Linary Loc: UK

I do not have a mirrorless camera and nor do I know a lot about them.

If I look through a 10 stop filter it is almost opaque.
If I affix the filter to my DSLR camera, I see nothing or almost nothing through the optical viewfinder.
If I affix the filter to a MILC, I would see the image as clear as day through the EVF.

My question is:
I know the incoming light from the subject goes straight to the sensor and is then sent to the EVF (like a TV?) but as the exposure still has to be (say) 30 seconds to get a good image, how come the EVF can display the image immediately with an almost opaque piece of glass in the way?

I am guessing the signal sent from the sensor to the EVF (or Liveview) has a large amount of gain added and the image in the viewfinder is of a much lower quality than friends with MILCs imply, but if there is a better explanation I would very much like to hear it.

CHG_CANON Loc: the Windy City

What do you mean by "If I affix the filter to a MILC, I would see the image as clear as day through the EVF"? Is this a statement or clarifying question? You said you don't have a mirrorless camera, so why are you presenting this as a statement? Did you mean otherwise?

For the DSLR, what you see in the viewfinder is the "through the lens" view of the light and scene where the camera & lens are pointed. If you have the exposure set for maybe 20-seconds, the DSLR does not determine what the resulting image will look like after these 20 seconds. The DSLR simply shows you the current "live view" through the lens opening. The meter tells you the exposure based on the aperture, shutter and ISO, but that's the only assessment of the result of the exposure settings, after the fact.

However, the EVF can show you the resulting image. Or maybe to be more exact, a simulation of the resulting image as it doesn't show the elongation of a 20-second exposure and any movement of subjects that should occur within the frame while the image is being captured.

But, what do you mean when you reference the "gain added and the image in the viewfinder is of a much lower quality than friends with MILCs imply"? Yes, the EVF can be grainy with this simulated image. I just did the exact situation. Some the "grain" is the focus highlighting (red on my set-up) within the darker scene of my 6-stop ND again the wall lamp behind me. I don't know anyone claiming "image as clear as day", nor would I defend that likely inaccurate assessment.

But, the "issue" of what I see in the EVF (being 1000% better than the black DSLR viewfinder) does not impact my ability to frame the image, to focus the lens with the ND installed, nor to adjust the exposure, that is: the EVF overcomes the real problem with ND filters and DSLRs. Moreover, when the image is captured, that gain / grain to the viewfinder 'view' has no impact nor relation to the actual image captured.

burkphoto Loc: High Point, NC

Your assessment is accurate. The camera amplifies the signal for the EVF, but sends the appropriately processed signal to the file created during exposure. I use a 6-stop ND64 filter for video in daylight. The EVF image is perfectly clear and usable at all times.

Haydon

Robert Hall uses this technique on a Sony MILC with ND filters to battle the 1/8000 second barrier since he doesn't own a A9.

https://www.youtube.com/watch?v=LltjDbMjdX0

bsprague Loc: Lacey, WA, USA

I took a YouTube tutorial on long exposures. I wanted to know how to do the blurry waterfall thing. I went through all the steps, corrections and adjustments for a DSLR. Then I bought a 10 stop filter, screwed it to my camera and I discovered I didn't need to do all that crap.

With a mirrorless you can set a fixed ISO, put it on A, pick an aperture and the camera will figure out the long exposure. During this, the preview on the screen and in the EVF are suitable for composition and focusing.

Linary Loc: UK

I think you may have misunderstood my phraseology but Burkphoto nailed it. Thanks anyway.

Linary Loc: UK

Thank you.

My reason for asking is that I often go shooting with a group of friends and three of them have MILCs. The vintage DSLR camera I use does not have live view thus when using dark filters I have the ritual of compose, focus, affix filter, shoot etc. whereas my companions fit filter, compose, focus, shoot - much more efficient. Both my DSLRs are approaching their end of useful life and I am determined on a new DSLR, but am tempted by the EVF on a mirrorless.

Linary Loc: UK

Thanks for info. It is going to be a difficult decision - new DSLR or MILC.

Linary Loc: UK

Even more food for thought - I often use HSS flash but never thought of incorporating ND filters into the equation. Thanks for the link.

User ID

You understand properly.

But do realize there are limits
to the camera adding gain to
the EVF so at some point it is
unable to sufficiently brighten
the viewing image.

------------------------

Also, EVFs are switchable for
either of two modes:

1. As you describe, bright view.

2. "Constant Preview" [or other
similar terms] wherein the view
brightens or darkens when you
alter your exposure settings to
over or under exposure.

.

User ID

Dinosaur or primate. Soooo difficult.