My thoughts on the Kipon Medium Format "Speedbooster"

[Tim Fraser]

On 21/02/2017 at 4:33 AM, tweak said:

I hope everyone knows that in part modern lenses are far superior to equivalent vintage lenses. Thus you must throw all your old lenses away as they are worthless and there is no point to shoot with them  .

well, ahemmm, in part

 

[Nikkor]

8 hours ago, Mattias Burling said:

I will also do some side by side with my Mamiya film camera to see how they differ.
Just bought a new 645 house that included yet another 80mm f1.9 for free

Can't wait for this part, if you take the same picture in the tricky situations for swirly bokeh it would be even nicer. I was really looking forward to this adapter but after seeing samples it just reminds me of the cheapo chinese focal reducers.

[tweak]

13 hours ago, Tim Fraser said:

well, ahemmm, in part

 

Sorry, my sarcasm obviously isn't too obvious.

[Mattias Burling]

Stumbled upon a pair of lenses at a local fleemarket today that will be good for comparing to an 80mm with a x0.7 crop (56mm FF).

My GF wanted to buy a chair and the seller was asking $20 bucks. I said $25 if she threw in the two Helios 44 - 58mm f2 lenses she had. One silver and one black.

Turns out the silver was the 13 bladed version

I will of course compare to modern glass as well using the Nikkor 24-70/2.8 and 70-200/2.8. And the modern Zeiss prime from earlier. But I thought against other vintage options could be interesting as well.

[Brian Caldwell]

On 2/23/2017 at 5:33 PM, jcs said:

I did those tests- it's not really possible to do perfect equivalence with physical lenses unless all the settings can be exactly matched. In the first example, the only major difference was shadow detail which could be related to ISO... In the second example, maybe I made a mistake or it's still related to optics not really being equivalent. The 'normal' test matches almost perfectly.

Brain Caldwell, the optical engineer and inventor of the Speed Booster says the same thing regarding FF vs. MF. That's why he wasn't interested in making a MF to FF SpeedBooster...

In any case, the differences are minor and most people couldn't tell the difference. Someone posted computer graphics (ray traced?) examples that matched perfectly, as the math predicted.

You should be aware that this is a religious discussion.  Comparisons, and discussions about comparisons, should be avoided and only discussed in private!

[kidzrevil]

This looks awesome ! you're probably gonna wanna jump off a bridge if you plan on pulling focus wide open though LOLLLL

[tweak]

This talk of lens "equivalence" reminds me of childhood physics where you compared things as if they were in a "perfect vacuum" hahaha.

[Don Kotlos]

6 hours ago, Brian Caldwell said:

You should be aware that this is a religious discussion.  

 Yes but since its physics we are talking about it is just sad. 

[tupp]

7 hours ago, Brian Caldwell said:

You should be aware that this is a religious discussion.

37 minutes ago, Don Kotlos said:

Yes but since its physics we are talking about it is just sad. 

Perhaps one of you could explain -- from a physics perspective -- why the DOF doesn't appear to be equivalent in the DOF equivalence demonstrations that you linked.

[jcs]

6 minutes ago, tupp said:

Perhaps one of you could explain -- from a physics perspective -- why the DOF doesn't appear to be equivalent in the DOF equivalence demonstrations that you linked.

Thanks for creating the animated gif which clearly shows equivalence, even when the settings aren't exact (which mostly effects shadows- bokeh matches pretty nicely). If you want to see perfection, dig up the computer graphics renderings from one of the "FF/MF look" threads on this forum: the results are pixel perfect (probably (photon) ray-traced optics).

I think what people are liking about the MF lenses is their character, and even what some might call artifacts (including artifacts from the focal reducer).

[tupp]

52 minutes ago, jcs said:

Thanks for creating the animated gif which clearly shows equivalence

It most definitely does not show equivalence -- the foreground (front of lens) stays sharp in both images while the focus on the background changes between images.

 

 

52 minutes ago, jcs said:

even when the settings aren't exact (which mostly effects shadows- bokeh matches pretty nicely).

The circled items in the above image do not seem dark or shadow-like:  they appear to be a well lit counter-top edge and a detail on the front of a cabinet door.  Nevertheless, the focus one those to items is most certainly changing.  It is obvious that they go soft and then back to sharper focus.

 

In addition, the bokeh changes significantly -- a telltale sign that the DOF/background-focus has changed:

In the read circle, note that the bokeh changes size dramatically, while the dark rectangular object that it overlaps changes less so.  It is very obvious how the proportions of that bokeh changes relative to the dark corner it overolaps.

 

The bokeh in the yellow circle changes size and its edge changes softness.

