A Work Commenced May 26 2023
In Part I of my review, I described the general optical and ergonomic features of the Svbony SA405 20x-60x 85mm ED spotting scope. In Part II I would like to reveal more about its ability to incorporate different eyepieces as well as its imaging capabilities.
The zoom eyepiece accompanying the SA405 is removed simply by rotating the rubber sleeve at the base of the eyepiece housing anticlockwise which loosens the grip on the zoom, allowing it to slide up and out of the ocular interface. The photo below shows the rectangular face of the Porro prism just beneath an anti-reflection-coated optical flat situated immediately above it, which effectively seals off the optics from the ambient environment.
The nicely designed stops prevent any direct contact between the inserted eyepiece and the flat so there’s no chance of it cracking or scratching the glass. After inserting the new 1.25” eyepiece it can be tightened via a helical mechanism by rotating the rubber sleeve clockwise until its tightly fixed in place.
In the next series of photos, I‘ve attached a Sirius Plossl 7.5mm and a Celestron X-Cel 25mm- to the scope.
But by far the most versatile eyepiece I found for this scope is the Svbony SV 191 7.2-21.6mm zoom eyepiece offering a magnification range between 22.3x to 67x, so a modest gain in magnification over the original 20x- 60x. More on this zoom later.
Determining the Maximum Field of View Available to Ordinary Eyepieces using the SA405
The provided zoom serves up a maximum field of view of just under 2 angular degrees. I determined to establish whether I could expand this field by using fixed focal length eyepieces. In this capacity, I set up some experiments using both a Celestron X-Cel LX 25mm with a 60 degree AFOV. In theory this should have served up a true field of 3.1 angular degrees. In addition I tested a 32mm Skywatcher Plossl eyepiece which should serve up a field of 3.45 angular degrees(52 degrees AFOV). However, the effects of vignetting would likely come into play, restricting the true size of the fields generated by these long focal length eyepieces.
Accordingly, I measured the fields of these eyepieces by conducting a star drift timing test. In the wee small hours of a late May morning, under decidedly twilit conditions, I centred the bright star Altair with a declination of +8.87 degrees, so just above the celestial equator(well within the +/- 20 degrees required for accurate results), I timed how long it took for the star to reach the field stop and used these values to calculate the true field( times were actually doubled). The results I got were as follows:
25mm Celestron X-Cel LX – 3.05 degrees
32mm Skywatcher Plossl- 2.93 degrees
Comments: The Celestron eyepiece served up a field size in good agreement with its specifications. The Skywatcher, as expected, vignetted the field, delivering a field size pretty much indistinguishable from the shorter focal length Celestron. Since there is no material advantage to having a lower magnification with the same field size, the Celestron is the better eyepiece for dedicated low-power widefield viewing.
Experiences with the Svbony SV 191 7.2-21.6mm Zoom Eyepiece
The SV 191 7.2-21.6mm zoom is a very nicely designed eyepiece. The zoom motion is extremely smooth and continuously variable. It has twist up eyecups with excellent eye relief. Unlike the 20x-60x zoom that comes as standard with the SA405, the SV 191 can be used comfortably with eyeglasses throughout the entire magnification range. Another really neat feature of this zoom eyepiece is that it’s parfocal – or very nearly so. That means that only very minor tweaking is necessary if you decide to change magnification. Moreover, the SV 191 zoom tips the scales about 100g lighter than the supplied zoom, reducing the overall weight of the scope – surely a good thing when portability is to be considered.
Optically it’s very nice too. The image remains tack sharp all the way through the full magnification range. Contrast is very impressive with accurate colours coming through. The SA405 remains very well corrected for false colour using this eyepiece, as the image below illustrates.
On the evening of May 27, I took a simple handheld shot of the first quarter Moon at the 67x setting through my iphone7. I hope you’ll agree the image generated shows excellent details along the terminator with the magnificent Apennine Mountain range visible near the top of the image.
Zoom eyepieces have really come along way over the last decade or so. Having owned and enjoyed the Baader 8-24mm Hyperion zoom for astronomical applications, this nifty Svbony eyepiece delivers equally good images in my opinion but at a fraction of the former’s retail price. I picked this up for £58.99 on Amazon UK.
I took the opportunity to do some more star testing with this new eyepiece, taking advantage of its higher maximum power over the supplied zoom. Conducting several tests over a few nights of good, stable seeing, I’m confident to declare that its figure is a solid 1/6 wave P-V under-correction; an excellent result.
The SV 191 also afforded an excellent opportunity to see the effects of boosting magnification while observing a star field.
Starting at the 21.6mm setting, the sky is quite bright with only the brighter stars being visible. Racking the magnification upward allowed me to immediately see much fainter stars in the same field, as the sky became progressively darker; an easy and compelling way to see the dramatic effects of magnifying power on a telescopic image.
Higher Power Experiments and the Grey Heron that Came to Nest
I’ve tried using a few Barlow lenses to boost the power of the spotting scope in the hope that it can be called into play for higher power astronomical observing. The results I’ve achieved thus far are mixed. For example, by unscrewing a regular 2x Barlow lens housing and mating it to the either the SV 191 or a 10mm and 7.5mm Plossl eyepiece, I can get rather good images but only on nearby objects. The arrangement doesn’t come to focus on targets beyond abut 40 metres or so. Still, what I’ve seen thus far encourages me. There is more chromatic aberration in evidence, as expected, but the images remain sharp and well defined. I have ordered up a decent quality 4mm Plossl eyepiece that I hope to use to boost the magnification to 121x, thereby bypassing the need for a Barlow. I’ll report back on my findings once I’ve conducted those tests.
