Lacerta ED 40mm Impressions

[Louis D]

I had been intrigued by the TMB Paragon 40mm for quite some time now based on many favorable reports both on here and on CN by experienced observers.  However, every unauthorized rebranding of it had been sold out for quite a few years, until this June.  When I saw @badhex's post below, I realized a new batch had been ordered from the factory by Lacerta and could be bought new from European retailers:

 

I did my research and ordered one from Europe within a week.  It arrived 5 days later, so not bad for crossing the Atlantic.  Being VAT and sales tax free (as well as tariff free being from Europe and under $800) helped pay for the stiff shipping fees.

First Impressions

It arrived in a plain black box so many eyepieces are being shipped in recently, except that it didn't have any white end label identifying what's inside.  The foam appeared a bit old.  I'm wondering if they did a huge production run of these a decade or more ago, and put them on a shelf just waiting to be marked with a brand name when a new order comes in.  The actual rubber parts of the eyepiece don't seem old, though.  However, the rubber band holding the inner eyepiece bag shut was getting a bit gooey and brittle and broke immediately as I removed it, adding to my suspicions.

Having the OVL Aero ED 35mm already, I was a bit taken aback by the larger size of the 40mm version.  It's noticeable wider and taller than the 35mm.  It seems just as solidly made.  Overall, it is a very handsome eyepiece without being overly bulky or heavy.

Observation Impressions

Being in the middle of a drought, I was able to go outside with it the same night it arrived.  I used my TS-Optics 90mm f/6.6 FPL-53 triplet APO with TSFLAT2 field flattener for comparison.  Being that my view of the sky is obstructed by trees and houses, I was only able to test it on a bright star versus several other 40mm and 35mm eyepieces.  Contrary to Badhex's report of it being worse corrected than the 35mm, I found it to be better corrected, but not by a wide margin at ~f/6.  I'll stick by my long held view that the 35mm is good out to 75% to the edge from the center.  The 40mm pushes this out to about 85%, a nice gain in usable field of view.  The 40mm Pentax XW-R performs slightly better.  It shows more chromatic aberration and field curvature, but less astigmatism near the edge.  There's astigmatism out there in the last 15%, but it is significantly less pronounced once refocused for the edge.  The 40mm Meade 5000 SWA performs nearly perfectly to the edge, showing just a bit of astigmatism in the last 5% or 10%.  However, it has lots of pincushion distortion, inflating the size of everything at the edge.  The 40mm has a sharp field stop while the 35mm seems to have a fuzzy field stop.  If I push in and tilt my head, I can see under the fuzziness that there is a sharp field stop in the 35mm ED.  This is similar to the Meade 26mm MWA's field stop behavior; however, I'd say you only gain a degree or so at the edge instead of 2 degrees or more for the Meade.

On a later night, I was able to observe the moon just past first quarter in my 8" Dob with GSO coma corrector.  It really showed how much chromatism the 40mm Pentax XW-R has, and by comparison, how little the two ED eyepieces have.  The 40mm Meade falls somewhere between the two extremes.  The 40mm Meade distorts the moon the most while the others barely distort it at all toward the edge.  I added the 35mm Baader Scopos Extreme and 26mm Meade MWA to the mix for near widest field comparison purposes.  The Scopos is basically sharp to the edge while the MWA is nearly so.  However, the extreme SAEP of the MWA made it all but impossible to see the edge.  The Scopos yields the best contrast of all of them by far.  Crater rays and shading in the maria were very pronounced and lively, seemingly jumping out at me.  The others barely showed these features once I had noticed them in the Scopos.  This aligns with my experience viewing rich star fields in the Scopos.  Stars are tighter and more pronounced relative to other widest field eyepieces in my collection.

