Jonathan Slack: Leica APO M lenses

[Jeff S]

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12 minutes ago, jonoslack said:

 But I do think there is a thing about making a lens f2 and being able to make it either a)smaller or b) better.

 

 

Hey Jono, I know that you’re very familiar with Karbe’s thoughts on the Summilux ASPH, and I thought this old interview (apologies for posting before) especially addresses his joint concerns of reducing aberrations while maintaining compactness.  I found his comments about reinventing glass types, at significant expense, particularly interesting.

https://www.shutterbug.com/content/leica-lens-saga-interview-peter-karbe

Jeff

[Shu_downunder]

15 hours ago, jonoslack said:

Hah - I'll take that as a compliment, and yes, it does mean something on a monochrome body (just the same thing)

all the best

Jono

Surely looking forward for more articles like this, and photos!

Yes I just relaised that light, with or without colour, hit CMOS eventually. 

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[Winedemonium]

On 10/6/2021 at 9:14 PM, jonoslack said:

an Apochromatic lens is where 3 wavelengths of light focus on the same plane.

 

On 10/6/2021 at 9:14 PM, jonoslack said:

Leica's definition of an APO lens seems to be, quite simply, one which utilises low dispersion glass in construction with the intention of reducing chromatic aberrations, both in focus and out of focus. 

If I understand correctly then Jono, apochromatic is a measurable scientific fact - the three wavelengths are focused on the same plane, or not, while Leica's use of the term APO is a combination of lenses using low dispersion glass and an intention to lower chromatic aberration in all areas (in-focus, out of focus), and that this intent has been a work in progress since the first 'APO'-designated lens - the 180/3.4 APO-R in 1975. 

It's quite a distinction to make because the apochromatic claim has been made so widely in the Leica space over the years, by dealers, by users, by reviewers and other pundits (but not by Leica?). Sounds like a myth that needs putting to bed then?

 

On 10/6/2021 at 9:14 PM, jonoslack said:

Reducing the aberrations increases contrast noticeably when in focus, which has the visual effect of simulating a narrower depth of field, because the contrast drops sharply as focus is lost. 

This has allowed them to produce a range of f2 lenses which have the apparent depth of field of faster lenses, this in turn allows the lenses to be smaller and lighter and makes it possible to make them very high quality

I think this is interesting, and your point about it having been a work in progress is key. I haven't yet tried the 35mm APO-Summicron-M, but I can well believe it may represent a step forward from the 50mm APO-Summicron-M, which itself really set a new bar when released in 2012. The 75mm is clearly a half generation older and the 90mm (with no FLE) clearly one step behind that. I'm fine with that. 

Jono - this was a really useful post/article, and I hadn't considered your conclusion about the chief characteristics in common - lower aberration = higher contrast = faster falloff giving the impression of a faster lens than f/2. 

Your comparison montage of the flower at close focus distances - do you have those photos online somewhere at higher resolution that you might share please? It would be interesting to have a closer look at the rendering resemblances. 

Thanks again for this great post! 

[jonoslack]

48 minutes ago, Winedemonium said:

 

Jono - this was a really useful post/article, and I hadn't considered your conclusion about the chief characteristics in common - lower aberration = higher contrast = faster falloff giving the impression of a faster lens than f/2. 

Your comparison montage of the flower at close focus distances - do you have those photos online somewhere at higher resolution that you might share please? It would be interesting to have a closer look at the rendering resemblances. 

Thanks again for this great post! 

Hi There 

Thank you for reading it so carefully, and for understanding what I actually meant! Indeed, what Leica appear to be trying to do is to stop chromatic aberration in all areas (in and out of focus). 

There has been a lot of discussion about this around here - and it seemed to be a good opportunity to try and get a straight story together - Adan and Farnz were particularly helpful, although I fear they might think that my description is a bit superficial.

I have the article on my website: https://www.slack.co.uk (top middle article). If you scroll down to the comparison photo and then click on it, it will open it in a new window and you can zoom right in (it's not 100% but it should give you a better idea). 

All the best

Jono

[LocalHero1953]

4 minutes ago, jonoslack said:

Hi There 

Thank you for reading it so carefully, and for understanding what I actually meant! Indeed, what Leica appear to be trying to do is to stop chromatic aberration in all areas (in and out of focus). 

There has been a lot of discussion about this around here - and it seemed to be a good opportunity to try and get a straight story together - Adan and Farnz were particularly helpful, although I fear they might think that my description is a bit superficial.

I have the article on my website: https://www.slack.co.uk (top middle article). If you scroll down to the comparison photo and then click on it, it will open it in a new window and you can zoom right in (it's not 100% but it should give you a better idea). 

All the best

Jono

Hi Jono

Just for clarity, do you mean that Leica's APO lenses are NOT apochromatic in the strict sense of three wavelengths converging to the same point? Or that they ARE  intentionally apochromatic in the strict sense but Leica ALSO aims to go beyond that and remove/reduce chromatic aberration in OOF areas? Or that APO lenses MAY OR MAY NOT be strictly apochromatic, but Leica just isn't interested in aiming for that specific 3-wavelength standard?

