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Pre Swarovision EL vs SLC HD

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Old Wednesday 24th April 2019, 22:00   #1
peakbagger46
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Pre Swarovision EL vs SLC HD

Greetings all, first post here but Ive been lurking for some time now.

I recently bought a used 2009 8X32 for a steal ($830). The glass is phenomenal, but I think I am going to sell it and go with a 42mm objective for low light use and general ease of view with a large exit pupil.

I cannot afford a Swarovision EL so have narrowed down my choice to either a 8x42 SLC HD or a 2007-2009 range 8.5X42. Which of these choices is optically superior?

Thanks in advance, Ive been impressed reading all the knowledgeable posts on this forum.
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Old Thursday 25th April 2019, 07:26   #2
John A Roberts
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'Peaky'

The pre-Swarovision EL (in x42 to mid 2009)
Has an objective of 3 elements in 2 groups (2 + 1 focusing); and an eyepiece of 5 elements in 3 groups (2 + 1 + 2)

The SLC HD (the new x42 design introduced in 2010)
Has an objective of 4 elements in 3 groups (1 + 2 + 1 focusing); and an eyepiece of 5 elements in 3 groups (2 + 2 + 1)

The SLC HD also has the additional advantages of:
- An HD element in each objective
- More recent lens coatings, resulting in both a 'paper white' image (see the highlighted reference in my post here: https://www.birdforum.net/showpost.p...2&postcount=14 ), and
- Potentially a slight increase in transmission

While the SLC HD is technically optically superior, we're talking about incremental improvements which may not be significant in practice
- especially, when balanced against other considerations (e.g. haptics and ergonomics)

As always, the best bet is try before you buy, and get what fits you/suits you the best overall

John

p.s. for general reference I've attached a cross section of each model
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Old Thursday 25th April 2019, 18:36   #3
elkcub
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John,

Thanks for the drawing of the original 8x42 SLC-HD. Would you happen to have one of the current 8x42 SLC for comparison?

Ed
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Old Friday 26th April 2019, 00:33   #4
John A Roberts
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Ed

In addressing your specific query, I've gone into greater detail to provide context for others . . .

The SLC HD x42 (an all new design, distinct from previous SLC production) was introduced in 2010, and the cross section is the most recent one for SLC models provided by Swarovski
I’ve also attached an alternate view from that time

In 2013, the new x42 SLC design was simplified in two ways:
- the use of dual texture all over rubber coating
- increasing the minimum focusing distance from 1.9 to 3.2 meters
Otherwise, the designs are identical - including optically (although no longer included in the designation, the 2013 version still has HD glass)

The changes had the effect of providing greater product differentiation between the EL and SLC lines, especially visually and price wise
(it seems that increasing the minimum focusing distance allowed the use of a mechanically simplified focus assembly)

n.b. in contrast, production of the original x56 SLC continued until 2013, when an all new design was introduced with the same style of covering as that of the 2013 x42


I’ve also attached an image from the current SLC catalogue (see: https://aa.swarovskioptik.com/custom...d=10007.466400 )
It shows from the front:

2013 x42 SLC (current model, all over two texture rubber coating) EDIT: although the image seems to show 2 different colours, it is all the same colour

2010 x42 SLC HD (all new model, forrest green with blackened exposed metal in bridge area)

2005 x42 SLC neu (mechanically and optically identical to previous models, forrest green with black rubber in bridge area)

1997 x42 SLC upgraded covering (it lacks the ‘shoulders’ of the original covering, also with either green or black covering)

1992 x42 SLC introduced (with either green or black covering)

And while the above describes the obvious hardware changes, there were of course various 'firmware' changes across the period in terms of lens and prism coatings


John


p.s. as near as I can determine, the x42 SLC's were introduced in 1992 with locking diopter adjustment (x30's only had friction 'locking'), and push-pull eyecups. Twist eyecups were introduced in 1997 and could be retrofitted to the earlier production
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Last edited by John A Roberts : Friday 26th April 2019 at 01:55.
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Old Friday 26th April 2019, 02:35   #5
peakbagger46
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Thank you John for your very detailed response. What does the added lens at the objective end accomplish functionally?
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Old Sunday 28th April 2019, 01:49   #6
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PB

The human eye can see a range of colours, which correspond to the portion of the electromagnetic spectrum from around 400 to 700 nanometers
The range of colours was originally identified by Isaac Newton, using a refracting prism (see the example from Wikipedia)

Newton identified the principal colours as: red, orange, yellow, green, blue and violet (i.e. from high to low frequency)
However, the total range of visible colours is of course a continuous gradation, rather than a set of distinct steps

When the light from a scene is focused through a single lens - to a single focal point - the various wavelengths/colours are refracted to different degrees (as with a prism)
This results in the colours focusing to a range of slightly different points along the optical axis, with the short wavelengths (violet and blue) being the most refracted (again see a diagram from Wikipedia)
And this is observed as chromatic aberration (aka colour fringing), which makes the image appear very slightly unsharp - since not all of the colours can be simultaneously at the same point of focus

A long standing correction for binoculars and other devices, is the use of two objective lenses with different optical characteristics - referred to as an achromat pair
They are commonly used to move the focal points of the shortest wavelengths to those of the longest wavelengths (again see an image from Wikipedia)
n.b. while for clarity the diagrams show 3 discrete pairs of lines/colours, each line represents a range of wavelengths

However, this still leaves the mid-range wavelengths at slightly different points of focus. And that is the function of the third HD glass lens

Whether this makes a significant difference in your choice of the El pre-SV or SLC HD is best judged by actual comparision