One other thing that stood out was how hard the Lacerta 40mm was to insert into and remove from the GSO CC.  I mean, really hard.  I was afraid I'd get it stuck in there.  None of the other eyepieces had this issue, although the 35mm ED was exhibiting a bit of stickiness.  I didn't notice this in the GSO dielectric diagonal on the 90mm APO, nor was it a problem when using the eyepiece natively in the Dob's focuser.  I measured the insertion barrel diameter of all of them with a micrometer, and all seemed to be right at 2" within a few thousandths; so I'm chalking it up to the black finish on the Lacerta's barrel somehow causing the issue on a really humid night.

I then tried all without the CC, and none were happy with the inherent field curvature or coma from the primary.  The Scopos probably handled it best having an integral telenegative element (Smyth lens) decreasing the speed of the incoming light cone for the positive, image forming elements.  However, it had an indistinct field stop without the CC for some reason.  The rest maintained field stop appearances similar to their non-CC versions.

Next, I tried them all in a GSO ED 2x 2" Barlow with a Tele Vue Panoptic Barlow Interface without the GSO CC since I don't have enough in-focus for both at the same time.  Surprisingly, the 40mm Lacerta didn't improve very much at the edge.  The 35mm ED improved a bit more, but was not perfect.  The 40mm Pentax didn't play well at all with it.  The outer field wasn't sharp anymore.  The 40mm Meade SWA worked exceptionally well with the Barlow, showing a sharp edge and flat field.  The 35mm Scopos and 26mm MWA both worked well Barlowed, but there was a bit of exit pupil instability with the former and no change in SAEP with the latter.  The 40mm Lacerta was a bit tight in the TV PBI, but not as bad as in the GSO CC.

I also tried them all with the Dob on the sun with a Baader solar filter.  It pretty much reinforced my lunar impressions.  Stray light control seemed best in the Scopos for both the sun and the moon.  It had the least "fogging" around both and the highest contrast.  I could begin to make out subtle surface patterns near the edge of the sun in the Scopos that were nonexistent in the others.  The 40mm Lacerta was no better or worse than the rest on axis as far as fogging.

In all cases, the 40mm Meade SWA has the most eye relief by far (almost too much) for eyeglass wearers, followed by the 40mm Pentax XW-R (just enough), then the 40mm Lacerta ED (able to just take in the entire field by pushing in), and dead last the 35mm Aero ED (impossible to take in the entire field at once with eyeglasses).  Blackouts of any type were not an issue in any eyepiece on the moon or sun.  The wide, flat top of the Meade made it the most uncomfortable to view through (head tipping is required).  The rest viewed with a similar level of comfort.  The rubber grip rings of all the non-Meades were equally nice for handling.  The bare metal of the Meade makes if feel kind of anti-establishment or industrial, which is fine.

Testing

Over the last few weeks, I've been doing some indoor "optical bench" testing, so to speak.  Overall, they reinforce my observation impressions that the 40mm Meade 5000 SWA is the best corrected, the 40mm Pentax XW-R is the next best (but with noticeable chromatic aberrations), closely followed by the 40mm Lacerta ED and then the 35mm OVL Aero ED.

Here is a side by side image of the four comparison eyepieces showing the decloaked 40mm Meade 5000 SWA on the left and the Aero ED 35mm on the right.  I chose these four because all have at least a 44mm field stop diameter and reasonably good field correction.  Notice how tall the 40mm Lacerta is relative to the others.  It's definitely not compact.

Here is a table of measured values I obtained by taking images through my AT72ED f/6 refractor and then taking measurements and making calculations to get the focal length, FOV and FS values.  I also did the flashlight test as a second AFOV measurement technique and to measure the eye relief.

Notice that the Lacerta ED has the least additional edge magnification of the three 40mm eyepieces.  As a result, it has the narrowest AFOV, yet has a field stop diameter second only to the Pentax.  The Lacerta is also closest to being a true 40mm in the center.  The measure eye relief of the 40mm Lacerta is a bit misleading since it feels like 16mm in use, needing to push in just a bit to see the entire FOV.  The 35mm Aero feels like 14mm of eye relief, needing to smash my eyeglasses into it to see the entire field, so also a bit misleading.  I've experienced this discrepancy between measured and feels like eye relief values with other eyepieces as well, so it's not unique to these ED eyepieces.

