607 replies to this topic

[Scott in NC]

Not that this means one or the other is better or worse, but Roland Christen of AP has been using FCD-100 instead of FPL-53 for his AP92 Stowaway and new AP110GTX scopes for at least 4 years now.  I suspect that has more to do with glass availability than anything else though. And keep in mind that you can’t really discuss which glass is better without getting into a discussion about the different grades of each glass. FCD-100 and FPL-53 have similar dispersion characteristics. That’s a fact. But high-grade FCD-100 will be better than low-grade FPL-53.  And conversely, high grade FPL-53 will be better than low-grade FCD-100. Don’t think for a second that AP is using the lowest grade ED glass and AT or TS are using the highest grade glass in their scopes.

[Alan S]

So we agree…these scopes use different glass, a different focuser and while similar are not the same scopes.  Note that I never implied one was superior, simply stated they are not the same.

[Oldfracguy]

Thanks, Scott in NC, for that last tidbit of info.  I suppose the availability of a particular type of glass is the main factor in explaining why newer ED refractors are, and have been, being made with different glass types.  Even if the glass is called F-XYZ" and its optical properties meet the requirements, then it really doesn't matter what the exact name is, does it?

 

My question is why the decision was made to phase out the AT80EDL.  Is it because so many folks are migrating to triplets for imaging applications?

[wrvond]

Thanks, Scott in NC, for that last tidbit of info.  I suppose the availability of a particular type of glass is the main factor in explaining why newer ED refractors are, and have been, being made with different glass types.  Even if the glass is called F-XYZ" and its optical properties meet the requirements, then it really doesn't matter what the exact name is, does it?

 

My question is why the decision was made to phase out the AT80EDL.  Is it because so many folks are migrating to triplets for imaging applications?

My guess would be not enough profit margin. Judging by the quality of my scope I imagine it cost nearly as much to make as it sold for.

[Oldfracguy]

In another thread, or maybe even this one way back in the early posts, I asked the question why the AT80EDT, that comes with a nice hard case, was priced lower than the AT80EDL (that was regular pricing, not the sale pricing).  Mike of Astronomics posted that the AT80EDL came with a dedicated reducer/flattener.  He also commented that he tried to sell the AT80EDL for a lower price without the reducer/flattener, but had very few takers, so that experiment was abandoned.

[Scott in NC]

My guess would be not enough profit margin. Judging by the quality of my scope I imagine it cost nearly as much to make as it sold for.

Yes, this. 

 

Mike B. told me that hardly anyone was buying them at the initial price, which I believe was $899 or somewhere thereabouts.  People really didn't start buying enough of them to make it worthwhile keeping in stock until the price was dropped to $699.  And at that price, by the time Astronomics covered shipping charges, credit card charges, etc., they were essentially selling them at pretty close to the cost that they actually paid.  And if you consider all the unaccounted for costs (i.e., the fixed costs of running the business, keeping shelf space open for those scopes that could have been filled with something else, paying their employees, etc.), Astronomics was actually losing money.

 

It's a shame that that's how it is, but my guess is that many people who wanted an entry level scope for visual use were much more attracted to the rock-bottom $369 cost of the AT80ED.  Most imagers who wanted an AT opted for the AT80EDT for not much more cost.  And this is yet another reason why we almost never see the f/9-11 refractors that many visual users clamor for.  A small company like Astronomics cannot afford to commission the production of a scope that no one will buy for the price that it would need to sell for, no matter how fantastic it really is.

[wrvond]

None of the EDL scopes were on my radar until I needed an 80mm, and happened upon the sale. I don't do imaging, but anticipate that some years hence this scope could be very desirable - even more so with the reducer/flattener I bought with it.

Actually, I think I bought the 80EDL at "full" price with a free reducer/flattener and the 125EDL on sale and paid $200.00 to get the reducer/flattener with it.

 

In any event, I feel like I got an excellent value and am glad I got mine while the getting was good.

[mondo1948]

Hi All,

Here are a couple of photos I'd like to share.  First, note the orange "hammock" I've set underneath the eyepiece tray.  A friend named Gary on CN suggested this $10.00 addition.  It has 3 compartments that each can hold a lot of stuff.  I went out with the scope last night and the orange storage unit gave me a place to store the telescope end cap, my eyeglasses, my journal where I record what I'm viewing each night, and a pen.  It doesn't need to ever be removed because you can just fold up the legs of the tripod with it attached.  Also notice the black tray I added on top of the steel eyepiece tray....I've posted a picture of this before.  Last night, I was able to place all 6 of my 100 degree eyepieces on the tray, including the caps for the one inserted into the diagonal.

