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Explore Scientific AR152 6" F/6.5

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#1 hypergolic

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Posted 18 December 2013 - 09:41 AM

I am considering a scope change, while keeping my GPDX mount with drive. I understand the AR152, like any APO, has issues with CA. I've read primarily positive reviews about this scope. My interest is prime focus astrophotography with a DLSR.

I've used an R200SS for some time. My primary beefs are diffraction spikes and coma (even with the Vixen corrector). Of course, I'm a lot wiser now since I first acquired this scope.

The 152's are going for 750 shipped. That's not a bad price for a large acro.

Years ago (late 70's), I remember my first view thru a large scope (a richfield 6" F/5, Jaegers objective). I've never seen anything that quite had the visual impact; pinpoint images across the field, excellent contrast, etc. Of course, I was only 15 at the time.

Taking the known drawbacks of a pseudo-richfield acro, what say you?

Tnx.

#2 Joe Aguiar

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Posted 18 December 2013 - 10:25 AM

i had a few 6" acro if you want a large refractor at that price point you really cant go wrong. It will show alot of detail from planets to double stars to the brighter dso, and great for those wide views.

Its smaller than its bigger brother in the f/8 model so its more portable.

I like the scope overall, if you dont mind the colour then its fine if the colour bothers you and theres quite abit then it may not be for you. It never bothered me so much, others may say they couldnt deal with it.

As far as AP goes normally that colour is ok for viual work but it photos its gonna shows alot more and its not desired, so you may wanna think about this part.

I think most will say get a 5" ED scope if you wanna do AP. BUT for visual work i think its a decent scope, you can find them in the 350 to 450 range used depending on accessiors.

#3 jbalsam

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Posted 18 December 2013 - 02:09 PM

I imaged with a DSLR and a ES AR152 for a few months before getting a mono CCD camera and doing narrowband-only work with the scope.

With the DSLR you will see blue halos around stars (obviously bigger ones for brighter stars). There's not much that I found that could be done about that without adding filters. If you want to remove that blue you might be able to image with a long-pass filter that cuts out most of the blue spectrum. Most of those filters are designed for visual work, not imaging, so they might give you reflection artifacts.

I tried doing LRGB imaging with the scope with my mono camera, but even refocusing for the blue filter the stars were very very bloated (like 20 arc-seconds FWHM or bigger).

For narrowband imaging, the scope is fantastic. I did some NB imaging with my DSLR (un-modded) of bright O3 objects by using a visual nebula filter. It worked alright for just playing around. With my mono camera the scope really excelled at narrowband imaging. I did a comparison of it against a friend's AP-155 imaging in H-a, and over ~90% of the field it was difficult to tell the images apart. The main difference was in the corners, where the AP's dedicated field flattener beat my AT field flattener.

#4 Jon_Doh

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Posted 18 December 2013 - 03:14 PM

If you image with a Longpass filter attached you won't get any of the blue halos in your photos.

#5 Gray

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Posted 18 December 2013 - 08:38 PM

I'll be frank. No one else has. When I ask questions like this, I would rather someone be blunt or frank. If I would've had someone tell me straight up, it would've saved me time, money and frustrations. Of course, when I called ES about this scope about four years ago, Scott Roberts came on the line and chit chatted with me for a few moments. I thought, man this is nice. Then he directed me to the warehouse in Arkansas, where a lady who spoke little English told me she had one scope left and she would ship it to me. I was astounded and grateful of my luck. I'll cut through the fat and get to it now. The scope came. I checked the collimation with a tool I had and the collimation was severely off. I remember reading this scope was factory collimated and I was suppose to be assured of this. Well, I collimated back and took it out for a star test. To beat all, the scope had severe astigmatism. Nothing I could do about that. I consider that a $350 loss. I sold it for $400 to someone on here and I'm sorry! Maybe I just got the only DUD ES ever made IDK. I tried the DSLR with the Semi-Apo filter thing and the halos were awful. I let my 6 year old step-daughter look at the Moon through it and the first thing she said was, "What's all that purple around the Moon ?". Sorry, grammar is not a strong point of mine. I'm glad I got rid of it, because it was the worst scope I've ever owned. Maybe, it was my fault for getting the last one. I would suggest looking elsewhere even if I didn't have this experience. Refractors are terribly expensive for AP. I'm going to stick with reflectors from now on. Matter of fact the refractor in my sig is for sale and does not show any halos with a DSLR. In the classifieds. Sorry for the rant, but I feel it is necessary to let my experience be known. Ya'll can jump on me if you'd like, it's not gonna hurt my feelings.

