50mm Charts: OKS vs Cooke | oks1-50-1 vs Cooke Speed Panchro vs Cooke SP Ser.II

[Ilya O.]

A little vintage cine 50mm lens comparison, OKS vs Cooke. Oks1-50-1 vs Cooke Speed Panchro vs Cooke SP Ser.II
Here is the lens schemes/diagrams and main optical characteristic taken from the NIKFI Catalogue of 1968 for pure lens nerds:

Cooke Speed Panchros first version look like this:

They were in production like late 20-s to postwar times. These at the photo are in black enamel finish (brass barrels) with round L-shaped wires locking the lens cells from loosening.
All or most were uncoated.

 

[Ilya O.]

well, technically speaking Cooke 50mm ser.II is a killer lens even as of today standards, better than oks1-50-1!!!
50mil ser.II has nearly zero distortion, nearly zero astigmatism, very good chromatic aberration correction, low sharpness falloff, high contrast black-to-white transition (edge definition).

!!! that been said guys you gotta keep in mind that in real life situation one must test both lenses to choose the better one cause there is ALWAYS lens copy quality variation!!!

Besides this NIKFI Cat-s choose the best oks1-50-1 I think whilst I am not sure if it was the case with Cookes. I think they tested what they had at hand, still I am sure they would NOT take obvious bad copy of Cooke.

 

[Tommaso Alvisi]

Ok Ilya, now it's official, dinner is on me if you ever come to visit my city...

Yeah 50mm SP SerII is great I totally agree!

But I like 50mm Lomos too...and later designs are very good!!!

 

[Tommaso Alvisi]

Ilya, hope everything is good on your side!

Did you ever managed to upload the OKS part of the NIKFI Catalogue?

I'd be curious to compare the SP 50mm Ser. II to the 1-50-6 and SP 75mm Ser. II to the 6-75-1

Have a nice weekend!!!!

 

[paulcurtis]

I had a cooke 50 and a Lomo 50 together. They were 99% identical in any of my tests, from bokeh, flare, look and so on. To the point where i was fairly convinced that formula must be very similar. I doubt anyone except someone looking very closely would tell them apart.

cheers
Paul

 

[Tommaso Alvisi]

Thanks Paul, do you remember which 50mm Lomo was exactly? Presumably the 1-50-1, right?

 

[Vladimir Cazacu]

The PO3-3M is very similar to the Speed Panchro 50mm F2.

The flares and overall contrast of the lenses show some subtle differences due to the different coatings used but other than that it's really hard to tell them apart.

 

[Tommaso Alvisi]

The PO3-3M is very similar to the Speed Panchro 50mm F2.

The flares and overall contrast of the lenses show some subtle differences due to the different coatings used but other than that it's really hard to tell them apart.

Not the Ser. II SP I think, you're talking of an older 50mm Speed Panchro of the same era of the old PO3-3M, right?

 

[Vladimir Cazacu]

My bad, I thought I wrote it down: Ser I Speed Panchro.

 

[Ilya O.]

Tommaso, greets.

Check your inbox for private messages, I've made little amends for delay

 

[Tommaso Alvisi]

arty:

 

[Ilya O.]

Adding Lomo OKS 75mm oks1-75-1, oks6-75-1 versus Cooke 75mm SP and SP Ser.II grafs:

Tommaso Alvisi asked:
Ah btw what do you think of Cooke SP 50mm Ser II VS 1-50-6 ?

— I have searched for 1-50-6 test diagrams, but found nothing. Since the first two digits are he same as in oks1-50-1 I think they are more or less optically the same but oks1-50-6 is later model, mod number 6, could have reduced front or back element (?), has a bit different optical block barrel and has multi-coating. Why I put comparison here? If 1-50-1 and 1-50-6 are more or less the same, it's classical opic/double gauss/planar 6/4, — so, we can take 1-50-1 graphs from above and compare it to Cooke SP II. But again, till I found the real graphs of 1-50-6 my comparison in that thread is pure theoretical.

On the other hand, one need to gather two lens together, oks1-50-6 and cooke sp II to make a real test. I have 1-50-6, but no Cooke SP II...


Tommaso Alvisi asked:
And 75mm Ser II VS 6-75-1?
Also 1-50-1 VS 1-50-6 and 1-75-1 VS 6-75-1 ? Personal opinion on bokeh? Less/more swirly? Harsher/Smoother?
These Lomo designs should be more modern and theoretically improved but what's your take?
The fact that newer Lomo designs have (I think?) a more complex double gauss design so bokeh could suffer?

— No, both LOMOs are double-gauss planars, the 6-75-1 has just all 6 lenses not cemented for better correction (uses air gaps as a lens). It has original 6/6 formula but still double-gauss, so I do not expect bokeh to suffer. Overall technically 6-75-1 is superior to 1-75-1: more resolution, less resolution fall-off, multi-coating, sharper definition (black-to-white transition), a bit better CA correction, bit less astigmatism, has a technological advantage of a shorter back focal lenght — all these advantages are just marginally better, regular user won't ever notice the difference between 1-75-1 and 1-75-6 (despite the MultiCoating and color, the latter should be less warm but still it has a reduced transmission in violet-cyan range so again warm look, see the Spectral transmission graph). So all you notice if put both head to head on camera is, realistically speaking, more of a lens copy variation but not the true lens difference.

In what oks1-75-1 advances oks6-75-1 is the distortion — it is just negligble, ~-0.2% at image edge while oks6-75-1 has -0.7%. Do not think these are high values, for example Zeiss in their MTF brochures calls that numbers "the absence of distortion".

As for bokeh suffering of not so symmetrical non double-gauss design — it is Cooke SP II 75mm which is not double-gauss design! It has unsymmetrical telephoto lens design similar to Cooke Kinetal tele lenses, namely 16mm Cooke Kinetal 50mm design:

This is modified Sonnar design which is known for superbly smooth bokeh.

Is there anybody here who shows us the real Kinetal 50/75mm bokeh, guys?

 

[W. Su]

This is modified Sonnar design which is known for superbly smooth bokeh.

Speed Panchro is a commercial trade name, there are various optical design sharing this name, even with the same "Speed Panchro 50mm"

Goes for telephoto lens. At the early period before 1930, Taylor-Hobson used to apply 5-glass Ernostar type on 108mm Speed Panchro, for better out-of-focus/bokeh effect. Then TH discovered the "surface treating" technology, improved the field bokeh of Double-Gauss type, that became 100mm Deep Field Panchro. But for lower priced telephoto lens, TH put Ernostar/Sonnar design on Kinetal 50mm and SP SerII 75mm.

 

[W. Su]

The optical formula of Kinetal 50/1.8 and Speed Panchro SerII 75/2, was recorded in Example-2 of British patent 653,227 (also USP2,502,509). You could find some details there.