Merging different exposures.....

[DIW35]

A while back I recall reading a thread that explained how you could merge two or more photos of the same subject that had been exposed differently to compensate for different areas of the subject being photographed. i.e. One exposure for sky detail and a second exposure for ground detail. Combining different areas of the two photographs would give a combined result correctly exposed for both sky and ground.

Unfortunately I don't know if this technique has a name, so I haven't a clue what to put into the search field to try and find the original thread. Does anyone remember the thread and can point me in hte right direction?

[RobDickinson]

Theres many ways of doing this.

You can use HDR techniques (high dynamic range) if you want to combine the whole frames.

You can use layers & masks in photoshop to mix one sky with one landscape etc.

[hawkaye]

HDR sounds like what you are after. Photomatix is the software for merging the shots.

edited to say, is this the type of shot you were after?



There's a couple more on my flickr account ..

Edited by hawkaye on Tuesday 27th November 08:47

[DIW35]

High Dynamic Range. That's the fella. I knew someone on here would know what I was after. Thanks guys.

[TonyHetherington]

I've no idea how I do it wrong, but I've used the HDR part of adobe bridge/ps cs3 and it looks, frankly, crap!

Is there a secret to it's success?

[stigmundfreud]

TonyHetherington said:

I've no idea how I do it wrong, but I've used the HDR part of adobe bridge/ps cs3 and it looks, frankly, crap!

Is there a secret to it's success?

all you are doing there is creating an hdr image, you then need to adjust it. In photomatix you can do it on the fly then output to tiff/jpeg. In CS you need to then convert the mode to get the adjustment tools. TBH I much prefer the dedicated approach of Photomatix then output into PS for final touch ups.

Hawkeye, you need to work a bit more on your luminesence - your light smoothing looks off in that image

eta also remember HDR only works in images where there is a definite high contrast between shaddows and whites. We're talking at least 1 or 2 stops eitehr side of grey. Otherwise you may as well just do a normal exposure

Edited by stigmundfreud on Tuesday 27th November 16:12

[hawkaye]

stigmundfreud said:

Hawkeye, you need to work a bit more on your luminesence - your light smoothing looks off in that image

eta also remember HDR only works in images where there is a definite high contrast between shaddows and whites. We're talking at least 1 or 2 stops eitehr side of grey. Otherwise you may as well just do a normal exposure

thanks for the tip, I only started trying out hdr two weeks ago

[TonyHetherington]

Ah I see. Thanks stig; I'll have a play

[Chris71]

Was thinking about this the other day - wouldn't be surprised if the next generation of cameras has a basic HDR capability built in. If you left the camera 100% still on the tripod it could run a series of photos (my entry level SLR already has 'exposure bracketing') and then combine them.

I suppose the answer is probably that anyone aware of the technique will also have access to a decent photoediting package and some knowledge of how to use it, so that perhaps defeats the object.

[stigmundfreud]

a hdr camera wouldnt take multiple scans it would use a hdr sensor (which are out there just cost $$$$$$$$$)

[Chris71]

Ah, wasn't aware they existed. It just struck me that with the capability to take multiple shots at a set difference of exposure (as you use for basic post-processed HDR from what I can gather...) it wouldn't take that much for a camera that knew all shots were taken from the same tripod, with set variations to assembly them. Maybe not to studio levels, but enough to make an interesting 'special effect' to flatter amateurs such as myself.

[stigmundfreud]

to combine the multiple exposures takes a beefy PC quite some time. A camera would take all day! HDR as we see them, on our LDR monitors and in Jpeg/8bit colour, are not actually HDR just a close representation.

All a HDR sensor is, is a sensor that is closer to our eye in the amount of tonal ranges it can see simultaniously - not as simple as that. I think, from memory, its to do with the contrast range the sensor can see and therefore expose for. Our eyes have a range of X and a current camera has a range of Y, a HDR image is closer to X than Y.

It seems a lot of HDR stuff hat is turned out people go for the sureal look, I did at first as its addictive. The otehr thing is if taking HDR I find with myself I tend to think less about the shot I am working on at the time as I think I'll compensate for mistakes later so it leads to sloppyness. Just got back to using filters and doing things oldskool and liking the results

bog standard image, nothing exciting but used a gradient nd8 filter at f11 1/20 -1ev based on spot meter reading off the brickwork



Detail is there, I believe anyway , in all the ranges. I chose to go to -1ev to compensate and aim for a mid way on the shaddows. There were no blacks but dark grey so the -1 stop exposes closest to that tonal range.

eta basically the bottom half of the image is at -1ev then as the nd creeps in towards the top it goes close to -2 or possibly -3. Not sure on what the nd8 rating is off top of my head

Edited by stigmundfreud on Wednesday 28th November 11:38

Edited by stigmundfreud on Wednesday 28th November 11:44

[scotty328i]

stigmundfreud said:

stuff and posted this

Edited by stigmundfreud on Wednesday 28th November 11:38

WOW

Edited by scotty328i on Wednesday 28th November 11:43

[RobDickinson]

For HDR in cameras just wait.

Canon (and nikon?) have moved to 14bit sensors and stretched the dynamic range a little each generation. Hopefully in a few years time we'll have 11 stop sensors with 24bit conversion.