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12-03-2016, 08:38 AM   #1
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Full spectrum converted K-01, bought new lens, IR filters not working

Hello,
I have a K-01 full spectrum converted camera. I had been using my 50mm 1.4 to shoot my IR subjects (paintings), but sometimes a painting is really large and the 50 mm can't shoot at the range needed. I just bought a Pentax DA 55-300 lens so that I could shoot at different distances. However, when I attach my IR filters, I can't seem to find my subject matter. It's all dark no matter if I adjust the lens. Both 850 and 950 nm show nothing. I tried my Schott UV-1 Bandpass filter and I'm able to see my subject but there is an odd flaring of light which can be seen in the attached photo that I can also see while I adjust the zoom with the other filters.



I guess I'm just hoping that I'm not doing something right and that this lens will work with my filters. Anyone have any pointers?

12-03-2016, 09:06 AM   #2
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Can you focus first and then attach the filter?
12-03-2016, 09:32 AM - 1 Like   #3
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Your zoom is several F-stops slower (darker) then the prime, so it is not the best choice for task at hand. Hopefully dcshooter's suggestion will work for you.
12-03-2016, 09:46 AM - 1 Like   #4
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Strange! There's a chance that some of elements of that lens might attenuate infrared but I've never heard of that issue. And that flaring is very strange, too. Where are the light sources?

P.S. I'm surprised you got this lens for larger paintings. It's longer focal length would imply you'll need even more distance between the camera and the painting than you need with the 50 f/1.4.

12-03-2016, 11:37 AM - 1 Like   #5
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I also don't understand the reason for choosing the 55-300mm.. Are the paintings so far away? For things like Paintings I would recommend DFA 100mm macro, DA 35mm macro, DFA 50mm macro.. (Or Sigma 105mm, Tamron 90mm or older FA and F series macro primes).

It might be just too dark, because the DA 55-300mm has much less brightness than the fast 50mm prime. This also affects AF. Can you try the lens on a normal camera, not converted? Try to narrow down the problem
12-04-2016, 08:16 AM   #6
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QuoteOriginally posted by photoptimist Quote
Strange! There's a chance that some of elements of that lens might attenuate infrared but I've never heard of that issue. And that flaring is very strange, too. Where are the light sources?

P.S. I'm surprised you got this lens for larger paintings. It's longer focal length would imply you'll need even more distance between the camera and the painting than you need with the 50 f/1.4.
To be honest, I am a very amateur photographer and could really use a mentor to help lead me in the right direction as to what lenses are best to use. I guess I just got confused. I have two 1800 w soft boxes flanking the painting, so there is a lot of light.

Does the flaring have anything to do with the K01 being mirorless? Again, I basically know nothing about photography, I just use this camera for photographing my work.

Thanks.

---------- Post added 12-04-16 at 08:17 AM ----------

QuoteOriginally posted by UncleVanya Quote
Can you focus first and then attach the filter?
I tried it. It didn't work. Thank you.

---------- Post added 12-04-16 at 08:29 AM ----------

QuoteOriginally posted by dcshooter Quote
Use an IR flashlight to illuminate the subject, and you should be able to see it on the lcd.
Https://www.ledsupermall.com/eternalfire-ir-850nm-led-adjustable-zoomable-in...quipment.html?
Do you think a flashlight would illuminate the whole painting or just a certain spot? What I could really use is a large lamp that can illuminate the whole painting and something I wouldn't need to hold. Any recommendations for something like that? I recently bought two halogen light bulbs to point at the paintings as I've read halogen puts out more IR than other light sources.

---------- Post added 12-04-16 at 08:30 AM ----------

QuoteOriginally posted by dcshooter Quote
Use an IR flashlight to illuminate the subject, and you should be able to see it on the lcd.
Https://www.ledsupermall.com/eternalfire-ir-850nm-led-adjustable-zoomable-in...quipment.html?
Do you think a flashlight would illuminate the whole painting or just a certain spot? What I could really use is a large lamp that can illuminate the whole painting and something I wouldn't need to hold. Any recommendations for something like that? I recently bought two halogen light bulbs to point at the paintings as I've read halogen puts out more IR than other light sources.

