Using the canister for this purpose is an old trick. I used a piece of a 40mm diameter PVC tube, black canson paper for the spacer between the lenses and a film canister which fits nicely in the 1.25' tube of the scope. The realization of the eyepiece was easy. For example the Pleiades open cluster in Taurus extends 110 arcmin. This is useful for two reasons a) actually it substitutes the finderscope and b) large open star clusters may fit fully in the frame. I selected 34mm which gives a magnification 700/34= 20.6x and a large field of view of 146 arcmin=2.43 degrees. In the case of two identical lenses of 42mm the focal distance is between the limits 21mm < F < 42mm. The focal distance depends also on the actual distance of the two lenses (see relation). This is obtained by placing the convex parts facing each other. The simplest and probably the most standard design involving only two lenses is the Plossl. I found two planoconvex lenses with focal distance 42mm, probably from binoculars and I decided to make a low magnification eyepiece with them. Still, I intend to get a 5mm in the future. Furthermore it has a 42mm threading so that you can mount a DSLR camera and photo using the 'projection' method (see step 13 for discussion on this). I got an 8-24 zoom Celestron wide field which has become my main tool, since it covers the 20mm and 12mm eyepieces with a much better performance. I intended to buy a Barlow but the nice people at the shop advised me differently and I am glad I listened to them. The scope included three eyepieces a 20mm, a 12mm both adequate but not optimal and a 4mm (too much distortion and aberrations). A 5mm (140x) or a Barlow Lens x2 to use with the 10mm. If the scope had no eyepieces at all, I would buy at least three of them, the best quality I could afford :ģ. The rule for finding the maximum useful magnification is to multiply the diameter of the objective in mm x2 or in inches x50. You may magnify but you are not getting any more information from the image. A higher magnification is not so usefull because the resolution is limited from the size of the objective lens anyway. In the case of a 70mm/700mm scope one needs magnifications in the range x20-140. Now we arrived at the most critical point for a scope : eyepieces. Everybody's favourite Albireo in Cygnus (35 arcsec) is even easier to resolve in its two colourful components. For example Mizar A (magnitude 2.25) and Mizar B (magnitude 4.0) in Ursus Major, distant 14.5 arcsec is an easy target. I also have resolved double stars distant 8-10 arcsec apart, provided their magnitude is high enough. Saturn with this scope appears as an oval shape, no chance of seeing more features. To compare with, the apparent size of Saturn is 15-20 arcsec. The theoretical minimum feature size that a 70mm objective lens can resolve is ~2 arcsec. You may use a scope of this size and type to observe the planets (zones on Jupiter and satellites, the phases of Venus, Saturn, Mars), the moon, nebulas, clusters and double stars. The set included also an orthoscopic tube with a plastic lens in order to turn it into a spotting scope. Hanging a weight makes the whole system more stable.Ĥ. The main source of instability are the legs of the tripod. The guiding system that supports the scope is well designed and well made. Even a weak breeze will make the scope tremble. The tripod tries to do it all but there is a cost. A 2x Barlow lens for use with the 12mm eyepiece would be preferable but I suspect that at this low price the Barlow would not be good either.ģ. This was included in order to advertise 175x magnification. The 4mm eyepiece is inevitably of very low quality with plenty of distortion and chromatic aberrations. The viewfinder's lenses are plastic and diffuse light.Ģ. The viewfinder is not too secure on its holder but this can be dealt with.

The tripod works both as an Alt-Az and Equatorial. The 20mm and 12mm eyepieces are usable.ĥ. I tested the field of view with a Celestron 8-24mm zoom eyepiece and the result was about 90%.ģ.

Light weight, it will go anywhere, the biggest advantage.Ģ.

I summarize how I feel about it: ADVANTAGESġ. This scope has been included in a comparison test for 70mm refractives in the BBC edition 'Sky at Night ' November 2010. I found a lot of reviews and modifications for it, coming from Germany, Austria and England although for a different equatorial mount with a counterweight. I bought this small scope as a department store offer of LIDL in Athens a few years ago for 70 Euros (the current internet value is about 150Euros).

Homemade sun spotter telescope