 

 

Lastly, just in case you're like me and didn't think about it at first....note that the azimuth slow-motion control is out to the left of the telescope.  My scope came from the factory with the azimuth control extended directly under the OTA, which made it difficult to reach.....in fact, I was pulling it out along side the OTA.  I didn't realize until I read it somewhere, that you could unscrew the 4 screws holding the top of the mount to the base and rotate it about 25 degrees and reattach the top to the bottom of the mount.  In this way, the azimuth control is out to the left, where you can easily grasp it with your left hand.

 

Here's a link the the hammock on Amazonprime....

 

https://www.amazon.c...ct_details&th=1

 

And, here a link to the tray on Amaonprime....

 

https://www.amazon.c...ct_details&th=1

 

Simply drill a 1/2" hole in the tray and slide it onto the rod that goes through the existing tray.  Let it sit on top of the original tray with the eyepiece holes in it.

 

 

 

 

 

Hope this helps,

Mondo

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Edited by mondo1948, 25 April 2023 - 05:00 PM.

[Scott in NC]

I really like the hammock idea!

[gstrumol]

Just ordered the hammock for myself! 

[Doug Culbertson]

Well, I already added the tray to my tripod after an earlier post, now I’ve added the hammock to my Amazon cart.

[mondo1948]

I'm real glad to see some of you are taking advantage of my mods.  I was a high school teacher for a couple of years back in 1970 and loved sharing information, which I don't get to do very often any more.  This forum provides an opportunity for that.

 

Clear Skies,

Mondo

[Enceladus96]

Quick question:

I’m viewing in some spectacularly cool Phoenix summer time weather right now. And I can’t help but notice the airy disc on specific stars. I see it with the 8mm Ethos or higher power in the AT80EDL. Now, I’m not sure if this is a good thing or whether you would prefer to see all stars as pinpoints dots at any power.

Maybe someone can quickly explain to me if seeing an airy disc in a refractor is a good thing and if it’s related to exit pupil (1mm or smaller “higher powers”) or if it’s simply dependent on the glass type used.

I’m just wondering if the airy disc is a good thing to see.

Some spectacular views tonight btw. Man, I love this EDL!

Greg

Edited by Enceladus96, 28 May 2023 - 03:36 AM.

[Cpk133]

Quick question:

I’m viewing in some spectacularly cool Phoenix summer time weather right now. And I can’t help but notice the airy disc on specific stars. I see it with the 8mm Ethos or higher power in the AT80EDL. Now, I’m not sure if this is a good thing or whether you would prefer to see all stars as pinpoints dots at any power.

Maybe someone can quickly explain to me if seeing an airy disc in a refractor is a good thing and if it’s related to exit pupil (1mm or smaller “higher powers”) or if it’s simply dependent on the glass type used.

I’m just wondering if the airy disc is a good thing to see.

Some spectacular views tonight btw. Man, I love this EDL!

Greg

Smaller scopes show a diffraction pattern at lower powers than larger ones.  What your seeing is the wave nature of light, perfectly normal and not a good or bad thing.  In terms of quality you want to assess how even and bright the first diffraction ring is relative to the airy disc and whether or not you can see multiple diffraction rings or veiling glare.  Rack in and out of focus and observe the shape is round and focuses symmetrically to an unambiguous position “snap focus”

[Enceladus96]

Smaller scopes show a diffraction pattern at lower powers than larger ones.  What your seeing is the wave nature of light, perfectly normal and not a good or bad thing.  In terms of quality you want to assess how even and bright the first diffraction ring is relative to the airy disc and whether or not you can see multiple diffraction rings or veiling glare.  Rack in and out of focus and observe the shape is round and focuses symmetrically to an unambiguous position “snap focus”

The shape is round and the rings are very concentric in and out of focus, at least to my eyes.

 

I always figured that concentric rings meant perfect collimation. 

[Cpk133]

The shape is round and the rings are very concentric in and out of focus, at least to my eyes.

 

I always figured that concentric rings meant perfect collimation. 

What you don't want to see is uneven intensity in the rings (like a persistent hot spot at 3 o'clock on first diffraction ring, or an oval that flips orientation 180deg in and out of focus (astigmatism).  These are the very basics.  If you cut a circle in a piece of paper that's 30% the diameter of the objective and tape it via thread (like a newtonian secondary) across the front of the objective, you can rack in/out of focus the same amount and compare the size of the shadow in the diffraction pattern to evaluate spherical aberration.  Here's a youtube that CN user Pinbout made showing the process:

 

https://www.youtube....h?v=r3gbGxgz8cM

 

If stars and planets snap into focus under good seeing conditions and Jupiter shows some good detail, that's all the star test I personally need to tell if an optic is any good.

