Acuter ST20-60X80A Spotting Scope Review

The Acuter ST20-60x80A Angled Spotting Scope is part of their Pro series of entry level spotting scopes that still includes many high-end features and should appeal to first time spotting scope buyers, money conscious birdwatchers, general wildlife and nature observers, or those looking for a cheap scope for target shooting and even for the occasional look at the stars and moon.

Having just finished a review of the top of the range Acuter DS20-60X80A Spotting Scope, I took the Acuter's cheaper ST20-60x80A out of the box and was immediately impressed with just how much lighter it was. Lighter and about £100 cheaper, we are off to a great start, but how would it compare in all other areas? Read my full review below to find out:

The Body

Build Quality
Whilst I could not find any confirmation, I am pretty sure that the body of this angled (45 degrees) 80mm Acuter spotting scope is made from aluminium. Whatever the case, apart from being light (see the section on weight below), it feels really solid as well as robust which is great and definitely not like many other cheap spotting scopes in this price bracket have a definite plastic feel to them.

Most of the body (apart from a small section at the end of the barrel) is covered in fairly soft and nicely tactile rubber coating. Whilst it is not as thick as the armour that you get on some scopes, it should help protect the instrument from scratching and light knocks.

This coating fells great to hold, and definitely improves your grip on it and also has the added benefit of dampening down any sounds from an object like your watch or wedding ring connecting with the body when grabbing hold of the scope, which could frighten away some birds and other wildlife.

The mounting plate is fairly long and wide and considering the weight of the scope offers plenty of support. It only has one screw location where you can attach your tripod head to it, making it a little more difficult to get the balance exactly right. This should not really be a problem in most situations, but may be an issue when digiscoping for example where the extra weight of the camera and adapter can upset the balance of your scope on the tripod.

I like the fact that this plate is deeply grooved which really helped to keep it secure on my tripod head plate.

One thing to mention is that unlike some scopes, including the more expensive Acuter DS-Pro scopes, this scope does not come with a collar that goes right round the barrel that allows you to move the mounting plate, effectively changing the orientation of the eyepiece. For me this is not a big deal, but is something to take note of.

The scope also does not come with a extendable sunshade (dewshield), that are commonly found on a lot of scopes these days.

Waterproof
According to Acuter this scope is O-ring sealed as well as nitrogen purged (has the internal air replaced with dry nitrogen gas) which makes them waterproof, fogproof and provides dustproof protection. The supplied "stay on" cover (case) will also help with protecting your scope from the elements, for more on this take a look at the carry case in the included extras section

Focusing
Unlike more expensive scopes, the Acuter ST20-60X80A only has a single speed focussing knob, even so I found that focusing was smooth and fairly quick. As you would expect fine tuning the focus is a little more tricky than scopes that have a dual speed focussing mechanism, but it was in no ways bad.

The focusing Knob itself has a really nice soft rubber coating on it and is deeply grooved to help with grip, it is also nice and long, making locating it when you are looking through the eyepiece very simple.

When changing the magnification on the zoom eyepiece, you almost always have to refocus the image.

Rating for Body Construction Quality: 6/10

Weight
I took this angled Acuter ST20-60X80A out of it's box and I was immediately taken by just how light it was - taking a look at it's specifications my initial thoughts were supported as this Acuter scope weighs just 57oz (1615g), making it one of the lightest 80mm scopes that I have ever reviewed. I am not 100% sure, but I think aluminium is used for the body which apart from being fairly light is pretty robust.

For comparison and to put it into some sort of context, I have included the weights of a few other scopes:

• Celestron Regal 100 F-ED - This 100mm scope weighs 89ozs (2523g)
• Nikon EDG Fieldscope 85-A: - This 85mm scope weighs 71.6ozs (2030g)
• Acuter DS20-60X80A - This 80mm scope weighs 63.5ozs (1800g)
• Kowa TSN-881 - Incredibly this 88mm scope only weighs 53.6oz (1520g)
• Barr & Stroud Sahara 20-60x80 This 80mm scope weighs 47.97ozs (1360g)

Weight alone can sometimes be a little misleading as some of the lightest scopes on the market are also amongst the cheapest (and worst) - this is because some very light scopes use sub-standard materials in their construction that may be lighter, but are definitely not as durable. I can happily report that this Acuter that feels both robust and durable, but possibly not quite up to the standards of scopes like the Kowa TSN-881 that use magnesium bodies, but you must remember that they cost up to 10x the price of these.

