New APM "super zoom"

[johninderby]

So it looks like being a spotting scope zoom with distortions that aren’t a problem for daytime use but can be a problem for astro use.

Crossed off my want one list now. Pity as I was looking forward to a geat astro zoom. Oh well. 😢

Edited June 3, 2022 by johninderby

[Ags]

44 minutes ago, Louis D said:

Markus confirms sub-70 degree AFOV and has removed the 75 degree claim from the website.  He has offered refunds to those who pre-paid their pre-orders if they want to go that route.  Markus's mea culpa.

Based on CN report so far, aside from the nearly constant ~67° AFOV, the main negatives found are its RD (which is great for terrestrial viewing) instead of having AMD and EOFB (which even high end zooms suffer from).  Eye relief seems good for eyeglass wearers, it's sharp to the edge even in fast scopes, very nearly parfocal throughout its range, and it's comfortable to use with no appreciable SAEP.  1.25" usage may be limited by available in-focus on a particular scope.  This is not an issue in 2" usage.  The zoom motion is apparently quite stiff.  Still no confirmation on Dioptrx compatibility.

It sounds like a winner for spotting scope usage (apparently what it was designed for).  It might be a bit less of a winner for astro usage.

66 degrees is still quite nice, as long as the other optical qualities are up to the claimed standard.

[Ags]

Regarding the RD, at least it will be less of a problem at 67° FOV as opposed to 75° FOV.

[jetstream]

I wouldnt write this zoom off yet- anyone tried it here? is it a sharp lunar/planetary eyepiece? hows the transmission? contrast on DSO? All eyepieces have distortion, including many orthos I have tested...

[johninderby]

Spptting scope eyepieces are optimised for daytime use and correct for the types of distortion that are evident in daytime terrestrial use but this usually comes at the expense of distortions that show up in astro use.

So while it may be fine for astro use I’m waiting for a proper test by an SGL pr CN member that knows their stuff. If they give it the thumbs up then OK I’ll reconsider.🤔

. 

[jetstream]

1 hour ago, johninderby said:

Spptting scope eyepieces are optimised for daytime use and correct for the types of distortion that are evident in daytime terrestrial use but this usually comes at the expense of distortions that show up in astro use.

What type of distortion are we talking about?

TV uses pincushion distortion and a whole pile of it in some of their eyepieces, very noticeable. The Docter 12.5mm is pretty much orthoscopic except for a bit of barrel distortion right at the edge.

All of the eyepieces I tested (a pile of them) showed a variety of distortion including "moustache" distortion.

I wonder how many have tested for distortion or know about the effect?

Some say pincushion is "astro" friendly distortion and some say "barrel" is for daytime use... I like a minimum of distortion- I really dislike watching the moon "turn into an egg"  from "astro friendly" pincushion in a widefield eyepiece.

So what type of distortion does the APM zoom actually have? Is there a lot of it?

If it does have barrel distortion does it induce the "globe effect" when panning?

[jetstream]

Back to Holger, thanks to YKSE for relating this info many years ago.

http://www.holgermerlitz.de/globe/distortion.html

[Deadlake]

Until the APM has been compared with the Leica or Baader, it's whatever. 

I'll just wait until the review, possible to pick some up second hand as quite a few ordered based on the CN hysteria around the APM zoom.

As far as the FOV spec I must admit why it was not part of the spec, surely Markus could send them all back as what's been produced is not as the order......

 

However the Leica is €755 vs the APM €360.

Edited June 4, 2022 by Deadlake

[Stu]

75 degrees ‘constant’ afov with good performance in other specs would have been interesting to me, but at 66 degrees it’s not much more than the Leica at its narrowest (~60 degrees @17.8mm). Much of my use of the Leica is at the mid to short focal lengths where the afov opens out nicely to 80 degrees, so I think I will just stick with that as it is very sharp on axis.