[Cpk133]

one last thought.  I'd recommend reading this thread:

 

https://www.cloudyni...tars-on-a-diet/

 

many people think seeing the airy disc is a telltale of good optics but in the case of an 80mm, it's just a telltale that your using a small aperture with relatively low resolving power.  But as you'll understand from reading that thread, it's not necessarily a bad thing.  I've always had the motto when it comes to brighter stars or double stars that the smallest aperture to cleanly resolve resolves best (unless your seeing conditions are superb, something that rarely happens in MI).  Alberio for example looks incredible in a 60mm refractor, maybe not so great in a 12" newtonian.  Enjoy your scope and its strengths.  

Edited by Cpk133, 29 May 2023 - 02:26 PM.

[Enceladus96]

Thank you for the info. Cheers to all.

[Oldfracguy]

Cpk133 is so right about all that.  These smaller ED refractor with excellent optics, like the AT80EDL, are capable of 1) hitting much higher magnifications than regular ED refractors or achromats; and 2) being able to show the tiniest details within their respective resolving power capability (only a function of aperture).  What you are seeing is what you should be seeing.

 

Suiter in his star-testing book recommends using an eyepiece with a focal length in millimeters equal to the focal ratio of the telescope when assessing the diffraction pattern.  The AT80EDL is an f/7 scope, so using an 8mm Ethos is close to Suiter's suggested magnification.  You should see perfect little well-separated concentric rings, and that is what your AT80EDL is providing.

[Enceladus96]

Are you guys using the 3-6mm Nagler in the 80 EDL?

My highest power is a 6 Ethos and I reckon a 4mm Delite would get used or a 4.5 Delos when the seeing permits.

But I don’t see many reviews on the Nagler Zoom. Seems pretty useful

Greg

[Alan S]

I’m using a 6 Delos, 4 Delite, and very rarely, a 3 Delite.  For me, these are much more comfortable than the Nagler zoom and I’m also on a non tracking mount most of the time…so the wider FOV is helpful in manual tracking.

[Oldfracguy]

I bought a TeleVue 4mm DeLite to use on an AT125EDL a few months ago.  On that f/7.8 scope a 4mm eyepiece will provide an Exit Pupil of 0.5 mm, which is about the smallest recommended to continue to see detail with any scope.  What I discovered was that using my existing KK Fujiyama HD-OR 12.5mm Orthoscopic in an Explore Scientific 3x Focal Extender (equivalent of a 4.2 mm eyepiece) I could see sharper detail and a darker black background, albeit with a smaller field of view.  I even switched to a 9mm Fujiyama Orthoscopic (equivalent to a 3mm eyepiece) and continued to see detail at 325x on that AT125EDL.  I sold the 4mm DeLite after doing that comparison several times, with the same results.

 

On smaller aperture SD scopes like the AT80EDL or William Optics Zenithstar 81 (both made by Kunming United), it is totally possible to crank up the magnification well past the typical "2x aperture in millimeters" rule.  They will operate fine above 200x.  I used to have a 3.2mm AT Paradigm clone, an Agena StarGuider 3.2mm Dual ED (same purple trim), and saw great detail on the Moon, Jupiter and Saturn at 175x.  I would even think--no, I know--you could Barlow your 4mm DeLite to split double stars at near 300x.

Edited by Oldfracguy, 01 June 2023 - 06:14 PM.

[Enceladus96]

You’re right about manually tracking. I totally forgot.

That narrow field in the Nagler zoom would definitely make it difficult to keep the object in view.

[KWB]

A few months back I decided to abandon this telescope for night time usage because I own the 102EDL and use it on the same AZ5 mount. The thinking was it isn't that much more difficult to get the 4 incher outdoors and I would take advantage of the larger aperture at every opportunity.

 

After using the 80 EDL during the day to test my newly corrected vision, I decide to leave it on my porch and use it to view the Moon later in the evening. Using a couple of AT UWA 7 and 10mm eyepieces what I got was in essence a cold bucket of water thrown in my face. This refractor has amazing low power sharpness and detail in lunar objects I have never seen at such low powers and with this small an aperture telescope. I'd also pretty much given up low power, wide field scanning from my location because of the highly light polluted skies but when I also used an ES 32/62 for real low power viewing, the stars were tightly focused, point sources of light across nearly the entire field of view. At 18X there are still a lot of stars visible and maybe my previously clouded vision had clouded my judgment as to what not only is possible when viewing from the big city, but also what is enjoyable viewing from the big city. I am now delighted that I did not sell this telescope.

 

 My strategy for not using an 80mm at night is undergoing a serious re-evaluation. 

 

Edited by KWB, 27 June 2023 - 02:53 PM.

[Nightskyman]

Kenny, you and Oldfracguy were of great help in guiding me to this 80mm wonder. I debated for quite some time, the 102mm vs 80mm, but not having the 102mm to compare side by side, it has been a great first scope for me. I am so glad that I sold my 8” StarSense dob to buy this one. It addressed all of my issues and complaints I had with the dob and gets a lot of use.