EXPLORE SCIENTIFIC AR152 152MM F6.5 REFRACTOR

[mareman48]

Just wondering if anyone has used one of these before and what are your thoughts are.

Ive been offered one and thinking of getting this as my second scope for Planetary and Lunar observation.

 

Edited October 21, 2021 by mareman48

[rl]

What is your first scope?

Short focus achromatic doublets are not considered the best for lunar / planetary due to residual chromatic aberration and possibly spherical aberration as well. They are very good for contrasty low magnification widefield viewing on deep sky if you accept the aperture limitations. It will need a decent mount. I've owned a similar scope and it was ok for casual viewing on planets but not exceptional. I'm now lucky enough to have a 6" f/10 triplet and there is no contest which is the best..

You might do better with a 4" f/10 (TAL or Skywatcher) or save up for an apochromatic scope. Sometimes 4" apos come up for £500 secondhand, but the s/h market has gone a bit crazy at the moment. 

A 6" f/8 Newtonian makes a good planetary instrument....

[vlaiv]

Read this review:

https://www.scopereviews.com/page1y.html

[mareman48]

1 hour ago, rl said:

What is your first scope?

Short focus achromatic doublets are not considered the best for lunar / planetary due to residual chromatic aberration and possibly spherical aberration as well. They are very good for contrasty low magnification widefield viewing on deep sky if you accept the aperture limitations. It will need a decent mount. I've owned a similar scope and it was ok for casual viewing on planets but not exceptional. I'm now lucky enough to have a 6" f/10 triplet and there is no contest which is the best..

You might do better with a 4" f/10 (TAL or Skywatcher) or save up for an apochromatic scope. Sometimes 4" apos come up for £500 secondhand, but the s/h market has gone a bit crazy at the moment. 

A 6" f/8 Newtonian makes a good planetary instrument....

I have a Meade 8” LX10 

The Apo scope sounds like a better option, thanks 

 

 

 

[mareman48]

1 hour ago, vlaiv said:

Read this review:

https://www.scopereviews.com/page1y.html

This was very helpful, thanks for the link.

[Franklin]

The one in the picture needs a bigger mount.

[Guest]

I too have always had an interest in the 150 mm achromat at shorter focal ratios. I understand it's limitations. But would still like one for general stargazing. I have an ST 120. The moon looks half decent through it. Saturn shows up well. But Jupiter is a different story.

If you decide to pass,perhaps you would put it a word for me. Bit mercenary I know.lol

[Nyctimene]

6 hours ago, rl said:

A 6" f/8 Newtonian makes a good planetary instrument....

+1 for that. The best option, IMO, and hard to beat, when paired with good orthoscopic eyepieces, e.g, the Baader Classic orthos. You want to do lunar and planetary observing, not wide field observing with low power. No false colour, hardly spherical aberration or coma, easy to collimate and handle, tolerant regarding eyepieces,and very affordable.

Stephan

Edited October 21, 2021 by Nyctimene

[Andrew_B]

2 hours ago, Grumpy Martian said:

I too have always had an interest in the 150 mm achromat at shorter focal ratios. I understand it's limitations. But would still like one for general stargazing. I have an ST 120. The moon looks half decent through it. Saturn shows up well. But Jupiter is a different story.

If you decide to pass,perhaps you would put it a word for me. Bit mercenary I know.lol

How does the false colour in a large achromat compare to what you'd see with something like a small f6 ED doublet?

[Franklin]

There will be noticable CA on bright objects, particulerly at higher powers. Large, fast refractors excel at low power, wide field observing. I had a 150mm f/8 achro and the views of starfields were amazing but with higher powers on lunar/planetary stuff the minus violet filter had to come out. I've now got an ED102 and the difference is chalk n cheese. When the seeing allows, I can get upto 200x and the detail is still clear and sharp.

[vlaiv]

That scope can be used as very good planetary and lunar scope - but "in a second role" - not as it's primary role.

Primary role would be DSO and wide field.

Since it is F/6.5 - it has FL of 988mm. It can be easily turned into 120mm F/7.5 achromat (equivalent to SW evostar 120/1000) or 100mm F/10 (equivalent to SW evostar 102mm F/10) with simple aperture mask. It can even be "apochromatic" 3" - with 76mm aperture mask, it will be F/13 scope. Yes that is 3" F/13 - color index of 4.33 - that is color free for most intents and purposes.

Drawback of course is that it needs Heq5/Eq6 class mount to hold it steady as it is very heavy scope (probably 11-12kg with accessories and possibly even more).

[Guest]

2 hours ago, Andrew_B said:

How does the false colour in a large achromat compare to what you'd see with something like a small f6 ED doublet?