#6 PowellAstro

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Posted 18 December 2013 - 10:08 PM

The AR152 is a great scope and a very good deal for what you get. They are a large refractor with some weight and something UPS can mess up for you very quick. I have had two different units, many months apart and both had the ability to perform better than 1/12 wave on the wavefront. An Achro is a different scope and can do very good imaging but the process is different from doing this with other types. While I have no doubt that your scope may of had issues when you got it, I also know the shipping added to any issues you ended up with. The second one I received was slammed so hard on my front step, my wife said there was a big bang out front and she was at the back of the house. I guess the bottom line is what the instrument can and will do, once it is setup as it should be. I hate to here you had such a bad experience with it. The link below is a single shot color image of the moon off of my AR152.

ar152 color moon image

#7 Gray

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Posted 18 December 2013 - 10:19 PM

Local folk. That's a nice image you have there. Of course, I also thought that shipping could've been the problem for the collimation but, the astigmatism was from the figuring of the lenses. From what I've read over the years, I must've gotten the only bad one ever made. I haven't seen a bad review yet. I bought mine after reading a review from someone on here matter of fact. My image of the Moon from that scope had a Borealis of purple around the entire limb. Not sure if that's how you say it. You sure you didn't process your shot to remove most of the purple?

#8 coopman

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Posted 18 December 2013 - 10:20 PM

I don't do A/P, but I have read here that a smaller aperture high quality apo is a better choice than the 6" short focus achromat. I am sure that others will chime in soon.

#9 Dakota1

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Posted 18 December 2013 - 11:16 PM

I have a brand new AR152 and it does show a little purple on the moon. I use a 495 longpass filter and it Illiminates most of it. What is left I can live with. Same looking at Jupiter and Venus. I am more that happy with this scope. Thanks
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Bill

#10 PowellAstro

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Posted 19 December 2013 - 12:08 AM

I did no processing on the image other than a one pass unsharp mask. I did this to compensate for the anti alias filter in the 7D. If the lens centering is off, the unit will show astigmatism, even if the glass is not astigmatic. I think this is what you saw in your unit. In the eyepiece, I do see a yellowish fringe or a violent fringe showing if I am not dead on with the focus, but the image is very sharp. I see no color in Saturn or in Jupiter except a hairline of violent. This is with Nagler eyepieces. In some of my cheaper eyepieces, I do see some color but I also see it with these same eyepieces in my SCT.

#11 T1R2

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Posted 19 December 2013 - 02:19 AM

I love my AR127, they are great scopes for those on a budget but still wanting good performance, I think Gray's was dropped, maybe several times, which isn't hard to do with a AR152, sounds like it just needed to be slapped back into place. If its dropped the lens index marks will misalign and this will cause a wedge which will induce astigmatism and if dropped enough, will cause miscollimation. collimation is easier to fix than a wedge and most people just think they got a bad scope and unless you send the scope back or is apt at taking the lens cell out and realigning everything, what else can one think, so if your ok at collimating I think you'll be happy with it, I've never seen a scope that wasn't out of collimation just a little if not more from its long ride, nothing unusual there, I'd buy another if I had the money.

#12 Gray

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Posted 19 December 2013 - 03:40 AM

Just for the record, and I don't mean to take over Philip's post, I did take care in removing the lens cell afterwards while paying very close attention to the aluminum foil spacers and the white paint marks on the sides of the lenses. The lenses were aligned to their marks and the spacers were intact in their original positions. Folks, this was just a flat out misjudgment in quality control on ES's part. I can at very least speculate that this "last one" was probably a return or reject that was sent to me in loom of the next shipment. I was told the next shipment was in two months. I believe if I would've not waited so long or inquired about returning the scope, I may have received a better scope, but I did not. Not every scope is out of collimation from shipment. My current refractor was checked first thing, you can understand, and it is in perfect collimation with no adjustments. Philip, good luck with your decision Sir.

