Official shutter/iso tests

you can tell the exposure is the same by just looking at the the image on your camera, and i'm not talking specifically those tests. just try it. take your camera stop the lens down to the lowest speed, lock the AE, enter LV...now do the same with your lens at it's fastest. Same picture shutter/iso as your slowest speed. but make sure it's the same light source for both tests. Now if you're already in LV and you close your iris down, then your results will be significantly different.
 
that's what i mean, that's obvious since it sets it to what i thinks is correct. how do i verify that it hasn't changed the shutter speed and iso to accomplish this? i guess this is what you're trying to do in this test, but it's not really something you can "see" yourself without an oscilloscope and careful evaluation of noise levels.

what happens if you don't use the bright light, do you still get 1/60 and higher iso, or do both change, or neither?

/matt
 
yeah, okay, at least we are talking about the same thing. which test are you referring to? prior to enter LV or or locking AE while in LV?
 
either. seems like you get the same shutter speed with the "before lv + polarizer" as with the "+/- 0 f/4", the difference is just that the former is overexposed. what if you stop that down to the same exposure, don't you get very similar results? i'm still not sure what benefit there is with locking before live view. since i work with 50hz lights i can't really use that method unless i find a light source that gives me 1/50 every time so i'm curious what i'm missing.
 
you know there probably isn't any real benefit, except that once in LV you can see the results in real time.

I don't know what exactly you mean by if i didn't use a bright light? Are you saying what would happen if I were to expose to a wall or the whatever light is in the room instead of using the light? Only thing that would happen with the former, is that the light won't be constant and you can't expose to the same light source every time which would mean different iso/shutter for different shots. I think that's what you're asking.
 
but you get constant exposure if locking after entering live view too as long as the light is constant, right? no what i was asking is what happens with the shutter, when does the camera adjust the shutter speed and when the iso? as i gets darker and darker it probably opens the shutter to a point, then close it a bit and increase the iso, then repeats this pattern? at least that's what i think i see trying to remove the 50 hz lines.

/matt
 
but you get constant exposure if locking after entering live view too as long as the light is constant, right?

correct.

no what i was asking is what happens with the shutter, when does the camera adjust the shutter speed and when the iso?

still testing that. the iso is the trickiest thing to figure out about this camera. testing the shutter done, but testing the iso beyond me.

as i gets darker and darker it probably opens the shutter to a point, then close it a bit and increase the iso, then repeats this pattern?

yes. but you also have to factor in your +/- values affect the shutter speed/iso.
 
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the iso definitely changes while in live view, as well as the shutter. the +/- values seem to affect the shutter first rather than the iso but only to a degree, then it goes back and the iso changes instead.

/matt
 
Testing the Iso should be pretty easy. You have aperture, plus shutterspeed. Get a graychart. Light it. Frame it whole and let your camera auto expose to it. Get this image and see the waveforms, where is the gray (tip, probably 60% by my tests) Put it side by side with your oscilloscope. Measure the light hitting the gray with your meter, using an arbitrary iso and get an F-Stop. Bracket your camera on the lens and see the images on the waveform. Whenever you get the same exposure than auto on the gray (60%), check you aperture. The difference from what the meter told you will make you able to tell the difference your actual iso was from the iso you set in your meter.

Makes sense?
 
BTW, led closet lights flicker too, so we can set exposure and know if our shutter is correct (even though we can't tell exactly what it is...)

I'm digging car3o light trick.
 
Except they flicker at around 1khz. We need one that flickers at 50 or 60 hz. Not very difficult to build, i think i could get it close enough with a simple 555 driver...
 
mattsand said:
Except they flicker at around 1khz. We need one that flickers at 50 or 60 hz. Not very difficult to build, i think i could get it close enough with a simple 555 driver...
Click to expand...

I dn't really need to know the exact shutter, if I have one that feels good to my eye and I can replicate it, by just looking at the size and speed of the scan lines on my led light, I'm happy enough.

My main problem with shutter was not only the high speed, but the inconsistency. Constant, low shutter, is good enough for now... ;)
 
taubkin said:
I dn't really need to know the exact shutter, if I have one that feels good to my eye and I can replicate it, by just looking at the size and speed of the scan lines on my led light, I'm happy enough.
Click to expand...
for sure, but it's not only about the exact speed, it's just that if the frequency is high enough you won't get any lines at all at the slow shutter speeds we're aiming for. at 1000 hz and 1/60 each line will get exposed by 16 or 17 pulses, the difference is so small i doubt you'll see it and the higher the frequency the harder it gets. at 50 hz you'll see the lines all the time, except when you're dead on at 1/50.

/matt
 
Funny, using my leds I can see 6 or 7 different kinds of flicker, and there is only setting that the flicker is completely gone. That seems to be the best so far. But, certainly, a 50Hz led would be awesome, but until someone makes one, we'll have better cameras on the market...
 
that you run off the mains? that would explain it. it would be weird if somebody built an electronic pwm driver and decided to modulate it at 60hz rather than maybe 1000.

EDIT: looked it up. so it is battery powered after all. very interesting.

/matt
 
from the Osram DOT-IT light specs-

"Special DIM function offers three levels of light "

Is this even helpful to us? Or is it better to leave it at full power all the time? Also, how does it compare to the closet light Car3o uses? Better for finding shutter speed because of the LED flicker?

I have a project coming up later this week and am trying to find a workable solution by then.
 
continuous dimming with 50/60hz pwm would be ideal, then it's just a matter or dimming up and down until the flicker stops, then lock and shoot. a manual lens is probably a must though since you'll have to adjust the exposure to the scene, but that's the same with car3o's light.

/matt
 
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