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The Skywatcher Evostar ED150 DS Pro Is Here !


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2 minutes ago, Ben the Ignorant said:

Why is there felt tape between the cell and dewshield if the dewshield does not slide?

To keep dust out of the hex screw holes perhaps and to keep things neat and tidy ?

 

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17 minutes ago, John said:

A further effect that I noticed was that the extra and intra focal star images had a very slight hexagonal form to the outermost ring of light. 

Hexagonal because the three sets of screws push too hard. I've seen the same effect in an achro that I optimized. To suppress play in the cell I put 6 shims that were too tight at the first trial. The hexagon showed more in the extra image than in the intra for some reason. Thinning the shims solved the problem. Try loosening the screws on one lens only first. If nothing improves, try the other.

While you're at it you might solve the decentering problem with an improv artificial star. It's best to have someone at the eyepiece and someone at the screwdriver, will make the process vastly faster.

Set one lens at a fixed position by driving all its screws at the same depth. Then only one lens has to be adjusted relative to the fixed one.

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37 minutes ago, John said:

I only use a dew shield with my ED120 when I'm observing away from my back yard. I don't seem to have dew issues here so I just have a light Astrozap ED120 dew shield extension. I don't have a dew shield that will fit the ED150. Sorry about that.

Having owned collimatable and non-collimatable examples of the Evostar 150 F/8's I know that the collimatable objective cell added a fair amount ot top end weight to the scopes which pushes the centre of gravity forwards quite noticably. Both the fitted dew shield and the objective cell weigh less in the ED150 than I would think.

If you can let me know what the dew equipment that you mention might weigh in total, I can see if I can add a suitable weight to the top end of the ED150 and see how that effects balance ? :smiley:

 

I'm showing 300g on my scales. That's a homebrew dew tape and dew shield so may differ a bit from commercially available tapes/ shields.

Thanks again mate.

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7 minutes ago, Ben the Ignorant said:

Hexagonal because the three sets of screws push too hard. I've seen the same effect in an achro that I optimized. To suppress play in the cell I put 6 shims that were too tight at the first trial. The hexagon showed more in the extra image than in the intra for some reason. Thinning the shims solved the problem. Try loosening the screws on one lens only first. If nothing improves, try the other.

While you're at it you might solve the decentering problem with an improv artificial star. It's best to have someone at the eyepiece and someone at the screwdriver, will make the process vastly faster.

Set one lens at a fixed position by driving all its screws at the same depth. Then only one lens has to be adjusted relative to the fixed one.

Thanks for the suggestions.

This won't surprise you but I'm not going to try any of this. The scope will be going back, either to be replaced or to have the objective adjusted by an expert.

I am looking forward to giving the ED150 another run out in the near future though :smiley:

 

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46 minutes ago, John said:

I think the ED150 is a really exciting scope but the example that I have been using is hampered by some sort of optical misalignment, likely the result of an impact in transit.

I confess I feared that when I saw the photo you posted earlier showing the damage to it's case when delivered. I guess because the Evostar 150ED's lens cell is larger and heavier than Sky-Watcher's other ED scopes, it is more likely to shift if bashed during transit. We are arranging collection and replacement as I type. 

Regarding the packaging (or lack of it) we have advised Sky-Watcher's UK importer/distributer who will relay the info to Synta/Sky-Watcher. Meanwhile, until we are confident the packaging has been updated all Evostar 150ED scopes (purchased at FLO) will be dispatched from our warehouse, not drop-shipped from the distributor's warehouse. This will enable us to open each one, rotate the tube-rings so the camera mount (on top of one tube-ring) cannot poke a hole through the case, add more packing where appropriate and remove the plastic straps that cut into the outer-box. 

Was very pleased (and relieved!) to hear your thoughts regarding handling and CA. It sounds a lot like a grown-up Evostar 120ED, which is what we have all been hoping for ? 

Steve 

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4 minutes ago, John said:

This won't surprise you but I'm not going to try any of this. The scope will be going back, either to be replaced or to have the objective adjusted by an expert.

It will be replaced. You might even receive the replacement tomorrow ? 

5 minutes ago, John said:

I am looking forward to giving the ED150 another run out in the near future though :smiley:

Excellent ?

Steve 

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I know on this occasion the courier should get 40 lashes but it's a shame they don't follow Bresser's thinking with their collimateable cells on refractors. Admittedly I'm not 100% sure their new 152 ED has a collimateable cell but I'm positive they do on the 127 ED. Thinking about it I am sure the APM 152ED has a collimateable cell. I guess cost has a lot to do with it and SW wanted to offer a 6"ED to us poor folk but personally when it comes to collimation in refractors I'd rather save that bit longer and pay that bit more and know I can correct for these little alignment issues that inevitably happen over time rather than forking out for a pro to do it or even worse just settling for a slight slip in performance.

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It might be worth mentioning that two recipients of the 150ED in America received them with damaged packing, one similar to the one John had delivered and one in a much worse state resulting in damage to the actual telescope. The strong consensus of opinion over there is that the packaging is inadequate.

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Fascinating report John . I don't think that many here would be able to cope with the deep snow of comments and suggestions ! As for testing ,easiest way is to look at your familiar best friendly targets and see what hatches . Silly that SW have let us down with possible transit damage.

Looks like a great scope which can handle the faint and the bright ! Contrast and colour will always belong to 4" fracs , but there's such charm in turning a refractor to the sky,

clear skies ! Nick.

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16 minutes ago, spaceboy said:

I know on this occasion the courier should get 40 lashes but it's a shame they don't follow Bresser's thinking with their collimateable cells on refractors. Admittedly I'm not 100% sure their new 152 ED has a collimateable cell but I'm positive they do on the 127 ED. Thinking about it I am sure the APM 152ED has a collimateable cell. I guess cost has a lot to do with it and SW wanted to offer a 6"ED to us poor folk but personally when it comes to collimation in refractors I'd rather save that bit longer and pay that bit more and know I can correct for these little alignment issues that inevitably happen over time rather than forking out for a pro to do it or even worse just settling for a slight slip in performance.

