OS-TM3932AO-SFP

Magnification  :8.95x——3.04x
Effective objective diameter (mm)  :32
Exit pupil diameter  (mm)  :3.57——15.7
Eye relief  (mm):72——83
Field of view Feet@100Y  :13.31——39.28
Diopter adjustment  :-2.2——+2
Center tube diameter  :25.4mm    
Water proof  （Yes/No） :YES    
Elevation travel  (MOA)  :±35
Windage travel  (MOA)  :±35
Click value :0.1MIL
Parallax Compensation  :10Y ～～∞    
Ocular tube diameter  (mm)  :Φ39
Length  (mm) :262.9
Weight (g)  :500    
FFP or SFP: SFP

In close range and short to medium range shooting equipment, the KROS-TM 3932 AO-SFP specification has become a popular choice for entry-level hunting, shooting training, and civilian security due to its lightweight design, fast aiming response, and convenient operation. Compared to high magnification and large objective lens models, its parameter system is more suitable for the core requirements of "close range search+medium to short range precision strike", especially in the collaborative design of AO focusing function and SFP focal plane, balancing practicality and cost-effectiveness.
1、 Specification Core Parameter Solution
The parameter design of TM 3-9X32 AO-SFP accurately matches short to medium distance usage scenarios, and each indicator serves the core logic of "quick discovery+precise targeting":
3-9X magnification range: 3x low magnification can provide a super wide field of view of 14 meters/100 meters or more, suitable for quickly capturing targets at close range of 20-100 meters (such as hunting in the forest encountering prey, multi-target switching in the shooting range); The 9-fold high magnification can clearly magnify the details of targets within 300-500 meters, meeting the requirements of precise shooting in medium and short range. The 3x zoom ratio operation is smooth and does not require frequent adjustments to cover the entire "search aim" process, making it particularly suitable for novice shooters and outdoor quick response scenarios.
32mm objective lens diameter: Compared to the 50mm large objective lens, the 32mm aperture achieves lightweight body, and with optical coating technology, the transmittance can still reach 90%. It can maintain clear imaging in daytime and low light environments (such as cloudy days and tree shade), perfectly balancing portability and basic optical performance.
AO (Adjustable Objective) objective focusing function: Parallax adjustment is achieved by rotating the knob at the end of the objective lens. The adjustment range is usually from 5 yards to infinity, making focusing more direct and efficient. Compared to SF (side focusing), AO focusing is more precise in adjusting close range (5-50 yards) and can quickly eliminate imaging offset caused by close range aiming. It is particularly suitable for indoor range training, close range hunting, and other scenarios.
SFP (Second Focal Plane): The differentiation line is fixed to the focal plane at the eyepiece end, and its size does not change with 3-9x magnification. This design makes the differentiation line clear and easy to distinguish during low magnification search, avoiding visual fatigue; The distance measurement and trajectory compensation scales of the differentiation line are only accurate and effective at the highest magnification (9 times), simplifying the operation logic and adapting to the usage habits of non professional users.
2、 Core performance and technological advantages
（1） Optical performance: Suitable for clear imaging in the medium to short range
This specification focuses on "lightweight+practical imaging" in optical design, taking into account both basic observation needs and portability:
Coating and Light Transmittance Optimization: Single layer anti reflective film or simple multi-layer coating is used to achieve light transmission similar to standard long sighting, and the target contour is clear and distinguishable within 200 meters in daytime environment. It can effectively reduce glare interference under strong light and adapt to backlit shooting scenes.
Field of view and imaging balance: At 3x low magnification, the field of view can reach 14-15 meters/100 meters, which is wider than the same magnification large objective lens model, making it easier to quickly lock moving targets; At a magnification of 9 times, the field of view is about 4.5 meters/100 meters. Although it is not as high as the high magnification model, it is sufficient to meet the precise aiming requirements within 300 meters. This design has significant advantages in forest hunting and close range tactical training, as it can quickly connect the "target discovery aiming shooting" process.
Advantages of Lightweight Structure: With a small objective lens and simplified optical system, the length of the lens body is controlled at 26cm, and the weight is only 300g, which is about 50% lighter than the 4-20X50 model, greatly reducing the weight of firearms. Long term aiming with a gun is not easy to fatigue, especially suitable for lightweight firearms such as AR-15 and small caliber hunting rifles.
（2） Mechanical structure: practical oriented stable and durable design
For short to medium range usage scenarios, the mechanical structure focuses on "reliability, durability, and easy operation" to reduce the threshold for use
Material and strength of the mirror body: 6061 aviation aluminum alloy is commonly used for integrated molding. After hard anodizing treatment, the impact resistance can reach 800G, and it can adapt to the recoil of small and medium-sized ammunition such as. 223 Rem and. 243 Win, meeting the durability needs of daily training and hunting. Some models have passed the shock resistance test and can still maintain structural stability when the laser sight and optical sight are designed together.
Simplified adaptation of the regulation system:
Turret design: It often adopts a "protective cover type simple turret" with an adjustment accuracy of 1/4 MOA, which is intuitive to operate and can be zeroed without complex calibration. Suitable for novice shooters to quickly get started.
AO focusing mechanism: The focusing knob on the objective lens end has clear patterns, moderate rotation resistance, and smooth adjustment from 5 yards to infinity. With the scale markings, it can quickly locate the target distance and is more suitable for close range rapid focusing than SF side focusing.
Environmental adaptability guarantee: The waterproof level generally reaches IPX6, which can cope with common outdoor environments such as rainy days and splashes of water; The anti fog performance is achieved through nitrogen filling, with no fogging phenomenon within the temperature range of -10 ℃ to 45 ℃, meeting the needs of most civilian outdoor scenes.
（3） Humanized design: lowering the threshold for entry-level operation
Differentiation and display optimization: The mainstream adopts duplex differentiation lines, with thick edges and thin centers, which are easy to quickly identify at low magnification and achieve precise targeting at 9x high magnification. Equipped with red dot center lighting, combined with 3-speed red/green light brightness adjustment, it can enhance differentiation visibility in low light environments and can be switched without complex operations.
Grip and adaptive design: The mirror body is equipped with a lightweight structure, allowing for one handed zoom and focusing operations. The exit pupil distance is 70-80mm, combined with a fixed eye cup, which can quickly obtain a complete field of view even if there is a slight deviation in shooting posture, suitable for users of different heights and gun habits.
3、 Applicable scenarios
（1） Core applicable scenarios
Short to medium range hunting: such as hunting squirrels and rabbits in the forest (20-100 meters), hunting small deer on the plain (100-300 meters), low magnification wide field of view for easy discovery of prey, 9-fold high magnification precise targeting of key points, AO focusing quickly adapts to close range targets.
Introduction and Training of Shooting: Suitable for beginners to familiarize themselves with the logic of sight operation, fixed differentiation line and simplified adjustment system to reduce learning costs, with 3-9x magnification covering the entire training process from close range fast shooting to medium and short-range precision shooting.
Civilian security and observation: Lightweight design makes it easy to install on security rifles, with a 9x magnification that allows clear observation of targets within 300 meters. AO focusing is suitable for different distance monitoring needs and can be quickly responded to in case of emergencies with laser sights.