Here is my standard 32mm to 42mm eyepiece AFOV image taken through the AT72ED, but with the Lacerta 40mm added near the bottom.  Please excuse the different lighting due to different sky conditions outside the nearby window.

Notice how well the Lacerta hangs with the Pentax left to right.  Also notice how much smaller the Lacerta AFOV appears than the Meade above and the Pentax below despite all having a similar TFOV.

Since I was at the resolution limit of my Galaxy S7's camera, I decided to get out my 90mm APO for another round of images of just the four main contenders to have increased image scale.  The scope was placed at roughly the same position as the AT72ED (which I slaving recreate for each of its photoshoots), but not exactly.  I ordered the images this time by best to worst overall correction, top to bottom.

Notice that the Lacerta again is not that far behind the Pentax, but both are well behind the Meade.  However, the 35mm Aero is definitely a step behind the 40mm Lacerta.

Next, I got out my 127 Synta Mak and took the same images on the same day from the same position.

Notice that all get sharper, but the 35mm Aero is still not completely sharp at the edge.

Last, I added the Lacerta to my SAEP/CAEP comparison image at bottom center.  Like the 35mm Aero, it doesn't exhibit obvious blackouts.  There is a bit of a shadow that dances around the field, but it is as unobtrusive as the ones in the APM UFF 30mm and TV Panoptic 27mm.

Conclusions

Overall, I really like the Lacerta ED 40mm as a light weight, lower cost alternative to the Pentax XW-R 40mm at f/6 or slower.  If eye relief were a bit longer, it would be even better.  The eye lens is recessed 7mm, so it could have really comfortable eye relief for eyeglass wearers if the top were redesigned.

If anyone has been wanting to get a 40mm ED, but couldn't because they were sold out, now is the time to get one before this run is sold out as well.

[Voyager 3]

Great job Louis. This is exactly how I want my reviews to be written. 

[badhex]

Excellent review Louis, and I would advise anyone to listen to your thorough reviews and testing over my finger in the air guesswork any day!

TBH, I was comparing my possibly faulty memory of the 35mm + ZS73 from months earlier, I've been using the 35mm most recently with my TS102, so with no direct comparison it's likely just me misremembering performance.

Funnily enough I recently did a quick daytime test of the 35mm and 40mm against a 30mm GSO and remember thinking that the 40mm was certainly not worse than the 35mm as I has suspected, at least in daytime. I was however focused more on the performance of the GSO (which was terrible). 

 

 

[badhex]

Oh BTW, mine also had old-seeming foam and IIRC the eyepiece itself was wrapped in some rubbishy thin plastic bag, not the resealable type we usually expect. That was also true of the TS version I think. 

[Louis D]

Had a quick peek at the moon this morning through the 127 Synta Mak with both the 40mm Lacerta ED and 40mm Pentax XW.  Surprisingly, not much improvement over the views through faster scopes.  The Lacerta still starts to blur at about 85% to the edge, the Pentax just a bit closer to the edge.

Overall, I was very surprised that neither was sharp to the edge at f/12 and improved only slightly from f/6.6.

[badhex]

I have been thinking that I need to try out the 40mm and 35mm side by side in my ZS73. Have been using the 40mm and ZS73 quite a lot recently and in general I really enjoy it. It definitely suffers at the edge but I'm not sure which performs better in that scope. 

I also recently read that as well as obviously wasted light which I knew about, an overly large exit pupil can supposedly exacerbate some potential aberrations caused by your own eye? Trying to remember where I saw this. Last time I had an eye test a few years ago, the doctor said I had excellent vision with no issues, but maybe the larger exit pupil on the 40mm is causing some issues too?