The traditional push-pull, objective tilt adjustments would not have helped here. The objective tilt was good. I checked it with both a laser collimator and a cheshire eyepiece. The ED150 lens cell does allow for adjustments to the centering of the lens elements relative to each other though but adjusting that is a more complex issue than sorting out the tilt of the objective. Decentering of elements can only be detected though a star test I believe.

 

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5 minutes ago, Peter Drew said:

.... The strong consensus of opinion over there is that the packaging is inadequate.

I think there is strong consensus on that over here as well ! :smiley:

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5 minutes ago, John said:

The traditional push-pull, objective tilt adjustments would not have helped here. The objective tilt was good. I checked it with both a laser collimator and a cheshire eyepiece. The ED150 lens cell does allow for adjustments to the centering of the lens elements relative to each other though but adjusting that is a more complex issue than sorting out the tilt of the objective. Decentering of elements can only be detected though a star test I believe.

 

Can you loosen off the objective and give it the old gentle tap all the way around to re-seat everything? Hypothetically talking of course as this is a loaner.

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Worth a try if it was your own telescope and you had damaged it yourself. It's probably not the way they set them up at the factory. ?

If FLO can get a replacement to John over the next couple of days it will give us all a chance to get our breath back.

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8 minutes ago, spaceboy said:

Can you loosen off the objective and give it the old gentle tap all the way around to re-seat everything? Hypothetically talking of course as this is a loaner.

The retaining ring is cemented in two places but I guess you could break that, loosen it, and try the old "slap the tube" method. I have used it with pre-owned refractors that I've bought. Achros though. The ED doublets that I've owned have not needed this treatment.

Also I'm not sure that would address decentered elements other than by lucky chance.

There is a method to deal more precisely with decentred elements but it's much better, in this instance, to allow an expert to sort it out.

Both the large Meade ED's (back in the 1990's) and the APM 152 ED doublets have suffered from such issues so Skywatcher are not alone in this challenge.

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1 hour ago, spaceboy said:

I'm showing 300g on my scales. That's a homebrew dew tape and dew shield so may differ a bit from commercially available tapes/ shields.

Thanks again mate.

The metal ED150 dust cap weighs a bit more than that and when thats on it only shifts the balance point a couple of cm or so.

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21 minutes ago, Peter Drew said:

It might be worth mentioning that two recipients of the 150ED in America received them with damaged packing, one similar to the one John had delivered and one in a much worse state resulting in damage to the actual telescope. The strong consensus of opinion over there is that the packaging is inadequate.

My colleague noticed that so we did mention it to Sky-Watcher's UK distributer, but it is good to hear you confirm it ? 

15 minutes ago, John said:

I think there is strong consensus on that over here as well ! :smiley:

We agree. Sky-Watcher's packaging for this model needs to improve. Until it does we will open and add packing material ourselves here at FLO. 

4 minutes ago, Peter Drew said:

If FLO can get a replacement to John over the next couple of days it will give us all a chance to get our breath back.

Already in hand. He will be back up and running again soon, hopefully in time for the weekend. 

Steve 

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Despite the unfortunate mall alignment it sounds really very promising! The fact that it seems to handle CA well despite being a much larger aperture than the ED120 is a big deal, I can't imagine controlling CA so well was an easy task to achieve, well done to Skywatcher.. once they've sorted the packaging issue of course. 

I guess once you've got hold of a correctly adjusted ED150, you can give some impression about SA control please, John :) 

Edited by Lockie
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3 hours ago, John said:

Thanks for your patience folks. I am working on something to post later today. I've a few pages of rather rough notes to mould into something vagely readable :smiley:

My other half seems to have some other priorities for me in the daytime as well - very unreasonable ! :rolleyes2:

 

John, you are already doing a Stirling job putting this newcomer through its paces, and yes there is a life outside of SGL.........so in your own good time sir

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Great job John. Let's hope it lives up to expectations. The sort of "collimation" system I think is on the scope is similar to the Meade 5000s and I damaged the glass trying to adjust mine as the pointed grubs bore straight on the edges of the elements. Will be interesting to hear how cold temperatures affect collimation with this sort of cell

 

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3 minutes ago, Moonshane said:

....Will be interesting to hear how cold temperatures affect collimation with this sort of cell

 

Thats a very good point Shane. It's rather the opposite of that now - when is the cold snap due ? :smiley:

Slightly ironic, in the light of the earlier jibes involving snow drifts :rolleyes2:

Who knows, maybe I'll still have an ED150 in the winter ? :angel:

 

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2 hours ago, John said:

Thats a very good point Shane. It's rather the opposite of that now - when is the cold snap due ? :smiley:

Slightly ironic, in the light of the earlier jibes involving snow drifts :rolleyes2:

Who knows, maybe I'll still have an ED150 in the winter ? :angel:

 

Shane makes a very good point. A number of issues with theses sorts of scopes only show themselves in more extreme conditions. Nice warm summer evenings are not really going to challenge the cell at all. You have just made a very good case for a longer term loan ;) 

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2 hours ago, Stu said:

Shane makes a very good point. A number of issues with theses sorts of scopes only show themselves in more extreme conditions. Nice warm summer evenings are not really going to challenge the cell at all. You have just made a very good case for a longer term loan ;) 

No problem ?

The new Evostar 150ED is an important telescope so a long-term review would be good, assuming John is happy to continue using it. Hopefully he will have room in his car so it can also be at the SGL Star Party. 

Steve

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