Optical Solutions Saim SCL35 thermal gunsight review

Mat Manning swaps monochrome night vision for red-hot signatures as he puts Optical Solutions’ Saim SCL35 thermal gunsight through its paces.

Thermal imaging optics open a whole new world to the air rifle hunter. Their ability to see heat makes them great for after-dark pest control when targeting species like rats and rabbits, but they can also be used by day when they offer some surprising advantages over a conventional scope.

One of those gains is the ability to spot quarry that would otherwise be virtually invisible in our normal vision spectrum; squirrels that are just peeping over a branch high in the canopy suddenly stand out like a sore thumb when you’re able to see their heat signature.

One of the factors that initially stifled the popularity of thermal imagers was their price. Not so long ago, you had to pay four or five times the price of a top-end air rifle for a decent unit, which isn’t exactly a tempting proposition.

Thankfully, things are changing and thermal sights like the Saim SCL35 (IRay) in this test are making this innovative technology a lot more accessible.

Supplied by Optical Solutions, the SCL35 retails for £2,595. Still far from cheap, any would-be owner needs to be able to justify the outlay before forking out that money, but this Saim unit is still a lot more affordable than many of its rivals.

Of course, the justification of that asking price depends on many factors. Firstly, your own budget and whether it will make a substantial difference to your shooting, but just as significantly how well it actually works and how easy it is to use.

Optical Solutions Saim SCL35: Specifications

FROM: Optical Solutions (www.opticalsolutions.uk)
MODEL: Saim SCL35 (IRay)
PRICE: £2,595
LENGTH: 193mm
WEIGHT: 410g
MAGNIFICATION: 1-4x (boosted to 8x with PIP)
OBJECTIVE LENS: 35mm
RETICLE: Adjustable (choice of colours and designs)
BATTERIES: 2x CR123
STATED MAXIMUM BATTERY LIFE: four hours
STATED DETECTION RANGE: 1,283m

Speaking from experience, all too many new pieces of shooting tech are so complicated to use that they can end up spoiling a shooting session. The SCL35 is not one of them and you may recall that I had great success using it to pick off some rats that were raiding the chicken run in my garden. I wrote then that this great little sight deserves a more detailed appraisal, so here we go.

I was impressed with the SCL35 as soon as I opened the box – initially because of its compact proportions. Affordable night vision and thermal sights have a tendency to be large and heavy, but this one is a relative tiddler; it weighs a very manageable 420g and measures just 193mm.

Supplied with a Picatinny-type mount, it made for a great combo with
my HW100 Bullpup, feeling very pointable when shouldered and not in the least bit unwieldy.

A nice thing about the supplied mount is that it’s not too high; a welcome feature when using a bullpup on which the scope rail is already a significant height above the barrel.

With the unit mounted to the Weihrauch, I couldn’t wait to get it up and running. Turn the dial on the left-hand side of the unit anti-clockwise and the cap pops off ready to accept two CR123 batteries.

The cap then snaps back on with a click to fasten it back in place – it even features a very handy little strap which means you can’t drop it on the ground and lose it if you have to switch batteries in the dark.

You can use 3v or 3.7v batteries – just select the corresponding setting on the menu so the on-screen battery icon displays the correct power level.

The SCL35 is simple to operate, and most functions are selected and adjusted by means of the three buttons on top of the device: the front one is the Power button, the middle one is the Menu key and the rear one is the Calibrate key. Press and hold the Power button for three seconds and the unit switches on; press and hold it for another three seconds and it switches off.

As soon as the SCL35 has powered up you can see the thermal image when you look through the eyepiece, which features a soft rubber cup.  Looking at the sight picture, you now use the focus ring in front of the eyecup to adjust the display until it is perfectly sharp for your eye – this is an adjustment you should only need to make once. Future adjustments to the focus are made using the ring at the front of the scope to focus in on targets over varying distances.

To customise the sight to your own personal preferences, there are lots of options. Give the Menu key a short press and the shortcut menu pops up. At the top of the screen you see the colour palette with options for White Hot, Black Hot, Iron or Rainbow effect.

The Power button now enables you to scroll through these and make your choice. Image quality is displayed at the bottom of the screen and you use the Calibrate key to shift between the four levels. Press the Menu key again and you move on to the next menu, which shows magnification from 1x to 4x at the top and four levels of brightness at the bottom.

