Bulb utilities for ND and long exposure photography (bulb_nd)

[dmilligan]

Based on this discussion I've created a module to make calculating exposure for Neutral Density (ND) filters and long exposure photography easier.



This module will add a new setting to the Shoot menu. Here's how you use it:

• Set the ND filter strength in the menu.
• Meter however you like without the ND filter attached (ETTR or Tv/Av or just manual).
• Attach the filter
• Hold SET. Camera will switch to BULB mode and take a pic based on current expo settings and ND strength.

Source code: (already merged)

Obviously you will need an ND filter that is easy to attach and remove for this method to be effective. Or alternatively you can use an ND filter that is adjustable => adjust it to minimum to get expo settings, put max - min as the value in the menu, then adjust to max and hold SET.

You can also measure the actual strength of your ND filter (or filter stack). Select the 'Measure ND' option and follow the instructions.

(I'm also open to suggestions for a better name => 8 character limit)

[brapodam]

I just did a quick test and noticed some weird behaviour

1. 10 stops and 10.5 stops seem to be swapped. When I set exposure to 1/30s, 10 stops reports 47s exposure and 10.5 stops reports 31s exposure. Haven't tested the rest of the stops
2. The trigger does not turn off when you turn off the bulb timer; it only turns off when you turn the bulb->ND feature in the bulb timer sub-menu

[dmilligan]

1. fixed
2. expected behavior (this is kind of separate from the bulb timer, but I put it in the same menu, maybe thats a little confusing. But I have no way of determining if the bulb timer is enabled from a module).

[brapodam]

1. fixed
2. expected behavior (this is kind of separate from the bulb timer, but I put it in the same menu, maybe thats a little confusing. But I have no way of determining if the bulb timer is enabled from a module).

1. Thanks for fixing the incorrect half ev calculation
2. In that case, maybe it should have a separate menu entry?

[garry23]

@dmilligan

Just tried it out on my 5DIII with an ND1000 screw on filter.

Took me a few seconds to work things out.

First 'surprise' was that my ETTR wasn't working, then I realized there was a clash in switching on the ML functions, ie I use SET to trigger the ETTR. Moved this to a double press and all went fine.

I don't think you should put on any caveat regarding not using a screw on filter. If you are careful it works fine: you don't need to fully screw on, just enough to stop photons, which don't like going round thread corners :-o)

Looked at the two exposures and the overall exposure seems about right, within a stop and there is an expected shift in the WB, ie my filter is not one of the best quality ones, but acceptable.

I will play around with the few test shots to nail down my 'exact' ND effect, so I can use ETTR without and not move too far to the right when adding in my ND stacks, ie I  tend to use a 1000 and a 16.

Once again dmilligan, thanks for a nice ML add-on.

Cheers

Garry

PS I have posted about this on my blog, ie workflow, at: http://photography.grayheron.net/2014/08/another-great-magic-lantern-feature.html

[dmilligan]

okay, I updated it to have it's own menu, since putting it in the Bulb Timer menu is a little confusing. Also added an option to help you measure your ND filter(s).

[garry23]

David

Just tried your latests tweaks and they are great.

Calibrated my three NDs, ie 10Ev calibrate  at 9.5, 4Ev at 4.0 and 14Ev at 13.5.

Only minor thing I have noticed is that the ND time read out has a second symbol glitch. With three digit time it shows ", with two it shows "" and with one it shows """

As I say minor stuff.

Once again many thanks for the module.

Cheers

Garry

[dmilligan]

It's because it's not redrawing, just drawing over (you're just seeing part of the old value).

[garry23]

Ok. As I say, no issue for me.

Cheers

Garry

[garry23]

David

As I 'play' with it I can see an enhancement:-)

I see that the bulb time adjusts dynamically as you adjust exposure but not aperture.

To provide the user with final adjustments, would it be possible to dynamically link in the aperture.

At the moment the user can change the aperture but this will change the exposure.

Cheers

Garry

[dmilligan]

Try ML expo lock

[garry23]

 

[garry23]

David

Sorry to be a pain, but I haven't used your module for sometime.

How do you use the ND measure option?

I set the guess Ev and then what?

Cheers

Garry

[dmilligan]

It should tell you what to do on the screen.

This feature is really just if you have an ND filter that you have no idea what strength it is. If you know, then just input it, the measure isn't going to give you something more accurate.

[garry23]

David

I tried following the (limited) screen instructions and even looked at the code.

In the Menu I put a hint, say, 4Ev (for a 3Ev ND), and move the menu to "Measure ND" and press SET.

It says, "Take a picture without the ND...", which I do.

It takes an image and the above message stays on the screen.

The question is what to do next.

Cheers

Garry

[dmilligan]

Camera? Image review setting in Canon menu? If you know it's a 3 EV ND, why are you even bothering?

[garry23]

David

I simply wanted to try out the measurement feature: just curious ;-)

Damn!!!!!!!! I had forgotten I switched image review off!!!!!!!!

 

Cheers

Garry

[garry23]

@David

Hope you can help. I'm using the latest 5D3-123 nightly and 'added in' you Bulb_ND module, but there appears to me a problem, ie API mismatch.

I think your module is looking for an ML menu that isn't there anymore, ie Utilities.

Can you give me some advice please: I would like the Bulb_ND to run in the latest 123 nightly.

Cheers

Garry

[dmilligan]

You'll need to compile the module from the current branch. This module was merged into the mainline, but it's just not set to be automatically compiled and included with the nightly builds.

[garry23]

David

Thanks for the info. I'm afraid I'm still not up and running with compiling :-(

I guess I'll have to forgo the bulb_ND benifits until the module gets automatically included in the nightlies.

Once again, thanks for the info.

Cheers

Garry

[dfort]

@garry23 -- got to get you up and running with compiling when you get back from your trip.

In the meantime, don't leave home without it!

https://bitbucket.org/daniel_fort/magic-lantern/downloads/bulb_nd.mo.2017Jan01.5D3123.zip

This is just the module that you drop into the ml/modules directory.

[garry23]

Daniel

Thanks for the effort, but no good :-(

Still says old API and says expecting version 7.1.

Cheers

Garry

[dmilligan]

Still says old API and says expecting version 7.1.

That means you you are not running the latest nightly as you said.

[garry23]

Well I thought I was, but maybe mucking about and switching between 113, 123, Lua fix, I've just confused myself!

I dig about some more.

Cheers

Garry

[garry23]

David/Daniel

Damn :-(

It looks like I can't have my cake and eat it!!!

I need 123, for my x2 70-200 F/8 AF.

But I also need the Lua fix (not in the nighties).

I would like Bulb_ND, but this doesn't work in the Lua fix 123 I have.

Bottom line: I'll give up on the Bulb_ND, as all the other 'stuff' is essential to me.

Cheers

Garry