SharpStar 140 Refractor

SharpStar 140

My Meade 127 Refractor served me well for many years, but for some time I was tempted by the wonderful big glass in 6" refractors. Also although I experimented with refocusing (see the 127 page) the blue halos around bright stars got me hankering after a better quality large triplet. To be fair to the Meade, the halos were reasonably acceptable, and in general the scope behaved very well.

During early 2022, I spent much time researching, but eventually accepted that a 6" triplet refractor (I favoured the Esprit 150 ED Pro) would simply be too heavy for my 'Star Party' EQ6 Pro mount, and as I attend a number of events it would be a shame not to be able to use a big refractor under skies darker than I experience at home.

So in the end the decision was made to settle for a 5.5" SharpStar 140 PH 910 mm focal length triplet APO from First Light Optics. At f/6.5 slightly 'faster' than the f/7 Esprit 150, and 'faster' again than the f/7.5 Meade 127. The new telescope was promoted as having two ED glass elements giving negligible chromatic aberration. It was checked and pronounced good by the well respected tester, Es Reid, and duly arrived on 31st August (2022). I was very fortunate in purchasing it just before a substantial price increase!

As always, click on the thumbnails for larger photos.

The large and heavy cardboard box landed on my doorstep courtesy of DPD around lunch time. I managed to manhandle the bulky thing into the house and attacked the sealing tape with my heart racing. Only to find yet another cardboard box inside! But opening that revealed the aluminium carry case nicely protected by durable plastic foam (not polystyrene) blocks. Top marks to First Light Optics (and of course Sharpstar) for their service and care.

The case itself is sturdy and well made with strong lockable catches, and comfortable carry handles (also one each end not shown here). No problems there.

So what was inside? The telescope was well protected by shaped foam. No finder or diagonal as expected, but space at least for the small finder I intended to use. Because it will (for me at any rate) always be on a GOTO mount, I won't be star hopping so don't need a big finder scope.

Out of the box with the focuser extended it's BIG! A slightly shorter focal length at 910 mm than my venerable Meade 127 which it replaces, so no longer, but thicker of course, and the 4" focuser is massive - smooth and solid. A very slight criticism. The substantial lens cap is not screwed on, just a push fit. And as soon as I lifted the telescope out of the box, the cap fell off. On to carpet fortunately so no damage. A judicious application of extra felt courtesy of hook and loop adhesive tape cured the problem.

Later. Some of the adhesive from the extra felt got onto the tube, spoiling the appearance, and the tighter cap was tricky to fit. So I eventually removed the extra felt, cleaned the tube and fitted a couple of plastic thumbscrews. Problem solved, much easier and properly secure.

The beautiful 140 mm 5 1/2" objective lens. Slightly green tinted coatings and minimal reflections. Looking good!

Because both my Observatory G41 and 'Star Party' EQ6 mounts have Vixen style dovetail clamps, the supplied Losmandy style dovetail had to be replaced. I ordered a solid 18 mm unit from FLO, knowing it wouldn't be long enough, but intending to swap it with the even more sturdy unit on my TMB 105. That was just long enough and there were even tapped centre holes on the tube rings, so just a matter of drilling one new hole in the dovetail and screwing firmly on with socket cap screws.

And here she is on my Observatory mount. Beautiful!

First Light Optics clearly have a sense of humour, with this sticker on the outer box. It is a well known phenomenon that new astronomical equipment boxes release magic clouds when opened. And it was definitely the case with this one - not only cloudy but foggy that first night. And the forecast was poor for the next few nights before the Moon became obtrusive again. So awaiting first light.

A little later on 2nd September. While waiting for a clear night and first light (starlight anyway, daytime tests already carried out, partly to align the finder scope), I decided it would be prudent to try the telescope on my EQ6 mount prior to a forthcoming trip to the Kelling Heath Star Party later in September. Hopefully no additional balance weights would be needed.

When I installed the new focuser on my Meade 127 I made an adapter for the field flattener which screwed onto the 63 mm focuser thread revealed when the push fit unit was removed. The focuser on the Sharpstar has a number of reducers, the smallest thread being 68 mm in diameter. So I made a new adapter. Not absolutely essential, but the 48 mm rear thread allows me to screw on the flattener and camera, thereby ensuring that the camera is square on to the telescope and of course secure.

An added bonus of the big focuser is that it has two rotators, one at the front and one at the rear. So with the main rotator set to give a comfortable position for the finder scope, the camera can be independently rotated. And the 2" diagonal which has a 48 mm thread in the front can also be screwed on. Of course whether the diagonal is push fitted or screwed on, it can be easily rotated using the rear focuser rotator.

So here is the telescope with my QSI camera and Starlight Xpress Active Optics unit fitted. In this case using the 2" push fit clamp. Just balances with the standard weights. This photo was taken with both axis clamps slack. As can just be seen there is about 1/2" of movement left on the balance bar. Phew!