Again, you use the Power and Calibrate keys to make your selections. Another press of the Menu key shows the third and final shortcut menu with reticle colour (white, black, red or green) at the top and four options of reticle design (offering numerous varieties of aim point) at the bottom.

As before, you select the configuration you want by scrolling through the choices with the Power and Calibrate keys. It’s quick and very easy, even for a technophobe like me.

If you’re feeling more ambitious, you can press and hold the Menu key to access the advanced menu. The opens up a whole host of additional options including Ultraclear Mode for use in heavy fog, rain or snowy conditions, Bluetooth connecting, video output (which you’ll need to activate if you want to attach an external recorder to capture photos or moving footage), battery mode, picture in picture (PIP) function, blind pixel correction and zeroing. In fairness, even the advanced menu is straightforward to navigate, and you use the Power and Calibrate keys as before.

The zeroing function is the most important feature on the advanced menu. Once you have selected this mode, you simply shoot at a target at your chosen zero range.

In normal conditions, pellet holes show as a warm spot for a few seconds, and while holding the marker spot on the bullseye, you simply shift the reticle to where the pellet struck in order to achieve single-shot zeroing. The Power key moves the reticle up and the Calibrate key moves it down.

Give the menu key a quick press and the controls switch so the Power key moves the reticle left and the Calibrate key moves it right. Once you have it where you want it, press and hold the Menu key to save and exit zeroing mode.

Although it is called single-shot zeroing, it actually took me three or four shots to get it dead right. That’s probably more of a reflection of my technical ability than the sight’s performance, but it’s still very good. You also have the option of saving four different zero profiles for different guns or different ranges.

That’s all the technical stuff you really need to know to get up and running, but how does the Saim SCL35 cut it in the field? I must admit that I initially had my reservations about just how effective it was going to be, but after a few outings I have to concede that it is actually very good.

My first session targeting live quarry was dealing with those garden rats – small, fidgety targets that will test any gunsight and shooter to their limits. I did initially wonder whether the maximum 4x magnification would be sufficient, but it actually turned out to be more than enough.

Incidentally, you can shift the magnification up and down with short presses of the Power key when you’re in normal shooting mode, which is very handy. And if you do need to give it a boost, the PIP function magnifies the reticle area by an additional 2x, effectively extending maximum zoom to 8x.

For the ratting assignment, I chose the white reticle and switched between White Hot and Iron (which I would describe as Red Hot) colour palettes, which worked excellently.

Though slightly pixelated on the highest magnification setting, the image was clear enough to be able to identify quarry and shoot with precision, and I experienced no lag. I don’t know the technicalities of this unit’s onboard InfiRay detector, but it certainly delivers the goods in terms of image quality.

The picture is not as good in the images I managed to capture as it appears when viewed through the eyepiece – especially the definition of the reticle – so don’t be discouraged by the shots shown here.

After sorting the rat problem, I moved on to after-dark rabbiting with equal success and have also accounted for a couple of treetop squirrels in daylight.

The Saim SCL35 is a very efficient thermal gunsight, and my only slight complaint relates to its tendency to gobble through batteries – a common problem with affordable electronic sights.

I was using it in video output mode so I could record with my Yukon external recorder (the SCL35 does not have an internal recorder) which increases power consumption, and it was still good for a couple of hours before new batteries were required.

And there is always the option of connecting an external power source via the supplied Type C cable, which would greatly increase the run-time of this device.

Another interesting feature of the SCL35 is that you can remove the mount and use it as a handheld thermal spotter. It certainly is pocket-sized, but it also comes with a tough carry case that has a shoulder strap, and if you press and hold all three control keys you can switch off the reticle and screen display for a less cluttered viewing. I was able to spot rabbits out to several hundred metres, and foxes even further away.

So, is it worth forking out more than two grand for a thermal gunsight to use with your air rifle? As I said at the outset, that really does depend
on your own preferences and whether you have the budget and pest control needs to justify it.

If you are one of those shooters who puts in the field time and has the disposable income to warrant such an outlay, then I would most certainly recommend this unit as one to consider. 

Airgun shooter verdict

More reviews from Airgun Shooter

• Brocock Sniper XR Laminate review
• Pellet review: Sniper Light
• The Hill Air Pump MK4 review
• MTC King Cobra review
• Weihrauch HW 110 STK review