22C-D012N103

22C-D012N103

22C-D012N103

22C-D012N103

可变光圈镜头是指大光圈会随焦距变化的变焦镜头。回想一下什么是光圈：允许光线通过的光孔，用焦距的倒数来表示。所以，100mm焦距镜头f/2.0光圈表示孔径是50mm（译注：应为入瞳直径）。

让我们对28-135mm f/3.5-5.6镜头做一个数学计算。在28mm，你可以使用f/3.5光圈，28/3.5=8mm.当我们变焦到135mm，大光圈是f/5.6，孔径是135/5.6=24mm。

那为什么不能做成恒定f/3.5的光圈呢？在135mm端，f/3.5需要38mm孔径，为了控制镜头的体积，所以不能做出这么大的光圈。

可变光圈不好吗？

很多所谓的“专业”摄影师不愿意用可变光圈镜头，但其实并没有什么理由应该如此：可变光圈是一种妥协，但所有镜头设计都是妥协。与恒定光圈镜头相比，可变光圈镜头有一些很明显的优势：它们更轻，更小，而且便宜得多。

Modicon PC-0984-680 Programmable Controller PC-0984680

Siemens ITE Breaker ED63B030 30 A 30A Amp A01ED64 Aux

Siemens ITE Breaker ED63B050 50 A 50A Amp 50Amp

Modicon AEG AS-B802-008 115 VAC Output ASB802008

GE Fanuc IC600YR550L Rack Chassis IC600YR550-L

GE 8000 Series Size 1 Breaker Type MCC Bucket MCCB 7A

Square D I-Line FA22020AB FA22020 20 Amp 20Amp series 2

Square D I-Line FA22015AC FA22015 15 Amp 15Amp series 2

Square D MAL36300 300 Amp 300A A MAL-36300

Square D I Line ME ME36600LIG ME36600 800 Amp Frame

Square D I-Line Breaker KHB36225 225Amp A 225A NIB

Square D I-Line FA24020BC FA24020 20 Amp 20Amp A 20A

Square D I-Line FA26020AB FA26020 20 Amp 20Amp A 20A

Square D I-Line FA24020BC FA24020 20 Amp 20Amp A 20A

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LAMBDA SE-250-3 115VAC 5A Regulated Power Supply SE2503

ITE Sentron Series Breaker HF63F250 125Amp A 125A Trip

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ITE I-T-E Circuit Breaker KP3-F120 KP3B800 800Amp 800 A

ITE I-T-E Motor Circuit Interrupter E63A050 50 Amp 50A

ITE I-T-E Motor Circuit Interrupter E63A025 25 Amp 25A

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ITE I-T-E Motor Circuit Interrupter E63A005 5 Amp 5Amp

Reliance Electric 2GU41100 100HP GP2000 VS Drive 100 HP

GE 8000 Series Size 1 Breaker Type MCC Bucket MCCB 15A

GE Fanuc IC600YR560L Rack Chassis Plus I/O IC600YR560-L

Cutler Hammer WH JD3250F JT3200T JD3200 200 A ST/Aux

De-Ion Westinghouse NB38000PF 600 Amp A 600AmpTri-Pac

Westinghouse SPB 100 Pow-R Breaker SPB100 1600 Amp A

Westinghouse Breaker HLC3600F 600 Amp A 600A 600Amp

Westinghouse Breaker MCP MCP0322RC 3Amp A 3A Amp Trip

AB De-Ion Westinghouse 600 Amp A Tri-Pac ( NB3800PF )

Westinghouse Circuit Breaker MCP03150C 15Amp A 15A Amp

Westinghouse Circuit Breaker MCP0358R 7Amp A 7A Amp Aux

Westinghouse Breaker NB3800PF NB 400 Amp A Trip Tri-Pac

Westinghouse Breaker HFB3110ML HFB3110 10Amp A 10A Amp

Westinghouse Seltronic HMC HMC3800F 800 Amp A 800A

Westinghouse Circuit Breaker MCP13300R 30Amp A 30A Amp

Westinghouse Circuit Breaker 46A8101G21 200Amp A 200A

Westinghouse Circuit Breaker MCP0322R 3Amp A 3A Amp Aux

Westinghouse Circuit Breaker NC31200F 1200 Amp A 1200A

Westinghouse Breaker HFB HFB3025 25Amp A 25A Amp 25

Westinghouse Breaker HFB HFB3060 60A A 60Amp 60 Amp

Westinghouse Seltronic HNC31200F 1000 Amp A 1000Amp

Westinghouse Breaker FD3070LF 70 Amp 70A A 70Amp

Westinghouse Circuit Breaker MCP03150R 15 Amp A 15A Aux

ntum Hot Standby  双机热备 

140CHS11000 Quantum

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Quantum Power Supply  电源模板 

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