Eventually, someone will build a DSLR-like MILC camera

Started Feb 17, 2012 | Discussions thread
Sdaniella
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Re: exposure simulation live view?
In reply to 453C, Feb 19, 2012

453C wrote:

At least with my E-PL1 in M mode, the camera leaves the aperture wide open prior to exposure, regardless of the selected f-stop. Even though the actual aperture diaphragm doesn't move, if I adjust the shutter speed and f-stop, the display reflects the resulting changes in light levels that are recorded during capture, but not the DOF (aperture remains open). If I wanted to see what effect the f-stop will have on DOF, I can also press the DOF Preview button, but the light level displayed isn't accurate to what will be seen in capture (the Exposure Comp display flashes a warning, though).

in the E-PL1 case as you describe, it is a 'part-way' sim handling only for shutter speed, (does it handle ISO adjustments or not?), and given aperture is not stopped down, any aperture setting adjustment lacks the 'sim'; this is proven by stopping down your aperture, which the 'autogain' is temporarily suspended, and thus the preview appears darker... no, this means you LACK ES-LV for aperture, but at least for speed you do (assuming changes to speed alters the preview at all)

Does this sound like ES-LV, or some form of it? Ideally, while in A or M modes, I'd prefer the aperture be directly tied to the f-stop control, but I believe the camera leaves the aperture as open as possible to enhance CD-AF accuracy and speed.

yes, apertures are left wide open specifically so CD-AF can be more effective, thus why you do not stop down aperture for CD-AF or it will suffer from lack of light.

full ES-LV on integrated digicams (PowerShot G series) differ significantly from full ExpSim LV (on EOS Canon dSLRs), in that being an integrate lens, the apertures always are stopped down to the aperture selected, thus, the 'sim' need only handle speed + ISO. combine all three, speed, ISO, and full time stopped down aperture, with ES-LV you get 'full time' ES-LV.

downside to ES-LV is that, for CD-AF to work, the system actually suspends aperture stop down momentarily specifically for widest open aperture for a quick CD-AF check (as well as showing an 'autogain neutral' view for framing (if the look is different from desired speed/ISO/aperture choice))... what you see, then, will duplicate in the image you get after you shoot... so what you see in the PREVIEW is IDENTICAL to what you get when you shoot.

on the other hand... ExpSim LV of Canon EOS LV dSLR systems are a bit more sophisticated... one actually has the usual 'sim' of speed AND ISO, PLUS APERTURE for LIGHT... when aperture is set, the system actually suspends 'stop-down' for the 'sim' purposes... AND as an option, if you CHOOSE to stop-down the aperture for DOF preview... the SIM jumps over and matches the unstopped-down PREVIEW!!! there are slight differences but it's a fraction of less than 1/6 EV... more likely 1/12 EV difference. and much will depend on the lens, zoom setting and maximum aperture available (remember, contrast goes up with wider apertures, and down with narrower apertures; so this could account for slight differences in 'sim' non-stopped down vs stopped down aperture when comparing non-DOF preview to DOF preview)

the above is ideal for M mode

but you could optionally:

see DOF preview live 'sim' exposure, in P, Tv, and Av:

and watch with the DOF button pressed down (depends on EOS dSLR) all other preview effects should follow:

adjust speed in M mode: the DOF should remain fixed (aperture held constant)

ISO is Manually chosen and held: the image preview gets darker if speed gets shorter; brighter if speed gets longer

ISO is Auto: the ISO goes up if speed gets shorter, down if speed gets longer (the preview looks 'neutral'; compensation not relevant)

adjust aperture in M mode: the DOF should shift according to aperture chosen (speed held constant)

ISO is Manually chosen and held: the image preview gets darker if aperture gets narrower; brighter if aperture gets wider

ISO is Auto: the ISO goes up if aperture gets narrower, down if aperture gets wider (the preview looks held 'neutral'; compensation not relevant)

adjust speed in Tv mode: the preview is held 'neutral'; and changes brighter or darker when compensation is used; longer speeds, aperture narrows, and DOF goes up; shorter speeds, aperture widens, and DOF goes shallower

adjust aperture in Av mode: the preview is held 'neutral'; and changes brighter or darker when compensation is used; wider apertures DOF goes shallow, while speeds go shorter, narrower apertures DOF goes deeper

adjust speed in P mode: aperture balances off speed to maintain a 'neutral' std exposure, and any aperture changes show DOF changes... and can optionally be previewed (w/o the preview getting darker; if it does get darker... ExpSim LV is actual in 'framing mode LV' only), all compensation really does is alter along the aperture-speed pairing so one either goes above or below std exposure of 0EV

adjust aperture in P mode: aperture adjusts DOF... and can optionally be previewed (w/o the preview getting darker; if it does get darker... ExpSim LV is actuall in 'framing mode LV' only); speed balances off aperture to maintain a 'neutral' std exposure; all compensation really does is alter along the aperture-speed pairing so one either goes above or below std exposure of 0EV

you really have to 'see it'... to 'get it'... i may not have all the variations down exactly because if one uses Auto ISO, it 'suspends' the sim altogether even if one uses 'compensation' in AE modes.

and if one turns on flash to do flash intensity selection, the 'sim' is also temporarily suspended (but does not affect intended outcome for the non-flash portion of the exposure assessment).

if you've never seen it 'fulltime live' including 'adjustment change preview' in real time... you haven't yet experienced ES-LV the way it was meant to be seen (menuless!!!)

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