[selfbuilt]

Warning: pic heavy, as usual.



The SR51 is the latest member of the "small" class of SR-series lights from Olight. Unlike the SR90/91/92, the SR50/51 use standard batteries. In this case, you have the choice between 6x CR123A/RCR (with the standard carrier) or 2x 18650 (optional carrier).

Manufacturer's Specifications:

• LED: CREE XM-L U2 bin
• Max 900 lumens (OTF), 700 meters long throw.
• Battery: 6x CR123A or optional 2x 18650
• Optional Battery Bracket: CR123A batteries are standard, but optional 18650 bracket
• Working voltage: 4.5~8.4V
• High mode : 900 lumens /110 minutes
• Low mode: 250 lumens / 10 hours
• Strobe: 10 HZ
• Anti reverse battery polarity protection
• Two digitally controlled constant brightness levels and strobe, friendly user interface (press and hold the switch for transferring modes).
• Access to strobe instantly
• Excellent heat dissipation ability
• Highly water resistant to IPX-8
• Reflector: Mini Orange peel reflector
• Lens: Strong anti reflex coating lens, 99% effective transmission
• Head: Stainless Steel Bezel
• Material: Aluminum Alloy body, Mil-spec: MIL-STD-810F
• Anti-scratching type III hard anodization, Black
• Engineered anti-slip knurling for grip
• Dimension: D 63mm (2.48in) x L 190mm(7.48in), Weight: 400g
• Accessories: Includes one strap, one charger, one operator’s manual, one O-ring
• MSRP: ~$140

Packaging is high-end on the Olight SR-series lights. Inside the presentation carry case (with metal hinges and closing clasps) you will find the light, diffuser cap, wrist lanyard, belt-pouch, extra o-rings and manual – all securely packaged in cut-out foam.




From left to right: AW Protected 18650, Olight SR51, 4Sevens S18, Sunwayman M60R, 4Sevens X10.


From left to right: AW Protected 18650, 4Sevens S18, Olight SR51, Olight SR92, Olight SR90.

All dimensions are given with no batteries installed:

Olight SR51: Weight: 405g (505g with 6xCR123A), Length: 190mm, Width (bezel) 62.0mm
4Sevens S18: Weight: 700g (800g with 6xCR123A), Length: 233mm, Width (bezel) 63.0mm
4Sevens X10: Weight: 156.9g (245.7g with 1x26650), Length: 135.5mm, Width (bezel): 46.0mm
Eagletac M3C4 XM-L: Weight: 348.0g, Length: 164mm, Width: 61mm (bezel)
Sunwayman M60R: Weight: 262.0g, Length: 163mm, Width (bezel) 57.2mm

The overall weight of the SR51 is in keeping with its size (i.e. substantial, but not overly hefty). It is definitely toward the larger end of 2x18650 or 6xCR123A XM-L lights, but not as large as the SST90-based 4Sevens S18.










The styling of the SR51 is in keeping with the high-output SR-series lights, but without the built-in battery pack. Ridge detail is fairly high on the handle, so grip is good. Anodizing is a matte black, no chips on my sample (manufacturer claims hard anodized = type III). Lettering is sharp and clear, in bright white against the dark black gloss background.

Screw threads are square-cut and anodized at the head, to allow for lock-out.

The standard battery tube is reminiscent of the 4Sevens S18, but is removable here (there are also a few less contact points on the head). It fit 6x CR123A or RCR comfortably (but firmly). Note the carrier is mainly made of plastic. Given the parallel channel arrangement, you should be able to run the light with only 4x or 2x cells - but I wouldn't attempt this on anything other than Lo.

The optional 2x18650 tube holds two batteries, side-by-side. Design seems substantial, but also has all-plastic end-pieces.

NEW: Normally at this point in the review, I like to show the beamshots. But I’m trying something new - video reviews showing both the basic build and user interface. Beamshots will follow after the user interface and circuit discussion.

Прямая ссылка на видео YouTube

Videos were recorded in 720p HD, but YouTube defaults to 360p. Once the video is running, you can click on the 360p icon in the lower right-hand corner, and select the higher 480p or 720p options, or even run full-screen.