I could quite understand if your answer is "none of these"!

[jonoslack]

3 minutes ago, LocalHero1953 said:

Hi Jono

Just for clarity, do you mean that Leica's APO lenses are NOT apochromatic in the strict sense of three wavelengths converging to the same point? Or that they ARE  intentionally apochromatic in the strict sense but Leica ALSO aims to go beyond that and remove/reduce chromatic aberration in OOF areas? Or that APO lenses MAY OR MAY NOT be strictly apochromatic, but Leica just isn't interested in aiming for that specific 3-wavelength standard?

I could quite understand if your answer is "none of these"!

Hi there

Well, I don't think I clarified those points, but I think we can infer the answers to them

1. I think they must be  Apochromatic or one would get chromatic aberration at the point of focus (which you don't).

2. Clearly they do intend to go beyond that as well by dealing with chromatic aberration in OOF areas. (and they have stated it)

3. I also think that (theoretically at least) APO lenses MAY OR MAY NOT be strictly apochromatic. (as there really isn't a tight definition of APO)

4. I don't know whether Leica is interested in aiming for the 3 wavelength standard, but I would guess so

four answers to three questions!

all the best

Jono

[Winedemonium]

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18 minutes ago, jonoslack said:

If you scroll down to the comparison photo and then click on it, it will open it in a new window and you can zoom right in (it's not 100% but it should give you a better idea). 

Thanks Jono. 

BTW, your photo captioned May the Force be with you (Botallack, Cornwall 2016) - I really can imagine this as Luke Skywalker's dog in Ahch-To / Skellig Michael!

[LocalHero1953]

4 minutes ago, jonoslack said:

Hi there

Well, I don't think I clarified those points, but I think we can infer the answers to them

1. I think they must be  Apochromatic or one would get chromatic aberration at the point of focus (which you don't).

2. Clearly they do intend to go beyond that as well by dealing with chromatic aberration in OOF areas. (and they have stated it)

3. I also think that (theoretically at least) APO lenses MAY OR MAY NOT be strictly apochromatic. (as there really isn't a tight definition of APO)

4. I don't know whether Leica is interested in aiming for the 3 wavelength standard, but I would guess so

four answers to three questions!

all the best

Jono

Thanks, that's very helpful. (It satisfies my interest, even I don't know what I will do with the information!)

[jonoslack]

Just now, Winedemonium said:

Thanks Jono. 

BTW, your photo captioned May the Force be with you (Botallack, Cornwall 2016) - I really can imagine this as Luke Skywalker's dog in Ahch-To / Skellig Michael!

Yes well - Caspar actually looks very much like a Wookie when he's on his back legs . . . . and that pose reminded me of the end of the Force Awakens in Ahch-To when Luke is looking out to sea.

[jonoslack]

54 minutes ago, Winedemonium said:

Thanks Jono. 

BTW, your photo captioned May the Force be with you (Botallack, Cornwall 2016) - I really can imagine this as Luke Skywalker's dog in Ahch-To / Skellig Michael!

See what I mean!

 

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[SiggiGun]

All this lenses are "wunderbar". But the main point for me is her consistency in rendering, color transmission etc. 

[SiriusLux]

Hello Jono,

thank you for the nice article.

As someone else stated, I also sometimes combine my 75 Apo with the 28 Elmarit asph. for the M10 when I am traveling light.

In the future I would problably like to get the APO-M 35 as I really enjoy 35mm, let's see. In my plans is also doing more 6x6 with my Mamiya 6 using b/w film, whereas all my Leica equipment has only served digital bodies.

One remark on the Vespa man photograph, I think it is a Lambretta that we see on the photograph, not a Vespa.

Jörg

[jaeger]

On 10/6/2021 at 6:14 AM, jonoslack said:

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Closest Focus with the various APO M lenses
For the 35 APO I've shown both the rangefinder limit (0.7 metre) and the 0.3 metre needing EVF or Live View
Each image represents the whole of the frame

The 90 & 75 are switched.

 

 

[jonoslack]

34 minutes ago, jaeger said:

The 90 & 75 are switched.

 

 

No Jaeger

The 75 focuses down to .75 metres

[RexGig0]

On 11/30/2021 at 1:58 PM, jonoslack said:

No Jaeger

The 75 focuses down to .75 metres

Indeed, the closer MFD of the 75 APO Summicron is what prompted me to start keeping my eyes open for a nice pre-owned sample to appear, locally, and then, after some time, to extend my search into the “evil bay.” One eBay seller offered a $500 price drop, if I ordered within 48 hours, and when I saw that he was a quite reputable seller, and an established dealer of photo gear, I accepted his offer, today.

The APO Summicron 35mm ASPH has captured my attention, too, with its 0.3 meter MFD being a factor, though the price is much more of a barrier, and, its newness and rarity will keep prices of pre-owned samples quite high, for the foreseeable future.