Alberio double star in Cygnus is noted for it's contrast of rich colours. But the colours of this pair are washed out and not true. Saturn looks good. But Jupiter and Venus show the irritating fringing of violet.

[Dr Strange]

I did a comparison between the ES AR 152 and the APO 127 FCD1 CF. 

My experience with these two scopes from a non-scientific/engineering (even though I was an engineer before I was shoved kicking and screaming into administration) merits standpoint since I see questions come up on line all the time asking which is better to get a 5" Apo or 6" Achro that many times end up in "discussions" about very esoteric and complex subjects like unobstructed vs. obstructed systems, Japanese FPL-53 vs. Chinese FPL-51 glass, Modulation Transfer Function, Schlieren tests, and times to reach thermal equilibrium between reflectors and refractors. 

For the record I will so stipulate that the best value for dollars spent will always be with a reflector like a Newt or Dob. You just can't beat the light gathering ability of these platforms at their given price point. While many times I will publicly profess that “Mirrors are for shaving!” I do also own reflectors. And the views from them are amazing as well as stomp all over my refractor’s on small targets and planets when they are properly cooled down. I still love my refractors though…

Please note when I quote sizes of objects that is the size it looked to me. It may not have been that actual size were one to measure it in the EP but I am writing this from the working schlub perspective not a scientific/engineering accurate to the 5th decimal point one.

The problem I was trying to solve was that I wanted something I could use on nights (like when I had to be up at 0530 the next morning for work) when I wanted to take a quick view of whatever might have been up and visible but would still give me views that were comparable (or better) to  a 203mm reflector from my Bortle 8/9 Light Polluted front driveway skies. This would mean that I wanted to be observing in under 15 minutes start to finish of shlepping gear out, leveling the mount, balancing the OTA, and aligning.

At the time based on the views I was getting out of my 102mm ES ED Apo FCD1 refractor I knew that a larger 127-152mm refractor was the best choice for me. However at the time of this shootout my budget of under $2,500 USD eliminated pretty much everything in the high end refractor range like Takahashi, AstroPhysics, Tec, and the like. This left Canadian Telescopes, Explore Scientific, Meade, Celestron, and Orion.

My next criteria took all but Canadian Telescopes and ES out of the mix. That criteria being I didn't want something that looked like it came off of the Battleship Missouri's gun deck in terms of size and I could use for AP if I wanted to aka a "short fast tube".

Because of my breath taking experiences (and by that I actually mean gasping out loud) viewing with the 102 ED, the great customer service experiences I have had with them, their attention to detail, quality, and because the ES line comes with a 2" diagonal, dual speed focuser, Vixen dovetail bar, illuminated cross hair finder scope, and scope rings included I decided that I would stay with that line.

Again for the record CT, Celestron, Meade, and Orion make great OTA's but with them I would have had to purchase much if not all the kit that came with the ES line as extra's so value for money for me really was in the ES line.

This had me looking at the ES AR 152, 127 ED, and 127 ED Carbon Fiber OTA's as my choices. I picked these because I could mount them easily on a mount that wouldn’t break the bank for that quick nights viewing.

I was very fortunate in that Farrah from Woodland Hills Telescope and Camera was kind enough to offer me the use of an AR 152 and an 127 ED to see which one I liked viewing from better then purchase the one I decided to stay with.

Down to brass tacks. What I saw and what I used.

My targets for the comparison were Mars, Saturn, Spica, Messier 31 (Andromeda Galaxy), and Messier 5 globular cluster. I picked these because they all were moderately low on the West facing horizon for me so I wouldn't have to be laying down to see them based on where the mount I was using would place the EP, they would provide a fair diversity of objects to look at combining planets, bright DSO's, and bright point light sources (stars). Lastly they would provide "messy" air and light pollution conditions to best reflect what I would be seeing on an average night out. By the way I picked “work nights” because my primary use for this was going to be the times when I didn't want to bring out or had time to cool off a reflector.

Setup time for each OTA was under 15 minutes including setup of the tripod, getting it pointed North, getting the OTA balanced, getting the OTA level, and alignment. The mount was a Celestron Advanced VX mount. 

The EP's used were the Celestron 40mm 1 1/4", the ES 82 degree 14mm, 11mm, 8.8mm and 4.7mm line.

First up, the ES AR152.

It wasn't anywhere close to the monster I thought it was going to be in terms of size and it was very manageable to mount and balance which surprised me. After hearing stories about this size of OTA I was expecting something much bigger than it was. As has been true for me and reported by others the ES folks check their gear before it goes out the door and this OTA was no exception. After balancing it I popped in the 40mm and pointed it towards a radio/microwave tower that was a good 45 km from me on top of a mountain and it was in perfect focus right out of the box! The mount I was using handled the large OTA with zero issue and it didn't' feel to me like it weighed 10.5 like it says it does.

