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EOS M3 porting

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Re: EOS M3 porting
« Reply #580 on: 19 / July / 2019, 15:08:49 »
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« Last Edit: 19 / July / 2019, 17:09:14 by pigeonhill »

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Offline Ant

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Re: EOS M3 porting
« Reply #581 on: 19 / July / 2019, 17:48:36 »
Preceding calls (to fc43cd96 and fc2f2c0e in firmware 101a) appear to get the data those values are derived from.

fc43cd96 - AllocateEflensComBuffer
fc2f2c0e - EFLens.Send
fc43cdf4 - ReleaseEflensComBuffer

So these values are obtained directly from the lens and are not stored anywhere.

If someone want to get all distance info values using LUA there need to add new lua script command.

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Offline reyalp

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Re: EOS M3 porting
« Reply #582 on: 19 / July / 2019, 23:04:51 »
So these values are obtained directly from the lens and are not stored anywhere.

If someone want to get all distance info values using LUA there need to add new lua script command.
Or make the underlying shooting.c functions get_dofinfo / get_focus do something different under the hood for EOS cams.
Don't forget what the H stands for.

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Offline Ant

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Re: EOS M3 porting
« Reply #583 on: 20 / July / 2019, 04:48:08 »
Or make the underlying shooting.c functions get_dofinfo / get_focus do something different under the hood for EOS cams.
AFAIK these functions return only one value, but consumers want at least two values. How to do that?
« Last Edit: 20 / July / 2019, 04:52:25 by Ant »


Re: EOS M3 porting
« Reply #584 on: 20 / July / 2019, 05:47:05 »
@Ant

One thing we need to be cognisant of is that whatever focus distance we get access to, in mm or cm or upper or lower or something else, this distance is referenced to the sensor plane.

However, most who try and use the focus distance info want the distance from the front principal plane, which we don’t know.

The DoF equations that we tend to use make use of the simple lens equation and can be off by a lot, for DoF calculations in the near field.

One can make use of a split lens model, but it’s most probably not needed for non macro work, ie see my post here http://photography.grayheron.net/2019/05/splitting-things-apart.html

I’ve convinced myself, for my use case, ie landscape focus bracketing, accessing upper in cm will likely give me everything I need. This even more the case if you sensibly build in focus bracket overlaps.

Bottom line: yes it would be great to get ‘true’ focus distance info, but for most sensible use cases I think having access to upper and lower cm distances, via peeking, will likely be sufficient IMHO
« Last Edit: 20 / July / 2019, 06:05:58 by pigeonhill »

Re: EOS M3 porting
« Reply #585 on: 20 / July / 2019, 11:09:58 »
AFAIK these functions return only one value, but consumers want at least two values. How to do that?
But at least dof=get_dofinfo() could deliver dof.near and dof.far. So, the peeking in the lua code is not necessary.

M100 100a, M3 101a, 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

Re: EOS M3 porting
« Reply #586 on: 20 / July / 2019, 11:10:38 »
AFAIK these functions return only one value, but consumers want at least two values. How to do that?
But at least dof=get_dofinfo() could deliver dof.near and dof.far. So, the peeking in the lua code is not necessary.
M100 100a, M3 101a, 2*G1x (101a,100e), S110 (103a), SX50 (100c), SX230 (101a), S45,
Flickr https://www.flickr.com/photos/136329431@N06/albums
YouTube https://www.youtube.com/channel/UCrTH0tHy9OYTVDzWIvXEMlw/videos?shelf_id=0&view=0&sort=dd

Re: EOS M3 porting
« Reply #587 on: 20 / July / 2019, 11:18:49 »
Although CHDK provides near and far DoF info, I personally prefer to calculate these myself, ie in Lua using my formulation, and, of course, accounting for diffraction.

I can then handle vis or IR cameras.

Thus, ‘all’ I need is focus position ;-)


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Offline Ant

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Re: EOS M3 porting
« Reply #588 on: 20 / July / 2019, 12:01:58 »
Although CHDK provides near and far DoF info
These values are calculated by CHDK based on _GetFocusLensSubjectDistanceFromLens
But EOS lenses report two distances. It's not a problem to provide only one(near) subject distance.
But there need to modify the core/shooting.c file to return the values from the lens instead of the values calculated by CHDK.

Quote
Thus, ‘all’ I need is focus position ;-)
Getting an absolute position of focus is not possible for EF lenses.
« Last Edit: 20 / July / 2019, 12:09:56 by Ant »

Re: EOS M3 porting
« Reply #589 on: 20 / July / 2019, 12:12:13 »
@Ant

Yes I know.

As I said before, a close enough value is good enough most of time, at least for me ;-)

 

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