[Louis D]

Have you done a Panoptic 41mm vs Lacerta 40mm comparison for grins?  My 40mm Meade 5000 SWA (Maxvision SWA) is nearly perfect edge to edge compared to either the 40mm Pentax XW or 40mm Lacerta, but boy is it heavy and bulky.

[badhex]

No, certainly not in the ZS73 anyway - I should have a go with that. IIRC the Panoptic is sharp to the edge at the cost of angular magnification(?) , but it don't use it often so will have to confirm that. It's only recommended for F7 or slower by TeleVue I think?

It's a shame APM don't make a 40/41mm version of the UFF for max field 2" usage, that could be a winner!

[Louis D]

For an unobstructed system, you should be able to use the 41mm Pan in faster scopes as long as you don't mind losing a few photons to your iris and dealing with a brighter sky background.

Since the 30mm APM UFF's field lens is a bit over 40mm in diameter, it should be possible to scale the design upward a bit before it completely fills the inside diameter of a 2" (~46mm) barrel.  Perhaps a 35mm might be a possibility?

[badhex]

Yes, the ED 40mm and Pan 41mm give exit pupils of 6.79mm and 6.96mm respectively in my ZS73 so I'm pretty sure I'm losing photons with both, although I have not measured my max pupil dilation. I'm close to 40 so I imagine it will not be 7mm!

[Don Pensack]

On 16/09/2022 at 05:09, Louis D said:

Had a quick peek at the moon this morning through the 127 Synta Mak with both the 40mm Lacerta ED and 40mm Pentax XW.  Surprisingly, not much improvement over the views through faster scopes.  The Lacerta still starts to blur at about 85% to the edge, the Pentax just a bit closer to the edge.

Overall, I was very surprised that neither was sharp to the edge at f/12 and improved only slightly from f/6.6.

The Pentax is not free of astigmatism at the edge, and would have vignetted in that scope as well.  Add in a slight dose of lateral CA and a trace of FC, and yes, the edge is not perfect.

See the tests at f/10:

http://astro-talks.ru/forum/viewtopic.php?f=32&t=1483#p41976

go down the pages to the 2nd chart, which is significantly more complete.

I believe the Lacerta ED is listed under both the Levenhuk brand and United Optics.

[grjsk]

Thank you for this excellent review. I bought the eyepice because of it. I am having a problem with it though: even on medium bright stars, there are some irregular artifacts around them. It almost look like there are tiny solar flares around the stars. Focusing is very hard because of this. Did you experience something similar? If not I think I have to return it. 

[badhex]

1 hour ago, grjsk said:

Thank you for this excellent review. I bought the eyepice because of it. I am having a problem with it though: even on medium bright stars, there are some irregular artifacts around them. It almost look like there are tiny solar flares around the stars. Focusing is very hard because of this. Did you experience something similar? If not I think I have to return it. 

Hi @grjsk a couple of Qs:

What scope are you using it in?
Is the scope sufficiently cooled prior to use?
Are the aberrations/artefacts over the whole field of view or just around the edge?
What effect does defocusing have (both intra- or extra- focus)?

Have a look at this page for the various diagrams which show different types of aberrations to see if any of these match what you're seeing: https://www.handprint.com/ASTRO/ae4.html

Edited September 23, 2022 by badhex

[grjsk]

1 hour ago, badhex said:

Hi @grjsk a couple of Qs:

What scope are you using it in?
Is the scope sufficiently cooled prior to use?
Are the aberrations/artefacts over the whole field of view or just around the edge?
What effect does defocusing have (both intra- or extra- focus)?

Have a look at this page for the various diagrams which show different types of aberrations to see if any of these match what you're seeing: https://www.handprint.com/ASTRO/ae4.html

72mm f6 refractor.

It was sufficiently cooled.

The artefacts where present around all medium bright stars, all across the field. 

Focusing changed to a certain degree the pattern of the artefacts, but never removed them.

It did not look like any aberrations I have ever seen before, or any one of those in the link.

