601 replies to this topic

[KWB]

Now I realize that it’s much easier to produce an 80mm doublet with minimal aberrations than it is to produce a more complex 180mm triplet at the same focal length, but regardless, this AT80EDL appears to be a good example of the right way to make a scope.

 

I am more than satisfied with mine. I've never owned what I consider an all around first class 80mm telescope as to optics and build quality before and this telescope doesn't disappoint for only $700. I can say the same thing for the AT102EDL, however that one costs considerably more money but it is well worth it to me.

 

I got a taste of what these telescopes might be like last summer when I purchased the AT60ED. A lot of value for not much money. 

[gstrumol]

If you look at Stellarvue's comments on optical glass types:

 

https://www.stellarv...al-glass-types/

 

you'll see the distinction made between ED (extra low dispersion) and SD (super low dispersion) glass. Since the AT80EDL has the FCD100 (SD) glass mated with Lanthanum, shouldn't it be called the AT80SDL instead? 

 

Just a thought ...

[Scott in NC]

ED, or extra-low dispersion, is the more commonly accepted name for all of those glass types used in apochromatic refractors.  Anything else, SD, or whatever, is more of a marketing term in my mind.  So what’s next, UD, for ultra-low dispersion?  Just plain ED is fine with me.

[wrvond]

Personally, I tend to avoid anything labeled "super" or "pro".

I was once delivering a travel trailer that had "limited" as part of it's model name to a dealer, as they were performing their receiving inspection the guy told me that anything labeled "limited" meant that the options that would normally be included in the build were limited. 

 

I feel very fortunate to have stumbled into the two I have. I only wish I could get a couple RACI finders in a matching finish - that would really ice the cake!

[gstrumol]

Well the word "achromatic" means 'relating to, employing, or denoting lenses that transmit light without separating it into constituent colors.' Or simply 'without color.'

 

So we probably should stop using the term apochromatic, as it could also be called just a marketing term! 

 

Just sayin ... 

[gstrumol]

ED, or extra-low dispersion, is the more commonly accepted name for all of those glass types used in apochromatic refractors.  Anything else, SD, or whatever, is more of a marketing term in my mind.  So what’s next, UD, for ultra-low dispersion?  Just plain ED is fine with me.

Yes. Ultra - Super Ultra - Super Duper Ultra - and the ultimate 'mirror-like'! 

[Scott in NC]

Well the word "achromatic" means 'relating to, employing, or denoting lenses that transmit light without separating it into constituent colors.' Or simply 'without color.'

 

So we probably should stop using the term apochromatic, as it could also be called just a marketing term! 

 

Just sayin ... 

True.  But the term achromat came into use a long time ago (1800s?) after they figured out that a crown/flint doublet with a long focal ratio reduced chromatic aberration to an exceedingly low level when compared with a shorter focal length singlet.   By the time the technology developed to incorporate triplet optics and lower dispersion glass into refractor manufacturing, a new term had to be developed, as it became clear that achromats were not truly “without color,” yet that term was so entrenched in our vocabulary that it couldn’t easily be eliminated.

[gstrumol]

Took a look at the new sunspot group coming around with my AT80EDL. Just using a Baader solar film filter on front, and a Green #58 + UV/IR cut filter on the EP. 10mm Plossl giving a 56x. While seeing was poor (gray in Astrospheric with 15-20 mph winds and 22 degrees outside) I could see faculae faintly around the group. Took a single shot using the iPhone X camera over the EP. Here is the result, with a comparison to this morning's SDO image:

 

(click to enlarge)

 

Given the equipment and conditions, not bad I think. Thoughts/comments?

[Scott in NC]

I've been playing around a little more with CN'er Makiec's AOS program, which can be used to estimate Strehl values based upon the amount of spherical aberration seen on double-pass autocollimation (DPAC) testing.  Keep in mind that this doesn't take into account the effect that other aberrations (e.g., zones or turned edges) may have on Strehl, so take these results with a grain of salt. 

