Author Topic: Force fixed aperture for non chipped lenses (Read 17597 times)

leandroprz · « **on:** November 10, 2013, 05:00:38 AM »

Hi developers,

I recently bought a Samyang 14mm and it's a full manual lens. I'm okay with that, but there's one thing that bothers me and it's related to the camera not being able to read the aperture of the lens because it doesn't have a chip.

Being used to chipped lenses, I never experienced this, but now I noticed that both my 60D and 6D don't show the correct brightness when on live view mode. Even worst, the exposure readings I get are way off. Often I get underexposed images so it's a must to check the histogram (something I always do anyway). But the downside of all this is that it's almost impossible to use a semi-manual setting, like say aperture priority.

Now, what I'm thinking is: is it possible to cheat the aperture and force a fixed one in the camera? I think if the camera reads for example f/2.8 it will show a correct exposure reading. But maybe I'm wrong.

What do you think, is this possible?

a1ex · « **Reply #1 on:** November 10, 2013, 09:53:09 AM »

Enable exposure override.

leandroprz · « **Reply #2 on:** November 10, 2013, 07:49:47 PM »

Quote from: a1ex on November 10, 2013, 09:53:09 AM

Enable exposure override.

I tried that on my 60D with ML 2.3 but there wasn't any difference. Will try again on the 6D with the latest nightly build.

leandroprz · « **Reply #3 on:** March 05, 2014, 04:13:31 PM »

I forgot about this until a few nights ago when I tried the exposure override feature on my 60D with the new nightly. It worked perfectly!

Now, the problem I have is with a 6D. That feature is not working on that camera.

Is anyone else experiencing this?

a1ex · « **Reply #4 on:** March 05, 2014, 04:17:44 PM »

Remember that 6D is blindly maintained (we don't have it). So... http://www.chiark.greenend.org.uk/~sgtatham/bugs.html

leandroprz · « **Reply #5 on:** March 05, 2014, 05:16:59 PM »

I thought since it came back to the nighly builds there was a developer with the camera behind it.

Will test it again tonight under low light conditions and report back in bitbucket.

a1ex · « **Reply #6 on:** March 05, 2014, 05:21:45 PM »

Nope, this is mentioned in both the 6D dev thread and the announcement.

Morghus · « **Reply #7 on:** March 05, 2014, 08:03:43 PM »

This is another thing I could try my hands on since I have a 6D. Expo override doesn't let me change ISO anymore after enabling it but it displays the correct exposure in LV. Is it the same for you leandroprz?

1% · « **Reply #8 on:** March 05, 2014, 08:05:25 PM »

Quote

Now, the problem I have is with a 6D. That feature is not working on that camera.

Whoa whoa... this feature is for live view. So silent pics, raw, etc... I've never seen it keep the settings in photo mode. It appears to do the same thing on other cams I tried as it does on 6D... so how exactly isn't working?

Quote

Expo override doesn't let me change ISO anymore after enabling it but it displays the correct exposure in LV

The iso adjustment dialog is different... it lets you change ISO from the ML menu however. So maybe you found a bug... I speculate that its from there being a lack of "iso_adjustment_active". What does it do on 5DIII?

Maybe the fix would be looking what dialog handler if any exists for the iso menu.

a1ex · « **Reply #9 on:** March 05, 2014, 08:16:03 PM »

In M mode (or movie) it should basically work in the same way as with plain Canon firmware.

Differences:
- in photo M it fixes Canon's underexposure bug
- in movie it lets you dial finer exposure increments from menu or shortcuts

So, if you change ISO from Canon controls, it should listen to it and change it too. If shutter and aperture are working, probably ISO_ADJUSTMENT_ACTIVE is not true while you are changing ISO (should be).

Morghus · « **Reply #10 on:** March 05, 2014, 08:17:03 PM »

Quote from: 1% on March 05, 2014, 08:05:25 PM

The iso adjustment dialog is different... it lets you change ISO from the ML menu however. So maybe you found a bug... I speculate that its from there being a lack of "iso_adjustment_active". What does it do on 5DIII?

Maybe the fix would be looking what dialog handler if any exists for the iso menu.

That's right, from the ML menu it works. I also have a shortcut for holding SET and turning the small wheel on top to change ISO, which doesn't work either... might be a little more complicated to listen for that.

a1ex · « **Reply #11 on:** March 05, 2014, 08:21:47 PM »

Looking at that code, I think I found a bug that may affect 50D and 1100D (that is, cameras without manual movie controls). Try this one on 50D.

The effect is that it should not listen to Canon's auto-exposure algorithm (what you set in ML menu/shortcuts should be what you get). On 500D, without that, expo override syncs with Canon's auto-exposure.

ISO_ADJUSTMENT_ACTIVE also affects exposure lock. Does that one work?

1% · « **Reply #12 on:** March 05, 2014, 09:27:35 PM »

50D and others you can change the ISO from the canon dialog and the adjustment active memory location is altered... on 6D the same location from the same function doesn't change. When I was originally testing it I don't think it changed the dialog handler either. So ML never knows when you are changing the ISO from canon

Andy600 · « **Reply #13 on:** March 05, 2014, 09:30:29 PM »

Just tried this on the 50D.

