At FYRLYT, we're passionate about delivering the best possible thermal imaging experience to our customers. That's why we recently created a video that challenges the common misconception that a larger sensor size automatically translates to better thermal imaging. In reality, it's the Pixels Per Degree (PPD) that truly matters.
The Misconception of Sensor Size
We've noticed a common belief that doubling the sensor size equates to doubling the resolution in a simple linear relationship. This misconception, often perpetuated by salespeople and influencers, has led to confusion among our customers who have reached out to us through phone calls and emails.
The Video Busting the Myth! Within 9 days of publishing this had driven 170,000 views. It was clear that we've struck a chord with consumers who are seeking transparency and honesty in the thermal imaging market. This reinforces our commitment to customer education and our dedication to providing products that truly deliver on their promises.
Understanding Pixels Per Degree (PPD)
PPD is a crucial metric in thermal imaging that describes the level of detail and image clarity a thermal device can provide. It represents the number of pixels captured by the sensor per degree of the field of view. A higher PPD value indicates more pixels are packed into each degree, resulting in a sharper and more detailed image, allowing for better target identification and recognition at longer distances.
Calculating PPD
To calculate PPD, you need to consider the sensor's horizontal resolution, lens horizontal field of view, and the pixel pitch (the distance between the centers of two adjacent pixels). The formula for calculating PPD is:
PPD = SENSOR PIXEL COUNT DIVIDED FOV (FIELD OF VIEW) Horizontal & vertical
For example, if a thermal scope has a sensor resolution of 640 pixels and a lens field of view of 8.8 degrees, the PPD would be approximately 72.73 pixels per degree.

1024 & 1280? What you need to consider.
This misconception has become even more widespread with the recent marketing of larger thermal sensors, such as 1024 and 1280, which are often touted as having superior resolution. However, what is not realized is that these larger sensors only offer a wider field of view. The only factors that increase resolution is larger lenses or tighter pixel spacing on the thermal chip.
So the actual gain in resolution from going from a 50mm to 60mm focal length is 20%, as validated by the detection distance. Still doubtful? Check the manufacturer's specifications in the data table above re detection distances. How much are you paying for the claim and what is the real world relevance for your use? Beware the big number fallacy.
When a 384, 640 and 1024 are Equal.
This means you can have a any scope with a 12um 384, 640 or 1024 sensor and 50mm lens and they will have identical resolution as confirmed by their detection distance. The difference is the larger the sensor the lower the base magnification and the wider field of view. Bring any of these scopes to same magnification re field of view and they are identical. You can prove this to yourself in the store. If you typically shoot with an optical scope on 5X or above this is where you can save yourself thousands of dollars and you lose nothing.
FYRLYT's Commitment to Transparency
At FYRLYT, we're actively involved in innovating, designing, and manufacturing thermal products for various sectors, including the consumer market, aviation, and heavy industry. This hands-on experience gives us valuable insights into the intricacies of thermal imaging technology, allowing us to educate and guide our customers effectively.
Questions? Advice? As always just ask our design team direct with no obligation. Get the right product for your specific needs based on facts not marketing.
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