Double Exposure as HDR Technique?

[tevo]

I thought about it this morning, and wasn't sure if it would work or how to do it. Is it possible to expose the same frame twice so you can achieve higher dynamic range like an HDR? (i.e. to properly expose the sky and land)

Clarification: I am talking about doing this on a film SLR (or a digital that has a multiple exposure function)

 

[480sparky39 38]

If both images are the same exposure, you won't gain anything. Something must change... usually shutter speed... in order to obtain more DR.

 

[amolitor]

That's kind of what a graduated neutral density filter does, isn't it? You need SOME kind of masking for this to make sense, I think. There might be cases where making one exposure with a GND and a second one without might be just the ticket, though.

 

[Light Guru]

I thought about it this morning, and wasn't sure if it would work or how to do it. Is it possible to expose the same image twice so you can achieve higher dynamic range like an HDR? (i.e. to properly expose the sky and land)

I have never seen a digital camera that can do a double exposure in the camera like you can on film. You would have to do the double exposure on the computer and at that point you might as well do exposure blending, which in my opinion gives you a more natural image then HDR does.

If you want to do it in camera use a ND Grad filter.

 

[Onerider]

A 5dm3 will multiple expose if I'm not mistaken.

 

[Light Guru]

A 5dm3 will multiple expose if I'm not mistaken.

I did some looking and you are right it does. However after watching this video I dont think it would be a vary good option as you just dont have a the control one would want.

 

[480sparky39 38]

I have never seen a digital camera that can do a double exposure in the camera like you can on film. ...... ...........

Both my D7000 and D600 can. Retouch Menu > Image Overlay. I'm sure higher-class Nikons can do it as well.

 

[tevo]

I was talking about film, I forgot to add that. My F3 has a double exposure lever and I was wondering if it could be used to achieve higher dynamic range.

 

[Compaq]

Although double exposure should work if you can block out parts of the frame for each shot, you might see a line of sorts where you divide the frame.

 

[duhast]

With my old Argus C3, double exposures were essentially the norm...

 

[cynicaster]

I’m not a film guy at all, but I think the principle here is universal, regardless of recording medium.

As you know, a common way of doing an HDR shot involves setting your camera on a fixed scene and taking a range of different exposures to capture the full dynamic range of the scene for selective “synthesis” in post processing. Aside from shutter speed, not much changes from shot to shot.

If I’m understanding your question, it sounds like you are wondering if this same basic approach can be shoe-horned into a multi-exposure function on a film camera.

The problem is that the film is going to record the cumulative “high water mark” of light for each location in the frame, so even if you manage to capture the low end of the dynamic range in exposure #1 (for example), those shadows will be “overwritten” as soon as you take a brighter exposure, unless you somehow block light from hitting those areas. If you do the brighter exposure first, the shadows won’t record at all.

 

[480sparky39 38]

OK, so I just tried this idea.

And it doesn't work.

Two frames, one slightly underexposed, the other slightly overexposed. Combined in-camera results in a REALLY over exposed image.

In the slight OE original, just a bit of the whites are blown out. In the combined image, there's a TON of blown-out highlights.

 

[tevo]

OK, so I just tried this idea.

And it doesn't work.

Two frames, one slightly underexposed, the other slightly overexposed. Combined in-camera results in a REALLY over exposed image.

In the slight OE original, just a bit of the whites are blown out. In the combined image, there's a TON of blown-out highlights.

Keep in mind that in order to have a proper double exposure you need to use a -2 EV compensation, since the two exposures have to add up to the proper exposure. I missed sunset due to work but I'm going to try this out tomorrow.

 

[Josh66]

I don't see it working without masking part of the frame off, like others have said.

If you're going for HDR, the standard -2EV for a double exposure wouldn't apply, since that would result in the same range as a single exposure would have.

So, if you going to make one exposure for the shadows, and another for the highlights - you would have to mask the shadows when you make the highlight exposure, or the other way around - depending on which you expose for first.

 

[tevo]

I don't see it working without masking part of the frame off, like others have said.

If you're going for HDR, the standard -2EV for a double exposure wouldn't apply, since that would result in the same range as a single exposure would have.

So, if you going to make one exposure for the shadows, and another for the highlights - you would have to mask the shadows when you make the highlight exposure, or the other way around - depending on which you expose for first.

I was just responding to the overly overexposed result sparky got, I realize you would need to change the range of exposure.