Side Note: I didn't (and rarely do) use the included finder scope on either OTA. With that 40mm and doing a gunsight aiming I can pretty quickly get the alignment stars in the FOV so I find the extra step of the finder scope alignment useless.

A word about the dreaded purple haze aka Chromatic Aberration (CA) that everyone tends to bring up when talking about Achro's. In the case of the ES AR152 at a relatively fast f/6.5 it was barely there at all. The only time it was really noticeable was during alignment where I saw it on Arcturus and on Spica. The purple halo was there but it wasn't annoyingly bright and I would expect that a filter designed for Achro's would take care of it rather handily. Of note I did not see any of it on Saturn or Mars and saw it very faintly on Spica which really surprised me and reaffirmed my belief that ES makes darn fine quality scopes.

Based on the EP's listed and the 988mm focal length of the OTA divided by EP mm I was going from 24.7 magnification with the 40mm to a mid range of 70.57-89.81 with the 14 and 11mm's to the 112.27-210.21 range in the 8.8 and 4.7mm EP's.

Saturn in the 40mm was a bright yellow spec of light and I could just make out the rings with no detail. At 14 and 11mm it was a clearly defined crisp bright yellow and muddy yellow planet. No CA at all and not much difference in sizing. Jumping to the 8.8 it jumped up in apparent size with more detail visible keeping the same clarity and crispness of view and color. Though I was starting to see it "wiggle" a bit from atmospheric disturbance. At 4.7mm it got the overall best views. It was somewhat dimmer but with good detail accounting for those moments when atmosphere settles down and was stunning to look at. I could see bands of color and the Cassini divide was very clearly present. It presented on a dark black background and two moons were clearly visible. Again no CA at all.

Mars was… Well it was Mars. That means that at 40mm it was a spec of dust. Clearly orange but still a spec. At 14 and 11 it was a bigger spec of dust. At 8.8 it started to look like a planet and at 4.7 was still small but very clearly orange with some hints of the black/brown mountain regions. Still no CA.

Spica was… A star. A bright one and with a bit of CA to it but not too annoying or distracting at all. Again a filter would knock this down without problem I am sure. It had good clarity and while I had to focus each time I changed EP's the focuser worked very well giving good views.

On to M5. In the 40mm it was a very faint puff of smoke with no definition or details. In the 14 and 11 it was a defined puff of smoke with some hints of individual stars with averted vision. There was little difference between the 8.8 and 4.7mm with it being “bigger” in size and more hints of stars when looking directly at it. It was still faint but not as faint as before and clearly visible and noticeable.

I finished off by hunting for M31 the Andromeda Galaxy. I started with the 40mm but didn't see anything. The LP was just too strong. I didn't start to see anything even with averted vision until I plopped in the 11mm and only then I was able to catch it as a very faint puff with averted vision. It didn't become apparent until I was up to 4.7 and then it was still a very undefined puff of smoke. 

The ES 127 ED CF FCD1 glass scope.

I didn't notice much weight difference between the two and including the CF one. None of them were all that heavy though there is a 2.5kg difference between the 152 at 10.5 lbs and the CF at 8.1 kg. It mounted up quickly and with the removable dew shield it did make for a smaller feeling scope. Once again the Pro's From Dover at ES really showed their stuff. Looking at the same mountain top antenna gave brilliant views though since I do like the removable dew shield and metal lens cap on this OTA better than the plastic one and non-removable one on the 152.

Since this was an Apo there was zero CA at all on anything. And to be fair the views were overall more crisp, clean, and clear by a noticeable margin compared to the 152. But then at close to triple the price of the 152 I would expect it to be such.

Based on the EP's listed I was going from 23.8x magnification with the 40mm to a mid range of 68-86.54x with the 14 and 11mm's to the 108.18-202.55x range in the 8.8 and 4.7mm EP's. This is compared to the 152 which was 24.7x magnification with the 40mm to a mid range of 70.57-89.81x with the 14 and 11mm's to the 112.27-210.21x range in the 8.8 and 4.7mm EP's.

Of noteworthy mention here was that to my eyes there was no real appreciable difference in magnification between the 127 and the 152 even though the numbers say otherwise. However overall the clarity, contrast, and crispness was apparent moving from the 152 Achro to the 127 Apo.

I am not going to spend much time talking about Saturn, Spica, and Mars because in terms of overall size of object and brightness the views were very close. Close enough that I really couldn't see a difference between them. But as I mention above the clarity, contrast, and crispness were for sure apparent.

