Lenses with the fewest number of elements?

[Roger Hicks]

Here is my take on micro contrast. Your subject is a series of black and white strips gradually decreasing in width. The image is likewise a series of strips until the lens can't resolve them and that part of the image is grey (i.e. the average of black and white). Good micro contrast lenses preserve the 'blackness' and 'whiteness' of the strips until they can no longer resolve, but the transition is quick. Lenses with poor micro contrast resolve the lines but as 'dark grey' and 'light grey'. They might have much greater resolution (ability to distinguish strips) but the overall impact is not as punchy as a lens with less resolution that resolves 'black' and 'white' until it can no longer resolve. It's a subtle effect to do with how the lens aberrations effect the black and white strips. If the aberrations allow the lens to resolve (i.e. you can see the strips) while also allowing some light to spread out round the strips, the lens will have good resolution and poor micro contrast. This is completely different from macro contrast (or flare) which is light bouncing off glass-air interfaces and getting all over the place: this light effects all the strips, even the widest strips, equally. The Sonnars had good flare resistance because the number of glass air interfaces was minimised and good micro contrast because the 7 elements allowed a high degree of correction. I think to get good micro contrast you need a well corrected lens.

That pretty much sums it up -- and as I said earlier, In the 1930s the choice in standard lenses was stark: lower resolution with higher contrast (Zeiss) or lower contrast and higher resolution (Leitz).

Cheers,

R.

 

[Freakscene]

That pretty much sums it up -- and as I said earlier, In the 1930s the choice in standard lenses was stark: lower resolution with higher contrast (Zeiss) or lower contrast and higher resolution (Leitz).

This was the case when spherical abberrations were limiting. Modern optical glass, lens design and construction mean that this is no longer the case, so we can have lenses with high contrast and resolution. Usually this is based on cost and size considerations during design.

The OP should read some technical optical works, rather than uninformed rubbish on the internet. If you have modern lenses and your old lenses have higher microcontrast you are either judging good old lenses against bad modern ones, measuring the wrong thing, or you need to better understand what you are seeing.

Marty

 

[Dralowid]

Nothing to do with the current debate but the stunning Leitz 400 and 560mm Telyts have only two elements in one group.

 

[Roger Hicks]

This was the case when spherical abberrations were limiting. Modern optical glass, lens design and construction mean that this is no longer the case, so we can have lenses with high contrast and resolution. Usually this is based on cost and size considerations during design.

The OP should read some technical optical works, rather than uninformed rubbish on the internet. If you have modern lenses and your old lenses have higher microcontrast you are either judging good old lenses against bad modern ones, measuring the wrong thing, or you need to better understand what you are seeing.

Marty

Dear Marty,

Indeed -- but the other limiting factor in the 1930s was the absence of coating, which exacerbated the problem.

Also, I understand from my few lens-designer acquaintances that the advent of wave front calculations (as distinct from ray tracing) made an enormous difference.

Cheers,

R.

 

[Freakscene]

Indeed -- but the other limiting factor in the 1930s was the absence of coating, which exacerbated the problem.

Absence of coating decreases performance for both low contrast high resolution and high resolution low contrast systems. The effect is different but it's there for both types of approaches.

Also, I understand from my few lens-designer acquaintances that the advent of wave front calculations (as distinct from ray tracing) made an enormous difference.

That's what I meant when I mentioned lens design. Current model based approaches are even better.

There are still different approaches that can reach the same outcome, but the tools and materials are vastly more refined.

Marty

 

[Roger Hicks]

Absence of coating decreases performance for both low contrast high resolution and high resolution low contrast systems. The effect is different but it's there for both types of approaches.


Marty

Dear Marty,

Indisputably; but for the importance of the introduction of coating, compare coated and uncoated versions of the pre-war Leica and Zeiss designs.

Cheers,

R.

 

[wolves3012]

Human eyeball has 1 lens element.

Not quite, actually it has two. The cornea is the major refracting element, not the lens. So it's actually a doublet of sorts. As Roger says, it does need a lot of post-processing!

 

[narsuitus]

The cornea is the major refracting element, not the lens.

Learned something new. All this time I thought the cornea was nothing more than a clear protective filter that protected the lens from dust and damage.

Thanks!

 

[wolves3012]

Learned something new. All this time I thought the cornea was nothing more than a clear protective filter that protected the lens from dust and damage.

Thanks!

What I said is a bit of a simplification, since there's the aqeous humour behind the cornea and the cornea bulges to make a lens shape out of the aqueous humour - but it's still not a 1-element system. However, we digress!

