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When I was testing the handy Delta Optical 50ED spotting scope, I borrowed from Delta several plossl and SWA-58 eyepieces to show how the whole set would perform. This time, with the Evostar 72 ED, I decided to use eyepieces from my private arsenal as they provide a bit better overview of different options, available on the market.

First, I attached the Explore Scientific 26 mm 62 deg, a waterproof, argon-purged construction with a field of view of 62 deg so a bit wider than in the case of the SWA-58 series. Unfortunately, it is also almost two times more expensive. Still, if you add it to the Evostar 72 ED you get in return the 16.2x magnification and a wide field of view, amounting to as much as 3.84 degrees.

I have to say that looking through such a set is a great pleasure. Image is very bright, with natural colours and, what's the most important thing, sharp in the centre and also on the edge of the field. The only thing that might disturb you a bit is slight chromatic aberration near the diaphragm but, fortunately, its level is so low that doesn't deserve any harsh criticism. Geometric deformations are corrected in a proper way - the eyepiece shows just slight pincushion distortion.

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The next eyepiece, an ordinary 17 mm plossl construction from the Celestron's Nexstar series, shows that you don't have to spend a lot of money in order to enjoy excellent images. In this case you get the 24.7x magnification and a field of view of 2.02 deg. Images are once again very bright, with quite natural colours. What's more, this time chromatic aberration is practically reduced to zero in the centre and negligible on the edge. Also it would be difficult to say something bad about sharpness of images – they are crisp and clear in the centre and remain sufficiently sharp on edges. The only flaw is a noticeable level of pincushion distortion.

The next model belongs to the real top when it comes to eyepieces. This time we attached the lantan Vixen LVW with a focal length of 13 mm and an apparent field of view of 65 degrees. As a result we got the magnification of 32.3x and a field of view of 2.01 deg. What about its performance? Images are very bright but they come with slightly yellowish hue. Chromatic aberration is corrected perfectly well in the centre but on the edge of that wide field it makes itself felt. We didn't notice any distortion for a change and sharpness was excellent across the field.

Then we decided to use the Baader Hyperion 8 mm with a very wide field of view of 68 degrees. It is a really complex optical system, with 8 elements positioned in 5 groups; because of that, it is able to ensure a very wide field and a very comfortable eye relief distance, amounting to 20 mm. In this case you also get the 52.5x magnification and the field of view of 1.30 degrees.

Results were brilliant – a surprisingly bright image with neutral colouring which seems just slightly warm. Chromatic aberration, like in the case of the Vixen, is very low in the centre but rather visible on the edge of the field. Distortion couldn't be noticed almost at all; we did notice excellent sharpness in 90-95% of the field. Only near the very diaphragm you could spot some mist.

Progressing towards shorter focal lengths and higher magnifications we attached the Explore Scientific 5.5 mm eyepiece with an apparent field of view of 62 degrees as the next eyepiece. Combined with the Evostar 72 ED it provides the 76.4x magnification and a field of 0.81 degrees that allows you to observe the whole face of the Moon or the disc of the Sun (but, of course, only with a special filter).

In case of budget equipment, a magnification that exceeds the diameter of the objective lens in milimeters is a real challenge for the optics; stiil the Evostar deals with it without any problems. Images keep a very sensible degree of brightness and natural colouring but, compared to smaller magnifications, you can already notice some graying. Chromatic aberration in the centre is very small, practically invisible, and not higher than medium on the edge of the field. When it comes to distortion you can notice its barrel variant. Sharpness in the centre remains very sensible and its decrease near the edge of the field is really small.

In this case the dual-speed 1:10 focuser showed its advantage. With such a high magnification you simply have to use micro focusing because only that system guarantees a good result and fine-tune sharpness according to your needs and expectations.

A time for a real challenge - we attached the 4 mm Sky Watcher SWA-58 that provides the 105x magnification and a field of view of 0.55 degrees, and marginally includes the face of the Moon and the disc of the Sun.

Here images should only be called grey – there are no miracles, an objective 72 mm in diameter has its limitations. In the centre of the field you can spot chromatic aberration in a form of light-purple colouring. Of course as you move to the edge of the field that effect becomes more and more pronounced. Still, image sharpness remain on a sensible level but it depends greatly on conditions of your observations. Even on the edge of the field of view the sharpness remains decent. When it comes to distortion you deal with slight barrel. Overall I can say without any remorse that the 4 mm device still manages to perform well but I would definitely avoid any shorter eyepieces. After all the 105x magnification or the 76.4x presented earlier, is quite a lot; in fact it's something every owner of a spotting scope with a brand-name zoom eyepiece can only dream of.