---------- Post added 12-04-16 at 08:50 AM ----------

QuoteOriginally posted by Na Horuk Quote
I also don't understand the reason for choosing the 55-300mm.. Are the paintings so far away? For things like Paintings I would recommend DFA 100mm macro, DA 35mm macro, DFA 50mm macro.. (Or Sigma 105mm, Tamron 90mm or older FA and F series macro primes).

It might be just too dark, because the DA 55-300mm has much less brightness than the fast 50mm prime. This also affects AF. Can you try the lens on a normal camera, not converted? Try to narrow down the problem
Again, I'm new to photography and just don't know what I'm doing. I can easily return the lens. I only have this one camera to work with. I'm photographing paintings mostly at a distance of 5-15 feet for the whole painting and then of course I like to be able to zoom in for some macro shots. Sometimes i have a rather large painting, like 4ft x 4ft, and I'm just not able to get the whole painting in the shot. I'd rather not have to switch out 2-3 lenses during a photo shoot, but is that not possible? Especially since I have to attach filters to each lens and they might need step up/down rings and I'm not sure I could afford to buy so many.

My 50 mm takumar lens works okay but I think it doesn't produce the most crisp images. Perhaps because it is a vintage lens.
12-04-2016, 09:28 AM   #7
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QuoteOriginally posted by annalisa Quote
Again, I'm new to photography and just don't know what I'm doing. I can easily return the lens. I only have this one camera to work with. I'm photographing paintings mostly at a distance of 5-15 feet for the whole painting and then of course I like to be able to zoom in for some macro shots. Sometimes i have a rather large painting, like 4ft x 4ft, and I'm just not able to get the whole painting in the shot. I'd rather not have to switch out 2-3 lenses during a photo shoot, but is that not possible? Especially since I have to attach filters to each lens and they might need step up/down rings and I'm not sure I could afford to buy so many.
Affordable zoom lenses will have lower image quality. The macro primes I mentioned will give you top notch quality and are often used for documentary photos, product shots, and even for digitalizing older media. You don't need all of them. I would recommend something like the DFA 50mm and then you just focus it and move the camera/tripod closer until the photo almost covers the frame. You have the 55-300mm, you can try it out, and you can check whether 100mm is better for you than 50mm. Macro primes have great image quality, render a lot of detail, they have flat field of focus (so the painting reproductions would be sharp even in corners), and good colour reproduction as well, with little vignetting. Filters you can just unscrew and put them on the other lens. Most Pentax primes are 49mm and 52mm, I think.

You can get an older 50mm macro prime, like FA or F series. They would be more affordable. I just think a macro prime would give you much better image quality and low light capabilities than the 55-300mm zoom.

Also, from your post I see that you are mixing up "zoom" and "telephoto" and "magnification" . Zoom just means you can change the focal length of the lens. It does not mean that you shows far away subjects as close. Showing far away things as if they are close is the opposite of wide angle - it is telephoto. Magnification is different still. Magnification means the lens has close focusing capabilities relative to its focal length. For example, you can buy 21mm and 200mm lens, but they will both only have 0.17x magnification (though, they will achieve this at a different distance from the subject - 21mm will be very close, but the 200mm will be farther). The Pentax macro lenses have true 1:1 magnification. This means it will let you focus much closer. This might be required for small objects and smaller works. For large ones you can just step further back.

Switching lenses is one of the things a photographer has to do. Sure, you can use the DA 55-300mm lens and have it do almost everything for you. If you are happy with its results, then no need to change. If you want top notch results, you will have to take more control and use the right tools for the job. I suggest you work with this first. I think this lens has distance scales to help you focus. Just remember that the distance on the lens focus scales counts from the lens sensor (4.5cm inside of the camera from the lens mount), not from the end of the lens.