That’s not to say there wouldn’t be an attraction to the constant afov across the range if I didn’t have the Leica. I guess this all just shows how hard it is to design these complex eyepieces with so many different parameters to keep under control.

 

[Mr Spock]

I'll stick to my primes 

[Highburymark]

3 hours ago, jetstream said:

What type of distortion are we talking about?

TV uses pincushion distortion and a whole pile of it in some of their eyepieces, very noticeable. The Docter 12.5mm is pretty much orthoscopic except for a bit of barrel distortion right at the edge.

All of the eyepieces I tested (a pile of them) showed a variety of distortion including "moustache" distortion.

I wonder how many have tested for distortion or know about the effect?

Some say pincushion is "astro" friendly distortion and some say "barrel" is for daytime use... I like a minimum of distortion- I really dislike watching the moon "turn into an egg"  from "astro friendly" pincushion in a widefield eyepiece.

So what type of distortion does the APM zoom actually have? Is there a lot of it?

If it does have barrel distortion does it induce the "globe effect" when panning?

Squared paper is good for testing these type of distortions - here’s a Panoptic 24 (pincushion) against a Leica orthoscopic microscope eyepiece.

[johninderby]

A bit of info on the subject pf eyepiece distorion and aberationd.

https://www.telescope-optics.net/eyepiece_aberrations_1.htm

https://www.telescope-optics.net/eyepiece_aberration_2.htm

Edited June 4, 2022 by johninderby

[jetstream]

4 hours ago, Highburymark said:

Leica orthoscopic microscope eyepiece.

Hi Mark, this Leica sure looks good distortion wise 👍

[Don Pensack]

On 04/06/2022 at 10:15, jetstream said:

What type of distortion are we talking about?

TV uses pincushion distortion and a whole pile of it in some of their eyepieces, very noticeable. The Docter 12.5mm is pretty much orthoscopic except for a bit of barrel distortion right at the edge.

All of the eyepieces I tested (a pile of them) showed a variety of distortion including "moustache" distortion.

I wonder how many have tested for distortion or know about the effect?

Some say pincushion is "astro" friendly distortion and some say "barrel" is for daytime use... I like a minimum of distortion- I really dislike watching the moon "turn into an egg"  from "astro friendly" pincushion in a widefield eyepiece.

So what type of distortion does the APM zoom actually have? Is there a lot of it?

If it does have barrel distortion does it induce the "globe effect" when panning?

You cannot simultaneously remove both rectilinear distortion (RD) and Angular Magnification Distortion (AMD).

The way to have very small amounts of distortion is to keep the eyepiece apparent fields narrow, since distortion increases with apparent field.

If any eyepiece with more than about 40° of AFoV has zero RD, it will have a lot of AMD, and vice versa.

In daylight use in spotting scopes, reducing RD to keep straight lines straight seems important.  And if this means the magnification at the edge is not the same, it's not a problem, since you can simply move the object viewed to the center. (no RD, let AMD be larger)

In astronomy, though, having a different magnification at the edge is a problem (for many reasons I won't go into here), while there are no straight lines to keep straight, so having a more uniform magnification across the field is better (no AMD, let RD be larger)

Here are the curves for RD and AMD and you can see how apparent field affects the amount of distortion seen:

 

[jetstream]

17 hours ago, Don Pensack said:

since distortion increases with apparent field.

Any word on how the new APM zoom really performs, sharpness, f ratio friendliness, scatter etc? Hopefully the fact that the apparent field is narrower than advertised doesnt taint opinions before its real performance is evaluated.

[Don Pensack]

A couple reviews so far, but mostly from daytime users.

I think more will have to be in the hands of users to get better information on aberrations and eccentricities.

[Louis D]

Has no one on SGL ordered one of these?

[badhex]

On 07/06/2022 at 18:26, Louis D said:

Has no one on SGL ordered one of these?

I too am interested in the real world outcome.