 

Tonight I used it to calculate the estimated Strehl values for my AT80EDL in green, red, and blue light.

[Scott in NC]

AT80EDL in green light: estimated Strehl 0.995

 

 

 

 

[Scott in NC]

AT80EDL in red light: estimated Strehl 0.98

 

 

[Scott in NC]

AT80EDL in blue light: estimated Strehl 0.959

 

 

[Scott in NC]

This is a pretty nice lens IMO.  It has a thin turned edge, but very little spherical aberration.  Maciek is working on a way to calculate the effects that edge aberrations may have on the overall Strehl value, and I'll be interested to see how that changes my scope's measurements once he perfects and releases the update to his program.

 

But once again, as I've previously demonstrated with the testing I've performed on my AT125EDL, my AT80EDL also gives me no reason to doubt the manufacturer's guaranteed Strehl of >=0.95.  And before you ask what light that's in, I don't know whether it's in red or green. But at least based upon the amount of SA this scope has, it would seem to meet or exceed those criteria when measured in either wavelength.

[wrvond]

Scott,

It might be informative if you were to perform this test on a less than perfect scope, don’t you think?

[Scott in NC]

True.  But to be honest, any scope is going to be less than perfect on DPAC testing, as DPAC is so sensitive that it will show pretty much everything.  No lens is perfect, otherwise they’d all have a Strehl of 1.000, and we’d have nothing to discuss argue about.  And DPAC clearly shows the “less than perfect” edge on my 80EDL lens, but I’ll trade that for near-perfect spherical correction any day.

 

I think it would be very difficult for me to find a bad scope from the EDL line to test, but check out this Orion 120mm f/8.3 doublet achromat that I own:  https://www.cloudyni...mat/?p=12560094.  Despite the ugliness of the Ronchi patterns, this scope still gives nice low-magnification DSO views.  I just wouldn’t expect it to be up to the level of my higher end scopes for high-mag planetary viewing.

 

I haven’t used the AOS program to analyze the Ronchigrams, but strongly suspect that the Orion will be > 1/4 wave in green.

[wrvond]

That Orion is exactly what I was looking for. For me, it validates the results you are getting with the EDLs. 

[Scott in NC]

That Orion is exactly what I was looking for. For me, it validates the results you are getting with the EDLs. 

Thanks, Warren.  You’d probably think that I’d be upset about having a scope like that.  But the answer is no. First of all, I got it very inexpensively.  But more importantly, it makes me appreciate the fine results that I’m getting from my AT EDLs and other, higher-end scopes.  And like you said, it helps to validate those results too. It’s really hard to mess this test up, but if all I were getting were perfectly straight Ronchi bands on every single scope that I tested, you’d have to wonder.

[Mordakyblu]

First light with my AT80EDL. I looked at the Moon. Images were quite good. I was able to use my Clave 6mm for the first time. I also used my 4.8mm Nagler smoothie. I did see some color around the edge, but not enough to complain about. Even at high magnification the scope settled down quickly after focusing. 

 

 

I observed Venus too. Venus was full, but noticed diffraction rings around the image. I didn’t see any color though.

Edited by Mordakyblu, 26 March 2023 - 12:14 PM.

[Doug Culbertson]

Astronomics is showing that the AT80EDL is out of stock. I wonder if more are on the way and, if so, will they still be on sale? At any rate, I’m glad that I got mine. 

[iKMN]

I haven't posted in a while but last week/new moon we had a great run of astronomy weather in S. FL and I observed/logged the following DSO in Sky Safari with my 80EDL so I thought I'd share my list.  I really like this scope a lot - I purchased a 16.5 XWA a few months back and it is just amazing in this scope combo.    I have been using 23mm, 16.5, 10 and 7 XWs with this scope and it is just been great.  I really want to grab the 5mm soon to go after some closer double stars.    I know 80mm isn't the best aperture for galaxies but you can see them with this scope or at least detect a lot of the brighter ones.   It's mostly the open clusters that it really shines.  I haven't been this happy with a scope in years and it's only a 3".  I am really after the 125EDL for next season it's burning a hole in my pocket but I need to fill out my eyepiece collection first.

