EEVblog Electronics Community Forum
Products => Thermal Imaging => Topic started by: edubz on August 09, 2021, 07:57:25 pm
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I have the 25 MM lens, but it seems to close up, and not wide enough for 25 MM. it seems like its fixed in a small area. Weird field of view, with a 25 MM lens I think it should pick up more of my surroundings, instead its closed in.
It felt like my seek pro was wider for some reason.
seek says the compact pro has 32° Field of View
the AGM says it has Field of view (H × X) 10.5° × 7.9° (H × V)
is this the reason it feels to zoomed in?
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Yes.
What made you think that a 25mm lens would be 'wide' ?
Field of view depends just as much on the sensor size, and as pixels get smaller the field of view for a given lens and sensor format will also get narrower.
Bill
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Yes.
What made you think that a 25mm lens would be 'wide' ?
Field of view depends just as much on the sensor size, and as pixels get smaller the field of view for a given lens and sensor format will also get narrower.
Bill
It seems like they all have small field of views
Pulsar Helion 2 XP50 2.5-20 12.4 degrees
they make another model like mines called the ASP TM-25 and it has a FOV: 14.88° x 11.19°
but at just 4 degrees difference I wont be gaining much would I? I bought the taipan and not the ASP because the company said taipan was newer.
I checked the ht301 and it says Field of view: 28.2 * 21.3 Lens: 13mm, Manual focus
why does it seem like the cell phone lens are wider FOV? Even if I bought the pulsar I would still be at 12.4 FOV, the seek pro is 32 FOV, its the highest FOV I could find followed by the ht 301
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Spotting scopes and rifle scopes tend to have a narrower field of view in order to provide detection and identification at long range. As the lens field of view increases, the detection and identification ranges decrease. Many users of spotting scopes and rifle scopes want the best range possible so you will find the units equipped with powerful optics. Some general purpose thermal imaging scopes may offer a wider field of view but you need to check the specifications before buying. General purpose thermal imaging cameras have traditionally had a field of view of >24 degrees. The Industrial grade cameras tended to use 24 degrees FOV as it provides decent IFOV with the 320x240 pixel microbolometer array. Supplemental lenses were attached for a wider FOV of 45 Degrees or a narrower FOV of 12 Degrees. The thermal camera dongles for mobile phones often have a wide field of view as they are commonly used at relatively close range and many users want the greater FOV, but that comes at the expense of IFOV and so detail in the image. The ThermApp and Thermal Expert offered various lens options when you bought the dongle camera and also offered accessory lenses for those wishing to have more than one FOV available to them. This was forward thinking of these companies and a welcome change from fixed mount dongle camera lenses that could not be easily changed.
Another issue with powerful, long range, optics is that they can have very limited close-focus capabilities, with some not focussing closer than a metre or more. I have some that do not focus closer than around 10m !
Fraser
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Another common field of view is the 50° that is pretty standard across hand held fire cameras. Chosen to make a rapid sweep of a room to make sure nobody is in there. 50° really is wide angle, pretty much in 'fish-eye' territory for a visible photograpic camera.
The lens focal lengths therefore have got shorter over time for the same field of view:
- 18mm (for the 20mm tube)
- 15mm (320x240 @ 50um)
- 6.3mm (160x120@35um)
- 8.6mm (320x240@25um)
- 4.3mm (160x120@25um)
- 6.3mm (320x240@17um)
Bill
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Thats really funny question, man) you made a topic about seeking birds, birds are really small and easily scared so everyone thought you need narrow angle, i even offered you to consider 50mm*384p*17m imagers with 7.5*5.6 angle. Now you need angle closer to 32 (seek writes diagonal angles afaik so its almost 21*28 like in hti) with monoculars there are 4 "grades" of angles, on 17m sensor they have focal lengths:
<24mm, if you need wide angle check iray dl13, iray cabin or phone dongles
25-34mm,
35-49mm, your agm imager is here because 12m sensors multiply focal length by 1.4
50+mm, thats really narrow, on 384 especially
you can begin with wider angle, it lets find targets easier and some imagers like 2 mentioned irays are really small. then you can find one with narrower angle. or you can buy helion xp and find 28mm lens for it or even wider if you can make adapter.