89 replies to this topic

[barbie]

I wouldn't expect most 6" f/8 achros to be any better than 1/4 wave p-v, with anomalies up to 1/8 wave I'm sure. Same for the Evostar 150ED. Jim Barnett estimated his was around 1/4 wave. If both scopes are probably gonna fare no better than 1/4 to 1/6 wave (I'll be generous), the scope with less CA is the better choice for planetary and lunar viewing. I agree, though, that a good figure is significantly more important than good CA correction, but ideally you get both a good figure and good CA correction. And that's where prices really start to go up.

Great optical figure and good CA mitigation don't have to cost an arm and a leg.  My SW 100ED has both an excellent optical figure and no CA on bright objects and I didn't have to pay thousands of dollars for it.  The last SW 4" F9 apo I had six years ago also had both excellent figure and no CA so they've gotten this particular scope model, at least, to have the best of both and on a fairly consistent basis.

Edited by barbie, 12 February 2019 - 12:06 AM.

[SeattleScott]

The 100ED is also a very mature product. The 150 is quite new, so Jim estimating 1/4 pv isn’t necessarily surprising. There isn’t a consensus yet for the optical quality of these scopes, so if you want to be confident of great figure and and CA control, it can cost an arm and a leg.

Edited by SeattleScott, 12 February 2019 - 12:11 AM.

[barbie]

For now on the ED150 perhaps, but once they've been in production for awhile(and have all the bugs worked out) and are a mature product, I suspect that they will be excellent, at least far better than 1/4 wave.

Edited by barbie, 12 February 2019 - 12:41 AM.

[Jeff B]

Great optical figure and good CA mitigation don't have to cost an arm and a leg.  My SW 100ED has both an excellent optical figure and no CA on bright objects and I didn't have to pay thousands of dollars for it.  The last SW 4" F9 apo I had six years ago also had both excellent figure and no CA so they've gotten this particular scope model, at least, to have the best of both and on a fairly consistent basis.

True that.  My Orion 80ED has one of the best figures I've run across and I've the DPAC results to prove it.

 

But I feel the APM and SW 150ED doublets are a much more difficult design to execute properly due to finding good glass in that large of an aperture and designing and making a lens cell that can accurately hold the very steep internal lens radii concentric over a wide range of temperatures and handling.

 

I'm going to have try out one of the SW 150ED's one of these days.

 

Jeff

Edited by Jeff B, 12 February 2019 - 02:02 PM.

[25585]

I've actually used a couple of Skywatcher ED150's in their basic trim (as I think you know) and they seemed fine to me in terms of practicality. The tube rings, dovetail bar and focuser did their job pretty well. Don't judge them as inadequate until you have personally tried them I suggest.

I would want only the OTA, as one purchase, then buy the DX rings and tube as its only mounting hardware. I do not want to pay for the budget set, just that.

 

SW offer the DX spec scope in the US, not yet in the UK. So OTA only....

[CHASLX200]

True that.  My Orion 80ED has one of the best figures I've run across and I've the DPAC results to prove it.

 

But I feel the APM and SW 150ED doublets are a much more difficult design to execute properly due to finding good glass in that large of an aperture and designing and making a lens cell that can accurately hold the very steep internal lens radii concentric over a wide range of temperatures and handling.

 

I'm going to have try out one of the SW 150ED's one of these days.

 

Jeff

I will try one out as well.

[MSWcdavis]

What’s the cheapest equatorial mount to offer sub 2 second dampening time at 200-250x for this scope?

A solid command of the scope - does it have to be a g11? How about at Atlas?

[CHASLX200]

What’s the cheapest equatorial mount to offer sub 2 second dampening time at 200-250x for this scope?

A solid command of the scope - does it have to be a g11? How about at Atlas?

A used non GO-TO G11 is not that much and did fine with my 6" APM F/8 ED and a 80mm finder.  Atlas will be maxed out i would think.

[jay.i]

I think an Atlas would have no problem with it. Remember, they state a 40lbs capacity. This tube is what, 20? Add another 4lbs for finder, diagonal, and 2" eyepiece... that's nothing. My Atlas Pro (same capacity) doesn't break a sweat with 20lbs on it, granted that was with a shorter tube. Still, the 150ED is light for a 6" refractor. An Atlas or G11 would be just fine. I wouldn't go smaller, though.

[John Huntley]

I would want only the OTA, as one purchase, then buy the DX rings and tube as its only mounting hardware. I do not want to pay for the budget set, just that.

 

SW offer the DX spec scope in the US, not yet in the UK. So OTA only....

Well drop OVL (the importers) a line and see what they can do for you.

 

Maybe you could get them to include some sets of the Primaluce tube rings and DT bars to match your Tak ?

[Bomber Bob]

What’s the cheapest equatorial mount to offer sub 2 second dampening time at 200-250x for this scope?

A solid command of the scope - does it have to be a g11? How about at Atlas?

Well, for less than $400, I converted a vintage 1980s Meade StarFinder to a 5' pedestal:

 

 

Damping time is less than 3" at 400x in my APM 152ED.

