5231- depth of field issue?

C

cam26

Pulling my weight
Jan 21, 2019
238
100
USA
View attachment 143782

Hi all,

In the image, I have zoomed in my 5231 in an attempt to be within identification range at the sidewalk/street, approximately 50ft. I noticed once zoomed in that the picture was really only clear towards the center and right half of the screen, while the left side with the leaves and out into the street is blurry (basically anything from the tree and left). I only get a somewhat clear picture around the light post/mail box or closer, but still probably not identifiable unless totally stopped.

I understand that as you get farther left and deeper into the scene the distance grows, but I was surprised to see the amount of blur that I did in such a small field of view.

Is this as a result of the depth of field changing as I zoom in, or possibly a blurring effect on the edges of the view from being zoomed in?

just to note, shutter was set from 0-2 and gain <35 (overcast day). One click either way on the focus slider threw the whole thing off, as well.
 
The more you zoom in the more shallow the area/depth of focus as the f-stop gets larger.

It is not uncommon for us doing LPR to see this. Either side of the street is blurry but the center is in focus.

One of the many reasons why we suggest to have a vehicle stop in the center of the frame so that you focus on that important area. Otherwise auto focus may decide to focus on something other than the center of the road.
 
  • Like
Reactions: Lincos, looney2ns and cam26
wittaj said:
The more you zoom in the more shallow the area/depth of focus as the f-stop gets larger.

It is not uncommon for us doing LPR to see this. Either side of the street is blurry but the center is in focus.

One of the many reasons why we suggest to have a vehicle stop in the center of the frame so that you focus on that important area. Otherwise auto focus may decide to focus on something other than the center of the road.
Click to expand...
Makes sense. I was unable to get it any more focused on anything farther by clicking up or down on the slider. I’m assuming that’s because it’s beyond the capacity of the camera at around 50ft?
 
it appears fully focused on that lamp post in that shot....
 
get that thing turned left to get the lampost out of the scene and see where its focusing then ( probably on the tree)
 
Last edited:
  • Like
Reactions: looney2ns
Flintstone61 said:
get that thingturned left to get the lampost out of the scene and see where its focusing then ( probably on the tree)
Click to expand...
Even with the lamp post in the way, shouldn’t I be able to manually focus it so the tree is clear (beyond the lamp post), if it’s capable of that? If I use the focus slider and click it one more “farther”, the whole scene is unfocused.
 
my 5231 deployment is on hold....here it is fully focused on the foreground of the Radial Arm saws arm...
in another situation ( maybe due to day time) it decided to focus on the Rav4.....
1666720355827.png
1666720444356.png
 
@Bitslizer put a Reflective sticker out in the field of view, and changed what his was focusing on. maybe try it and watch how it focus's at night. Daytime im stumped.....
unless yourevert back to auto and let it focus hunt and see what its choosing....then you'll know what object is the problem...
 
  • Like
Reactions: Dingoboy77 and sebastiantombs
Flintstone61 said:
@Bitslizer put a Reflective sticker out in the field of view, and changed what his was focusing on. maybe try it and watch how it focus's at night. Daytime im stumped.....
unless yourevert back to auto and let it focus hunt and see what its choosing....then you'll know what object is the problem...
Click to expand...
Great idea. I feel like autofocus is able to fine tune more than manual, which could inherently be a problem (for situations such as these).
 
cam26 said:
Great idea. I feel like autofocus is able to fine tune more than manual, which could inherently be a problem (for situations such as these).
Click to expand...

For LPR, manual is for fine tuning, but you need to drop the Speed/step from 20 to 1 to fine tune it or else you are taking swings at focus at 20 step intervals.

With autofocus, it will focus one time on the bottom of the image, and the next time on the top of the image, and then you get a blurry plate.

1666733741133.png
 
  • Like
Reactions: cam26
wittaj said:
For LPR, manual is for fine tuning, but you need to drop the Speed/step from 20 to 1 to fine tune it or else you are taking swings at focus at 20 step intervals.

With autofocus, it will focus one time on the bottom of the image, and the next time on the top of the image, and then you get a blurry plate.

View attachment 143793
Click to expand...

I thought “speed” meant how fast it zoomed… well that may make all the difference in the world and explains why one click throws the whole thing off (since it’s actually 20).

On another note, I moved the camera to the left more so nothing was blocking and parked a car in the street. Also raked some leaves because that was confusing the focus. It focused much, much better (but not perfect). I’ll have to step (“speed”) it down to 1 and try again tomorrow during daylight.
 
  • Love
Reactions: Flintstone61
Good stuff...hope it Kicks ass!
 
  • Like
Reactions: cam26
Flintstone61 said:
Good stuff...hope it Kicks ass!
Click to expand...
Thanks for all your and @wittaj help! Much appreciated.

It may be slightly moot, though, as I’m realizing now that there’s like zero light out there in the street at night. Picture super grainy/ghosty or too blurred with enough shutter speed. Neighborhood has zero street lights and is tree lined. Frustrating.
 
wittaj said:
This is your LPR cam or using it as overview?
Click to expand...
Not LPR, idea was to be able to better identify vehicles driving by and people on the sidewalk. Sorry, I wasn’t clear.

Given the darkness I think I may need to move my identification goal back in the yard and closer to the camera.
 
Post a screenshot of the night image and screenshots of your settings and let's see if we can offer any suggestions to improve/tweak image.
 
8ms really didn’t give me any more brightness than 5ms did, and I really hesitate to bump it higher because of blur
 
You must log in or register to reply here.
Top Bottom