[DONE] Aperture bracketing

[trase]

I would find aperture bracketing extremely useful.
I often shoot two consecutive pictures in Av mode, one with f1.8 and the next with f5.6. I later combine them, putting the sharp part of the f5.6 picture on the f1.8 one.
That way you can get images with optimum sharpness and yet with a nice soft background.
(The two pictures are of course both correctly exposed, unlike HDR bracketing)

The problem with doing it manually - that is changing the aperture using the scroll wheel, is of course both that it takes time between the shots and also that you inevitable move the camera a bit, making it more difficult to align the pictures.

[discocalculi]

Sounds like an interesting feature.

I did a couple of image stacking tests using mirror lenses in order to get sharp tele pictures and have also tried a couple of shots with changing aperture on some manual lenses with some pretty interesting result.

What image software do you stack the images with?

[a1ex]

You can try it here: https://bitbucket.org/hudson/magic-lantern/changeset/d64144418367

[trase]

discocalculi: I usually just stack them manually in photoshop.
I align the sharp image as a layer on top of the one with the short DOF, and then using layer mask I paint out the sharp areas.

a1ex: wow, that was fast! I'm impressed, and appreciate your quick reply.
however - I'm afraid I haven't got a clue how to compile from source. I think I'm gonna have to wait and hope that it ends up in the next release - that would be so great.

[discocalculi]

That was really fast, Alex!

Already tried tweaking some with the new exposure tricks and it seems promising. Aperture and exposure bracketing in combination with focus it would be a killer...

Trase: That's how I tried some stacking as well, but also tried it with Helicon Focus. Then there's Zerene stacker, which might come in handy.

[engardeknave]

I often shoot two consecutive pictures in Av mode, one with f1.8 and the next with f5.6. I later combine them, putting the sharp part of the f5.6 picture on the f1.8 one.
That way you can get images with optimum sharpness and yet with a nice soft background.

I don't know how to compile from source either, but this sounds awesome. Can't wait to try it.

[discocalculi]

I experimented some this morning just to get a hang of the bracketing. There are of course endless possibilities but I'm wondering if the aperture should affect the exposure in similar way as the shutter does?

I used Helicon Focus to stack a bunch of images ranging from f/1.4 to f/22. The result is painterly, but dull.

50mm f/1.4 http://imageshack.us/a/img138/4493/img9815acr.jpg
50mm f/22.0 http://imageshack.us/a/img89/9545/img9822acr.jpg

Helicon Focus (depth map)http://imageshack.us/a/img811/4339/focusresult2b88.jpg
Helicon Focus (weighted average) http://imageshack.us/a/img546/9328/focusresulta88.jpg

[a1ex]

From what I understand from here, exposure should be maintained.
http://en.wikipedia.org/wiki/Bracketing#Depth-of-field_bracketing

To change the exposure using aperture, simply run bracketing in Tv mode.

[discocalculi]

Thanks for that article.

But I'm wondering if there's a possibility to see what happens if the aperture changes the exposure values as a extra feature and/or combined with shutter/iso?

Here's two manual examples with aperture and Shutter combined.

In the first example I went from a bright scene with a wide aperture, closing down the aperture and compensating somewhat with a slower shutter not to underexpose too quickly, gradually changing it into a dark scene. Merged in Photomatix.
http://imageshack.us/a/img9/7109/img9942and9moretonemapp.jpg

The other example i went from a pretty dark scene, with a wide aperture and fast shutter, slowly narrowing down the aperture and compensating with a slower shutter to gradually change it into a bright scene. Merged in Photomatix.
http://imageshack.us/a/img600/9576/img9931and10moretonemap.jpg
 
And for reference normal DOF bracketing merged in Helicon Focus:
http://imageshack.us/a/img834/1378/focusresult3a88.jpg

Exposure (Tv) bracketing with shutter and iso changes, aperture stuck at f/1.4. Merged in Photomatix:
http://imageshack.us/a/img100/6192/img9922345678tonemapped.jpg

At f/1.4
http://imageshack.us/a/img834/3776/img9904acr.jpg
At f/22
http://imageshack.us/a/img685/7884/img9912acr.jpg

[Edit]
Another example, this one running from bright with a narrow aperture, slowly opening up the aperture and also also adjusting shutter speeds not to overexpose but rather to darken the image:
http://imageshack.us/a/img713/2672/img9969and8moretonemapp.jpg


Also notice how fake photomatix images tend to look.

