@mealiejimmy what are your thoughts on the Td70L?
I looked through one while back in daylight, out to 270yds & I was right enough with it. Not viewed at night.
Just don't hear much said about them?
I've never used one so can't comment from experience
A 1920x1080 sensor with 4 micron pixels and a 70mm f1.8 lens should give it very good low light performance and still retain decent base magnification
However the image detail will not be as good as the Alpex 4k
Image detail is effectively pixel size (in microns) divided by the objective lens focal length (in mm)
The smaller the answer to that simple calculation, the more detailed the image will be.
So, for the Alpex 4k with its 2 micron sensor and 50mm lens the resolution is 2/50 = 0.04 mrad
For the TD70L with its 4 micron sensor and 70mm lens it's 4/70 = 0.057mrad
Although the answers are in mrad, you can also think of it as the size of a square that a single sensor pixel "sees" at some specific distance (say 100m)
and when that is done, a single sensor pixel on the Alpex 4k "sees" a square with sides 4mm long at 100m and for the TD70L, the box is 5.7mm
The more sensor pixels that "see" the target, the more detailed the image of the target will be
Imagine a target that's 57mm x 57mm (keeps the number simple)
On the TD70L that target will be "seen" by 10 horizontal and 10 vertical pixels (57/5.7) giving a total of 100 pixels "seeing" the target
If we view the same target with the Alpex 4k, it will be seen by 14 horizontal and 14 vertical pixels (57/4), giving a total of 196 pixels
So, the target is "seen" by almost double the number of Alpex 4k pixels compared to the TD70L, so the image of the target on the Alpex 4k will be twice as detailed as that produced by the TD70L
The lack of detail on the TD70L image is compounded by the fact that:
a. The display on the TD70L is 1440x1080 compared to 1920x1080 on the Alpex
b. The sensor the TD70L has an aspect ration of 1.77 (1920/1080) but the display has an aspect ratio of 1.33 (1440/1080) - that usually introduces some distortion into the image seen by the user, whereas the the Alpex 4k uses a 1.77 aspect ratio for both the sensor and display
Cheers
Bruce