What was of interest was M5 and M31. In the 127 M5 resolved with more detail at a lower magnification with the individual stars becoming more visible and clear. This was the same with M31. it was much more readily apparent at a much lower magnification and stood out much better than in the 152 which was a surprise. Up until seeing this I really did think that all that mattered was aperture. After looking at it in the 127 I still think that aperture does matter because seeing it in one of my reflectors at thermal equilibrium is much better than either the 127 or 152 because of the total light gathering difference between the two BUT in an Apo even at 1" overall smaller size the view was better than the Achro and I could see more detail. I attribute this to the clarity and contrast given by the triplet design in terms of focusing the light and that said light is unobstructed.

Conclusions:
Both the Explore Scientific AR 152 and 127 ED FC1 are fantastic scopes for the price and for all the extra's they come with. Both performed surprisingly well from my urban light polluted skies. Both were easy to handle and not cumbersome or heavy or hard to get onto the mount and balance.

The adage about the best scope for you is the one you use applies very well here. Both gave really great views of DSO's, planets, and stars with time between setup to viewing really good for a working schlub who just wants to look at something before going to bed because they have to work in the morning. In both cases and at both price points if you are looking for that OTA that will keep you coming back for views of the stars instead of sitting on the couch watching Dancing with the Stars then these scopes are a option to strongly consider.

If you are on a budget and you are looking for a very well made refractor at a very fair price for all of the kit included I strongly urge you to consider the AR 152. The value for the money really is there. For visual only this OTA will work on a HEQ5 with very good balance but just barely and I wouldn't recommend it. Plus any wind is going to be a problem and the vibrations could drive you up the wall. Better to put it on a EQ6-R and you can take photos with it as well. Just expect to have to deal with the purple and blue fringe in post processing.

If you have the extra budget, want to have that extra bit of oomph and sharp intake of breath when you look through the EP, or even the slightest hint of CA bothers you then for the price the 127 ED is the way to go. For visual use only this OTA will work on a HEQ5 with good balance. However you would be better off putting it on a EQ6-R or AZ-EQ6 (a mount I really like because I like to do visual and AP and visual works best in alt/az mode) where it will perform well as an AP scope as well as a visual one with the added bonus of less time in post processing removing of the purple/blue fringe or star bloat that can and will happen with an Achro.

I mention AP because I also did a comparison between the 127 and a AP 130. The AP 130 was noticeably better but at a much higher cost. Plus the AP uses FPL-53 matched with the other two elements by a well known very experienced master optician vs a mass produced scope using FCD1 glass mated by an optician with an unknown skill level. I should also note the AP 155 EDFS and TOA 150 comparison I did had the TOA remarkably and noticeably better in terms of colour and contrast. A surprising finding that lead to much hand waving, bellowing and cursing by AP fanboi's since AP is held out as the gold standard of best refractors of all time and that they walk on water and play a harp. 

I should also note that the new ES FCD100 scopes perform very well.  For those of you who are all about glass, remember that RC of AP is now using FCD100 glass because FPL-53 is expensive and hard to find. 

Personally at the end of this I went with the the Carbon Fiber version of the 127 ED. It was worth it to me to spend the extra on the CF one  because at the end of the day it gives those views that get you off the couch and under the stars and will do quite nicely for Astrophotography on a moderately priced equatorial mount like the HEQ5 or EQ-6R. The 127 was the most used scope of all of my scopes. I logged more hours with it than all my other scopes combined.

In your use case if you want the aperture the 152 will do nicely for you at a good price point. However if you want the best quality for the price and a smaller less bulky scope that is similar in focal length I would strongly encourage you to get the new FCD100 ES 127.

 

Edited October 22, 2021 by Dr Strange

[Sunshine]

36 minutes ago, Dr Strange said:

I did a comparison between the ES AR 152 and the APO 127 FCD1 CF. 

My experience with these two scopes from a non-scientific/engineering (even though I was an engineer before I was shoved kicking and screaming into administration) merits standpoint since I see questions come up on line all the time asking which is better to get a 5" Apo or 6" Achro that many times end up in "discussions" about very esoteric and complex subjects like unobstructed vs. obstructed systems, Japanese FPL-53 vs. Chinese FPL-51 glass, Modulation Transfer Function, Schlieren tests, and times to reach thermal equilibrium between reflectors and refractors. 

