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The Skywatcher Evostar ED150 DS Pro Is Here !


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On 01/08/2018 at 17:08, Alan White said:

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No comment on your fashion choice or age John, but.....
My dear old Dad used to have a pair of pyjamas of the same print.

Lol, do you really want to get on the wrong side of a man of such stature. What height are you, John?.........6ft4?

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15 hours 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.

For only £12,000.00 more, you could save yourself packaging worries and buy a 152 triplet from that Japanese company. Their name eludes me momentarily!

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39 minutes ago, mikeDnight said:

For only £12,000.00 more, 

For less you could collect an ed150 at the factory. And probably get a tour around the plant. ?

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What a fantastic and detailed report, John - Thank you very much! 

It looks as though the good weather's going to continue for a bit longer (geographically speaking, we're more or less neighbours :)), so fingers crossed you get the replacement soon. 

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19 hours ago, FLO said:

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

 

And lo, it was so :smiley:

The replacement ED150 has just arrived and the original one is on it's way back. No thin plastic strapping on the new packaging and the outer box is in good order.

Now to get inside !

Thanks FLO :icon_salut:

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Thanks for a very excitings report /thread!

Does anyone know what ED glass is used in this scope? On the FLO site it only says that "The Evostar-150ED Apo has a different objective lens glass combination to the Evostar-80ED/100ED/120ED models. "

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51 minutes ago, gorann said:

Thanks for a very excitings report /thread!

Does anyone know what ED glass is used in this scope? On the FLO site it only says that "The Evostar-150ED Apo has a different objective lens glass combination to the Evostar-80ED/100ED/120ED models. "

Skywatcher have not disclosed the glass type used for the ED element in this scope. The crown element is from Schott. From my use of the scope so far I can see that the colour correction is very good for an ED doublet - at least as good as the ED120 as I said in my report earlier in this thread:

 

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I just wonder how long it will take before someone pushes the buy button on that returned, recollimated and reduced scope, once @FLO put it on their "offers" webpage. ?

(It won't be me unfortunately)

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17 hours ago, FLO said:

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

@John are you going to SGL star party? I can't really do the whole camping thing due to conflicting term holidays but always enjoy popping along for the day. I'd love to see and maybe look through the ED150 if FLO still have it on loan. A bargain no doubt but still a lot of saving for me to gamble on a scope I have only seen on a web page.

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6 hours ago, spaceboy said:

@John are you going to SGL star party? I can't really do the whole camping thing due to conflicting term holidays but always enjoy popping along for the day. I'd love to see and maybe look through the ED150 if FLO still have it on loan. A bargain no doubt but still a lot of saving for me to gamble on a scope I have only seen on a web page.

 

 

I think there may be a long line of persons at John's pitch if he is at SGL party , wanting a little look through the SW 150ed??

 

 

 

 

3 hours ago, dweller25 said:

Daniel Mounsey - an American astronomer (and US vendor) has compared the SW 150ED to a TEC 140 triplet and found very little visual difference.

https://www.focusastro.org/equipment-reviews

 

 

If that's the case then I think John is going to have a very long line at the SGL party wanting a little look through the bargain of the year ????????

 

 

 

 

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6 hours ago, spaceboy said:

@John are you going to SGL star party? I can't really do the whole camping thing due to conflicting term holidays but always enjoy popping along for the day. I'd love to see and maybe look through the ED150 if FLO still have it on loan. A bargain no doubt but still a lot of saving for me to gamble on a scope I have only seen on a web page.

I hope to at least visit :smiley:

 

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12 hours ago, dweller25 said:

Daniel Mounsey - an American astronomer (and US vendor) has compared the SW 150ED to a TEC 140 triplet and found very little visual difference.

https://www.focusastro.org/equipment-reviews

Very interesting read. What I'd like to know is, will it split Alnitak in LRGB? That's a real imaging test. We know that the TEC140 will.

But for imaging I'd want to put a better focuser on it, a 3.5" Feather Touch as a minimum.

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20 minutes ago, DaveS said:

Very interesting read. What I'd like to know is, will it split Alnitak in LRGB? That's a real imaging test. We know that the TEC140 will.

I don't think that's a great challenge. My 130P-DS will, it's about exposure, not aperture.

image.png.d5a15be739e18efa802adfef45829906.png

 

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1 minute ago, DaveS said:

Exposure, yes I've split it with my 130 f/7, but can you hold it while showing depth on the Flame and HH?

Thinking of the images posted by @ollypenrice.

Agree. If we're going down this road,  it's not just the scope, but also filters and processing. Hardly the scope of this thread. (Sorry for the pun.)

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13 hours ago, dweller25 said:

Daniel Mounsey - an American astronomer (and US vendor) has compared the SW 150ED to a TEC 140 triplet and found very little visual difference.

https://www.focusastro.org/equipment-reviews

Interesting review. He says "According to Skywatcher there are several adjustable screws on the side of the cell." I had the impression from John's review here that it could not be collimated. Are the Americans getting a different version?

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47 minutes ago, DaveS said:

Exposure, yes I've split it with my 130 f/7, but can you hold it while showing depth on the Flame and HH?

Thinking of the images posted by @ollypenrice.

Olly uses layers with different processing/exposures. I couldn't compete with is dark skies, let along processing skills...

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1 minute ago, gorann said:

Interesting review. He says "According to Skywatcher there are several adjustable screws on the side of the cell." I had the impression from John's review here that it could not be collimated. Are the Americans getting a different version?