 

It sort of looked like the attached picture (but all in white light, not red, orange and black). 

Edited September 23, 2022 by grjsk

[Louis D]

Were you wearing eyeglasses?  It sounds like you might have astigmatism in your eye if you weren't.

How did the view compare to other ~40mm eyepieces you own?

That's the exact scope I did my testing in, and stars looked sharp out to about 75% from the center to the edge.

[grjsk]

3 minutes ago, Louis D said:

Were you wearing eyeglasses?  It sounds like you might have astigmatism in your eye if you weren't.

How did the view compare to other ~40mm eyepieces you own?

That's the exact scope I did my testing in, and stars looked sharp out to about 75% from the center to the edge.

No eyeglasses. This is the only 40mm eyepiece I own. I did try several other eyepieces, the widest beeing a 32mm plossl, but no other eyepieces showed the same problem. Astigmatism is suppose to make things blurry isn't it? These artefacts where in fact rather sharp. 

[Louis D]

No, astigmatism makes point sources spiky.  Extended objects will appear blurry due to all the point source spikes overlapping, but point sources like stars will be starbursts.

Astigmatism focuses light into lines.  The human eye can have multiple axes of astigmatism of varying strengths.  Eyeglasses attempt to correct the most egregious offender, so there's always some remaining uncorrected astigmatism unless you get LASIK which corrects all defects at once.

Have you had an eye exam in the last year?  If so, check your CYL or cylinder correction number on your prescription.  If it's above 0.5, you'll probably see spiky stars at large exit pupils as with this 40mm eyepiece.

Also, don't expect the outer field to be in focus at the same time as the center of field unless you're using a visual field flattener with that scope.  Short focal length refractors have strong field curvature.

[grjsk]

23 minutes ago, Louis D said:

No, astigmatism makes point sources spiky.  Extended objects will appear blurry due to all the point source spikes overlapping, but point sources like stars will be starbursts.

Astigmatism focuses light into lines.  The human eye can have multiple axes of astigmatism of varying strengths.  Eyeglasses attempt to correct the most egregious offender, so there's always some remaining uncorrected astigmatism unless you get LASIK which corrects all defects at once.

Have you had an eye exam in the last year?  If so, check your CYL or cylinder correction number on your prescription.  If it's above 0.5, you'll probably see spiky stars at large exit pupils as with this 40mm eyepiece.

Also, don't expect the outer field to be in focus at the same time as the center of field unless you're using a visual field flattener with that scope.  Short focal length refractors have strong field curvature.

Useful info, thanks! Haven't had an eye exam in years. The 32mm plossl (EP: 5.33) does not give the same problem, so perhaps a 35/68 og 28/82 might be a better fit, for a slightly smaller FOV. 

[Louis D]

Here's one last check for eye astigmatism.  Rotate your head around the optical axis of the eyepiece as you view through it to see if the star spikes rotate with the rotation of your head.  If so, it's your eye causing it.

My employer's insurance covers one free eye exam and one free pair of eyeglasses every year, so I've been very diligent about keeping my prescription up to date.  It's also good to go to check for glaucoma, cataracts, retinal tears, etc.

[great_bear]

On 16/09/2022 at 15:28, badhex said:

I have been thinking that I need to try out the 40mm and 35mm side by side in my ZS73. Have been using the 40mm and ZS73 quite a lot recently and in general I really enjoy it. It definitely suffers at the edge but I'm not sure which performs better in that scope. 

I also recently read that as well as obviously wasted light which I knew about, an overly large exit pupil can supposedly exacerbate some potential aberrations caused by your own eye? Trying to remember where I saw this. Last time I had an eye test a few years ago, the doctor said I had excellent vision with no issues, but maybe the larger exit pupil on the 40mm is causing some issues too?

No such thing as “wasted light” - at least not as far as refractors are concerned. It just means that you’ve reached the maximum light-gathering capability that’s physically possible (with any scope) for that specific power of magnification (and perhaps could achieve that same view with a smaller scope - not that there’d be any benefit in doing so, unless you’re planning on spending the entire evening in that view).

