Celestron Ultima Edge 30mm = APM UFF = StellaLyra UF

[Deadlake]

There is a 5% duty on astro gear imported into UK, well there is from US and EU.

 

[Deadlake]

Separate question, the 30 mm UFF was designed by APM. How does KUO get away with white boxing it to other companies. I thought KUA was only able to white box non ED/APO lenses/EP's etc.

[Louis D]

6 minutes ago, Deadlake said:

Separate question, the 30 mm UFF was designed by APM. How does KUO get away with white boxing it to other companies. I thought KUA was only able to white box non ED/APO lenses/EP's etc.

Mark Ackermann here in the US designed the 30mm APM UFF as he describes in this CN post.  It's not clear that Markus Ludes of APM commissioned him and paid for the design.  KUO built it, did they pay Mark?  It's not clear that APM ever had an exclusive right to sell the eyepiece based on the design.  Perhaps APM had a limited time exclusive right to sell it, maybe a few years.  It seems like that time period has expired, and now KUO can sell it to anyone wishing to market it.

[Deadlake]

1 hour ago, Louis D said:

Mark Ackermann here in the US designed the 30mm APM UFF as he describes in this CN post.  It's not clear that Markus Ludes of APM commissioned him and paid for the design.  KUO built it, did they pay Mark?  It's not clear that APM ever had an exclusive right to sell the eyepiece based on the design.  Perhaps APM had a limited time exclusive right to sell it, maybe a few years.  It seems like that time period has expired, and now KUO can sell it to anyone wishing to market it.

APM has a limited time of exclusivity until copied:

https://www.cloudynights.com/topic/562562-apm-new-ultra-flat-eyepieces-30-mm-70-degree/?p=7635881

[LDW1]

I just received my 30mm Celestron Ultima Edge and it is by far the heaviest ep that I own, the only others that I used to own were my several Celestron Omni's that I got rid of because of the weight factor. I hope this one functions better than they ?I think it will because I didn't think much of the Omni's, no offense to other owners though. A few good nites will tell the tale !

[Don Pensack]

Yes, APM had a period of exclusivity, now expired.

The eyepiece is now offered under 9 different labels, including KUO's house brand, Sky Rover.

I expect to see it under 2 or 3 more labels next year.

For purposes of figuring what the eyepiece is, it has:

70° apparent field

36.3mm field stop

30mm Focal length

9 elements

Fully multi-coated lenses with blackened lens edges

A VERY flat field

Works to very short f/ratios (though I can't see it being used under f/4)

It's the best-corrected of the UFF eyepieces in my coma-corrected 12.5" f/5.75 scope.

[Andrew_B]

On 12/12/2022 at 18:02, Deadlake said:

APM has a limited time of exclusivity until copied:

https://www.cloudynights.com/topic/562562-apm-new-ultra-flat-eyepieces-30-mm-70-degree/?p=7635881

I would expect that such an arrangement meant that APM could secure better terms with KUO and/or Mark Ackermann.

Two years gives APM a decent amount of time to sell their versions, while making the eyepiece range available to other brands after that would mean higher sales for KUO (and possibly greater royalties for Mark) without necessarily costing APM too many sales by widening retail availability and brand recognition. APM could also benefit if increased production resulted in KUO reducing their wholesale prices.

I've got a few eyepieces from the range (Svbony and Sky Rover branded) and I've been impressed by the quality and value for money. Haven't tried the 30mm yet but everything I've read suggests it's the pick of the bunch.

[Mr Spock]

I've ordered the StellaLyra 30mm. I'll be able to give it a full test in all my scopes in the new year.

[markse68]

Question for @FLO - in your descriptions of your SL UFFs you list field stop diameters but they don’t agree with the specs on the schematic document you show eg the 18mm is listed as 27mm field stop which seems wrong but the schematic says it’s 23.4mm which sounds more likely?

Mark

Edited December 18, 2022 by markse68

[Louis D]

Those are physical field stop numbers.  The effective field stops as I measured them photographically are 27.5mm for the 24mm (it gets fuzzy, so a bit of a judgement call) and 36.4mm for the 30mm (nice and sharp).  You could probably extrapolate the 15mm and 18mm to have approximately 17.8mm and 21.3mm diameter field stops, respectively, since the 15mm, 18mm, and 24mm all appear to be scaled versions of the same design.