For the record I will so stipulate that the best value for dollars spent will always be with a reflector like a Newt or Dob. You just can't beat the light gathering ability of these platforms at their given price point. While many times I will publicly profess that “Mirrors are for shaving!” I do also own reflectors. And the views from them are amazing as well as stomp all over my refractor’s on small targets and planets when they are properly cooled down. I still love my refractors though…

Please note when I quote sizes of objects that is the size it looked to me. It may not have been that actual size were one to measure it in the EP but I am writing this from the working schlub perspective not a scientific/engineering accurate to the 5th decimal point one.

The problem I was trying to solve was that I wanted something I could use on nights (like when I had to be up at 0530 the next morning for work) when I wanted to take a quick view of whatever might have been up and visible but would still give me views that were comparable (or better) to  a 203mm reflector from my Bortle 8/9 Light Polluted front driveway skies. This would mean that I wanted to be observing in under 15 minutes start to finish of shlepping gear out, leveling the mount, balancing the OTA, and aligning.

At the time based on the views I was getting out of my 102mm ES ED Apo FCD1 refractor I knew that a larger 127-152mm refractor was the best choice for me. However at the time of this shootout my budget of under $2,500 USD eliminated pretty much everything in the high end refractor range like Takahashi, AstroPhysics, Tec, and the like. This left Canadian Telescopes, Explore Scientific, Meade, Celestron, and Orion.

My next criteria took all but Canadian Telescopes and ES out of the mix. That criteria being I didn't want something that looked like it came off of the Battleship Missouri's gun deck in terms of size and I could use for AP if I wanted to aka a "short fast tube".

Because of my breath taking experiences (and by that I actually mean gasping out loud) viewing with the 102 ED, the great customer service experiences I have had with them, their attention to detail, quality, and because the ES line comes with a 2" diagonal, dual speed focuser, Vixen dovetail bar, illuminated cross hair finder scope, and scope rings included I decided that I would stay with that line.

Again for the record CT, Celestron, Meade, and Orion make great OTA's but with them I would have had to purchase much if not all the kit that came with the ES line as extra's so value for money for me really was in the ES line.

This had me looking at the ES AR 152, 127 ED, and 127 ED Carbon Fiber OTA's as my choices. I picked these because I could mount them easily on a mount that wouldn’t break the bank for that quick nights viewing.

I was very fortunate in that Farrah from Woodland Hills Telescope and Camera was kind enough to offer me the use of an AR 152 and an 127 ED to see which one I liked viewing from better then purchase the one I decided to stay with.

Down to brass tacks. What I saw and what I used.

My targets for the comparison were Mars, Saturn, Spica, Messier 31 (Andromeda Galaxy), and Messier 5 globular cluster. I picked these because they all were moderately low on the West facing horizon for me so I wouldn't have to be laying down to see them based on where the mount I was using would place the EP, they would provide a fair diversity of objects to look at combining planets, bright DSO's, and bright point light sources (stars). Lastly they would provide "messy" air and light pollution conditions to best reflect what I would be seeing on an average night out. By the way I picked “work nights” because my primary use for this was going to be the times when I didn't want to bring out or had time to cool off a reflector.

Setup time for each OTA was under 15 minutes including setup of the tripod, getting it pointed North, getting the OTA balanced, getting the OTA level, and alignment. The mount was a Celestron Advanced VX mount. 

The EP's used were the Celestron 40mm 1 1/4", the ES 82 degree 14mm, 11mm, 8.8mm and 4.7mm line.

First up, the ES AR152.

It wasn't anywhere close to the monster I thought it was going to be in terms of size and it was very manageable to mount and balance which surprised me. After hearing stories about this size of OTA I was expecting something much bigger than it was. As has been true for me and reported by others the ES folks check their gear before it goes out the door and this OTA was no exception. After balancing it I popped in the 40mm and pointed it towards a radio/microwave tower that was a good 45 km from me on top of a mountain and it was in perfect focus right out of the box! The mount I was using handled the large OTA with zero issue and it didn't' feel to me like it weighed 10.5 like it says it does.

Side Note: I didn't (and rarely do) use the included finder scope on either OTA. With that 40mm and doing a gunsight aiming I can pretty quickly get the alignment stars in the FOV so I find the extra step of the finder scope alignment useless.

A word about the dreaded purple haze aka Chromatic Aberration (CA) that everyone tends to bring up when talking about Achro's. In the case of the ES AR152 at a relatively fast f/6.5 it was barely there at all. The only time it was really noticeable was during alignment where I saw it on Arcturus and on Spica. The purple halo was there but it wasn't annoyingly bright and I would expect that a filter designed for Achro's would take care of it rather handily. Of note I did not see any of it on Saturn or Mars and saw it very faintly on Spica which really surprised me and reaffirmed my belief that ES makes darn fine quality scopes.