 

The two overlapping bokehs in the orange circle are more blurred and blend together in one image, but are sharper and more distinct in the other image.

 

Bokeh is not shadows.

 

In the blue circle, there is some purple item that is softer in one image, yet becomes more defined in the other image.  Is that a purple shadow?

 

In the green circle the leftward edge of the tripod head bracket is sharper in one image but blurrier in the other image.  It is lit brightly enough to see that the focus there has changed, while the focus on the front of the lens stays sharp.

 

The DOF is different -- not equivalent -- in these two images.

[leeys]

So, at this rate, when is 8x10 LF going to be the new premium look?

[Brian Caldwell]

2 hours ago, tupp said:

It most definitely does not show equivalence -- the foreground (front of lens) stays sharp in both images while the focus on the background changes between images.

 

 

The circled items in the above image do not seem dark or shadow-like:  they appear to be a well lit counter-top edge and a detail on the front of a cabinet door.  Nevertheless, the focus one those to items is most certainly changing.  It is obvious that they go soft and then back to sharper focus.

 

In addition, the bokeh changes significantly -- a telltale sign that the DOF/background-focus has changed:

In the read circle, note that the bokeh changes size dramatically, while the dark rectangular object that it overlaps changes less so.  It is very obvious how the proportions of that bokeh changes relative to the dark corner it overolaps.

 

The bokeh in the yellow circle changes size and its edge changes softness.

 

The two overlapping bokehs in the orange circle are more blurred and blend together in one image, but are sharper and more distinct in the other image.

 

Bokeh is not shadows.

 

In the blue circle, there is some purple item that is softer in one image, yet becomes more defined in the other image.  Is that a purple shadow?

 

In the green circle the leftward edge of the tripod head bracket is sharper in one image but blurrier in the other image.  It is lit brightly enough to see that the focus there has changed, while the focus on the front of the lens stays sharp.

 

The DOF is different -- not equivalent -- in these two images.

You are expecting a level of precision in this comparison that is entirely unreasonable.  Little things like changes in distortion and entrance pupil position during zooming make it impractical to make a blink comparator test completely perfect.  What the comparison does show - with more than sufficient precision - is that you can optically reproduce all aspects of an image shot on a large format with one shot on a smaller format - or vice versa.  

The notion that, say, an 80mm medium format lens has some inherent "80mm-ness" or "medium formatishness" that somehow stays with that lens after you attach a focal reducer is just silliness.  The combination of a 0.7x focal reducer and an 80mm lens is a 56mm lens.  Period.  Put that 56mm lens on a 24x36mm format camera and it will behave just like any other 56mm lens attached to that camera, the only caveats being related to aberrations and other flaws in the lens and focal reducer.

[kidzrevil]

Interesting stuff about the DOF ?, I really like the character of @Mattias Burling shots. Does the DOF equivalence really matter if the rendering looks this good ? Serious question, not trying to troll

[Timotheus]

51 minutes ago, kidzrevil said:

Interesting stuff about the DOF ?, I really like the character of @Mattias Burling shots. Does the DOF equivalence really matter if the rendering looks this good ? Serious question, not trying to troll

Of course results are what count. My 2 cents: just don't get caught up in a possibly expensive quest for medium format glass assuming there is a super different, unique, mythical look to be achieved. (Not to say that hunting down and using vintage glass is a blast!).

Understanding equivalence can help one understand what results can be expected from any combination of sensor size and lens. Yes, there are unique combo's at the extremes of the range (no m43 equivalent lens for a 50mm f1.0 on full frame). But in general: for the most frequently used focal lengths, you can find equivalent lenses for the current different sensor sizes, thus yielding (close to) identical optical results.

[Russell Alboroto]

Hey, just sharing some images I took with my adapter and camera. These are shot with my A7s or A7rii + Pentax 645 Kipon Speed Booster + Contax 80mm f/2 (Modified)

A7s

A7rii

A7rii

A7rii

[Mattias Burling]

1 hour ago, Russell Alboroto said:

Hey, just sharing some images I took with my adapter and camera. These are shot with my A7s or A7rii + Pentax 645 Kipon Speed Booster + Contax 80mm f/2 (Modified)

A7s

A7rii

A7rii

A7rii

Yey! Im not alone!

Great pictures and awesome bokeh!

BTW, if someone feel they would like to go for it but not "hunt for expensive lenses" I can say, the lenses are cheap. Like always its about knowing where to look and how.

My cheapest medium format lens so far is a 80mm f1.9 for $120 wich included a Mamiya 645 Pro camera. I can sell the camera for $120. 