Rating for Body Stats: 7/10

The Optics

The Prisms and their coatings
Acuter have used high quality BaK-4 prisms on this scope as opposed to the cheaper BK-7 ones sometimes found on cheap spotting scopes. This superior optical glass helps to produce clearer image and obviously this is what you want from your scope.

Lenses
The lens has been fully multi-coated which means all air-to-glass surfaces have received multiple layers of anti-reflective coatings which increases light transmission to produce a brighter image and therefore better low light performance.

Anti-reflective coatings can make a really difference on the brightness of the image produced. It is not uncommon for a scope with a smaller objective lens, but high quality anti-reflection coatings to outperform one with a much larger objective lenses, but with fewer or no coatings. Beware of these lower quality optics that will often only add multiple anti-reflection coatings to the outer surfaces of the lenses (Multi-Coated) and cheaper still are scopes that only have a single layers of anti-reflection coating added to the outer lenses (Coated). The very cheapest optics have no anti-reflective coatings at all and I highly recommend staying well clear of these.

The table below shows Transmittance by type of coating:

Rating for Optical Components Quality: 5/10

The 20x-60x (8-24mm) Zoom Eyepiece

This, like all Acuter Pro-Series Spotting scopes comes with a 8-24mm Zoom Eyepiece, which translates to a magnification of 20-60x using this eyepiece with this 80mm scope that has a focal length of 480mm.

It comes in it's own hard container and is attached to the scope by screwing the lock-ring into the thread on the body of the scope.

The zoom eyepiece is advertised as being multi-coated meaning that there are multiple layers of antireflection coatings on at least one lens surface (fully multi-coated have multiple layers on all air-to-glass surfaces) which helps with light transmission as well as image contrast.

As mentioned, the magnification is 20-60x using this eyepiece with this 80mm scope and would be 16-48x with the 65mm Pro-Series scopes that have a focal length of 386mm and 22.5-67.5x with the 100mm Acuter Pro-Series Spotting scopes that have a focal length of 540mm.

Depending on which magnification you are using, the exit pupil ranges from 4.1mm to 1.4mm

The Eye Cup
The zoom eyepiece comes with a soft rubber eyecup that is really comfortable even when pressed quite firmly against your face. Eyeglass wearers should fold down this eye-cup to enable them to use the scope without having to remove their glasses and still get the full field of view without any vignetting.

Digiscoping
A DSLR camera adaptor available for all models in the Acuter Pro-Series.

Optical Stats

Field Of View

Using the included 20x-60x (8-24mm) Zoom Eyepiece the field of view at 20x magnification is 35m @ 1000m (105 feet@1000 yards) and 17.5m @ 1000m (52.5 feet@1000 yards) when using the eyepiece at full 60x magnification. To try and put this into some sort of context, the FOV of the more expensive Acuter DS20-60X80A Spotting Scope is 37m @ 1000m (111 feet@1000 yards) at 20x and 19m @ 1000m (57 feet@1000 yards) at 60x magnification. The equivalent Nikon FEP-20-60x eyepiece attached to the very top of the range Nikon EDG Fieldscope 85-A, has a field of view ranging from 38-19m @ 1000m.

Close Focusing Distance
With a focal length of 480mm, it has a close focussing distance of 7.6m (25ft) which is a little further than the very best - for comparison the flagship TSN-880 series of spotting scopes from Kowa has a minimum focusing distance of 5m (16.4ft) and the Acuter DS20-60X80A Spotting Scope has a minimum focusing distance of 6.5m (21.3ft).

Eye-Relief:
The maximum eye-relief of 18 mm is pretty good and should easily be enough for most people who wear glasses.

Rating for Optical Stats: 6/10

Image Quality

Testing was carried out on a dull and overcast day as well as late afternoon, just before sunset. To make my opinions as objective as possible, I compared the view through this scope with that of my 80mm benchmark spotting scope, that I use for all my reviews.

Image Brightness
In terms of image brightness, these were to my eyes as bright as my 80mm benchmark spotting scope, and to be honest, I could not see any real difference between these and the more expensive Acuter DS20-60X80A Spotting Scope at the same magnification. Understandably they were not quite as bright as the 100mm Celestron Regal scope that I also happed to have with me at the same time and so because of this I rate them just above average in this department, which for me at this price point is pretty impressive.

More about Image Brightness & Low Light Performance
Good light gathering ability is important because quite often you will find yourself in situations where the lighting is sub-optimal, especially in thickly wooded or forested areas, early in the morning just before or at sunrise or late afternoon when most birds and other animals are at their most active. Scopes with larger objective lenses have the potential to take in more light and therefore have the potential to produce a brighter image.