Based on the EP's listed and the 988mm focal length of the OTA divided by EP mm I was going from 24.7 magnification with the 40mm to a mid range of 70.57-89.81 with the 14 and 11mm's to the 112.27-210.21 range in the 8.8 and 4.7mm EP's.

Saturn in the 40mm was a bright yellow spec of light and I could just make out the rings with no detail. At 14 and 11mm it was a clearly defined crisp bright yellow and muddy yellow planet. No CA at all and not much difference in sizing. Jumping to the 8.8 it jumped up in apparent size with more detail visible keeping the same clarity and crispness of view and color. Though I was starting to see it "wiggle" a bit from atmospheric disturbance. At 4.7mm it got the overall best views. It was somewhat dimmer but with good detail accounting for those moments when atmosphere settles down and was stunning to look at. I could see bands of color and the Cassini divide was very clearly present. It presented on a dark black background and two moons were clearly visible. Again no CA at all.

Mars was… Well it was Mars. That means that at 40mm it was a spec of dust. Clearly orange but still a spec. At 14 and 11 it was a bigger spec of dust. At 8.8 it started to look like a planet and at 4.7 was still small but very clearly orange with some hints of the black/brown mountain regions. Still no CA.

Spica was… A star. A bright one and with a bit of CA to it but not too annoying or distracting at all. Again a filter would knock this down without problem I am sure. It had good clarity and while I had to focus each time I changed EP's the focuser worked very well giving good views.

On to M5. In the 40mm it was a very faint puff of smoke with no definition or details. In the 14 and 11 it was a defined puff of smoke with some hints of individual stars with averted vision. There was little difference between the 8.8 and 4.7mm with it being “bigger” in size and more hints of stars when looking directly at it. It was still faint but not as faint as before and clearly visible and noticeable.

I finished off by hunting for M31 the Andromeda Galaxy. I started with the 40mm but didn't see anything. The LP was just too strong. I didn't start to see anything even with averted vision until I plopped in the 11mm and only then I was able to catch it as a very faint puff with averted vision. It didn't become apparent until I was up to 4.7 and then it was still a very undefined puff of smoke. 

The ES 127 ED CF FCD1 glass scope.

I didn't notice much weight difference between the two and including the CF one. None of them were all that heavy though there is a 2.5kg difference between the 152 at 10.5 lbs and the CF at 8.1 kg. It mounted up quickly and with the removable dew shield it did make for a smaller feeling scope. Once again the Pro's From Dover at ES really showed their stuff. Looking at the same mountain top antenna gave brilliant views though since I do like the removable dew shield and metal lens cap on this OTA better than the plastic one and non-removable one on the 152.

Since this was an Apo there was zero CA at all on anything. And to be fair the views were overall more crisp, clean, and clear by a noticeable margin compared to the 152. But then at close to triple the price of the 152 I would expect it to be such.

Based on the EP's listed I was going from 23.8x magnification with the 40mm to a mid range of 68-86.54x with the 14 and 11mm's to the 108.18-202.55x range in the 8.8 and 4.7mm EP's. This is compared to the 152 which was 24.7x magnification with the 40mm to a mid range of 70.57-89.81x with the 14 and 11mm's to the 112.27-210.21x range in the 8.8 and 4.7mm EP's.

Of noteworthy mention here was that to my eyes there was no real appreciable difference in magnification between the 127 and the 152 even though the numbers say otherwise. However overall the clarity, contrast, and crispness was apparent moving from the 152 Achro to the 127 Apo.

I am not going to spend much time talking about Saturn, Spica, and Mars because in terms of overall size of object and brightness the views were very close. Close enough that I really couldn't see a difference between them. But as I mention above the clarity, contrast, and crispness were for sure apparent.

What was of interest was M5 and M31. In the 127 M5 resolved with more detail at a lower magnification with the individual stars becoming more visible and clear. This was the same with M31. it was much more readily apparent at a much lower magnification and stood out much better than in the 152 which was a surprise. Up until seeing this I really did think that all that mattered was aperture. After looking at it in the 127 I still think that aperture does matter because seeing it in one of my reflectors at thermal equilibrium is much better than either the 127 or 152 because of the total light gathering difference between the two BUT in an Apo even at 1" overall smaller size the view was better than the Achro and I could see more detail. I attribute this to the clarity and contrast given by the triplet design in terms of focusing the light and that said light is unobstructed.

Conclusions:
Both the Explore Scientific AR 152 and 127 ED FC1 are fantastic scopes for the price and for all the extra's they come with. Both performed surprisingly well from my urban light polluted skies. Both were easy to handle and not cumbersome or heavy or hard to get onto the mount and balance.