Final check is the camera and flattener fitted. Until I do a star field test I don't know if the flattener will be needed, but just in case... The camera and flattener unit altogether weighs just under 2.5 Kg - quite a lump! But the focuser copes with it comfortably including the fine focus lifting it with ease. Still nicely balanced, and considering that the substantial lens cap weighs 300 g, all is well.

Here is the first deep sky image. Using the TS FLAT2 flattener successfully. Very poor sky conditions on 2nd September with haze and cloud, so would hope for a much better image in good conditions. QSI 683, Luminance and RGB all 3 x 2 minutes unbinned. But a good start. Full size

I was away on holiday for a week, returning on 12th September. And for once the night was clear, steady and cloud free, so I was able to do some more tests. Previously I had detected some astigmatism near focus, but now found that it only appeared when I used my Hyperion zoom eyepiece at maximum focal length of 24 mm. Zoom in to 8 mm and all was well, indeed very well. And no problem at all with my 8 mm Televue Radian. So it was all down to the eyepiece. Almost unnoticeable fringing on the fully lit edge of the bright (92%) Moon. Bright stars free of any chromatic aberration.

Intra and extra focal figures are almost identical. Not quite as good as my superb TMB 105 but very close, and certainly most acceptable. When Es Reid tested it he was very impressed, to quote First Light Optics he "spoke about it in glowing terms". I'm looking forward to many happy hours of use with this fine instrument.

The large and heavy cardboard box landed on my doorstep courtesy of DPD around lunch time. I managed to manhandle the bulky thing into the house and attacked the sealing tape with my heart racing. Only to find yet another cardboard box inside! But opening that revealed the aluminium carry case nicely protected by durable plastic foam (not polystyrene) blocks. Top marks to First Light Optics (and of course Sharpstar) for their service and care.
The case itself is sturdy and well made with strong lockable catches, and comfortable carry handles (also one each end not shown here). No problems there.
So what was inside? The telescope was well protected by shaped foam. No finder or diagonal as expected, but space at least for the small finder I intended to use. Because it will (for me at any rate) always be on a GOTO mount, I won't be star hopping so don't need a big finder scope.
Out of the box with the focuser extended it's BIG! A slightly shorter focal length at 910 mm than my venerable Meade 127 which it replaces, so no longer, but thicker of course, and the 4" focuser is massive - smooth and solid. A very slight criticism. The substantial lens cap is not screwed on, just a push fit. And as soon as I lifted the telescope out of the box, the cap fell off. On to carpet fortunately so no damage. A judicious application of extra felt courtesy of hook and loop adhesive tape cured the problem. Later. Some of the adhesive from the extra felt got onto the tube, spoiling the appearance, and the tighter cap was tricky to fit. So I eventually removed the extra felt, cleaned the tube and fitted a couple of plastic thumbscrews. Problem solved, much easier and properly secure.
The beautiful 140 mm 5 1/2" objective lens. Slightly green tinted coatings and minimal reflections. Looking good!
Because both my Observatory G41 and 'Star Party' EQ6 mounts have Vixen style dovetail clamps, the supplied Losmandy style dovetail had to be replaced. I ordered a solid 18 mm unit from FLO, knowing it wouldn't be long enough, but intending to swap it with the even more sturdy unit on my TMB 105. That was just long enough and there were even tapped centre holes on the tube rings, so just a matter of drilling one new hole in the dovetail and screwing firmly on with socket cap screws.
And here she is on my Observatory mount. Beautiful!
First Light Optics clearly have a sense of humour, with this sticker on the outer box. It is a well known phenomenon that new astronomical equipment boxes release magic clouds when opened. And it was definitely the case with this one - not only cloudy but foggy that first night. And the forecast was poor for the next few nights before the Moon became obtrusive again. So awaiting first light.

When I installed the new focuser on my Meade 127 I made an adapter for the field flattener which screwed onto the 63 mm focuser thread revealed when the push fit unit was removed. The focuser on the Sharpstar has a number of reducers, the smallest thread being 68 mm in diameter. So I made a new adapter. Not absolutely essential, but the 48 mm rear thread allows me to screw on the flattener and camera, thereby ensuring that the camera is square on to the telescope and of course secure.
An added bonus of the big focuser is that it has two rotators, one at the front and one at the rear. So with the main rotator set to give a comfortable position for the finder scope, the camera can be independently rotated. And the 2" diagonal which has a 48 mm thread in the front can also be screwed on. Of course whether the diagonal is push fitted or screwed on, it can be easily rotated using the rear focuser rotator.
So here is the telescope with my QSI camera and Starlight Xpress Active Optics unit fitted. In this case using the 2" push fit clamp. Just balances with the standard weights. This photo was taken with both axis clamps slack. As can just be seen there is about 1/2" of movement left on the balance bar. Phew!
Final check is the camera and flattener fitted. Until I do a star field test I don't know if the flattener will be needed, but just in case... The camera and flattener unit altogether weighs just under 2.5 Kg - quite a lump! But the focuser copes with it comfortably including the fine focus lifting it with ease. Still nicely balanced, and considering that the substantial lens cap weighs 300 g, all is well.