If my post is too confusing, just ignore it. I can't help myself getting technical
12-04-2016, 09:52 AM   #8
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QuoteOriginally posted by annalisa Quote
To be honest, I am a very amateur photographer and could really use a mentor to help lead me in the right direction as to what lenses are best to use. I guess I just got confused. I have two 1800 w soft boxes flanking the painting, so there is a lot of light.

Does the flaring have anything to do with the K01 being mirorless? Again, I basically know nothing about photography, I just use this camera for photographing my work.

Thanks.
We all start out as amateurs. Asking for help, seeking out information, and experimentation can lead to mastery.

The flaring is most likely from light from the softboxes getting directly into lens (or possibly reflecting off some very shiny bit of the frame holding the painting and getting to the lens). If the front of the lens can "see" the lights (even if those lights aren't in the picture), then that bright light will enter the lens and bounce around in hard-to-predict ways. Solutions include: increasing the light-to-painting distance, orienting the softboxes toward the painting (so the lens can't see the lit front surface of the softbox), adding a light-blocking strip to the side of the softbox nearest the camera, or using a deep hood on the lens.

What you are trying to do is doable but if can be tricky because of the need to adequately light the surface of the painting without any reflections off the shiny bits of varnish or paint. It's a Goldilocks problem of not having the lights too far (dim) or too close (flaring light into the lens) and not having the light angle too shallow (casts shadows and uneven light across the painting) or too steep (creates reflections off the shiny paint.

Good luck!

12-04-2016, 11:12 AM   #9
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I am lost. Let's retrace steps. If the 50mm you have can't get the entire painting in the shot and backing up farther isn't a viable option, then you need a less that has a smaller focal length not one that is larger. So the 55-300 does not seem like what you need.

My first thought is that you should look at the DA 35 f2.4 and DA 50 f1.8. These combined should be less expensive than the 55-300. A DFA 50 or 100 macro may offer the tight closeup you want if that is needed. If the macro seems necessary see if buying the DFA 50 is within budget.

Other approaches include buying an 18-55 and testing to see if this gives good corners that are acceptable. B



If you want to get very magnified pictures of the artwork (a small bit at a time) you can use macro lenses or techniques to do that. A large focal length lens may also do in some situations but often the minimum focus distance makes the close shots less magnified than you might want depending on the lens.
08-06-2017, 06:37 PM   #10
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Some lenses just don't work well in infrared. It might be the anti-reflection coatings which are designed for visible light, and actually become reflective at IR wavelengths, but in any case, internal reflections similar to those you are having are common with some lenses and IR. I've heard round-about that the 18-55mm DA performs satisfactorily and the shorter focal length would allow you to work closer to the paintings though that lens might not be the best in terms of image quality (can't speak to that). It should be available for a reasonable cost in the DA L version (around $60US on ebay).

Are you trying to do infrared fluorescence capture or just take an IR shot of the painting? For either, an IR source would be best. You can make your own using a string of IR LEDs. These are available in two different wavelengths 850 and 940 nm. It's probably easier to buy an assembly already put together like this one:

48-LED Infrared Illuminator Board for 60mm- Shell CCTV Security Camera 816412 2017 ? $1.63

You might have to work with it to get even illumination (possibly use several just like regular lights), but if you extinguish your visible lighting, you wouldn't need a camera filter - just the IR light source. The liveview image on the K-01 will show what you are getting. Use a little caution with these and don't look into them when they're on. You can't see the light but it can cause eye damage when you look into an intense source like these LEDs. No problem with the reflected light off a subject.

Tungsten lighting has infrared in it but not in abundance so that could be another reason you're not getting an image. Raw sunlight is pretty good though you may want to limit your painting's exposure to it because of the UV content which will fade the painting. Of course, you would use an IR lens filter if you use sunlight and sunlight isn't the best choice if you're going for IR florescence.

Although the K-01 autofocus should work in infrared, it's no guarantee, so use manual focus, zoom in with the liveview image (using the adjustment dial) and tweek your lens for the best focus. That might sharpen up the image significantly.

Know this was an old post but you might still be hanging on or there may be others with similar interest down the road so thought I'd post.

Last edited by Bob 256; 08-06-2017 at 06:46 PM.
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