 

cheers

 

Kristian

 

 

Needle Galaxy
M 66
M 65
Bode's Nebulae
Bode's Nebulae
NGC 1582
California Nebula
NGC 1647
NGC 1746
M 37
NGC 3201
NGC 2546
NGC 2451

Markarian's Chain
Whale Galaxy
Needle Galaxy
Needle Galaxy
M 94
Sunflower Galaxy
Whirlpool Galaxy
Izar
Eight-Burst Nebula
Mars
M 35
NGC 2174
Eskimo Nebula
NGC 2395
Christmas Tree Cluster
NGC 2302
NGC 2309
M 50
Duck Nebula
NGC 2353
Seagull Nebula
M 48
NGC 2506
NGC 2506
19 Pup
NGC 2539
NGC 2587
NGC 2439
NGC 2451
Ns 238
NGC 2579
NGC 2546
NGC 2670
IC 2395
17 Com
Cor Caroli
HR 2764
Gamma Lep
Rho Ori
Nair al Saif
Rho Ori

 

EDIT ADDED:  I was really impressed with the performance on some of the planetary nebulas for only an 80mm scope.  I could also see quite a bit of nebulas w/o a filter... I need to get one.  Even Thors Helmet I could see it - mainly because I've seen it in larger apertures so I knew what I was looking for.  It was subtle but it was there.  I am just loving this scope.

Edited by iKMN, 26 March 2023 - 05:52 PM.

[Scott in NC]

Astronomics is showing that the AT80EDL is out of stock. I wonder if more are on the way and, if so, will they still be on sale? At any rate, I’m glad that I got mine. 

Hmm…I had thought about possibly selling mine at some point.  Not because I don’t like it, but merely because I have way too many small scopes.  But if it’s possible that there may not be any more, then I’m going to rethink that plan and will likely hang onto mine a while longer.  

[Scott in NC]

Astronomics is showing that the AT80EDL is out of stock. I wonder if more are on the way and, if so, will they still be on sale? At any rate, I’m glad that I got mine. 

I just got word from Mike Bieler (Astronomics owner) that the AT80EDL is not just out of stock, but rather it's been discontinued.  

[Doug Culbertson]

I just got word from Mike Bieler (Astronomics owner) that the AT80EDL is not just out of stock, but rather it's been discontinued.

Bummer. I guess that I’m definitely keeping mine. I had briefly considered selling it to buy the AT102EDL.

[KWB]

The "out of stock" status was a big clue to me. I believe under normal circumstances, it would have stated more on the way. 

 

This is now what I see as a horse of a different color. I had thoughts of selling mine because the 102 EDL has replaced it as my primary night time refractor used from my suburban location. But after following the "Looking for a GnG, birding, solar refractor" thread, I decided I should keep mine. This news reinforces that decision. I'm delighted to have purchased it at the sale price. This is still the finest overall 80mm telescope I've ever owned and costs me nothing to keep in my collection.

 

I wonder why it was discontinued?

[Scott in NC]

 

I wonder why it was discontinued?

 

Despite that fact that it appears to have a huge fan base (if you define huge as a few of us "refractor guys" here on CN, lol), too few sold at the original price or the first price reduction.  In order to close out the remaining stock Astronomics essentially had to sell them too close to their actual cost once you factor in credit card fees, shipping costs, etc.  And if you factor in the cost of the time for Astronomics staff to process orders, etc., I suspect that they were actually taking a loss on these.

 

My guess is that at the original cost, most of the imagers preferred to get the AT80EDT.  And many of the visual users like us ended up opting for something with more aperture like the AT102ED or AT102EDL.  

 

So let's just say that those people who were lucky enough to get these at the final sale price got an amazing bargain!