#apertus IRC Channel Logs

hello!

and came up with an assembly that does not rely purely on material friction

http://www.youtube.com/watch?v=f3Fw4lJ-Jl4

se6astian: looks really interesting

hi, great

what range we really need... no idea

so that would be 5um

the pitch is 0.4mm and 0.25mm for the fine spacing

and the other interesting question would be, how much should the total/maximum adjustment be?

maybe we can talk to other camera makers at IBC to investigate these ranges

then did a simple tilt correction one with 3 setscrews

then a full featured one with rather complex mechanics with springs and moving parts

and then after that one another redesign to compensate for material expansion due to heat

interesting

the screws would be access from inside the camera (holes in sensor frontend pcb?) by the engineer calibrating the camera, should no be required to be recalibrated by the customer

you remember my .stl with the slits for fastening the joint?

i.e. basically you screw system but screwed on from the outside into the base

hmm, difficult for me to imagine, could you do a quick drawing? ;)

this was not enough and they had to redesign the parts completely

we use big sensors and big lenses

"Insufficient range of the sensor board tilt adjustment to the lens optical axis. It needed to be just about twice larger to be able to compensate for most sensor chip misalignments"

Model NC393 CAD rendering with M12 (S-mount) lens and thermally compensated sensor front end

haven't modeled the screws or done any animation, but I hope you get the idea

but there is no harm in having six, only for adjustment you should remove 3 of them first, then do the adjustments and after that, screw the other 3 back in

(because screw pitches are at lest 100um but likely more around 300-500um to have at least some stability

hmm, you can probably get away with a dual pitch screw system for small adjustments :)

yes, but that would be the same as in your design

in my design the moving part has no holes for the screws, they just push the flat surface in place

but in that case, you can simply turn it around and have the screws on the outside

true, yes

dual pitch?

this is used for microadjustments, but obviously requires a fixed counterpart

but I'm still not sure I completely understand the problem

do the sensors have different glass thickness across the sensor?

with shift you mean distance changes?

because the spherical design will definitely keep the distance constant

and the PCB itself might not be 100% plain either

assuming that we keep the/a socket, the pcb and socket is of no relevance

the sensor should be tightly screwed to the lens mount

and the sensor socket/pcb doesn't change that in any way

you had some concerns about that design though if I remember correctly

or we make the lens mount a 2 part assembly

i.e. I'd introduce a plastic foil or something similar between sensor glass and lens mount

(or ceramic in our case)

assuming that we do the stacked design

after the sensor was screwed into the lensmount (with foil)

screws fix the sensor, pcb is placed onto the sensor pins (with spacers on the sides)

where I'd make the lens mount cover the entire front of the camera

so the lens mount is sensor specific, yes, but it conencts to the rest of the camer block electrically and mechanically

I d say we see with the prototype how plain the sensor alignment will be

probably

(regarding the comment about the foil thickness)

yes, for example

okay, and what will be the effect?

you won't be able to precisely focus on infinity, I guess

for slight deviation it could mean that when you turn the focus ring to 1m the focus will actually be at 1.5m, in worst cases it would mean as you say that you either cant focus on infinite, cant focus on near objects or cant get anything in focus at all

a fun thing with the Elphel cameras ( I might show you soon) is that the c mount thread can be used to change the FFD of the lens by just unscrewing the lens

(which will probably be about 0.5mm)

you then see tiny hairs and dust that are stuck inside the lens :)

okay

or we do it when I visit to bake the PCB

ok time for bed for me, gnight!