why can't you evaluate flare and bokeh in the viewfinder?

[Spanik]

Both the flare and bokeh thread made me think about this. Why is it almost impossible to evaluate flare and bokeh in the viewfinder?

Of course it is impossible in a RF or TLR. But even in a SLR you just don't get the same impressions of it in the viewfinder then on film/sensor. The mirror is between the lens and film plane and you're looking at the image on the ground glass through the prism. But in theory both images should be the same.

Or am I just using gear that doesn't show it?

 

[Warren T.]

Both the flare and bokeh thread made me think about this. Why is it almost impossible to evaluate flare and bokeh in the viewfinder?

Of course it is impossible in a RF or TLR. But even in a SLR you just don't get the same impressions of it in the viewfinder then on film/sensor. The mirror is between the lens and film plane and you're looking at the image on the ground glass through the prism. But in theory both images should be the same.

Or am I just using gear that doesn't show it?

If your len's aperture is set to anything other than wide open, and If the slr has a DOF preview button, you can manually stop down the lens to get a rough idea of what the final image will look like. This method works better where there is enough ambient light to see the image through the viewfinder because stopping down will, of course, cause the viewfinder image to darken.

--Warren

 

[Peter^]

On an SLR the aperture remains fully open until you trigger the shutter. Close down the shutter and you can get a feel for the DoF. But the image is often dark.

Even then though, the images cannot be identical. The image to the eye goes through a completely different path that the image on the film plane. The optical path length, the effective pupil size, etc, are all different.

 

[Peter_Jones]

Some focussing screens are better than others (i.e. better at showing DOF etc) - most DSLR focussing screens are appalling for this purpose, D600 not bad though.

 

[thirtyfivefifty]

Haven't you learned by now through experience? In my mind, when I see strong light sources in the viewfinder (in my case, an SLR), I know when my lens might flare because as humans, we squint, and I know the tendencies of my lens. With that say, having shot photographs with my camera before, I am aware how bokeh may render. Also, our eyes can't see faster than f/2.2 (so I've heard).

 

[Rangefinderfreak]

For SLR, get a screen that is MATTE ! Microprism screens are bright, but don`t give a true image of the out of focus area or flare. Best is Leica M: there you have to KNOW how the lens performs, pre visualize the image in your brain...

 

[bugmenot]

You can ... with an Electronic Viewfinder 😀 I can do both of those with a NEX-5N and EVF attachment. 🙂 OR through a LCD screen of course, a liveview LCD screen.

 

[tunalegs]

It's kind of like how fog always looks denser in real life than it does in the photo...

 

[Roger Hicks]

It's kind of like how fog always looks denser in real life than it does in the photo...

A superb analogy! Also how hills seem steeper when you're driving up them in a 4WD than they do in the picture.

Cheers,

R. (Land Rover World contributor)

 

[craygc]

A recent and interesting discussion here about what you can and cannot observe through SLR viewfinders.

 

[Spanik]

If your len's aperture is set to anything other than wide open, and If the slr has a DOF preview button, you can manually stop down the lens to get a rough idea of what the final image will look like.

I do know that, might have been clearer on that point. But from my experience, the difference is there even if looked at it stopped down.

Even then though, the images cannot be identical. The image to the eye goes through a completely different path that the image on the film plane. The optical path length, the effective pupil size, etc, are all different.

I agree it is a different path, but path length should be the same, otherwise focusing wouldn't be possible. Effective pupil size? Don't know to be honest.

Some focussing screens are better than others (i.e. better at showing DOF etc)

For SLR, get a screen that is MATTE ! Microprism screens are bright, but don`t give a true image of the out of focus area or flare.

Might be a good point, I never looked at the same scene through different viewfinders at the "same time". But then again it would mean different lenses. So how much would that give an idea. And while some SLRs have a microprism area in the center, all those I have have a very large area of nothing but matte.

It's kind of like how fog always looks denser in real life than it does in the photo...

It isn't an analogy, it is a similar phenomen. And a good point as well. Why?

Going to read that last link.

 

[tunalegs]

A plain ground glass without fresnel screen will actually do a pretty good job of showing DOF and boke'. The condensor introduces some distortion though.

As for the fog thing I think it probably has to do with a difference in color sensitivity between our eyes and film/sensors.

 

[splitimageview]

You can ... with an Electronic Viewfinder 😀

This.

67890