GBo

GBo

Lives in France Paris, France
Joined on Jul 29, 2001

Comments

Total: 8, showing: 1 – 8
On Sony Alpha SLT-A99 preview (326 comments in total)
In reply to:

GBo: Hi all, will the a99 refuse to take pictures and video if the semi-transparent mirror is removed ? I mean to use this camera with manual focus lenses (in particular for video), in that case the 30% light loss is pure loss.
Thanks,
GBo

Thanks lassero

Direct link | Posted on Sep 23, 2012 at 10:14 UTC
On Sony Alpha SLT-A99 preview (326 comments in total)
In reply to:

GBo: Hi all, will the a99 refuse to take pictures and video if the semi-transparent mirror is removed ? I mean to use this camera with manual focus lenses (in particular for video), in that case the 30% light loss is pure loss.
Thanks,
GBo

I consider VG900 but it is even more expensive; D600 does not have an articulated screen (that I need), FF NEX will not appear in the near future, so no much choices here ! To answer my own question, it seems that some tried to remove the mirror on the A55 and make it work, so it may work as well for the A99.

Direct link | Posted on Sep 23, 2012 at 09:20 UTC
On Sony Alpha SLT-A99 preview (326 comments in total)

Hi all, will the a99 refuse to take pictures and video if the semi-transparent mirror is removed ? I mean to use this camera with manual focus lenses (in particular for video), in that case the 30% light loss is pure loss.
Thanks,
GBo

Direct link | Posted on Sep 20, 2012 at 10:35 UTC as 39th comment | 4 replies
On Lytro announces Light Field Camera article (269 comments in total)
In reply to:

gberger: Put me down as skeptical. First of all they are throwing around a lot of fancy-sounding jargon without answering specific questions such as what is the actual resolution, what is the shutter speed, etc.
Secondly, as at least one other comment pointed out, they say the lens is an 8x optical zoom with constant f2 aperture. Come on people, is anyone paying attention to this claim? They've suddenly created a compact F2 zoom with that kind of range in a 400.00 camera? I find this hard to believe and i think anyone who thinks about if for 10 seconds will agree.
My feeling is that they have something innovative in one respect but they are throwing up a lot of smoke and mirrors to hide the shortcomings and are hoping people will swallow it.

It's a small sensor after all, such as CCTV ones, and manual zooms can both be cheap and with large aperture :
http://www.cctv-4sale.com/products.cfm/LENSES/Varifocal-Lenses/Manual-Varifocal-Lenses/
And remember that the Lytro don't even need focus ring or iris.
rgds,
GBo

Direct link | Posted on Oct 28, 2011 at 13:51 UTC
On Lytro announces Light Field Camera article (269 comments in total)
In reply to:

simply sner: so the camera doesn't have the specifications you want? so what? don't buy it.

did you look into the PhD thesis on the company's website? - Ren Ng's work is beautiful.
the camera is not ready for the market? well it is still the most innovative prototype that came out since the first digital camera. back then you stored images on a floppy disc... what are you guys complaining about?

It's within the law of physics. Please see Fig.4 of this paper from Stanford :
http://graphics.stanford.edu/papers/lfcamera/lfcamera-150dpi.pdf
=> you’ll have as many viewpoints as there are pixels under a microlens. If you take the center pixel from each microlens (see the ones marked with a red spot in the following image), you can build an image showing the full field from a given viewpoint, and in focus like in a pinhole camera. If you take another pixel coordinate (let’s say the ones marked in blue), you’ll have another viewpoint:
http://gbotet.perso.sfr.fr/Ng/pixels.jpg

Hard to believe ! So I tried with a homemade matlab and a sample of a raw plenoptic image... and it worked. Here are all the viewpoints that I could build from a single Light Field shot :
http://gbotet.perso.sfr.fr/Ng/imagettes.gif
The viewpoints are not very far away from each other, they are in the limits of the physical aperture. 3D effect will be rather limited, unless the subject is very close from the lens.

Direct link | Posted on Oct 24, 2011 at 16:52 UTC
In reply to:

ProDesignTools: Of interest: Some brand new before-and-after images from the tool have just been released, along with further details

http://prodesigntools.com/photoshop-image-deblur-adobe-releases-new-photos.html

The historical B&W Capa D-Day photo is a notable inclusion. Independent submissions are also invited

Thanks for the link

Direct link | Posted on Oct 24, 2011 at 12:31 UTC
On Lytro camera overview and discussion with CEO Ren Ng article (103 comments in total)
In reply to:

Ravncat: Can it do deep depth of field? All of the samples i've seen show only moving narrow depth about in the image...

Based on several narrow depth of field images (with a range of different focus plans), you can always try a focus stacking technique in a separate software :
http://en.wikipedia.org/wiki/Focus_stacking
regards,
GBo

Direct link | Posted on Oct 20, 2011 at 09:08 UTC
In reply to:

tkbslc: So it would have been too hard to take a shot of Kevin at 1s handheld to use for the example?

Hi all, I tried to unblur the "crowd" image and it worked :
http://gbotet.perso.sfr.fr/deblur/guess.jpg
In PNG full size :
http://gbotet.perso.sfr.fr/deblur/exampleOut.png

I used the program found here :
http://www.cse.cuhk.edu.hk/~leojia/programs/deblurring/deblurring.htm
More info here (incl.a paper):
http://www.cse.cuhk.edu.hk/~leojia/projects/motion_deblurring/index.html

=> there are still some artefacts, but that's maybe because I did not try to refine parameters except the kernel size : 17x17

This deblur.exe program is using the same kernel for all points of the image, that's means that the motion blur is uniform, i think that it is called "spatially invariant motion blur" in this research field, right ?
Is it a realistic/average case of camera shake blur ?
I don't know about Adobe's plug-in capabilities, but for sure the crowd image they used can be perfectly deblurred with only one kernel. Simple case I guess.

regards,
GBo

Direct link | Posted on Oct 19, 2011 at 16:53 UTC
Total: 8, showing: 1 – 8