On the aberration front yes, the outer edge of the eye’s lens will - for some people - be not-so-good in terms of focusing the light bundle, so it’s entirely possible that optical quality might drop off for some individuals when you reach that point.

Edited September 23, 2022 by great_bear
Punctuation for clarity

[badhex]

1 hour ago, great_bear said:

No such thing as “wasted light” - at least not as far as refractors are concerned. It just means that you’ve reached the maximum light-gathering capability that’s physically possible (with any scope) for that specific power of magnification (and perhaps could achieve that same view with a smaller scope - not that there’d be any benefit in doing so, unless you’re planning on spending the entire evening in that view).

On the aberration front yes, the outer edge of the eye’s lens will - for some people - be not-so-good in terms of focusing the light bundle, so it’s entirely possible that optical quality might drop off for some individuals when you reach that point.

Ah, sorry for clarity I meant that an overly large exit pupil results in wasted light if your own pupil cannot dilate that much. I'm don't know for certain what my pupil dilates to but as I'm approaching 40 I suspect it's less than 7mm. 

Regarding mention of edge performance, I meant more the eyepiece edge performance than your own eye specifically. 

[great_bear]

34 minutes ago, badhex said:

Ah, sorry for clarity I meant that an overly large exit pupil results in wasted light if your own pupil cannot dilate that much. I'm don't know for certain what my pupil dilates to but as I'm approaching 40 I suspect it's less than 7mm. 

Regarding mention of edge performance, I meant more the eyepiece edge performance than your own eye specifically. 

I know - it isn’t wasted light - that’s the myth (albeit a common one). 
 

It’s not “wasted” any more than the sunlight on the ground when you go out for a walk during the day. 
 

That’s because there is no optical configuration for that magnification that could “squeeze” that light into your eyeball. Your eye is already fully illuminated - no waste. 

Edited September 23, 2022 by great_bear

[Mr Spock]

9 minutes ago, great_bear said:

I know - it isn’t wasted light - that’s the myth

So, you were mythtaken... 

[Louis D]

8 hours ago, great_bear said:

I know - it isn’t wasted light - that’s the myth (albeit a common one). 
 

It’s not “wasted” any more than the sunlight on the ground when you go out for a walk during the day. 

I've heard it more as "wasted" aperture.  In that, your entrance pupil is cutting of some of the exit pupil from the telescope system, so the latter is operating at a smaller aperture and higher f-ratio.  The argument goes, at that particular exit pupil, why not just haul out a smaller telescope.

Other than the night sky background tends to get a bit washed out in suburban skies at large exit pupils with refractors, I don't really care about the slight loss of aperture because it allows me to view a wider true field of view without having to swap telescopes.  In obstructed systems, the CO can sometimes start to become quite intrusive, especially on bright objects as with solar and lunar observing when your eye's iris contracts to the projected size of the CO.

[great_bear]

The argument goes, at that particular exit pupil, why not just haul out a smaller telescope

If that’s the only eyepiece you’ll be using for the night, that’s a perfectly good argument for choosing a smaller, lighter scope to take that evening. 

Similarly it’s a reasonable argument to say that I’ve “wasted money” on this eyepiece (for my 8” Dob) when I can get an almost identical view in my wife’s 130P with the Meade 24mm SWA that I already have.

I do think that unnecessary cost is something that owners of multiple scopes should consider at low magnifications. 

In my case, I felt the hassle of setting up a second scope was worth eliminating by purchasing this relatively inexpensive eyepiece (in practice the central obstruction issue is easily avoided by off-centre eye-placement)

In the case of refractors however, it’s important to point out that there is precisely nothing to be gained by changing scopes - the view is identical in both cases - that’s why “wasted light” as a concept is a nonsense idea - there are no optical efficiencies to be gained. 

Edited September 24, 2022 by great_bear