The scopes are the same. The cell has hex screws that allow the adjustment of the centering of the lens elements but there is no provision to adjust objective tilt. The latter is usually achieved through push-pull screw arrangement using a cell and counter cell but Skywatcher have not built that into this design.

I can't comment on the imaging issues I'm afraid, just the visual performance.

 

 

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Ok. The replacement ED150 arrived as reported earlier in this thread. So how is it ?

Well the packaging of the replacement scope was in a much better state when it arrived. No signs of damage to the outer cardboard box beyond the normal wear and tear that a 20kg 1.5 metre long package will sustain in delivery. Opening the box I was pleased and relieved to see that the aluminium case was completely undamaged on all sides. Some more cardboard had been wrapped around the case and the thin plastic strapping around the outer box was not used so could not be used as carry handles by the courier. 

Opening the aluminium case I was also pleased to see that additional heavy duty bubble wrap had been added surrounding the scope tube and also that the tube rings had been rotated so that the camera mounting screw could not come into contact with the carry case walls. The additional bubble wrap would have helped ensure that the scopes movement during transport was much more limited.

Removing the ED150 from the case and stripping off the protective plastic bag and thin paper protection revealed a pristine scope in all respects. Excellent !

Given the less than perfect star test that the previous scope had delivered, I wanted to check the collimation of the replacement as quickly as I could. I used my collimated laser to check the focuser axis was in alignment with the centre of the objective lens and it was. The laser dot stayed pretty much central on the outer surface of the objective lens as the laser unit was rotated around 360 degrees.

I then used a cheshire eyepiece to check that the objective lens of the scope was not tilted. Oh dear !. The images of the illuminated 90 degree face of the collimator reflected on the objective lens rear element were quite separate indicating that the objective, or at least an element of it, was tilted. These reflections should overlap each other completely if things are OK . Things were definitely not OK with this ED150 objective lens collimation.

Here is an illustration of the project image of the cheshire eyepiece. Not what you want to see:

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Without a great deal of optimism I waited for darkness and the emergence of some stars suitable for star testing. The ED150 was outside for around 2 hours to allow it to fully cool before star testing. I wanted to be as fair as I could to the scope !

As darkness fell I mounted the scope up and turned it onto Vega and examined the star at 240x. The star test at focus and either side of focus very clearly told the same story as the cheshire image had. The objective collimation was a long way from what it should be.

One of the worst star tests that I’ve ever seen to be brutally honest. At focus the diffraction rings were all to one side of the airy disk of the star and were shaped like an arrow head with the airy disk at it’s tip and the rings flaring as they moved away from that point. The airy disk of Vega itself was not round but tear drop shaped. Not a good sign at all.

Either side of focus the disk of diffraction rings became roughly circular but were not concentric and the airy disk was well offset from their centre. The pattern reversed inside of focus.

Here is an illustration of what the at focus star test looked like – quite hard to find an example that was as bad as what I saw !:

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Very disappointing to see this, I can tell you. The pattern repeated itself with another test star, Altair, of course. No reason that it would be any different.

I had a quick look at Epsilon Lyrae, the famous “double double” star. The ED150 resolved the two pairs but each star had a little tail of tiny diffraction rings trailing from it even when at best and sharpest focus. Really not at all what a scope of this type should be showing.

I’d had enough of the ED150 at that point and took the scope off the mount, replacing it with my ED120 and I then proceeded to have some lovely views of various double stars, reminding myself what star images should look like with a very good refractor.

The following day I removed the ED150 dew shield to see if I could find any visual signs of issues with the objective lens. The objective appeared fine but I noticed that the top objective lens retaining ring was projecting above the rim of the cell and was not evenly showing at the top and bottom of the cell, ie: it was tilted by a couple of mm from top to bottom.

I recalled that the same ring on the original ED150 that I’d been sent was pretty much flush with the rim of the cell and was quite flat all the way around, ie: not tilted at all.

The retaining ring on the second scope was not only tilted but had been cemented in place using two blobs of cement (often normal practice) so I can only conclude that it left the manufacturer this way.

Here are some photos of the retaining ring in the cell from the side (top, bottom and the whole thing) which I hope show it’s tilted position:

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The objective lens itself did not rattle in it’s cell but other than that, without removing the lens from it’s cell I have no way of knowing what is causing the tilt or the extent to which the uneven retaining ring is a symptom or a cause of this.

Shoddy manufacture and quality control where it matters most I’m afraid.

I’ve not used the scope since the above tests were conducted. There seems no point in testing it further with such a compromise to it’s optical performance.

I’m really sorry that I could not post more positive reporting on the performance of the Skywatcher ED150. The scope does have real potential. It’s a simple design and it should be fairly straightforward for Skywatcher to execute consistently well as they have with the other ED Pro doublets and also the Evostar 150 F/8 achromat doublets which are out there in their 1000’s.

The optical problems with the first scope were quite possibly the result of damage sustained in transit. The problems with the second scope were much more severe but seem to be a result of simply not assembling the objective in it’s cell with any care or quality checking. Both these issues can be addressed of course but it will need the combined efforts of the manufacturer and the importer to address I feel.

It can be done. There are a couple of positive reports on the ED150 on the web now and I expect others will follow. Come on Skywatcher – lets get this one right, all the time. We have been waiting a long time for it after all !

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What a shame John. So much anticipation and potential, let down by the manufacturer.

Fair play to FLO for shipping out unchecked scopes, this sort of thing, and your honest reporting, will help to identify the problems quickly and we can only hope that they fix them as quickly.

Seems that FLO and other retailers need to be doing 100% checking on these at the moment :(

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