 

Or, when I want zero damping times, I can use this antique Tinsley:

 

 

(Neither mount has go-to -- thankfully!  The Meade is battery-powered, and much easier to move than the Tinsley.)

[hfjacinto]

What’s the cheapest equatorial mount to offer sub 2 second dampening time at 200-250x for this scope?

A solid command of the scope - does it have to be a g11? How about at Atlas?

I have mine on a G11.

[ATM57]

For anyone interested, I joyfully received a Sky-Watcher Evostar 150 ED 4 days ago. The seeing conditions since then have not been kind (darn telescope gods) but last night, after the clouds cleared, the seeing unexpectedly settled down to about 7-8/10. Scope verdict: Absolutely stunning glass! As others have noted, once cooled, this lens is incredible. Who gives a flip what the glass elements are made of! With crisp images like this, I don’t care!  DR. D, you were right!

 

After initial setup, and peering through the sucker holes in the clouds, the scope star tested out to about 1/5th wave @240X (according to Suiters book images, Ronchi, and Aberrator 3). Just an average scope. Testing again, after about an hour or so after the parting of the clouds (about 90min after sunset), revealed a smooth, highly corrected optic that almost knocked me off of my observing chair. WOW is truly the word for expressing this telescope's performance!

 

Using a 250lpi etched glass grating (@two bands on both sides of focus), and star tests (375X), revealed what appeared to me as a smooth 1/8th wave of total correction. It was actually better than this but most are not going to believe that conclusion without an interferometer image. They probably won’t agree my visual assessment either but I know what I have seen. No zones, astigmatism, edge defects, or roughness. This lens is so good that I was able to clearly test it at a mere two rings in the out of focus diffraction pattern (very critical). Just incredible! After all the scopes I have built or owned over the past 40 years, I can remember only a handful that could do this “cleanly.”

 

In focus stars (after cooling) revealed no false color to these 67 year old eyes, all the way up to 375X. Venus was surprisingly good. The very minor false color I did see came from seeing tremors. I had the same result with the moon. For the type of observing I do (moon, planets, multiple stars), this scope is “off-the-chain.” I’m looking forward, with great anticipation, to a night of good seeing and the coming evening planet parade.

 

I’ve been doing the "scope thing" for a long time (over 40 years). This has to be one of the best, if not the best, star test I have ever seen in a refractor of this size or greater. The star tests reminded me of a visual star test I performed on a ridiculously good 4” Alvan Clark up on Mt Pinos. The test image was very close to what you see when you reduce a scope’s aperture to about 1” to see a perfect out of focus diffraction pattern. The area of precise focus on this scope is so tight that using the 10 to 1 focus knob is a requirement, not an option. After some minor focuser rework (smooth as glass and now holds my 2" prism diagonal without slippage), this scope is about as close to optical perfection as this lowly scope user dares to get.

 

Never being able to lay down coin, or wait, for a high-end refractor in this size range doesn’t hurt so much now.  Astro Psychic, Rock-a-hashi, TM Front, LZOOS, Penthouse? HA!

Don’t pinch me. I don’t want to wake up from this telescope dream…

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Edited by ATM57, 05 May 2020 - 11:29 AM.

[stevew]

 

Never being able to lay down coin, or wait, for a high-end refractor in this size range doesn’t hurt so much now. In fact, I’m healed. Astro Psychic, Rock-a-hashi, TM Front, LZOOS, Penthouse? HA!

Don’t pinch me. I don’t want to wake up from this deeply satisfying telescope dream…   

I get the impression that you kind of like your new scope...

[ATM57]

I get the impression that you kind of like your new scope...

 

Based on its performance, price, and ease of use... Yeah, I'd say so.   I will tone it down some.

 

I've owned my share of "scope monsters" seeking the same level of high performance. Some good, some not so good.

Edited by ATM57, 05 May 2020 - 11:24 AM.

[sw196060]

Tell us what you really think !   

LOL

[sw196060]

I am so tempted for one of these ....   you are no help to my credit cards!!

[ATM57]

I am so tempted for one of these ....   you are no help to my credit cards!!

Sorry about that.  I tried to find this scope used in the classifieds and I only found 1 that went up for sale back in January 2019 so I bought new. If they are all this good then they are a bargain. I, like many others, prefer being able to collimate my lenses but I found that this was not needed with this sample. As long as I don't bang it around it should stay collimated forever. If not, thankfully, I still have the skills to make a completely new collimatable cell for it (learned a lot from a Meade 178ED I owned over a decade ago). Let us know if you pull the trigger  

[areyoukiddingme]

It's great to hear that people are getting great optics in these scopes.

 

Given the inexpensive starting price, I would guess that once they are bought up, we will start seeing used ones popping up on the market for around $1600/1700. I might be tempted then . . .

[Wildetelescope]

What does a 1/4 wave optic look like compared to 1/6 wave in focus? Tell me what I should expect to see. 

Been asking that for years!  Sincere question, not smart alecky.  I would love to hear a detailed description from someone who owns scopes with a range of measured optical quality, strehl, wavelength, what ever.  I think that would be a useful discussion, especially if we could get more than one person to do that.   

