Night Vision Help understanding non-prisim thermal clip on magnification

[adamjma]

@koshkin @wigwamitus or anyone else who understands this stuff - can you explain how any of the lower end (non-Risley prisim) thermal clip ons work with their base magnification not being 1x/unity? I see that the Armasight Jockey 640 is actually a 1x thermal, so by my understanding it would work well with a daytime optic as you would have all of the 1024 x 768 pixels of the screen to work with as you zoom in beyond 1x on your (presumably) LPVO. They claim it's good to 6x, which I imagine is probably at the very limits of usable.

Being outside the US with limited options, the DNT series of Hydra thermals sure look interesting, especially at the price they are going for. I did up a quick table below to see if I can understand how they work as none have a 1x/unity base magnification.

	DNT	Hydra	Series		Armasight
	HS635	HS325	HS225	HS650	Jockey 640
Sensor H	640	384	256	640	640
Sensor V	512	288	192	512	480
Display H	1024	1024	1024	1024	1024
Display V	768	768	768	768	768
Base Magnification	1.5	2	3	2	1
Unity H	682.7	512	341.3	512	1024
Unity V	512	384	256	384	768
Max rec mag	4	3	2	3	6
Pixels H/x	170.7	170.7	170.7	170.7	170.7

So the first couple of rows are the specs of the sensor and the display. I'm assuming that to get back to 1x for clip on use, the image on screen is reduced in size inversely to the base magnification - so using 2/3 of the screen for the HS635 and only 1/3 of the screen for the HS225. By my reckoning, that means that at unity, there are about 683 x 512 pixels for the HS635 image of the sensor versus a paltry 341 x 256 for the HS225.

Assuming I have that right, it would also seem to indicate that the HS635 would offer higher magnification before things become fuzzy on the daytime optic? I looked at the Jockey pixels and assumed at 6x (max recommended) you would have about 171 pixels horizontally (wow) so working back from that I figure the HS635 might get you up to 4x on the daytime and the HS225 a lousy 2x.

Am I understanding this correctly or am I totally off base? Seems like the better options for scanning (moderate base magnification) are lousy for clip on use and the good clip ons would be lousy scanners...?

 

[Old Man with Gun]

I have a Berring Optics Hogster Clip-On that I use on several rifles, but here it is in front of a 1-6x optic.

The Thermal has a small screen that the scope looks at, and in this case on 1x it doesn't fill up the scope at all.

at 2x it is just touching the four corners

at 3x I've lost some of the screen corners, but just got rid of the wasted space above and below the screen

So if I crank up to 6x, I've halved the number of pixels I can see vertically and reduced the horizontal pixels by a little more than that.

Sorry pics are crappy, but hopefully gets the point across.

 

[wigwamitus]

As the eons have moved by us ... we now believe ... based on testing, that risley prims don't make a difference with thermal clipons (we know someone who tested with and without). The difference between military grade thermal clipons, that (generally - by design) don't require manual adjustments to their collimation and commercial thermal clipons - that generally do - is the QUALITY - or - LEVEL of collimation. To wit: the sophistication of the collimating equipment and the knowledge, skills and abilities of the folks doing the collimation.

All thermal clipons say they are 1x - and they have to be - if we will use our reticles in our day scopes for holding. But most thermal clipons, even the tiny ones, like the Voodoo S or the RH25 (and most likely the Jockey) have a little magnification on the front and hence the same offsetting demagnification on the rear. That gets them back to 1x.

But collimating a thermal clipon, means getting the entire electro-optical train lined up so that what the human sees from their mk1EB thru the rear optical lens, thru the display, through any software manipulations, though the sensor on the front thru the front optical lens all result in the real world image being lined up. Some devices have had a better job done at this than others and so some need the ability to move the image around on the display with the person shooting to verify things are lined up - to get the device "truly" collimated. Engineers collimating mil grade units, use improved gear and improved processes to get the E-O train much closer to perfect on collimation and hence no manual collimation required (except rarely when somebody messed up).

Further, while I believe there are a tiny few companies making cores made in yourUp, like by Hensoldt (and maybe those are the cores in the theons) - if you don't know where a sensor is made - then assume its made in the PRC. This is especially true in "low cost" thermal units, i.e. anything under $6k for sure.

 

[adamjma]

Sorry pics are crappy, but hopefully gets the point across.

Many thanks for the pictures. That seems to show what I expected.

 

[adamjma]

As the eons have moved by us ... we now believe ... based on testing, that risley prims don't make a difference with thermal clipons (we know someone who tested with and without). The difference between military grade thermal clipons, that (generally - by design) don't require manual adjustments to their collimation and commercial thermal clipons - that generally do - is the QUALITY - or - LEVEL of collimation. To wit: the sophistication of the collimating equipment and the knowledge, skills and abilities of the folks doing the collimation.