The adage about the best scope for you is the one you use applies very well here. Both gave really great views of DSO's, planets, and stars with time between setup to viewing really good for a working schlub who just wants to look at something before going to bed because they have to work in the morning. In both cases and at both price points if you are looking for that OTA that will keep you coming back for views of the stars instead of sitting on the couch watching Dancing with the Stars then these scopes are a option to strongly consider.

If you are on a budget and you are looking for a very well made refractor at a very fair price for all of the kit included I strongly urge you to consider the AR 152. The value for the money really is there. For visual only this OTA will work on a HEQ5 with very good balance but just barely and I wouldn't recommend it. Plus any wind is going to be a problem and the vibrations could drive you up the wall. Better to put it on a EQ6-R and you can take photos with it as well. Just expect to have to deal with the purple and blue fringe in post processing.

If you have the extra budget, want to have that extra bit of oomph and sharp intake of breath when you look through the EP, or even the slightest hint of CA bothers you then for the price the 127 ED is the way to go. For visual use only this OTA will work on a HEQ5 with good balance. However you would be better off putting it on a EQ6-R or AZ-EQ6 (a mount I really like because I like to do visual and AP and visual works best in alt/az mode) where it will perform well as an AP scope as well as a visual one with the added bonus of less time in post processing removing of the purple/blue fringe or star bloat that can and will happen with an Achro.

I mention AP because I also did a comparison between the 127 and a AP 130. The AP 130 was noticeably better but at a much higher cost. Plus the AP uses FPL-53 matched with the other two elements by a well known very experienced master optician vs a mass produced scope using FCD1 glass mated by an optician with an unknown skill level. I should also note the AP 155 EDFS and TOA 150 comparison I did had the TOA remarkably and noticeably better in terms of colour and contrast. A surprising finding that lead to much hand waving, bellowing and cursing by AP fanboi's since AP is held out as the gold standard of best refractors of all time and that they walk on water and play a harp. 

I should also note that the new ES FCD100 scopes perform very well.  For those of you who are all about glass, remember that RC of AP is now using FCD100 glass because FPL-53 is expensive and hard to find. 

Personally at the end of this I went with the the Carbon Fiber version of the 127 ED. It was worth it to me to spend the extra on the CF one  because at the end of the day it gives those views that get you off the couch and under the stars and will do quite nicely for Astrophotography on a moderately priced equatorial mount like the HEQ5 or EQ-6R. The 127 was the most used scope of all of my scopes. I logged more hours with it than all my other scopes combined.

In your use case if you want the aperture the 152 will do nicely for you at a good price point. However if you want the best quality for the price and a smaller less bulky scope that is similar in focal length I would strongly encourage you to get the new FCD100 ES 127.

 

This has to be the longest post in the history of posted posts 😂

very informative, though.

Edited October 22, 2021 by Sunshine

[neil phillips]

Having never looked or imaged with a ES AR 152  Hard to be certain of course. But the claims of hardly any CA with those stats is pretty surprising.

As its apparent to me slightly with a F12.9 70 mm Achro.

With a 102mm F11 Achro. Its there . Also a fair amount especially on jupiter with a bresser 127. F9.5. The 102 F11 fails to deliver accurate colour even with stats that obviously must be better than a 152. F6.5 ? Hard to understand why this could be. Observing is subjective. Imaging not so much. And all the scopes mentioned by me fail to deliver accurate colour balance. By varying degrees. 

Edited October 23, 2021 by neil phillips

[vlaiv]

9 hours ago, neil phillips said:

But the claims of hardly any CA with those stats is pretty surprising.

There could be several things happening that would explain this.

First off - not all of us are equally sensitive in violet part of spectrum. We don't notice it as much as other types of color blindness - but it can be there.

Second - not all of us are equally bothered by sight of purple. Similar to pain, discomfort threshold - there are different thresholds when people start saying it is annoying. Some get annoyed at slight hint of CA - others can tolerate quite a bit.

Third - give just 152mm and F/6.5 stats - there is really no way of knowing how good/bad CA will be. We don't know design of the lens nor type of glass used. We don't know how good spherochromatism was controlled. 

 

[neil phillips]

2 hours ago, vlaiv said:

There could be several things happening that would explain this.

First off - not all of us are equally sensitive in violet part of spectrum. We don't notice it as much as other types of color blindness - but it can be there.

Second - not all of us are equally bothered by sight of purple. Similar to pain, discomfort threshold - there are different thresholds when people start saying it is annoying. Some get annoyed at slight hint of CA - others can tolerate quite a bit.

Third - give just 152mm and F/6.5 stats - there is really no way of knowing how good/bad CA will be. We don't know design of the lens nor type of glass used. We don't know how good spherochromatism was controlled. 

