Is there an SLR with no viewfinder blackout?

Started Jan 14, 2014 | Questions thread
Vikas Rana
Vikas Rana Contributing Member • Posts: 916
Re: SLR mirror movement Lag

Erik Magnuson wrote:

Vikas Rana wrote:

Ok, I'm agree with you on others points but SLT EVFs are better then EVF designed for mirrorless. I know EVF lag is there but 125ms lag isn't possible on a camera shooting at 12fps

Look at the diagram again:

1. This was for 8 FPS - the A77 has infinitely less lag than a 7D at 12FPS (which even if it were possible would require complete mirror lockup.)

SLR requires mirror lock-ups for continues focusing & SLT have it always

2. The image initially appears ~50ms behind real-time but stays visible for ~125ms until it's almost ~175ms behind. The average then is ~112ms behind (sorry I used the wrong number if that 13ms mistake bothers you).

So for 12FPS, it would stay visible for ~83ms for an average of ~92ms.

lag of 9ms to 13ms is acceptable since we are not shooting at 1000fps, its actually better then when the mirror is up and SLR lost the focus..!

In SLR cameras there is a mirror movement lag and that is the only cause of slower burst rate speed in SLR cameras.

That's already part of the mirror blackout timing. But that lag does not make for any delay to the viewfinder image during the time the mirror is down.

It does delays the Autofocus, its beneficial if a camera has some Autofocus prediction algorithms which I don't think written till date

Because of SLR mirror movement lag No entry level SLR can shoot more then 4 to 5 fps.

Which is a different subject. If you recall, the subject was:

1. If SLT is the answer to the OP's issue. It's not - it can't show live updates during exposure.

2. If SLT has no blackout:

a. It does during exposure, both for single shooting and lower FPS. This is simply because the shutter has to close and the data has to be readout before the shutter can re-open for feeding the EVF again. This blackout may be shorter than other cameras in the same price range, but it's still there and relevant to the OP's question.

Just realized that our discussion is totally irrelevant to OP's question, OP needed an viewfinder which does not blackout in long-exposures and the answers is old pellicle mirror cameras

Its actually Canon EOS RT, but it reflects 2/3 (66.66%) of light to OVF & 1/3 (33.33%) to film that results in noise as well as slower shutter speed.

b. For it's fastest FPS, it replaces blackout with showing a delayed version of the image taken and does not update the EVF between exposures as you claimed it did. This may be better or worse depending on opinion and usage than blackout interleaved with brief real-time view like with other DSLR.

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