The other end of the spectrum

[jaapv]

Advertisement (gone after registration)

A very good UV camera as well, the M8:

B&W 403 filter, Iso 640. 1/30th Summarit @ 4.0

 

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[lars_bergquist]

Jaap, have you tried the B+W 92 filter?

 

The old man from the Age of the Infra-red Index

[gravastar]

This is something I must try I would assume the simpler the lens construction the more suited it would be for UV?

 

I see that the 403 filter passes about 63% in the UV and 20% in the near IR. Perhaps that explains why the grass and trees appear so light in Jaap's photograph.

 

Bob.

[lars_bergquist]

This is something I must try I would assume the simpler the lens construction the more suited it would be for UV?

 

I see that the 403 filter passes about 63% in the UV and 20% in the near IR. Perhaps that explains why the grass and trees appear so light in Jaap's photograph.

 

Bob.

 

Yes, this is a visually totally black filter for technical photography with quartz lenses in the ultra-violet. It has one transmission peak around 360 nanometers, which is of course completely blocked by modern camera lenses, and a secondary, narrow one in the very near infra-red around 750 nm, where it lets through less than 50 % of the radiation. In other words, an extremely inefficient filter for IR photography! A black B+W 093 filter, on the other hand, cuts from about 800 nm but transmits close to 100 %. The very dark red 092, often used for black and white IR film, cuts from c. 675 nm, also transmitting close to all radiation from that point.

 

Considering this, the short exposure Jaap uses is surprising. Of course, the 093 and 093 filters may not give the colours you want, if you decide to do IR false colour. I have ordered a 092 filter, and I also intend to dig out an old deep red filter (something like an 091) and do some hand-held experimenting.

 

BTW Jaap, how did you focus the thing?

 

The old man from the Age of the Infra-red Index

[lars_bergquist]

A further thought: Leica would do us a great service by publishing the sensitivity curve of the M8 (CCD plus integral filter on the sensor). How far down the spectrum does the IR sensitivity go?

 

Now it sems that the much-maligned IR sensitivity may well develop into a positive asset. (If only my two UV/IR filters would appear ...)

 

The old man – you know who

[scott kirkpatrick]

Kodak does exactly that. KODAK Image Sensor Solutions - KAF-10500

Since the cover glass is sold with the sensor, the full sensitivity curves appear in the product specifications, which can be downloaded at this link.

 

scott

[jaapv]

Advertisement (gone after registration)

The colourcast before balancing is exactly the same deep magenta as with IR and 092/093 filters, the false colour obviously very different.

[jaapv]

Yes, this is a visually totally black filter for technical photography with quartz lenses in the ultra-violet. It has one transmission peak around 360 nanometers, which is of course completely blocked by modern camera lenses, and a secondary, narrow one in the very near infra-red around 750 nm, where it lets through less than 50 % of the radiation. In other words, an extremely inefficient filter for IR photography! A black B+W 093 filter, on the other hand, cuts from about 800 nm but transmits close to 100 %. The very dark red 092, often used for black and white IR film, cuts from c. 675 nm, also transmitting close to all radiation from that point.

 

Considering this, the short exposure Jaap uses is surprising. Of course, the 093 and 093 filters may not give the colours you want, if you decide to do IR false colour. I have ordered a 092 filter, and I also intend to dig out an old deep red filter (something like an 091) and do some hand-held experimenting.

 

BTW Jaap, how did you focus the thing?

 

The old man from the Age of the Infra-red Index

 

 

On the Summarit (one ofthe last Leica lenses to transmit UV btw, although the 90/2.8 passes some UV) focus is surprisingly close.It is exactly the other way around from IR, but infinity is infinity. Both with IR andUV I bracket focus. My exposure is not THAT short, it is about 12 stops down. But I am told that this is the best UV performance from all digitals on the market. The Jupiter is a very good UV lens too.

[jaapv]

This is something I must try I would assume the simpler the lens construction the more suited it would be for UV?

 

I see that the 403 filter passes about 63% in the UV and 20% in the near IR. Perhaps that explains why the grass and trees appear so light in Jaap's photograph.

 

Bob.

 

Modern Leica lenses use Absorban UV blocking lens kit. The only current lens without a kitted element, the Elmarit 90/2.8 has (a bit less efficient) anti-UV coating. So it is not about simple. I believe Zeiss lenses block UV as well.I do not know about CV. Russian lenses generally have no UV block.

[lars_bergquist]

Kodak does exactly that. KODAK Image Sensor Solutions - KAF-10500

Since the cover glass is sold with the sensor, the full sensitivity curves appear in the product specifications, which can be downloaded at this link.

 

scott

 

If we may believe the curves, response is extremeley low beyond 700 nm, and nil at 750. So Kodak says that there is in effect no IR sensitivity ...

 

The suspicious old man from the Age of the IR Index mark

[scott kirkpatrick]

If we may believe the curves, response is extremeley low beyond 700 nm, and nil at 750. So Kodak says that there is in effect no IR sensitivity ...

 

The suspicious old man from the Age of the IR Index mark

 

Actually, the curves are linear scale where you would expect log scale, and they show quite a bit of sensitivity. I'd want the numbers to be sure, but when i looked at those curves, i thought they were an indication of the problem. Compare them with the information on the DMR's sensor (KAF-10100), which are not presented quite the same way.

 

scott