User Interface

The SR51 has the same straightforward interface as the SR90/91/92 - press and release the blue button to turn on. Press and release again to turn off.

While on, press and hold the button for 1 sec to switch between the Lo and Hi output states. The light has mode memory, and retains the last output setting for when you turn it back on.

To activate the “hidden” full-power strobe mode, do a quick double-press while on.
Repeat to switch back to constant output modes.

PWM/Strobe



Strobe on the SR51 is a typical fast "tactical" strobe at 9.6 Hz. This is the same as the early SR92 I recently reviewed.

There is no sign of PWM on Lo, I believe the SR51 is current-controlled.

Beamshots:

And now the part you’ve all been waiting for.



The SR51 uses a Cree XM-L emitter (well centered on my sample, with a masking disc around it). Reflector is a medium orange peel (textured reflector). Given that the reflector is fairly deep, I would expect throw to be pretty good.

The overall dimensions look very reminiscent to the 4Sevens S18 – in fact, the bundled SR51 diffuser cover will also fit over the S18 bezel.

And now the white-wall beamshots. All lights are on max output, on their typical battery configuration (6xCR123A for the SR51). Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.













The SR51 has a well-defined center hotspot, with a wide spillbeam. Overall effect is very similar to the Eagletac M3C4 XM-L.

I have now done 100-yard outdoor beamshots, in the style of my earlier 100-yard round-up reviews:



Output is clearly in a different class than the SR90 and SR92.





Again, overall beam profile looks a lot like the M3C4 XM-L.

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

I have recently devised a method for converting my lightbox relative output values (ROV) to estimated Lumens. See my How to convert Selfbuilt's Lighbox values to Lumens thread for more info.

Throw/Output Summary Chart:

Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1... for a description of the terms used in these tables.



No surprises here - the SR51 is again very comparable to the Eagletac M3C4. Output and throw are very respectable for this class of light.

Output/Runtime Comparison:




Interesting take-home message here – the 6xCR123A SR51 is a pretty close comparable to the 26650-based 4Sevens X10 in output and runtime. Of course, it is also a much larger light with greater throw.










Overall output and runtime is excellent for the class - consistent with a current-controlled light at these levels.

Runtime on 2x18650 is similar to other recent lights on that battery arrangement.

On 6xCR123A, you typically get even longer runtime that 2x18650 (of course, that depends on specific battery capacity). Regulation remains excellent on primary cells.

6xRCR shows good performance (for the lower capacity of RCR).

Potential Issues

Light is larger than most lights in this output class (especially if running on 2x18650).

Holster is serviceable, if a bit basic.

No real Lo mode (i.e. still above 200 lumens on Lo).

Preliminary Observations

The SR51 is something of an intermediate Search and Rescue-style light. Not as high output as the SR90-92 class lights, it still packs a pretty good punch for its size. And it has the advantage that it can run on all possible configurations of standard batteries – 6x CR123A/RCR or 2x18650. For that matter, you could probably get by with 4x or 2x CR123A/RCR configurations (though only on Lo).

Styling is similar to the other Olight SR-series lights, and gives the light a substantial feel. True, it is larger than most lights of this class, but that's mainly to accommodate the good size reflector (for decent throw) and the 6x CR123A/RCR arrangement.

Comparing it to the 4Sevens line (with which it shares some common ancestry), the SR51 is intermediate in size between the X10 and S18 Maelstrom-series lights. Output is clearly closer to the X10 class – but with a prettier beam and greater throw.

Performance is excellent on both output levels and on all battery types tested - great regulation and runtime across the board.

Olight has also chosen to keep the interface the same among the SR-series lights, so you always know what you are going to get. I think the solid implementation of the two-modes (with a hidden strobe) continues to be a positive for the keep-it-simple crowd.

Of course, given its size, this light isn't going to appeal to the EDC crowd. It is meant to be a S&R light – and one that runs on a wide range of batteries, including both primary CR123A and rechargeable Li-ions. If that's what you are looking for, the SR51 is worth your consideration.

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SR51 provided by Battery Junction for review.