#13 Vondragonnoggin

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Posted 19 December 2013 - 06:30 AM

I guess if he buys one and it gets damaged in shipping or displays issues, he can always call ES customer support. That's what I did when my AR127 was damaged in shipping. ES ended up replacing my scope after much work on it. Their service was top notch the whole time. They wouldn't be satisfied until I was satisfied. Took about a month, but they kept in constant communication while I waited out cloudy evenings until I got a clear nights to test. They were extremely helpful.

Probably why there are so many good reviews on the achros.

#14 coopman

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Posted 19 December 2013 - 07:51 AM

My (new to me) AR152 has only been used for two short sessions so far, but I have not found a whole lot to gripe about. It give impressive views and I'm looking forward to exploring the winter constellations with it as soon as the moon and clouds cooperate better. I'm using the Baader yellow longpass filter in my 2" diagonal.

#15 spongebob@55

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Posted 19 December 2013 - 10:01 AM

could you image through a friend's scope? That would be very helpful. I club mate of mine was considering a ES 127 Triplet so I let him use it for a night. He politely turned it down. But if you know ES triplets, you know they're more like ED scopes. So if you can do that with a friend who won't get his nose out of shape, the that's the way to do it..
Good luck
Bob

#16 Dakota1

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Posted 19 December 2013 - 11:10 AM

I would call Lance at ES and explain what is happening with that scope and see what he can do for you. Thanks
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Bill

#17 jbalsam

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Posted 19 December 2013 - 01:54 PM

After reading Graham's post I did remember that I forgot to mention one thing about my version of the scope that was initially a problem. Like Graham, after using my scope for a few months I thought it had some significant astigmatism. However, I found reports that the same star shapes could also be caused by a lens-centering error. I adjusted the centering of the rear lens element and the problem went away.

So, you may have to tweak your scope when you get it. There are plenty of walkthroughs on how to do that.

If you do buy the scope directly from Explore Scientific, you should call them up and ask to speak to Lance. Tell him that you would like to be sure that someone actually visually inspects the lens element with a flashlight before shipping it to you just to double check that there are no scratches or anything. Better safe than sorry.

#18 jbalsam

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Posted 19 December 2013 - 01:58 PM

If you image with a Longpass filter attached you won't get any of the blue halos in your photos.



Yes, but you also won't get any of the blue spectrum in your photos either. And most longpass filters that are sold are specified as being for visual use. This generally means that they don't have anti-reflection coatings that are as good as filters designed for imaging, and they may cause severe halos around brighter stars. If you already have a longpass filter that you can try, then it's a very cheap experiment.

#19 roadi

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Posted 20 December 2013 - 05:10 AM

I'll be frank. No one else has. When I ask questions like this, I would rather someone be blunt or frank. If I would've had someone tell me straight up, it would've saved me time, money and frustrations. Of course, when I called ES about this scope about four years ago, Scott Roberts came on the line and chit chatted with me for a few moments. I thought, man this is nice. Then he directed me to the warehouse in Arkansas, where a lady who spoke little English told me she had one scope left and she would ship it to me. I was astounded and grateful of my luck. I'll cut through the fat and get to it now. The scope came. I checked the collimation with a tool I had and the collimation was severely off. I remember reading this scope was factory collimated and I was suppose to be assured of this. Well, I collimated back and took it out for a star test. To beat all, the scope had severe astigmatism. Nothing I could do about that. I consider that a $350 loss. I sold it for $400 to someone on here and I'm sorry! Maybe I just got the only DUD ES ever made IDK. I tried the DSLR with the Semi-Apo filter thing and the halos were awful. I let my 6 year old step-daughter look at the Moon through it and the first thing she said was, "What's all that purple around the Moon ?". Sorry, grammar is not a strong point of mine. I'm glad I got rid of it, because it was the worst scope I've ever owned. Maybe, it was my fault for getting the last one. I would suggest looking elsewhere even if I didn't have this experience. Refractors are terribly expensive for AP. I'm going to stick with reflectors from now on. Matter of fact the refractor in my sig is for sale and does not show any halos with a DSLR. In the classifieds. Sorry for the rant, but I feel it is necessary to let my experience be known. Ya'll can jump on me if you'd like, it's not gonna hurt my feelings.