All thermal clipons say they are 1x - and they have to be - if we will use our reticles in our day scopes for holding. But most thermal clipons, even the tiny ones, like the Voodoo S or the RH25 (and most likely the Jockey) have a little magnification on the front and hence the same offsetting demagnification on the rear. That gets them back to 1x.

But collimating a thermal clipon, means getting the entire electro-optical train lined up so that what the human sees from their mk1EB thru the rear optical lens, thru the display, through any software manipulations, though the sensor on the front thru the front optical lens all result in the real world image being lined up. Some devices have had a better job done at this than others and so some need the ability to move the image around on the display with the person shooting to verify things are lined up - to get the device "truly" collimated. Engineers collimating mil grade units, use improved gear and improved processes to get the E-O train much closer to perfect on collimation and hence no manual collimation required (except rarely when somebody messed up).

Further, while I believe there are a tiny few companies making cores made in yourUp, like by Hensoldt (and maybe those are the cores in the theons) - if you don't know where a sensor is made - then assume its made in the PRC. This is especially true in "low cost" thermal units, i.e. anything under $6k for sure.

Interesting. I had always assumed the prism system was far superior. Much appreciated.

 

[Old Man with Gun]

I like mine, you have to calibrate the scope to each rifle but mine gives me four guns G1, G2, G3 and G4.

I use both G1 and G2 for a 300 blackout so I have a setting for both supersonic and subsonic... Handy to have the Clip-on do the hold over for me, especially since that rifle moves my subs a bit left as well as the drop.

 

[adamjma]

I like mine, you have to calibrate the scope to each rifle but mine gives me four guns G1, G2, G3 and G4.

I use both G1 and G2 for a 300 blackout so I have a setting for both supersonic and subsonic... Handy to have the Clip-on do the hold over for me, especially since that rifle moves my subs a bit left as well as the drop.

Yeah, I suppose that is the one big benefit of the prism-based collimation is that it should be consistent across optics.

How far off are the different profiles out of curiosity. @wigwamitus description above suggests there may yet one day be a one and done prism-free device if all the doodads can be lined up just perfect.

 

[Old Man with Gun]

Each rifle is different and it can be noticeable. Don't expect to get away without sighting in each one.

It is hard to compare my rifles because the cartridges are 300BO, 6.5 Grendel and 6.5 Creedmoore.

 

[koshkin]

@koshkin @wigwamitus or anyone else who understands this stuff - can you explain how any of the lower end (non-Risley prisim) thermal clip ons work with their base magnification not being 1x/unity? I see that the Armasight Jockey 640 is actually a 1x thermal, so by my understanding it would work well with a daytime optic as you would have all of the 1024 x 768 pixels of the screen to work with as you zoom in beyond 1x on your (presumably) LPVO. They claim it's good to 6x, which I imagine is probably at the very limits of usable.

Being outside the US with limited options, the DNT series of Hydra thermals sure look interesting, especially at the price they are going for. I did up a quick table below to see if I can understand how they work as none have a 1x/unity base magnification.

	DNT	Hydra	Series		Armasight
	HS635	HS325	HS225	HS650	Jockey 640
Sensor H	640	384	256	640	640
Sensor V	512	288	192	512	480
Display H	1024	1024	1024	1024	1024
Display V	768	768	768	768	768
Base Magnification	1.5	2	3	2	1
Unity H	682.7	512	341.3	512	1024
Unity V	512	384	256	384	768
Max rec mag	4	3	2	3	6
Pixels H/x	170.7	170.7	170.7	170.7	170.7

So the first couple of rows are the specs of the sensor and the display. I'm assuming that to get back to 1x for clip on use, the image on screen is reduced in size inversely to the base magnification - so using 2/3 of the screen for the HS635 and only 1/3 of the screen for the HS225. By my reckoning, that means that at unity, there are about 683 x 512 pixels for the HS635 image of the sensor versus a paltry 341 x 256 for the HS225.

Assuming I have that right, it would also seem to indicate that the HS635 would offer higher magnification before things become fuzzy on the daytime optic? I looked at the Jockey pixels and assumed at 6x (max recommended) you would have about 171 pixels horizontally (wow) so working back from that I figure the HS635 might get you up to 4x on the daytime and the HS225 a lousy 2x.

Am I understanding this correctly or am I totally off base? Seems like the better options for scanning (moderate base magnification) are lousy for clip on use and the good clip ons would be lousy scanners...?

Risley prisms do not make any sense for modern thermal clipons. I think i talked shot how they work in a livestream a while back.