So $0 for the super fast 80mm feels alright compared to any vintage glass. I also passed on a $180 Pentacon 6 camera including two nice lenses.

Both deals where on ebay but settled outside.

[Brian Caldwell]

4 hours ago, kidzrevil said:

Interesting stuff about the DOF ?, I really like the character of @Mattias Burling shots. Does the DOF equivalence really matter if the rendering looks this good ? Serious question, not trying to troll

Character/rendering are entirely separate issues from photographic basics like DOF and perspective.  Certainly, if you like the character then there's nothing wrong with that.  Heck, if you find that using an 80mm lens with both a 1.4x teleconverter and 0.7x focal reducer (in series!)  to get back to 80mm but with some funky aberrations gives you the results you want then you should certainly do it.  My only real objection is with pseudo-explanations - basically "fake physics" - that cross the line into mysticism.

Mini correction:  techically, aberrations can and do influence DOF.

[jcs]

2 hours ago, Mattias Burling said:

Yey! Im not alone!

Great pictures and awesome bokeh!

BTW, if someone feel they would like to go for it but not "hunt for expensive lenses" I can say, the lenses are cheap. Like always its about knowing where to look and how.

My cheapest medium format lens so far is a 80mm f1.9 for $120 wich included a Mamiya 645 Pro camera. I can sell the camera for $120. 

So $0 for the super fast 80mm feels alright compared to any vintage glass. I also passed on a $180 Pentacon 6 camera including two nice lenses.

Both deals where on ebay but settled outside.

This discussion reminds me of similar ones for analog vs. digital audio, vinyl/tape vs. digital, tubes vs. MOSFETs, one preamp vs. another preamp, one mic vs. another, crisp and clinical vs. warm and creamy, etc. Head on over to GearSlutz for a taste of audio drama for those inclined: https://www.gearslutz.com/board/ (around 10 million posts!). It's a great resource for audio related questions for filmmaking too.

In agreement with what @Brian Caldwell just said- these lens combos are creating interesting character, analog optical filters (transfer functions), which is art, and that is cool. It has nothing to do with sensor size per se, only the combination of optics to get the desired (or discovered!) look.

Here's an example of Shane Hurlbut comparing Leica Summicron-C to Cooke S4, same sensor size (Super35), and getting vastly different results (his perception, some of you may even disagree with his results):

http://www.thehurlblog.com/lens-tests-leica-summicron-c-vs-cooke-s4-film-education/

To wrap it all up:

Leica Summicron-C Lenses:

• Flatter image
• Makes Monette look more sophisticated and older
• Makes her look wider than the Cooke S4
• More of a white out with lens flares; doesn’t do as well as the Cooke S4 with lens flares.
• Bokeh less stop signing, more round
• Neutral lens
• Less detail in her face
• Doesn’t hold highlights as well as Cooke S4
• Less contrast
   

Cooke S4 Lenses:

• More three dimensional quality
• Makes Monette look younger
• Makes her look skinnier
• Better with lens flares than the Summicron-C lenses
• Slightly more yellow than the Summicron-C
• Bokeh has more of a stop signing effect
• More detail in her face
• Holds highlights more than the Summicron lenses
• More contrast

Thanks @bunk for creating these excellent computer renderings, which physically simulate perfect lenses and sensors via ray tracing photon paths for different sensor sizes and using perfect mathematical equivalence with pixel perfect results:

http://www.eoshd.com/comments/topic/20975-full-frame-aesthetic/?do=findComment&comment=167154

@Mattias Burling offered $100 if the images matched perfectly (if I read the thread correctly, see link above). Mattias did you pay bunk? The time and effort to set up and render those examples was worth way more than $100, and should end any further arguments regarding sensor size for anyone interested in a scientific and rational discussion (bunk also included the Cinema 4D project files for anyone to replicate as per the Scientific Method). @gatopardo replicated the results with VRay (another photon ray tracer) and 3DSMax.

Mattias' comments on medium format lenses being very cheap and 'free' in some cases is very useful information for those admiring the kinds of looks possible with a focal reducer and old medium format lenses, which create interesting analog filters which a lot of people love. As noted by Hurlbut and others, the Cooke S4 causes distortion and has other artifacts which make people look thinner, more 3D, better highlights, etc. Imperfection is the spice of art- makes the flavor interesting which will be loved by many where different forms of spice will be loved by others (or for some uses, no spice at all- clinically accurate (Sony/Zeiss for example)). Like comparing Neve/Avalon preamps (warm/colored) to Grace (clinically clean). Neither better than the other, chocolate vs. vanilla...

[tweak]

"Equivalence" is relative, relativity is based on perspective, I feel this is where the problem lies.