John


p.s. I’ve attached a ‘stylised'/extreme example of Chromatic Aberration - it appears as a degree of fuzziness around a sharp core (the image is from a Swarovski advert for the EL Swarovsion)
Note the use of the word ‘can’ in the description. Individuals have markedly differing degrees of sensitivity to CA - and it’s a frequent topic of discussion/dispute on this forum in regard to various binoculars
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Old Sunday 28th April 2019, 15:23   #7
henry link
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Quote:
Originally Posted by peakbagger46 View Post
What does the added lens at the objective end accomplish functionally?
Robert is right in general terms, but the Swarovski SLC and EL objectives were changed in more ways than one and the glass types are unknown, so it's a bit hard to say what, if anything, was accomplished by adding a lens. The original SLCs and ELs had fixed doublets combined with moving positive focusing lenses. The current ones have fixed triplets combined with moving negative focusing lenses, a design that goes back at least as far as the original Leica Trinovids. Because they're combined with negative focusing lenses the doublets in the earlier Swarovski models required less refractive power than the later triplets to arrive at the same effective focal ratio once combined with the focusing lenses. The later designs may need to be triplets just to achieve the same level of corrections as the earlier doublets.

The earlier Swarovski design hasn't completely disappeared. There is at least one current high end binocular that uses a fixed doublet and moving positive focusing lens design: the Zeiss SF. Ironically, it has replaced the Zeiss HTs, which had objective designs similar the the current Swarovskis, so neither design is necessarily more "advanced" but rather is a matter of the designer's personal preference. It's probably not a coincidence that some members of the team responsible for the original EL later moved to Zeiss and designed the SF.

Henry

Last edited by henry link : Monday 29th April 2019 at 00:39.
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Old Sunday 28th April 2019, 16:21   #8
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ROYGBIV Wikipedia has interesting details re. spectrum.

We always used Richard of York gave battle in vain.

Apparently people in York prefer Rowntrees of York gives better in value.

The article says that Aristotle also named seven primary colours as did Newton.
The I is indigo, but Newton's colours differ slightly to today's.

Looking at a bright rainbow one sees the range of colours.
I think the secondary rainbow colours are reversed.
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Old Monday 29th April 2019, 01:02   #9
John A Roberts
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Picking up on Henry’s observations, and going from the general concept of achromatic objectives, to the specifics of Swarovski construction . . .

The cross sections included in Swarovski’s patents better show the lens shapes than Swarovski's 3D cutaway images


ORIGINAL EL
The positive and negative curves of the objective lenses can be clearly seen in both:
- the first image from the EL patent
- and the second EL image from the EL SV patent (see the next post), which also includes the eyepiece

As Henry observed, the objective pair is mildly positive combined with a positive focuser

n.b. I’ve not been able to find any patents showing the optics of either old or new SLC models (the old models have objectives similar to the EL, and the new models similar to those of the EL SV)


EL FOCUS MECHANISM
The patent also shows the complexity of the EL and EL SV focus mechanisms
Although I’ve not seen this mentioned before (or it didn't stick in my memory), it appears that rotation of the focus knob is converted into a back-and-forth movement of a pivoted arm
The motion of the arm then moves the rod that moves the focus lens (there are additional images in the EL SV patent)


The mechanism is obviously much more complex than a typical one, where: focus knob rotation, via a cog system, rotates the rod that moves the focus lens
The EL mechanism would have been necessitated by the limitations imposed by the open bridge design
And it would also seem to be a significant factor in the criticisms over the years, regarding the smoothness and evenness of the focuser movement, of both the original and SV versions

ctd . . .
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File Type: pdf US6266185 (EL, 1999).pdf (734.9 KB, 13 views)

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Old Monday 29th April 2019, 01:09   #10
John A Roberts
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EL SWAROVISION
The EL SV patent clearly shows the difference in objective lens shapes including the negative focusing lens
I’ve attached 3 images

n.b. in comparing the second and third images, there is an error in the third - the 4th lens in the eyepiece assembly has not been shaded in (the front lens of the doublet), though the space for it is present


ctd . . .
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Name:	EL SV 3 (4th lens missing in EP) .jpg
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File Type: pdf WO2009137860A1 (EL SV, 2009) .pdf (743.8 KB, 15 views)

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Old Monday 29th April 2019, 01:15   #11
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EL RANGE
For completeness, I’ve enclosed an image from the EL Range patent
It shows the same objective construction as the EL SV (number of lenses and groups) - however, the lens curves differ *

* EDIT: on reflection (no pun intended), the EL Range objective lenses may very well be identical to those of the EL SV
- the Range image shows an external view of the lenses, rather than the cross-section view of the EL SV lenses


n.b. as matter of interest, the patent also shows 2 design variations using Uppendahl prisms (see the image). Presumedly this was a pre-emptive claim in relation to Leica


John
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Last edited by John A Roberts : Monday 29th April 2019 at 23:01.
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Old Saturday 11th May 2019, 15:52   #12
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Thanks for the responses. After handling both, I ordered a brand new SLC 8X42 for $1,500 USD. Somehow the SLC felt better in hand than the open bridge EL.
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Old Saturday 11th May 2019, 22:00   #13
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Quote:
Originally Posted by peakbagger46 View Post
Thanks for the responses. After handling both, I ordered a brand new SLC 8X42 for $1,500 USD. Somehow the SLC felt better in hand than the open bridge EL.
Good choice. I don't think you'll regret the decision. Make sure to wear it out observing things.

Ed
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Old Saturday 11th May 2019, 22:06   #14
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Originally Posted by peakbagger46 View Post
Thanks for the responses. After handling both, I ordered a brand new SLC 8X42 for $1,500 USD. Somehow the SLC felt better in hand than the open bridge EL.
That's the one I would have gone with...
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