You also need to take into account that the exit pupil will change depending on which magnification you are using - with the 80mm objective lens and a magnification set at 20x the exit pupil is 4mm, whilst at 60x it reduces right down to 1.3mm.

But no matter how much light your spottingscope gathers, it is no good if that light is not passed onto your eyes (transmittance) and this depends hugely on the quality of the glass and optical coatings and not just the size of the objective lens. Good coatings on the lenses and the prisms can in some cases double the amount of light that gets through the scope, when compared to those that have none or poor quality coatings.

Color Fringing
Considering that this scope does not use ED (extra low dispersion glass) or an achromatic lens, both of which help to limit the effects of chromatic aberrations (color fringing) I was really impress with just how little there was and what little there is is only really noticeable if you are really looking for it and so shouldn't bother you during normal use. To check for any, I focus on light coloured and white objects sitting in front of a dark backgrounds as this is where it is easiest to notice if there is any on the objects edges.

Softening
Whilst there is a small amount of softening of the image at the edge of the view, it is really not bad and I have seen worse on far more expensive scopes. Compared to the very best, which have almost none, you can notice the difference, but this will be one of the reasons why high end spotting scopes can cost 10x the price of these.

Contrast & Colour Reproduction
I thought that the amount of contrast was fairly good, but in poor light conditions and to my eyes I could see a slight improvement with the Acuter DS20. The colors that are produced look and feel pretty natural, but also possibly not quite as vivid as on a more expensive scope.

Overall I was really surprised and impressed with the view through this scope and whilst it may not be as good as ones at the very top end of the market, it was far better than I expected for a scope in this price range.

Rating for Image Quality: 6/10

Included Extras & Attention to Detail:

Carry Case
The soft "stay-on" carry case that comes with the scope is great. It is perhaps not as padded as some I have used, but it should be enough to protect your device from scratching and minor knocks. The fact that it can be kept on the scope whilst you are using it, even when attached to your tripod is excellent as this brings some extra protection to your scope from the elements, including light rain.

The case itself looks really well made and can be attached and taken off your scope really easily. It has Velcro fastened openings for the tripod mounting shoe as well as one that opens to revel the focusing knob on the scope. There is also an eyepiece and objective lens hood that can be closed when transporting your scope and then quickly opened when you want use it. The case also has a carry strap to make it easy to carry it when not in use.

Also included is a hard container to protect your eyepiece when you have removed it from the scope.

Lens Covers
The eye-piece cover is a small plastic cap that fits over the eyecup, which fits well and therefore should not accidentally fall off, the same can also be said for the hard plastic objective lens cap that clips into the end of the body and also fits really well.

A fairly basic instruction manual is also included that deals with assembling your scope, using the rubber eyecup, focusing, using the zoom eyepiece, storing and carrying the spotting scope.

Rating for Extras & Attention to Detail: 6/10

Conclusion

Strong Points: Considering the extremely low recommended retail price of just �149, I am amazed that this scope is so good. Sure you can't really compare it to ones that cost more than 10x this, but at this price I was expecting it to be a pretty poor scope. This is not the case, the quality of the waterproof body and the good quality optics that result in more than a decent view mean that in my opinion, this scope punches well above it weight. Speaking of weight, I also love just how light it is, which really helps on long walks.

Weak points? I could go on about how I wish this scope had extra low dispersion glass, or an even lighter magnesium body, but these and other similar improvements would only add to it's price tag. At this price point and comparing it to other low cost scopes, I would say that you are definitely are getting a good deal and as such there are no really bad points compared to other scopes in their class. Having said that, it would have been nice if the body had a sunshield and a duel focusing mechanism would have made fine tuning the focus just that much easier.

Ideal Uses: With the included 20x-60x (8-24mm) Zoom Eyepiece, this scope is ideal for a variety of uses including birdwatching, general nature and wildlife observation, target shooting and the fairly large 80mm objective lens means that you can even use it for casual astronomy.

So to sum up, the Acuter ST20-60X80A Speed Spotting Scope easily outperforms it's price tag and makes an excellent choice for anyone looking for a good all round entry-mid level scope.

Acknowledgements

I would like to thank Optical Vision Ltd. the UK distributor of Acuter Spotting scopes for sending this one to me to review. I would also like to point out that this and all the other reviews on this site are my opinion and are not influenced in any way by manufacturers, distributors or suppliers.

More on Acuter: Acuter is the terrestrial optics brand of Synta Technology Corporation, the owner of Sky-Watcher, a world-famous, market leading brand of Astronomical Telescopes. You can also read about this scope on the Optical vision website.