with the Pentax Photo Gallery? robert Photographic Technique 17 04-23-2010 03:17 AM
For Sale - Sold: B+W 72mm 486 UV IR cut multicoated konraDarnok Sold Items 0 11-02-2009 06:00 AM



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