Your disappointment is understandable when reading claims of near Apo performance of a fast 6" f6.5 Achromat like those here in this thread!!

What several posters report about their very high PV and color corrected (Achro's ??) might be true, but if so they are certainly not Achromats and ES must be using differently lens elements/glass in their claimed Achro's.

Mine shows lots of purple yellowish hue around Jupiter but looking through it the view is sharp. This f6.5 is a litle better color corrected than my two former SKW 6" f5 were.
Mechanical the ES is very well build much better than the SKW IMO.
I'm very pleased with mine for the intended purpose, richfield and casua low to medium (at best) mag. planetary viewing but I didn't expect apo performance before buying. ;)
Sorry to hear your disapointment.

#20 Vondragonnoggin

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Posted 20 December 2013 - 06:20 AM

What thread were you reading? Didn't see any claims of near Apo performance in this thread. Can you point those out for me? Having trouble reading the same things....


I guess I am a little curious to hear what customer service said to the person you quoted when he explained the issues with his scope. Did they offer help? Did they refuse help? Did he even call and give a chance for it to be fixed before taking a $350 loss? You know, little things like that....

#21 jbalsam

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Posted 20 December 2013 - 09:03 AM

What thread were you reading? Didn't see any claims of near Apo performance in this thread.



My thought exactly. No one said anything of the sort.

What several posters report about their very high PV and color corrected (Achro's ??) might be true



I don't see anyone claiming to have a well color-corrected achro, and the only mention of PV on this thread was in that post.

I'll be frank. No one else has.



I haven't seen any posts here that look overly sugar-coated or like they are trying to make this scope look better than it is.

The only person who inferred that the AR152 was an APO was the OP, and I think he only did so by way of typographical error.

#22 roadi

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Posted 20 December 2013 - 11:39 AM

Powellastro wrote:
(In the eyepiece, I do see a yellowish fringe or a violent fringe showing if I am not dead on with the focus, but the image is very sharp. I see no color in Saturn or in Jupiter except a hairline of violent.)

And:
(I have had two different units, many months apart and both had the ability to perform better than 1/12 wave on the wavefront.)

close to that of a fast apo!

#23 Vondragonnoggin

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Posted 20 December 2013 - 12:08 PM

You wrote:

What several posters report about their very high PV and color corrected (Achro's ??) might be true, but if so they are certainly not Achromats and ES must be using differently lens elements/glass in their claimed Achro's.



So, it wasn't really several posters, and they didn't say their scope was color corrected.

How is this exaggeration different than what you are complaining about (exaggerations) ?

"Lets be frank here" is the message I think you wanted to elaborate on, but you weren't very frank about it.

;)

I still would like to hear what Gray was offered by customer service to rectify the situation.

#24 jbalsam

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Posted 20 December 2013 - 02:24 PM

close to that of a fast apo!


Wavefront errors have nothing to do with Achro or Apo design. They have to do with how well the lens is figured. Good numbers in an interferometric test don't tell you if you're going to see color on a planet's limb or not. That has to do with the optical design (lens shape and glass choice), and how well the lens elements are spaced/centered/collimated.

I can't say anything about how much color my scope showed on planets because I never looked through it. I do know that Glen (PowelAstro) took a lot of care to correct any issues with spacing/centering/collimation in the AR152's he had, so it really would not surprise me if he say so little CA on bright objects.

#25 Dakota1

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Posted 20 December 2013 - 03:10 PM

My AR152 had the same over correction problem as PowellAstro"s AR152 had. The scope was reworked to
correct this. It was at 1 wave out. It now sits at 1/12 wave. What little bit of CA it has is not bothersome to me. I use an Baader 495 longpass filter and that takes most of it out. For the money this scope is hard to beat for a 6 inch scope. I feel lucky mine did not suffer any damage in shipping. Thanks
------------------
Bill


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