 

True but its touted as a achromat. So thats what i considered.  Your other points are valid of course. Saturn is dim so wont show bad CA. Mars is small so similair problem. Seems unlikely a Doublet without ED glass with those stats will have hardly any CA.  if so. would like to try a scope like that.  Will i ever get a clanger like. Must try much harder lol

 

[Stu]

3 hours ago, vlaiv said:

There could be several things happening that would explain this.

First off - not all of us are equally sensitive in violet part of spectrum. We don't notice it as much as other types of color blindness - but it can be there.

Second - not all of us are equally bothered by sight of purple. Similar to pain, discomfort threshold - there are different thresholds when people start saying it is annoying. Some get annoyed at slight hint of CA - others can tolerate quite a bit.

Third - give just 152mm and F/6.5 stats - there is really no way of knowing how good/bad CA will be. We don't know design of the lens nor type of glass used. We don't know how good spherochromatism was controlled. 

 

This is an oft posted chart that relates aperture to focal ratio and the likely levels of CA. It indicates quite severe CA at the stats for this scope but as you say, some people are more sensitive to it than others, plus I guess some scopes are better than others.

[vlaiv]

1 minute ago, Stu said:

This is an oft posted chart that relates aperture to focal ratio and the likely levels of CA. It indicates quite severe CA at the stats for this scope but as you say, some people are more sensitive to it than others, plus I guess some scopes are better than others.

I think that this chart holds for Fraunhofer doublet with F2/BK7 glass combination.

There are scopes out there that are marketed as achromatic refractors - yet employ different glass types, for example this scope:

https://www.teleskop-express.de/shop/product_info.php/info/p2229_TS-Optics-6--f-5-9-Refractor---2-5--R-P-Focuser---Ohara--Japan--Objective.html

It uses K9 and F4 glasses (according to TS) and has better CA correction than "standard" 6" F/8 achromat (to quote TS: " The Ohara objective has a better color correcture than a standard 150mm f8 achromatic refractor").

I've read reports of that telescope being rather good performer for fast achromat. There has also been one instance where someone measured 127mm ES scope and concluded that objective is stopped down - which helps with level of SA and CA (not saying that above 152 is stopped - but that is something that should be checked).

 

[neil phillips]

26 minutes ago, vlaiv said:

I think that this chart holds for Fraunhofer doublet with F2/BK7 glass combination.

There are scopes out there that are marketed as achromatic refractors - yet employ different glass types, for example this scope:

https://www.teleskop-express.de/shop/product_info.php/info/p2229_TS-Optics-6--f-5-9-Refractor---2-5--R-P-Focuser---Ohara--Japan--Objective.html

It uses K9 and F4 glasses (according to TS) and has better CA correction than "standard" 6" F/8 achromat (to quote TS: " The Ohara objective has a better color correcture than a standard 150mm f8 achromatic refractor").

I've read reports of that telescope being rather good performer for fast achromat. There has also been one instance where someone measured 127mm ES scope and concluded that objective is stopped down - which helps with level of SA and CA (not saying that above 152 is stopped - but that is something that should be checked).

 

Thats interesting Vlaiv. Certainly could explain the discrepancy. Though why ES Would not be mentioning better glass types in there Ads is strange ? The 127  F 6.5 is touted as crown and flint

Edited October 23, 2021 by neil phillips

[alacant]

Hi

If it's anything like as good as the 4-element AR152 f5 from the same manufacturer, you're in for a treat. Loadsa wide field 'wows' to be had.

Sagittarius is breathtaking. Available here.

HTH

Edited October 23, 2021 by alacant

[neil phillips]

Observing is indeed subjective 

Was just reading this

Review – Explore Scientific AR152 Achromatic Refractor | One Tree Observatory (wordpress.com)

[Stu]

47 minutes ago, vlaiv said:

I've read reports of that telescope being rather good performer for fast achromat.

Yes me too and I’ve looks through one and they are significantly better than, say, the Skywatcher 150mm f5

[johninderby]

Ed Ting did a comparion a while ago that is worth reading. I had the TS version which is the same as the Astrotelescopes one and found it was surprisingly good for low and medium power observing and CA wasn’t a big problem. Quote a heavy lump though.

https://www.scopereviews.com/page1y.html

 

Edited October 23, 2021 by johninderby

[Stu]

30 minutes ago, johninderby said:

Ed Ting did a comparion a while ago that is worth reading. I had the TS version which is the same as the Astrotelescopes one and found it was surprisingly good for low and medium power observing and CA wasn’t a big problem. Quote a heavy lump though.

https://www.scopereviews.com/page1y.html

 

They are nice scopes. Always fancied one at some point.