Edited December 18, 2022 by Louis D

[markse68]

it’s confusing huh. So i’m guessing the effective field stop should be used to determine vignetting? And do you know Louis if the field stop diameters Televue list in their specs are also the actual rather than effective? Could explain the vignetting i’m getting with my new finder and a nagler 16mm

Mark

Edit: TV do say the quoted fs is the effective one

Edited December 18, 2022 by markse68

[Don Pensack]

3 hours ago, markse68 said:

it’s confusing huh. So i’m guessing the effective field stop should be used to determine vignetting? And do you know Louis if the field stop diameters Televue list in their specs are also the actual rather than effective? Could explain the vignetting i’m getting with my new finder and a nagler 16mm

Mark

Edit: TV do say the quoted fs is the effective one

Eyepieces with negative field lenses have a physical field stop in the form of an iris between the negative lens and the positive set higher in the eyepiece.

One thing that happens is that the negative lens moves the focal point up in the eyepiece, away from the physical field stop to a "virtual" field stop in between the lenses.

Since the image is expanded by the negative lens, this virtual field stop will be a different size than the physical stop itself.

The confusion comes from the listing from the manufacturer of the actual physical field stops, which no other manufacturer quotes in negative/positive designs.

All the other manufacturers quote the "virtual" field stop figures, because THEY are what determines the actual true field you see, not the physical stop in the eyepiece.

 

I find it useful to think of the virtual field stop as merely a magnified view of the physical stop that is below it.

 

The measured virtual field stops are (lab, not field measurements):

30mm--36.3mm (though a couple people have seen 36.4mm, an inconsequential difference)

24mm--27.6mm (though the edge is a bit vague, and some have measured 27.3-27.5mm)

18mm--21.7mm

15mm--18.2mm

10mm--(actually a 10.5mm FL)--11.2mm

[markse68]

1 hour ago, Don Pensack said:

Eyepieces with negative field lenses have a physical field stop in the form of an iris between the negative lens and the positive set higher in the eyepiece.

One thing that happens is that the negative lens moves the focal point up in the eyepiece, away from the physical field stop to a "virtual" field stop in between the lenses.

Since the image is expanded by the negative lens, this virtual field stop will be a different size than the physical stop itself.

The confusion comes from the listing from the manufacturer of the actual physical field stops, which no other manufacturer quotes in negative/positive designs.

All the other manufacturers quote the "virtual" field stop figures, because THEY are what determines the actual true field you see, not the physical stop in the eyepiece.

 

I find it useful to think of the virtual field stop as merely a magnified view of the physical stop that is below it.

 

The measured virtual field stops are (lab, not field measurements):

30mm--36.3mm (though a couple people have seen 36.4mm, an inconsequential difference)

24mm--27.6mm (though the edge is a bit vague, and some have measured 27.3-27.5mm)

18mm--21.7mm

15mm--18.2mm

10mm--(actually a 10.5mm FL)--11.2mm

Yes for some reason i thought the effective fs would be larger than the actual but it makes sense that a diverging negative lens would result in the efs being smaller than the afs. Anyway @FLO’s numbers are wrong.

Mark

[Don Pensack]

FLO, like APM and Altair, merely copied the numbers from the mfr, which are the actual FS diameters, not the virtual field stops that matter to us.

Effective field stops ARE usually bigger than the internal physical stop but not always.  Sometimes it depends on the aperture of the next lens up or the type of distortion in the field.

[markse68]

23 minutes ago, Don Pensack said:

FLO, like APM and Altair, merely copied the numbers from the mfr, which are the actual FS diameters, not the virtual field stops that matter to us.

Effective field stops ARE usually bigger than the internal physical stop but not always.  Sometimes it depends on the aperture of the next lens up or the type of distortion in the field.

No Don, they really got them wrong. For the 18mm, manufacturer says 23.4mm. you say 21.7, Flo says 27mm. They’re all wrong I think 

Mark

Edited December 18, 2022 by markse68

[Don Pensack]

21.7mm was measured in a lab.

It could be in error a couple tenths, I suppose, but unlikely in error by much.  A distortionless 18mm 65° would have a field stop of 20.4mm.  Of course, it isn't distortionless.

23.4 is the diameter of the diaphragm in the eyepiece, the mfr's quote, a figure irrelevant for our purposes.  You can unscrew the barrel and measure it.

27mm is simply a misprint, as it is impossible in a 1.25" 18mm eyepiece since that translates to an apparent field that cannot fit into a 1.25" barrel at that focal length.