With Exp Override on you can't now change ISO with Canon controls. Previously you could. ISO and shutter readouts were the same in LV as in the ML menu (after Albert's fix). Not sure what I'm looking for here

a1ex · « **Reply #14 on:** March 05, 2014, 09:33:13 PM »

So, before this change, you could go from extreme bright to extreme dark and back without Canon changing the exposure settings?

1% · « **Reply #15 on:** March 05, 2014, 09:46:33 PM »

without expo override canon always changed the ISO to make fake shutter/aperture adjustements. it was required to have it on. did not seem to have a problem

Andy600 · « **Reply #16 on:** March 05, 2014, 09:47:57 PM »

Previously Canon ISO would work up to 3200 and shutter worked up to 1/150 with Exp Override ON (with FPS override at 25fps)

It's the same with the bug fix only now you can't use Canon ISO on the top wheel, which is how I usually change ISO. I know you can use FUNC + Joystick but I find the ISO button+wheel faster.

a1ex · « **Reply #17 on:** March 05, 2014, 09:50:49 PM »

That means, when doing auto adjustments, 50D does not trigger PROP_ISO, PROP_SHUTTER, PROP_APERTURE or PROP_APERTURE2?

Try putting some printf's in these 4 properties and let me know how it behaves.

Also try this one on 50D: https://bitbucket.org/hudson/magic-lantern/commits/8c2d1a82ee6e

Andy600 · « **Reply #18 on:** March 05, 2014, 10:00:08 PM »

1% can you? I'm not sure how

a1ex · « **Reply #19 on:** March 05, 2014, 10:06:38 PM »

Code: [Select]

PROP_HANDLER(PROP_ISO)
{
    static int k;
    bmp_printf(FONT_MED, 50, 50, "%d: %x ", k++, buf[0]);

   ... (whatever it did before)
}

=> you will see exactly when the property is triggered and with what value. I've added the counter to catch these cases where it may trigger the property without changing the value (just in case).

1% · « **Reply #20 on:** March 05, 2014, 10:09:36 PM »

Also can look at it with the prop browser after getting the numbers from property.h/c

Andy600 · « **Reply #21 on:** March 05, 2014, 10:12:30 PM »

Quote from: a1ex on March 05, 2014, 09:50:49 PM

Also try this one on 50D: https://bitbucket.org/hudson/magic-lantern/commits/8c2d1a82ee6e

This lets me use Canon ISO (button+wheel) again.

1% · « **Reply #22 on:** March 05, 2014, 10:23:30 PM »

The props do change and behave like in photo mode... but you can set bulb in movie mode and the expo sim will be affected but the other props will not... so the shutter prop will be 0xc and the display will be brighter but real shutter blanking is surely not "bulb" for live view

leandroprz · « **Reply #23 on:** March 05, 2014, 11:51:16 PM »

Quote from: 1% on March 05, 2014, 08:05:25 PM

Whoa whoa... this feature is for live view. So silent pics, raw, etc... I've never seen it keep the settings in photo mode. It appears to do the same thing on other cams I tried as it does on 6D... so how exactly isn't working?

I only tried on live view, not other modes.

This is what I do:

Put the camera in M mode. Let's say it's incredible dark, a moonless night with no light pollution so I set the shutter speed to 4s so I don't have to wait a lot of time, I just need to frame my shot. f/2.8 (which doesn't matter since the camera can't read that information because the lens is not chipped) and ISO 25600.

Instead of seeing at least some detail in the screen, I just get a dark image and no visible noise moving around.

On the 60D, which has max ISO 12800, I see much more detail (and noise, of course) than on the 6D. I also use the same settings here, 4s and f/2.8.

Quote from: Morghus on March 05, 2014, 08:03:43 PM

This is another thing I could try my hands on since I have a 6D. Expo override doesn't let me change ISO anymore after enabling it but it displays the correct exposure in LV. Is it the same for you leandroprz?

I am able to change the ISO after enabling exposure override. I tried from ML and Canon menu. Also with the top button near the LCD orange screen.

Edit: after doing a few more tests, it seems I got the features mixed up. What I described above seems to be exposure simulation, right? Now I feel like an idiot -.-
Still, that feature is not working for me.

Morghus · « **Reply #24 on:** March 05, 2014, 11:56:31 PM »

Quote from: a1ex on March 05, 2014, 09:50:49 PM

That means, when doing auto adjustments, 50D does not trigger PROP_ISO, PROP_SHUTTER, PROP_APERTURE or PROP_APERTURE2?

Try putting some printf's in these 4 properties and let me know how it behaves.

Also try this one on 50D: https://bitbucket.org/hudson/magic-lantern/commits/8c2d1a82ee6e

Tried this on the 6D, ISO still can't be changed by canon, only ML works

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Author Topic: Force fixed aperture for non chipped lenses (Read 17597 times)