 

[Spavinaw]

The Spiratone 100mm f4 Portragon T-mount is a one element lens.

 

[ChrisPlatt]

I remember my mom claimed that a pinhole "lens" should have no distortion.

Chris

 

[David Hughes]

Hi,

Back to the question which was "So I was wondering, what are the very simplest designed lenses?".

Well, my money's on the Kodak meniscus f/11 fitted to the Vest Pocket Kodak (VPK); fixed focus and using 127 so miniature by most standards. I know there's a lot of variation in the posh versions of the VPK; one of them even could be focused (gasp!). But for simplicity it can't be beaten.

There's a book "The Soldier's War" by Richard Van Emden that has dozens of photos in it from the Great War and almost every one was taken with a VPK. And there's lots on the www.

Add to that Kodak's Panatomic film (new in 1933) and their claim that a half VPK negative could be enlarged to exhibition size photos and it should be a winner. BTW, half VPK means 40mm by 32-ish.

Regards, David

 

[k__43]

I'd like to mix my personal view on this. I think a sonnar has more elements in it than a tessar but to me the sonnar formula is the one resulting in the most interesting transitions from focus to non-focus. hence less cut-out more pop-out a.k.a. 3D-pop
Also Zeiss is said to have generally more of this so it all might be a question of details like coating and overall (company inherent) stradegy towards designing a lens not only the number of elements/lenses.

 

[tunalegs]

The standard "meniscus" used in the VPK was actually a cemented doublet. Shouldn't really matter so far as contrast is concerned since there is no air space between the elements.

At the time the only cameras in Kodak's range with single element lenses were the Brownie box cameras (and even then the larger ones had achromat doublets.)

There's a person on flickr with an album of nice shots taken with a Brownie Model D, one can judge the results for themselves: https://www.flickr.com/photos/ericswanger/albums/72157630920246298

 

[k__43]

while we are at simple lens MF cameras - the Agfa Clack corrected the the meniskus with a bend film rail - basically the same trick the human eye uses (sort of). it gets quite good results actually. I'd use mine more often if film wouldn't be that expensive (I rather use a "real" camera, not to waste the good stuff)

 

[Roger Hicks]

I'd like to mix my personal view on this. I think a sonnar has more elements in it than a tessar but to me the sonnar formula is the one resulting in the most interesting transitions from focus to non-focus. hence less cut-out more pop-out a.k.a. 3D-pop
Also Zeiss is said to have generally more of this so it all might be a question of details like coating and overall (company inherent) stradegy towards designing a lens not only the number of elements/lenses.

Both the Tessar and the Sonnar are derivatives of the Cooke triplet, the Tessar with the third element replaced with a cemented doublet and the original 50mm Sonnars with two elements replaced with cemented groups: 1-3-2 (glasses per group) for the f/2 and 1-3-3 for the f/1.5.

And to quote from a conversation with the late Dr. Hubert Nasse of Zeiss -- Google his name if you're not familiar with his work -- "You can do all the modelling and theory in the world, but the only way to find out how a lens performs is to make it." Which he was in a position to do...

I have tears in my eyes as I write this, because I only just learned that he had died when I Googled his name to provide a link. He was an unbelievably nice person and an incredible enthusiast as well as a brilliant optical theoretician and lens designer.

Best,

R.

 

[Redseele]

It's amazing to think that there's so much history behind lens designs... not only the actual lenses, but manufacturing processes, designers, political events (think of FSU lenses as a consequence of WWII), etc. Thank you Mr. Hicks for letting us know about Dr. Nasse.

 

[Redseele]

Now... what about lens for LTM or M-mount with the fewer elements? 🙂

 

[sevo]

Now... what about lens for LTM or M-mount with the fewer elements? 🙂

Many of the longer, slower Visoflex Telyt heads are cemented doublets (and so are the period Novoflex lens heads). It will hardly go any less than that...

 

[David Hughes]

The standard "meniscus" used in the VPK was actually a cemented doublet. Shouldn't really matter so far as contrast is concerned since there is no air space between the elements.

At the time the only cameras in Kodak's range with single element lenses were the Brownie box cameras (and even then the larger ones had achromat doublets.)

There's a person on flickr with an album of nice shots taken with a Brownie Model D, one can judge the results for themselves: https://www.flickr.com/photos/ericswanger/albums/72157630920246298

Hi,

This is Kodak's opinion:-

Regards, David