[a1ex]

Got it, but it's a bit hard to do without complicating the menu (would require a setting for aperture step and another for exposure step). And if you don't overexpose, should be easy to do in post.

[discocalculi]

I fully agree. It would make things difficult and the problem with manual lenses is still there. As of now HDR bracketing still works with manual lenses without having to change the aperture (shutter and iso only). Adding DOF to HDR bracketing complicates things, but it sure looks pretty interesting... Combined with White balance bracketing and focus stacking, one would get a very powerful bracketing tool.

[a1ex]

I don't see the point for WB bracketing - just shoot raw.

Focus bracketing can already be combined with expo/DOF bracketing.

[discocalculi]

Ah. That's excellent! Havn't run Bracketing and Focus stacking at the same time.

From what I've learned faulty white balance can be tricky at times to save in post processing. Especially pink/purple flowers tend to overexpose quickly in post production for some weird reason. Might be that Adobe Camera Raw dont handle it too well or due the general curves are not symmetrical. I'm not sure if one would benefit from multiple exposures in such a case.

[a1ex]

That's probably one of the channels being clipped. You can use RGB histogram (which may force you to underexpose by 1 stop), or UniWB.

[trase]

yes, exposure should be maintained.
here's an example (view at 100%):


as you can see - at f1.8 the background blur is nice, but even the subject isn't very sharp.
at f5.6 sharpness is good, but background is very busy.
combined, you get the best of both worlds.

discocalculi: nice too see your experimentation. helicon focus and zerene stacker is something I might look into. however, for this purpose (stacking only two images), I find doing it manually works well and gives complete control of the result.

[ilguercio]

Nice stuff, never thought about this.

[Digital Guy]

Interested? Hell yea.. where do I click?

[engardeknave]

Ok, I sent my bribe (eatyummypuppies at gmail). Can I get a compiled version?

[a1ex]

We'll try to implement nightly builds (just be aware that they might be completely untested, unlike stable releases where I usually spend weeks trying every single feature).

[nanomad]

I'm working on that right now

[bart]

I find doing it manually works well and gives complete control of the result.

And how do you do this manually? As sharper details like to moss tops take less space then blurred details. What do you do with the edges. Does this involve some serious photoshop editing and precise skills on how things still  look natural?

[a1ex]

I'm working on that right now

Nanomad did a great job, so you should be able to try this here:

http://nanomad.magiclantern.fm/nightly/

disclaimer: I was too lazy to try it

[engardeknave]

And how do you do this manually? As sharper details like to moss tops take less space then blurred details. What do you do with the edges. Does this involve some serious photoshop editing and precise skills on how things still  look natural?

No, it looks pretty easy. Just put the photos on top of each other as layers and mask the areas you don't want to see from the top one (or simply erase). Use a brush with no hardness to blend at the edges.

[trase]

This is great - I'm very impressed and thankful that you implemented this feature so quickly.
I have tried it out now and it works very well.
Thanks a1ex, good job!
Thanks also to nanomad for the nightly.

Now, this may seem like nitpicking but it might be preferable in this case if you could choose the sequence " - 0 " . For example, when shooting a portrait it would be better if the shot with the shortest shutter time would be taken first, to minimize the risk of the model moving between the shots. A minor detail for sure, but worth considering.

engardeknave: That's right, however:

b4rt: That's a correct observation. You have to use your artistic sense. - sometimes it's better to leave the edges from the blurry image to have a smooth transition, and sometimes it works very well to mask a few pixels outside of the edge. In that case, you will get a part of the sharp image where it 'shouldn't be', but oftentimes that is not visible.
I find it quite easy to get good results quickly.
The merging is of course easiest with pictures such as portraits where you have a single sharp object against a blurred background.

[a1ex]

First shot has to be 0 - that's a limitation. You take the first shot (with Canon settings), ML figures out that you took a picture and continues from there.

But you can select 0++.