[Elphel-support] Motorized zoom lens

[Michael Bedford]

Andrey,

Thank you for the response!  I understand your point about the zoom lenses.

Interesting idea on using several sensors and switching between them.  For
the record, I do not like to use the 5MPix sensor as it is overkill for our
application and I need as much low light sensitivity as possible.
Therefore, I prefer the same family of sensor but in 3MPix.  Do the same
statements regarding Iris and Focus apply to the 3MPix sensor?  I know that
the pixel size is a little bigger but maybe not enough to where your
comments will still apply?

How fast can you switch between sensors?  If we want to stream at 10fps and
want to switch, will we lose any frames during the switch?

Thanks!


PLEASE NOTE OUR NEW PHONE NUMBERS BELOW.

Mike Bedford
Product Manager
APS Technology
a member of the ABB Group
3949 Ruffin Road, Suite A
San Diego, CA 92123 USA
858.836.7990
858.836.7999 fx

www.aps-technology.com



-----Original Message-----
From: support-list [mailto:support-list at support.elphel.com]
Sent: Wednesday, July 3, 2013 9:43 AM
To: Michael Bedford; Elphel List
Subject: Re: [Elphel-support] Motorized zoom lens

Hello Mike,

It should be possible to connect lens that has some digital control where
you can use RS232 or USB, available in the camera. There could be some COTS
adapters to use regular motorized lenses, but I'm not aware of any
particular. We did plan to make such adapter ourselves, until realized that
it will not be that useful.

Iris
When using a small pixel sensor diffraction limits the highest aperture
setting (it is a ratio of the pixel size and the wavelength). With the 2.2um
pixels in the 5MPix sensor we use now, this maximal value is ~3.5, for the
modern sesnors with 1.4 um (we will use them with the new camera I'm working
on now) this goes to maximal F#=2.0, so iris can be fixed. And with ERS
(rolling shutter) exposure control is perfect, so motorized iris would not
add much even if diffraction was not a problem.

Focus
Small format sensors have very wide depth of field, so for many applications
even the focus can be fixed.

Zoom

That limits number of useful motorized controls to just one - zoom, but here
is another problem. The quality of lenses lags behind the resolution of the
sensors, and it is more difficult to make otherwise the same performance
zoom lens than the fixed one. So instead of controlling zoom I would rather
try to use several sensors with fixed lenses and switch between them (i.e.
using our 10359 board).

Andrey