 

[markse68]

Misprint maybe but they are all wrong. Maybe a miscalculation across the range. Anyway, hopefully they see this and correct it.

Mark

[LDW1]

Why do companies of that stature publish incorrect numbers that are that far off ? Surely they must know that some ........ will check them and will make sure the incorrect whatevers are brought out for all potential customers to see ? Especially if practically every measurement is wrong, it doesn't make sense or maybe ? What other industry, company does that with their products for the world to see ? This doesn't make sense or maybe ....... !

[LDW1]

Has anyone ever pointed these discrepencies, these errors out to these professionals for their purusal and explanation ? I am sure they would be receptive !

[Andrew_B]

28 minutes ago, LDW1 said:

Why do companies of that stature publish incorrect numbers that are that far off ? Surely they must know that some ........ will check them and will make sure the incorrect whatevers are brought out for all potential customers to see ? Especially if practically every measurement is wrong, it doesn't make sense or maybe ? What other industry, company does that with their products for the world to see ? This doesn't make sense or maybe ....... !

You'd be amazed at the mistakes that make it through to publication. I've seen scientific papers about medical research that have passed peer review and been accepted by major publications that had basic errors in arithmetic which hadn't been caught until it reached me. One of them looked at the effects of weight on diabetes risk in overweight and obese individuals. Out of the 50 people in the study group, 29 of them were classed as overweight while the remaining 22 were classed as obese... 

You would expect school kids to catch something as obviously wrong as that, but a lot of very smart people had read it and not noticed.

Marketing materials and spec sheets are even more error-prone. They're often written by very busy people and any proof reeding is likely done in a hurry by a single person so it's easy for a typo or a misread detail to be missed, especially if it's not very obviously wrong. I wouldn't be surprised if mistakes are actually less common in this industry than in many others due to the relatively knowledgeable customer base and the closer relationship between them and small retailers and manufacturers.

The best thing to do if you see a mistake is to send a polite message with a link to the offending page together with your correction, and ideally a link to a source for that info.

Edited December 19, 2022 by Andrew_B

[LDW1]

I spent 42 yrs. in the transportation industry on some major designs so if you think numbers, its the scale of these errors, those developing these specs should check the numbers before it even gets to the proof readers stage because it is very hard to believe that many get through. In your example I would suggest the rational, the process, the whatever may have been wrong right from the start ? But I wouldn't know !  PS :  I know any time I checked some one elses work, their numbers the number of errors were minimal. In these posts it seems that the vast majority are way off, really ! How do they stay in business because if they are wrong in this one small segment what else is screwed up ??

[FLO]

On 18/12/2022 at 12:20, markse68 said:

Question for @FLO - in your descriptions of your SL UFFs you list field stop diameters but they don’t agree with the specs on the schematic document you show eg the 18mm is listed as 27mm field stop which seems wrong but the schematic says it’s 23.4mm which sounds more likely?

We didn't have the schematic when making our product pages. It arrived after. 

19 hours ago, Don Pensack said:

FLO, like APM and Altair, merely copied the numbers from the mfr, which are the actual FS diameters, not the virtual field stops that matter to us.

Yes. Probably. 

22 hours ago, Don Pensack said:

The measured virtual field stops are (lab, not field measurements):

30mm--36.3mm (though a couple people have seen 36.4mm, an inconsequential difference)

24mm--27.6mm (though the edge is a bit vague, and some have measured 27.3-27.5mm)

18mm--21.7mm

15mm--18.2mm

10mm--(actually a 10.5mm FL)--11.2mm

So, if we list both 'Physical Field Stop Diamaters' and Don's 'Virtual Field Stop Diamaters' on our product pages, are we then covered? 🙂 

Steve 

[markse68]

Yes I think that would be good although knowing the physical dimension isn’t very useful? Maybe just the “Effective fs diameter” like Televue do would be all that was needed? Where did you get those values you listed from though? they don’t seem to correspond to the physical mfrs dimension- did you calculate them from something?

Mark

[LDW1]

My how quickly things get done, get changed, get corrected when !

[FLO]

16 minutes ago, markse68 said:

Yes I think that would be good

Done 🙂 

In our specification tables, we now list physical dimensions (from the schematics) and virtual dimensions (from Don). 

StellaLyra Ultra Flat Eyepieces

Thank you to @markse68 for mentioning this and to @Don Pensack for the virtual dimensions. 

Steve