ND Filter Auto Exposure vs Polarizer AE

Started 3 months ago | Questions thread
Garthom Regular Member • Posts: 227
Re: ND Filter Auto Exposure vs Polarizer AE
1

mfinley wrote:

Miike Dougherty wrote:

mfinley wrote:

Miike Dougherty wrote:

At this point, if I'm going to use the 6 stop ND, I'll just take a reference photo in auto aperture, change to manual, and use my newly acquired NiSi app to calculate the new shutter speed. It seems to work properly.

Sorry but this isn't making any sense to me. How is the Nisi app doing anything more than simply adjusting exposure based on the difference in F stop light blocking of the filter?

Isn't the app just saying if you meter 2.8 @ 1/500 without a filter, and you tell the app you're using a 3ND filter then the app is just telling you to adjust the exposure 3 stops to 2.8 @ 1/60? If you're telling it you're using a 6ND it's just going to say 2.8 @ 1/8?

Is there more going on? Are you placing the filter over the phone and it's reading light transmitted through it? This isn't film so there is no reciprocity to be calculated.

If the Nisi app is just doing simple math and the exposures are coming out correct with the App but not for you doing it without the app, then this whole issue isn't about an inconsistent camera meter as you said, because how could the app know? Please give us a little bit more information here.

It's just doing the math. I believe there are more comprehensive apps but I'm trying to keep thinks simple. I was trying to get away from any kind of manual process. That's all. It looks like auto exposure with exposure compensation is hit or miss. I'll also pay more attention to the Histogram in the view finer.

Okay, there seems to be a disconnection somewhere in your knowledge in how to use your camera. You said you're shooting in aperture mode so you know the differences, you said you can judge a correctly exposed image in the EVF, you said you're using a 6X ND so you know that it is a 6 stop filter, you understand stops...

But you seem to mix up what manual is. Manual is only one thing - it's setting your camera to manual mode, manual isn't adding exposure compensation, that's adding exposure compensation while you are in aperture priority mode. All you are doing is adjusting the shutter speed when you do that.

You said "I'll just take a reference photo in auto aperture, change to manual, and use my newly acquired NiSi app to calculate the new shutter speed. It seems to work properly."

The red flag is, It can't work properly if the camera meter is the issue here.

There is no difference of you taking a reference photo without the filter in place and using an app to tell you the correct exposure, the app is just telling you with a 6X filter you need to adjust 6 stops and spitting out the adjustment. If doing that gives you a correct exposure, that is no different than you - taking a taking a reference photo without the filter in place(actually just looking at the aperture & shutter speed numbers) and simply adding 6 stops of over exposure by adjusting the shutter speed.

If the correct reference exposure is F5.6 @ 1/2000 and the app tells you to adjust to f5.6 @ 1/30 and it works, that's the same as you simply understanding that with your 6X filter you need to adjust your shutter speed 6 stops which is again the same thing - from 1/2000 it would be 1/30.

So from everything you have said so far the problem can't be the camera, its got to be either 1) you don't know shutter speeds and how to calculate 6 stops of compensation, or you 2) you're confused on operation of your camera or a combination of two and 3) which is you aren't shooting in Aperture priority mode when you're having this problem and in the process of trying to adjust exposure compensation you aren't doing it correctly.

Because you can't get around that if you can use the app and do it all in Manual Mode and get the right exposure, then that proves the camera is working & can be adjusted properly to yield a proper exposure, but you're trying to do something that isn't correct when you're doing the same thing not in Manual mode. If the app just tells you a 6 stop adjustment because you have a 6 stop ND filter then it's no different then you just dialing in 6 stops of over compensation every time you use it, the issue has to be how you are making the adjustment.

mfinley wrote:

If the camera meters correctly without a filter, doing the calculation (or using an app) will work, which is what the OP describes. The whole point is that he doesn't want to have to do this, as the camera should be able to adjust this automatically based on the amount of light coming through the filter.

So for example, you set up without a filter, pick an aperture, and the camera chooses a certain shutter speed for 0 EV. You take a photo, and it's properly exposed. Now, you put on the filter and obviously it gives a different shutter speed for 0 EV. When he takes the photo at those settings, the resulting image isn't properly exposed, it's -2 or -3 EV. That is an issue of the camera not metering correctly.

I agree that the easiest solution would be to shoot pairs of test shots, where one shot is taken with the shutter speed based on the calculation, and the other shot is taken with whatever shutter speed the camera gives you for 0 EV. My guess is that it's going to be off by roughly the same amount each time, at which point you know to dial in that much EC when using the filter.

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