Over the last few weeks I’ve come to discover that there’s a Grey Heron nest within a stone’s throw of my back door. I was first alerted to this not by seeing anything, but by hearing it. One evening, as the dusk was darkening, I was setting up my 130mm Newtonian telescope for a night of double star observing. The air was filled with the sound of Rooks, many of which roost in the copse beyond my back garden, but every now and then, I heard an entirely different sound; a sound I had heard before – the sound of a Grey Heron!
It was coming from the trees immediately to the left of my house, but judging by how loud it was, it couldn’t have been more than a few tens of metres away. On another evening, I was coming back from a walk with my binocular, when I first sighted something unusual as I made my way through the swing park just across from my house. Something was fluttering in the conifer trees to the left of my back garden which caught my eye, but for a few days I was unable to make a definite ID. Finally one evening, I saw something that enthralled me: an adult Grey Heron flew over the roosting Rooks, creating one hell of a kerfuffle, as it landed in a medium-height conifer where I had previously pinpointed the sounds! This was the hard evidence I had sought! Grey Herons had indeed made a nest in these trees!
To say I was surprised would be an understatement!
I mean, Grey Herons are notoriously timorous, flying away at the mere sight of anyone coming within a hundred yards of them. At least that’s what I had experienced from a few years birding at one of my local patches up at Culcreuch Pond. Boy was I surprised to discover they were roosting in some trees just beyond my garden! But as I started to converse with some more knowledgeable neighbours of mine, they confirmed that these birds do indeed choose conifers to nest in.
On the sunny afternoon of Sunday, May 28, I picked up the scope astride the photographic tripod and made my way across to the swing park, setting up the instrument along a line of sight to the nest, some 150 yards in the distance. Zooming in using the SV 191 eyepiece I was delighted to see a youngster concealed among the branches. Racking up the magnification to 67x, I waited to get a better view, and my patience paid off, as the young Heron poked its long, slender neck upwards to have a look around. It was amazing! I ran down to get my wife and a next-door neighbour also joined in to have a gander at the sight. Indeed, truth be told, my wife didn’t quite believe me when I first disclosed my suspicions, but, as they say, seeing is believing! lol
I’m now thinking about how I can best image this bird before it flies the nest!
Using the Svbony SC001 Imaging Camera
Svbony also sent me their latest imaging camera, the SC001, with the SA405 spotting scope. This neat little device has a 2 megapixel chip, with a screw-on aerial that creates a WIFI hot spot which links to the SC001 camera App that can be downloaded free from the App store.
It’s dead easy to use. Simply insert the camera into the eyepiece interface, turn on the camera and open the App. The SC001 allows you to take single images or record video. The SC001 also has a built-in UV-IR blocking filter.
After playing around with the instrument for a few minutes, I set up the scope at the spot in the swing park where I had been scoping the young Heron the previous evening. I made sure to bring the zoom eyepiece to get my bearings, as the SC001 produces pictures with an image scale equivalent to the 60x zoom setting. Once the camera is switched on and the aerial attached you open the App and the camera begins delivering live images to your phone. Simple. The stored images must be downloaded to your photo gallery in order to get the full resolution details.
As luck would have it, the young Heron was active in the nest this evening, and after focusing carefully, I began taking a series of shots, three of which are shown below. All the images of the Heron(s) were taken on a warm sunny evening making imaging at long distance more challenging.
The reader will note that no image processing was conducted.
What an impressive piece of kit! So easy to use, small and easy to carry about!
As soon as it got reasonably dark on Monday May 29, I ventured out again with the SA405 spotting scope with the SC001 imager. Here’s a shot I took of the waxing gibbous Moon. The reader will note that this was the raw image delivered by the camera with zero processing.
As you can see the camera did a great job picking up those finer lunar details. The image scale is more like 75x though and not 60x as originally stated. I also note the amount of colour fringing is even less using the SC001 imaging camera, indicative that at least some of the already minimal amount of colour fringing was attributed to the use of the SV 191 eyepiece. Indeed, I was able to verify that the same level of colour fringing was captured using the supplied 20x -60x zoom eyepiece.
Conclusions & Recommendations
The SA405 is an excellent, high performance spotting scope, offering crisp, high-contrast images with minimal colour fringing consonant with its triplet ED billing. It can be used for purely visual work but also works well with modern Digi scoping methods, and when coupled to the SC001 imaging camera, it serves up excellent images with even better colour correction than that observed visually. The SC001 camera is a brilliantly designed device that can be used virtually anywhere, as it creates a WIFI hotspot with your mobile phone. and is small and lightweight for easy transport in the field. I would heartily recommend these instruments to both novice and advanced birders and naturalists who wish to get the very best bang-for-buck for their hard-earned cash. That’s got to be good news in these hard economic times we find ourselves in.
Dr Neil English’s new book, Choosing & Using Binoculars: A Guide for Stargazers, Birders and Outdoor Enthusiasts, will be published later this year.
24/6/23 Postscriptum: Svbony has compiled a short YouTube video presentation of some of the Images I captured through the SA405 and SC001 Imaging Camera!