 

Jmd 

[Illinois]

I bought SW 150 Evostar on sale last year $1,999! I saw Jupiter and Saturn last September before it went gone behind the Sun. Jupiter and Saturn in SW150 is better than I saw in my ES 127 APO. I sold my ES127 APO and I will not sell my SW 150! Open Clusters and double stars is great, sharp and pinpoint star. SW150 is BIG telescope and if its too big for anyone then get 120mm refractor! SW150 is 1200mm length is perfect for planetary! ES 100 deg. 5.5 mm eyepiece for 218 power is great for planetary! I can not wait to see Mars this Fall!

Edited by Illinois, 07 May 2020 - 06:01 AM.

[ATM57]

After over a month of use this Sky-Watcher Evostar 150 continues to amaze. The continuing amazement comes from expecting the scope to be good, but not THIS GOOD. Zeta Hercules companion star B is an easy target at 240-300X. The simulated images presented here represent what I'm seeing at the eyepiece (2" APM prism diagonal included).

 

Star: Regulus

Seeing: 5-6/10

Scope at ambient.

Etched glass Ronchi grating: 254lpi/10lpmm

 

On the next night of good seeing (mid-week looking good) I plan on keeping my old butt awake so I can stay up and see what this scope can do with Jupiter and Saturn.

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[ATM57]

I can't help myself... Low Tech zonal mask tests for spherical aberration are next (Ernie Pfannenschmidt method, Sky & Telescope, Apr2004, Vol. 107 Issue 4, p124). Since I don't have access to an interferometer, like some, this is the best this lowly amateur can do as far as hard data is concerned. At the least I will have some test numbers to compare against my visual testing results (my old eyes may be deceiving me ). I will be using a helical focuser adapter with class 3A thread (fabricated it when I had access to a machine shop) and digital calipers for measurement.

 

This may be a bit much to some but for me it's fun. I love to tinker with scopes. This should prove interesting...

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[ATM57]

Still having fun, Po’ Boy style… The lunar images presented here were taken last night through my Sky-Watcher Evostar 150ED with a 59 dollar astrocamera (Svbony SV105). The one taken of the Messier craters region shows the Messier craters well but the “trailing craterlett” in the rays appears more as a “contrast feature” than a craterlett in the shot. This trailing craterlett was clearly seen visually as a crater with a very short rim. Both photographed regions visually were very “crisp” at high power revealing a lot more detail at 375X than I could photograph with my inexpensive astrocamera. The Torricelli region has a myriad of small crater pits that didn’t show in the photo. I also noted that there was no false color on the moon, in the shadows or on the limb, seen with these old eyes at any magnification.

 

My zonal measurement tests confirmed my star and ronchi tests. The first set of measurements had an average result of 0.0015”. The second series was 0.001” and the third came in at 0.0015” again. At F/8, that averages out to 1/8th wave (0.0013”) using the Ernie Pfannenschmidt method of spherical aberration measurement. The numbers made me chuckle to myself in the dark.   Excellent spherical correction!

 

I believe I have shared enough here and may have worn out my welcome.  If so, forgive me.   I’m not trying to hijack this thread. I’m just happy having this level of refractor performance without leaving a sink hole in my bank account.

 

So… anyone else having good results using their Evostar 150? Please share!

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Edited by ATM57, 29 May 2020 - 01:39 AM.

[Dame Edna]

Still having fun, Po’ Boy style… The lunar images presented here were taken last night through my Sky-Watcher Evostar 150ED with a 59 dollar astrocamera (Svbony SV105). The one taken of the Messier craters region shows the Messier craters well but the “trailing craterlett” in the rays appears more as a “contrast feature” than a craterlett in the shot. This trailing craterlett was clearly seen visually as a crater with a very short rim. Both photographed regions visually were very “crisp” at high power revealing a lot more detail at 375X than I could photograph with my inexpensive astrocamera. The Torricelli region has a myriad of small crater pits that didn’t show in the photo. I also noted that there was no false color on the moon, in the shadows or on the limb, seen with these old eyes at any magnification.

 

My zonal measurement tests confirmed my star and ronchi tests. The first set of measurements had an average result of 0.0015”. The second series was 0.001” and the third came in at 0.0015” again. At F/8, that averages out to 1/8th wave (0.0013”) using the Ernie Pfannenschmidt method of spherical aberration measurement. The numbers made me chuckle to myself in the dark.   Excellent spherical correction!

 

I believe I have shared enough here and may have worn out my welcome.  If so, forgive me.   I’m not trying to hijack this thread. I’m just happy having this level of refractor performance without leaving a sink hole in my bank account.

 

So… anyone else having good results using their Evostar 150? Please share!

 

As the one who started this thread, I say that you have definitely not worn out your welcome and that I'm very pleased indeed to read your posts and see your images!  Please post more whenever you like!  This is a lot of fun!  

 

And congratulations on your fabulous big glass!

 

D.E.

Edited by Dame Edna, 28 May 2020 - 07:02 PM.