Pellicle Dslr?

[Mr G]

Hi guys, took my RT out for a spin at the weekend, it was a joy to use and was like going back in time 25 years.
We all know the advantages and disadvantages of having a pellicle mirror and it got me wondering, especially with the advancement in electronic viewfinders, is there a place for a pellicle mirror on a modern Dslr, maybe an EOS D1N RS or an F1D?

[TrueLoveOne]

Sony did use it in the SLT series. I have never used them, so i can't comment further.

[duckrider]

An additional optical element in the way light has to move to the sensor will not make sense, optical quality will become more worse.
In film based times pellicle mirror was necessary for high speed sequences used in Nikon F2high speed e.g.
Today You can choice between DSLR (with mirror up option in better cams) and evil cams without mirror.

[miran]

[iangreenhalgh1]

Only pelicle mirror camera I have used was the original one - the Canon Pellix. It was a horrible experience as the VF was a LOT dimmer and harder to focus.

I'm sure Sony's SLT is much better though, being nearly half a century on from the Pellix.

[dan_]

[Gerald]

"Everything you always wanted to know about the semi-transparent mirror technology (but were afraid to ask)":

http://www.lenstip.com/137.1-article-Everything_you_always_wanted_to_know_about_the_semi-transparent_mirror_technology.html

[dan_]

Thanks for the link, Gerald. Really interesting.
The conclusion is in accordance with the users common experience with the pellicle mirrors from the Sony cameras:

"...a fast lens might be not limited by diffraction…if it was limited previously at all. It may be still significant if you can find a lens faster than f/2.8 and with a resolution higher than 200 lp/mm. As there are no local disturbances (high-frequency) f/2.8 lenses and slower won’t lose their resolution in a noticeable or even measurable way."

If I understend well that means that a difference in IQ may be noticed only with a lens faster than f/2.8 on a camera with more 34.5 MPX (200lp/mm), if the lens outperformes the sensor on wider than 2.8 apertures.

[Mr G]

Hi guys, interesting comments, my main reasons for starting this thread was the advantages, no lag or vibration caused by mirror movement, no blackout in the viewfinder. I agree that losing a 1/3 stop of light in the viewfinder is frustrating but with fast modern lenses becoming ever more affordable is this a real issue?
Surely the idea of a full blown Dslr with aspects of rangefinder operation would be beneficial.

[iangreenhalgh1]

I haven't used an a99 to know what the VF is like but I have briefly used an A7R and while the EVF is excellent, it still can't match the optical VF of the a850 or a900. I doubt the a99 VF can match up to the a850/a900 so any advantage from the fixed mirror is mitigated by that. Mirror vibration isn't really an issue, it's so well damped on the a850/a900 and I've never found the blackout to be a problem. Depends on how you use the camera I suppose, those things might be more of an issue to someone else.

I am sad that Sony has dropped DSLRs though, means the upgrade to my a850 will have to have an EVF which is a downgrade in that respect.

[dan_]

I made a mistake!
In fact 200lp/mm = 400pix/mm.
That means the sensor should be 138 MPX!

[miran]

[Gerald]

SLT is an interim technology used by Sony to build cameras that are basically "mirrorless" with phase detection autofocus capability. SLT cameras use phase detection autofocus even during video recording, which a traditional DSLR cannot do. SLT also allows the electronic viewfinder be used for video recording, whereas the optical viewfinder of a DSLR gets totally dark in the same situation.

One of the disadvantages of SLT technology is a loss of light of little less than half stop, but this loss is negligible in most practical situations. The pellicle mirror is very delicate and is easily dented if hit by a solid object. Cleaning the pellicle mirror must be done very carefully because it scratches easily. On the other hand, the replacement of the pellicle mirror is a very simple and can be made by the user himself. And, if you use a SLT camera only with manual focus lenses (my case), the pellicle mirror can be removed altogether because manual focusing can be done using Focus Peaking or Magnify Focus, which don't depend on the pellicle mirror.

[luisalegria]

I think EVF's are getting very good.
I borrowed a pals Fuji XT-1 and its EVF is really amazing, much better than the A7.
Thats an EVF even better than optical.
More clear, difference between in and out of focus is precisely as in the final output, and very very easy to manually focus.
Optical VF's are never perfect as there is usually some compromise between brightness (fresnel) and a plain groundglass which can be dark. This is true even on excellent old film cameras like Pentax LX.

[Gardener]

[wolfhansen]