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[討論]有人有使用紅外線底片的經驗嗎? [複製連結]

曲士

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發表於 2006-5-13 08:31:09 |顯示全部樓層 | 字體大小
有人有使用紅外線底片的經驗嗎?
是底片,不是數位+紅外線濾鏡喔

我想請問加了紅鏡之後,測光怎麼補償?
應該是說,使用紅外線底片,測光要怎麼測?相信TTL就好了嗎?
而ISO又要怎麼設定呢?

另外,使用紅外線底片不是會有對焦點偏移的問題嗎,要怎麼修正?
是要以眼睛看到的為準
還是依照鏡頭的標示以估測距離為準做修正?
生命的焠煉,聖稜的榮耀 There is no should be but death in mortals 人生除了死亡,沒有什麼事是肯定的 Mein Flickr http://www.flickr.com/photos/photozither/sets/
匿名  發表於 2006-5-13 13:56:10 | 字體大小
Read the film's technical info and instruction. There is no definite data for this question. It depend on what kind of lighting situation and your film type. And yes of course you need to manually adjust the focus to the IR index mark on the lens .. and at least stop down to made sure there is minimal chance of failure. So what's the film type, which kind of camera and lesn, and shooting what under what kind of conditions ?

And by the light, which body are you using. Made sure you read the instruction of the film regarding loading and using new bodies ( might fog the film with their internal IR diode )

There is quite a number of online article about that , just Google/Yahoo search for them and Kodak had technical info and related ones in pdf format on their website that you can dowdload. Don't know about this, but I would advise fellow Forum memebers to do some research before posting question and let's be more specific about it please ...

曲士

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發表於 2006-5-13 23:22:17 |顯示全部樓層 | 字體大小
FTL:
我五月下旬要上玉山,假定期望天氣是穩定的,至少是多雲
我想拍溫暖的岩石、草原,而且高山的天氣條件也與平地不一樣
因此除了黑白外,我想弄最少一卷的紅外線底片上高山試試
我以前從沒接觸過紅外線底片,以及相關知識,所以一時之間也不知道要去哪找

我用Spomatic F、S-M-C Takumar 24/3.5,一機一鏡


ps.不過如果最後認為093貴到我無法負擔,我可能就不玩了
生命的焠煉,聖稜的榮耀 There is no should be but death in mortals 人生除了死亡,沒有什麼事是肯定的 Mein Flickr http://www.flickr.com/photos/photozither/sets/
匿名  發表於 2006-5-13 23:49:47 | 字體大小
As any IR film goes, putting up the RED filter will only fool the meter in the camera as IR film do not record visible light as normal film do and of course large chunk of exposure is from near spectrum IR reflected off natural subject. If you intend to go shooting in situation as stated, the IR reflection would almost equate the visible reflectio. That is you should base your exposure on metering without filter and for sack of preserving capture, brakcte at 1/2 to 1 stop over and under.

One have to also note that IR reflection in natural scene tend to run higher in bright sunny situation, just after sunrise and just before Sunset due to the Sun's angle to the ground.

曲士

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發表於 2006-5-14 00:13:59 |顯示全部樓層 | 字體大小
FTL:
好有趣喔,如果我英文沒理解錯的話,為什麼IR反射值會約略等於可見光呢?

我的想法是這樣的:
先跟你解釋一下,爬玉山的時候是面向東北方前進,大致是前峰、西峰、南峰,然後主峰
在稜線上一定是上上下下繞來繞去的,所以不是所有地方都是整天能曬到陽光
那在逆光時拍照山頭跟草原,還有岩石(尤其是斷崖)(尤其是下午太陽在另外一邊的時後)
有些地方,他上午的時候是順光有給太陽烤到
可是下午的時候是背對的太陽,照不到光線,在可見光反射裡是暗的
可是在IR反射裡,他不是應該還是亮的嗎?

我不知道我的說明夠不夠清楚
生命的焠煉,聖稜的榮耀 There is no should be but death in mortals 人生除了死亡,沒有什麼事是肯定的 Mein Flickr http://www.flickr.com/photos/photozither/sets/
匿名  發表於 2006-5-14 19:30:44 | 字體大小
Normal film capture light in the visible spectrum, IR film capture light in the very end of visible and the IR range ( not emission type ). As almost all natural scene goes, the intensity of visible spectrum and IR is pretty much equal and roughly linear. I think you have confused IR film ( whoich do not record IR range, but insdtead record Near range infrared up to 1 Micron, a sizable chunk opf visible spectrum, and most of all also UV spectrum ) with real IR capture whioch require both near rane and Far end IR range ( up to 10 or above micron, typically associated with heat emission ).

Thus if there is a scene that require certain EV value for visible light, its almost always that IR capture require an exposure of similar EV. As a general rule, there will be very minimal deviation ( usually less than 2 EV ). However, the inclusion of the RED filter on camera will reduce the in camera TTL by a wide margin as the meter is corrected for visible spectrum opnly and the filter will further reduce the light by 2 to 4 stop ( depending on what kind of filter )

So the normal way to meter is to figure out the difference. In bright sunny situation, this is pretty much just stright forward as the broad spectrum of IR and Visible is just about the same. In shade, the usual case is IR ( as in low K vlue spectrum ) is reduced ( usually by 0.5 to 1.5 EV ) and thus require an exposure correction of such. During early morning and evening when Sun is at low angle and light is shifted towards the low K range, the IR emission tend to run instead to 1 EV above visible or similar.

With these general idea. One can usually meter ( with no FILTER ) as usual and use that exposure as starting point and correct for exposue. The thing that one need to consider is though Metering on normal camera / Hand held meter is such that it is calibrated to a visible reflective. While in nature, any Flora Tend to reflect IR far higher than usual. That is the general idea, and in praktice, we have to consider that most lens simply do not let in near range IR as linear as visible spectrum, and of course do not focus proper either. SO the best approach is still meter and bracket ( good IR photographer usually take a ascene and bracket out to 2 EV or so ). There is no way to avoid such hassel as IR is not measurable by normal metering equipment and all must be done via experience and guesswork. That is why I think in the long term, IR in digital is far more useful than Film as it offers some form of inetractive check up with the capture and exposure .. )

Again I must stress the best technical source is to fromt eh Mfr .. check this 2 page

http://www.kodak.com/global/en/p ... .14.19.22&lc=en

http://www.kodak.com/global/en/p ... hPubs/f13/f13.jhtml

曲士

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發表於 2006-5-15 00:56:52 |顯示全部樓層 | 字體大小
都是英文,會瘋掉
原來您找的是en我找的是tw,難怪都沒有

您的意思是利用IR的ev值與vis的ev值的不一樣來拍攝是嗎?
看來IR攝影比我想像中的還要難上許多

原來IR跟heat不一樣,真的搞混了
奇怪我怎麼老是把軍方的夜視熱影像儀想成是紅外線影像儀...
還有台灣那什麼廣告紅外線熱毛毯
害我老是把紅外線與熱劃上等號
生命的焠煉,聖稜的榮耀 There is no should be but death in mortals 人生除了死亡,沒有什麼事是肯定的 Mein Flickr http://www.flickr.com/photos/photozither/sets/
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