in camera hdr

my first serious attempt at using the k10's multiple exposure feature.

3 exposures with auto exposure. it was quite windy with relatively long exposure speeds. i think the vibrations over 3 exposures added to the blurred, out of focus look.

mind you, I didn't realise i had the aperture wide open so that didn't help foreground sharpness either!




Comments and critique welcome.

Interesting experiment.

Interesting to note the banding in the sky. I can see two distinct cyan bands, which I presume is the clipping in the sensor that happens just before a part of the frame is completely burned out. Except that when several exposures are merged, the clipping happens in different places and you get them all.

forgot to add, i used a ND grad filter on a cokin holder, this is as 18 mm with the 18-55mm DA lens.

There is a fair amount of vignetting evident. Could this be part of the banding you are seeing chris?

I have done no PP after import into LightRoom using 'zeroed' import (no adjustments to image), i just exported at 90 dpi, max 1000 pixels.

It looks very similar to the vignetting I've had with my 18-55.

But vignetting has the effect of underexposing the corners. So if the centre (of the sky in your case) is overexposed, which it is, there's got to be a point before it gets completely burned out where it's only partially so.

Hence the cyan band, which I have on several of my overexposed skies.

So if you have two shots where the exposure's different, the cyan band will happen in a different place.

And if you merge them, it doesn't seem too far-fetched to hypothesise that you'll get both bands, and there are definitely two.

I'm not seeing discrete banding, only continuous lightening from corners to middle.

Can you still not see it?

From the top right corner, it's dark blue, cyan, light blue, cyan, lighter blue still where it meets the horizon.

The bands are curved - like an arc of a rainbow centred above the scene - except not as many colours!

Come on folks, help me out here - surely I'm not the only one that can see it?

I see it in both the original and your clip as well.

Its definitetly there AJ Just above the ridge and another just above that

I'm not denying you can all see it, but i can't. whether it's my old eyes or my superior monitor ( ) i can't tell.

All I can see is gradual shading.

Wait a mo, I can see definite bands if I look at my monitor for really awkward angles. The colours go all funny but i can see the banding then.

I'll have to check out all my other images whilst looking at my screen from below my keyboard.

But I made 3 exposures. would they perhaps be more evident if more of the sky was visible?

Seeing it on my CRT too, so I don't think it has anything to do with viewing angles and TFTs.

Dan

so perhaps in camera hdr is not so useful for landscapes.

is there a technique for using this?

I started off about 4 stops underexposed, then 1 stop under then 1 stop over the in camera meter. opting to let the camera take care of the exposure.

but thinking about it, this was fully manual, i chose the apperture and shutter speed. What 'exposure' is the camera automating?

I can't see that it would be automating anything, other than combining the exposures.

Anyway, call me thick, but I can't see how making three exposures in camera is in anyway 'HDR'. I know it wasn't you aj that first mentioned it here, so I'm not digging at you.

Surely you are just exposing the frame for the sum of the three exposures? Exactly the same as if two 1/2s exposures are the same as one 1s exposure?

Let's use aj's example of three exposures, and let's say (using the 4 stops under, 1 stop under and 1 stop over example), that if the metered exposure was 1 second, we would have three seperate exposures at 1/15s, 1/2s and 2s. These would be combined in camera, but would give a cumulative exposure of 2.56s, which would be overexposed. So perhaps you work out the exposures and then divide them all by three. Which would give a total exposure of 0.85s. Which would be slightly darker than the metered 1s. :

How is this supposed to give an 'HDR' result?

Dan

The menu setting for multiple exposures has an option for 'Auto EV Adjust'.
The manual says something like: 'when set to ON exposure is adjusted automatically according to number of shots'.

I can't see that this setting does anything when in manual mode. I've not tried multi exposures in any othe mode but manual. In fact it's only manual I ever use!

I'm calling it 'HDR' because I assumed I could capture greater tonal range, more detail in shadows and highlights, than I could with one exposure. This seems to be the case or this picture anyway.

I think that if the camera were clever enough to apply actual HDR algorithms to the set of exposures, so that shadows were given more, and highlights given less, they would be claiming so in the documentation, since it would be something of a selling point.

Although you may be seeing more shadow detail because of the fact that it's superimposed several shots, it clearly hasn't ignored the burned out highlights in the over exposed shots.

So I don't think it's at all likely to be doing anything at all in the the direction of actual HDR processing.

And if it did, it would potentially ruin the 'ordinary' use for multi-exposures, which is where the individual frames are different, not the same.

I reckon that thinking of the in-camera multi-exposure merge as HDR is barking completely up the wrong tree, interesting thing to try though it was.