I have a seben-branded version of the 8-24mm zoom which is the same as the Celestron one, but I've never really got on with it partly due to the large AFOV size change, not so small refocusing needed, and the fact that it... rattles 😱

I really like the APM 24mm UFF build and optical quality so if it lives up to that despite some of the other issues, it might be a nice if not perfect zoom option. 

[Deadlake]

Try it out, in stock:

https://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=%2FShops%2Fwww_astrograph_net%2FProducts%2FAPMZOOM&fbclid=IwAR0hCCrGBY73NCUbRwDdkDRjtNc34clbBZx3_PA3cELTfuqzpXgIZnfJbjk

 

[johninderby]

Waiting for the first SGL report. 😁

Having just bought a new scope a couple of weeks ago no new APM zoom for a few weeks anyway.😢

Edited June 17, 2022 by johninderby

[Space Hopper]

I'm hearing Rupert at Astrograph has managed to source a few of these new APM zooms.

I'm still waiting for mine.....

https://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/APMZOOM

Edit:  Sorry, i didn't spot the link a couple of posts up.

But at least they are starting to arrive 'in the shops' 🙂

Edited June 18, 2022 by Space Hopper

[badhex]

21 hours ago, johninderby said:

Waiting for the first SGL report. 😁

Having just bought a new scope a couple of weeks ago no new APM zoom for a few weeks anyway.😢

 

17 minutes ago, Space Hopper said:

I'm hearing Rupert at Astrograph has managed to source a few of these new APM zooms.

I'm still waiting for mine.....

https://astrograph.net/epages/www_astrograph_net.sf/en_GB/?ObjectPath=/Shops/www_astrograph_net/Products/APMZOOM

Edit:  Sorry, i didn't spot the link a couple of posts up.

But at least they are starting to arrive 'in the shops' 🙂

We're all waiting with bated breath for your first light report 🙂

[Highburymark]

My feeling is that the range of powers offered by APM’s new zoom is too limited for general use. And it looks to be relatively bulky, so barlowing could cause balance issues. Both of these were issues with the Leica ASPH too. Leica added a nifty 1.8x extender to turn the ASPH into a wonderful planetary eyepiece - but it was pricey and required fiddling about in the dark. Ultimately I sold it for these reasons. I now have a Baader zoom, which is much lighter and easier to barlow, though it’s not quite up to the Leica optically, and the fov is limited at low powers. However, I use it most to dial in the best magnification (particularly useful on double stars) and then swap it for a fixed eyepiece. 
Having said all that, if the APM is as sharp as the Leica with a constant 66 degrees, and can replace 3 Delos or Morpheus, it will provide great value.

[badhex]

My concern is also the bulk vs. range of mags. If it were, say, more like 8-24 that would be a lot more inviting. Having max FOV in 1.25 and being able to zoom down to 8mm, then only needing maybe one high power EP would make this great for a compact setup. Still, the constant FOV is a great achievement and I'm very interested in how it performs in the real world. 

Edited June 18, 2022 by badhex

[Deadlake]

3 hours ago, Highburymark said:

My feeling is that the range of powers offered by APM’s new zoom is too limited for general use. And it looks to be relatively bulky, so barlowing could cause balance issues. Both of these were issues with the Leica ASPH too. Leica added a nifty 1.8x extender to turn the ASPH into a wonderful planetary eyepiece - but it was pricey and required fiddling about in the dark. Ultimately I sold it for these reasons. I now have a Baader zoom, which is much lighter and easier to barlow, though it’s not quite up to the Leica optically, and the fov is limited at low powers. However, I use it most to dial in the best magnification (particularly useful on double stars) and then swap it for a fixed eyepiece. 
Having said all that, if the APM is as sharp as the Leica with a constant 66 degrees, and can replace 3 Delos or Morpheus, it will provide great value.

Zoom or TOE's for BV usage, maybe you could report back?

I'd like a zoom to fill in just the range provided by the APM Zoom, so I'll keep my eye open on reports.