Question about HDR and GND filters


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Aug 18, 2008
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#1
Hi guys, I was wondering whenever you guys make attempts on doing HDR photography, do you guys use GND filters? Or by using it, will it defeat the purpose of capturing different sets of exposures to accommodate the dynamic range?

Thanks to anyone who can enlighten me on this :)
 

night86mare

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#2
depends.

for sunset you may choose to use a gnd, and use hdr, at a certain timing when the DR required is very very wide, a gnd may lessen the number of exposures you need. in general any set of more than 7 pictures (each with 1 stop apart, so usually -3 ev to +3 ev) will not give you a good hdr output in photomatix.

most of the time, i do not use both at the same time.

the ONLY exception is when i do what i call a "fake hdr", or some people call it "raw file tone mapping", i.e. using photomatix to "salvage" marginally more DR than what you get from converting the raw file to jpg using other programs. there are reasons for this, i.e. plausible ghosting happening (like a shot of a swan, or a person). in that case, you need your DR "compressed" as far as possible with a gnd.
 

lunas

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#4
depends.

for sunset you may choose to use a gnd, and use hdr, at a certain timing when the DR required is very very wide, a gnd may lessen the number of exposures you need. in general any set of more than 7 pictures (each with 1 stop apart, so usually -3 ev to +3 ev) will not give you a good hdr output in photomatix.

most of the time, i do not use both at the same time.

the ONLY exception is when i do what i call a "fake hdr", or some people call it "raw file tone mapping", i.e. using photomatix to "salvage" marginally more DR than what you get from converting the raw file to jpg using other programs. there are reasons for this, i.e. plausible ghosting happening (like a shot of a swan, or a person). in that case, you need your DR "compressed" as far as possible with a gnd.
Hi Bro,

Thanks info. Very helpful.

You mentioned that "any set of more than 7 pictures (each with 1 stop apart, so usually -3 ev to +3 ev) will not give you a good hdr output in photomatix.". I thought that with more images, the higher the DR and more clarity to the output image. Is that a misconception?
 

night86mare

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#5
Hi Bro,

Thanks info. Very helpful.

You mentioned that "any set of more than 7 pictures (each with 1 stop apart, so usually -3 ev to +3 ev) will not give you a good hdr output in photomatix.". I thought that with more images, the higher the DR and more clarity to the output image. Is that a misconception?
hi yx,

i have gone beyond 7 stops of pictures before (more than 7 stops of DR, since each picture has its own DR) to make the necessary exposures to capture the correct range..

what happens it that to be natural (without haloing) the resultant image will be extremely dark. you can think of it this way, in the classic example of extreme, extreme DR required, looking into the sun uncovered by clouds. even with the naked eye (and not advisable) this will render the rest of the scene very dark in comparison.

so you can imagine what wonders it does to your hdr picture. :)
 

lunas

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#6
hi yx,

i have gone beyond 7 stops of pictures before (more than 7 stops of DR, since each picture has its own DR) to make the necessary exposures to capture the correct range..

what happens it that to be natural (without haloing) the resultant image will be extremely dark. you can think of it this way, in the classic example of extreme, extreme DR required, looking into the sun uncovered by clouds. even with the naked eye (and not advisable) this will render the rest of the scene very dark in comparison.

so you can imagine what wonders it does to your hdr picture. :)
I see. So HDR has it's own limitation although it is a technique to boost DR. You are right, in certain situation like back lighting of the sun where I need to get an even lighting across the image, it seems to be bit dark and halo is present.

Example: Is this a Correct example?


So in this situation, you would recommend a combination of GND and less exposure of HDR?

What is the best number of exposures to get the most natural effect?

How about night scene, I guess, the more the better right?

Thanks a lot. ;)
 

night86mare

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#7
i would recommend not shooting this scene, actually.

even the eye will not be able to take it, let alone digital format. :) if you see the building on the right, it is looking very artificial and graphic.

anywhere from 3 to 7 exposures usually gives ok results with the correct massaging.

not so sure about night scene, i have not done much night hdr.. :)
 

lunas

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#8
i would recommend not shooting this scene, actually.

even the eye will not be able to take it, let alone digital format. :) if you see the building on the right, it is looking very artificial and graphic.

anywhere from 3 to 7 exposures usually gives ok results with the correct massaging.

not so sure about night scene, i have not done much night hdr.. :)
I see. How many GND filters you have?
 

night86mare

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#11
How about cokin? How different is cokin from the 2 you have mentioned?
cokin gives funny yellow color cast

hazmee has started a thread about this before comparing tianya and cokin.. i think can still find if you do a search for threads by him,. :)
 

lunas

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#12
cokin gives funny yellow color cast

hazmee has started a thread about this before comparing tianya and cokin.. i think can still find if you do a search for threads by him,. :)
Yup, I will do a search.

BTW, for the tianya filter, how much does it cost? Is it sold in a set?
 

night86mare

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#13
Yup, I will do a search.

BTW, for the tianya filter, how much does it cost? Is it sold in a set?
i bought mine from ppcp last time

but that is a company that has closed shop, pity

if i do not remember wrongly, i was charged $12? i might be wrong though.

not sure where you can get it now. but you can try OP. i think there is a MO somewhere in the forums too.
 

lunas

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#14
i bought mine from ppcp last time

but that is a company that has closed shop, pity

if i do not remember wrongly, i was charged $12? i might be wrong though.

not sure where you can get it now. but you can try OP. i think there is a MO somewhere in the forums too.
What stop is the GND you got?

Yup, I have found it in the forum. Thanks a lot ;)
 

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