Worlds First Review - Dahua DH-IPC-HDW5849H-ASE-LED / IPC-Color4K-T - 2.8mm Turret

[bigredfish]

Wow, that is some reply, thank you kindly. Oddly that last video looks soft focused in the background, where as the others are tack sharp, assume the same camera. Looks like I will be ordering a bullet or two in 3.6mm, loving these 4K series cameras, these samples show all you need to know

Bright sunlight and a bit overexposed I think. along with serious shadows

 

[CamCrazy]

Bright sunlight and a bit overexposed I think. along with serious shadows

That could do it, superb images and video clips regardless and a fine selection in your post. Never thought I would be buying 8MP cameras, but here we are!

 

[CamCrazy]

Bright sunlight and a bit overexposed I think. along with serious shadows

Do you feel that by 18-20 feet the 3.6mm is beginning to move outside of it's optimum focus window, watching this again and looking at stills, almost seems like it is sharper between 12-15 feet. I am now totally confused whether to go with 2.8 bullet or the 3.6mm, maybe should just get both and see if the 3.6mm works OK, the two locations I have in mind are both essentially around the same distance, classic case of wanting everything sharp and in focus but requiring a touch more reach! The low light abilities on these is frankly enough of a benefit for me to sacrifice reach. I guess ideally focal length would be around 6-8mm for my application but this is no use if the camera cannot work well in low light/night conditions, this is where the 4K series are winning for me.

 

[bigredfish]

I could argue that past 20-25ft ANY 3.6mm is beginning to lose optimal focus and detail.

But I haven't played with a 2.8 so can't compare

Both are ultimately going to be an overview cam, though I enjoy it as an ID cam in my location from 6-12ft

 

[quest100]

With the 3.6mm bullet, what is the real world minimum focus distance as a rough guide. I have a distance to target of between 16-20 feet, am hoping the 3.6mm will work well for that. I have a couple of the 2.8mm turrets, the benefit of the close and near LED's on the bullet will be useful for me, are there any downsides for those who have both vs the turret?

Years ago I decided to actually measure the resolution of some Color4k-X cameras versus distance. The graph below shows my results.



The resolution is measured by noting the finest bar pattern that can be seen with the proper number of bars. The distance is measured from the front of the bullet camera. The target is a modified 191 USAF bar target printed out on card stock. I have only one camera with a 2.8 mm focal length lens but two each of 3.6 and 6 mm.

I find that both the 2.8 mm and 3.6 mm have the best resolution of around 1 mm around 4-6 feet from the camera. I was very disappointed in the performance of the 6 mm and would not use it until the subject distance is greater than about 20 feet. All cameras came close to their theoretical resolution at large distances. At short distances the defocus caused a rapid loss of resolution.

 

[CamCrazy]

Years ago I decided to actually measure the resolution of some Color4k-X cameras versus distance. The graph below shows my results.

View attachment 231538

The resolution is measured by noting the finest bar pattern that can be seen with the proper number of bars. The distance is measured from the front of the bullet camera. The target is a modified 191 USAF bar target printed out on card stock. I have only one camera with a 2.8 mm focal length lens but two each of 3.6 and 6 mm.

I find that both the 2.8 mm and 3.6 mm have the best resolution of around 1 mm around 4-6 feet from the camera. I was very disappointed in the performance of the 6 mm and would not use it until the subject distance is greater than about 20 feet. All cameras came close to their theoretical resolution at large distances. At short distances the defocus caused a rapid loss of resolution.

Wow, that is a lot of work but very interesting. This agrees with my findings based on user feedback and my own experience with the 2.8 at least, sharpness is good from 5-12 or even 5-15 but then falls away from there. I mean they are still insanely good past those distances frankly but this does make sense. The 6mm really not putting in a good show. I will be getting some more of these cameras, they are way too good in poor lighting. On a side note, you have quite a number of cameras listed there 20 by my count! and you like the 4K's which I can understand.

 

[quest100]

Wow, that is a lot of work but very interesting. This agrees with my findings based on user feedback and my own experience with the 2.8 at least, sharpness is good from 5-12 or even 5-15 but then falls away from there. I mean they are still insanely good past those distances frankly but this does make sense. The 6mm really not putting in a good show. I will be getting some more of these cameras, they are way too good in poor lighting. On a side note, you have quite a number of cameras listed there 20 by my count! and you like the 4K's which I can understand.

Looking back at my graph the curves are pretty much as I would expect. The Color4k-X 2.8 mm camera has a best resolution at around 4 feet. The hyperfocal distance increases with the square of the lens focal length. Thus the 3.6 mm version should have a best focus of 6.6 feet and the 6 mm at 18.4 feet. This agrees with the graph.

If a camera is focused at the hyperlocal distance the at half the hyperlocal distance and infinity will have the same circle of confusion in the image. Everything in-between will be better. This concept is used in photography to maximize the depth of field while also imaging distant object. It looks like Dahua used a circle of confusion barely larger than the size of a pixel.

Not all of the cameras I list are currently in use, but I do have way more than needed. I think I may be an addict.