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Zeiss Digiprimes on Gh5?


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#1 Ryan Constantino

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Posted 17 January 2018 - 04:07 PM

I'm having a hard time finding information about the Zeiss Digiprime image circle. Anyone have some experience with it? I found this brochure but cannot find anything about coverage: http://www.hdgear.tv...igiBrochure.pdf

 

I might have an opportunity to buy some digiprimes and wanted to know if the would cover the Gh5s sensor. Was thinking I would need an adapter like this: https://www.amazon.c...c/dp/B00B3FSMAQ

 

Any insight greatly appreciated! 

 

 

 


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#2 Macks Fiiod

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Posted 17 January 2018 - 04:13 PM

I recently bought a set for my f900 and have been wondering the same thing.

 

If the GH5 has the same sensor size to the GH4 then we may be out of luck due to this test

 

 

Also, not sure how much a glass adapter would decay the image quality of the digiprimes.

 

I know if someone invents an inexpensive glass adapter which stretches them over super35 flawlessly they'll skyrocket on the used market like bitcoin.


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#3 Ryan Constantino

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Posted 17 January 2018 - 06:39 PM

Interesting, yes the Gh4 and Gh5 have the same sensor size (17.3mm x 13.0mm) albeit different sensors. Are you theorizing a focal multiplier like a 2x tele-converter that would be B4 to MFT and 2x teleconverter all in one? That would be pretty good.....


Edited by Ryan Constantino, 17 January 2018 - 06:40 PM.

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#4 Macks Fiiod

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Posted 17 January 2018 - 06:48 PM

Or Metabones eventually doing a speedbooster adapter for it which could enable shallow DoF with high quality glass like that. The issue is, the market of people using digiprime lenses in 2018 is tiny.


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#5 Ryan Constantino

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Posted 17 January 2018 - 11:57 PM

I understand what you mean, the digiprimes are awesome, but sensors are just too big now a days...

 

From what I understand about metabones, such a piece of equipment wouldn't be possible. The speed boosters take a larger image circle and shrink it to fit on a smaller sensor. But in this particular case, I'm trying to take a smaller image circle and project it onto a sensor that's larger, in which case would need something like a magnifying glass inbetween the lens and the cameras sensor. 

 

Someone else with more experience might be able to elaborate. I wonder if it's possible to create such a thing....


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#6 Macks Fiiod

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Posted 18 January 2018 - 12:00 AM

Not enough of a market to warrant the engineering.

 

I know there's the HDx35 however you lose 2 stops if memory serves correctly.


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#7 Phil Rhodes

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Posted 18 January 2018 - 05:36 AM

Well you would.

 

They're 1.6 or 1.9 or something anyway, though.


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#8 Tom Visser

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Posted 19 January 2018 - 12:52 AM

Here's a snap from a tele Digizoom @ 17mm, it's worse case scenario wide open on a FF A7S.  You should be able to chop it up in PS to determine M43 coverage and be aware of the fact that you can do a nearly lossless digital zoom in on the GH5... I think of about a factor of 2x

 

anyone in the market for a 17-112 and MTF Services B4 to EF (allows S35 coverage with a loss of light) let me know - wasn't actively selling, but is taking up lots of space in my dehumidifier cabinet and running out of space.

 

Digizoom A7S.jpg

 

*** actually let me double check this tomorrow and make sure my memory isn't foggy and this is actually APS crop ***


Edited by Tom Visser, 19 January 2018 - 12:53 AM.

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#9 Mark Kenfield

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Posted 19 January 2018 - 01:16 AM

There are converters that take you from B4 to S16mm PL with minimal loss of light/quality. I always thought the Digiprimes could make an excellent S16mm option on the Sony F5/F55 via an adapter.

 

Fortunately they're so over-engineered, they have IQ to spare.

I don't think that pushing the image circle any larger than that is going to work in anyone's favour though.


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#10 Landon D. Parks

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Posted 19 January 2018 - 10:22 AM

Digiprime's are not generally a good idea for such use... Aren't they designed for 2/3" prism sensors? You will see the black circle of death when trying to use a digiprime on a m4/3 sensor - period. I'm also not sure how the optics are different when designed for cameras with a prism... Also from the above video posted, it looks as if the Digiprimes are not producing a very good image quality on the GH4. I don't know if that is because of the lack of a prism, or if the lenses are just not sharp enough for 4K...


Edited by Landon D. Parks, 19 January 2018 - 10:24 AM.

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#11 Tom Visser

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Posted 19 January 2018 - 01:13 PM

Digiprime's are not generally a good idea for such use... Aren't they designed for 2/3" prism sensors? You will see the black circle of death when trying to use a digiprime on a m4/3 sensor - period. I'm also not sure how the optics are different when designed for cameras with a prism... Also from the above video posted, it looks as if the Digiprimes are not producing a very good image quality on the GH4. I don't know if that is because of the lack of a prism, or if the lenses are just not sharp enough for 4K...

 

Wit the GH5's digital tel-extender option, you can crop the sensor down further to near S16 size, thus eliminate vignette if you are willing to acquire 1080p - as I think you are right, Digiprimes are not quite there for 4K (but close), but certainly more than enough for HD.  The prism design requires a delay to the red and blue channels.  I've seen cited that the blue channel lies 5um and red channel 10um behind the green channel.  When I adapt B4 without an optical adapter, I don't see an immediate night and day chromatic side effect, although probably means that in strong backlight the CA happens more strongly than on a 2/3" cam and an overall resolution drop.  If you use the optical adapters to cover S16, like the MTF kind, they have optics built in that corrects for the lack of a prism, so are a pretty recommended way utilize B4 lenses. Canon, IBE, Abakus, Sony, and BM on their Ursa cams, have similar adapters.  I have the B4 to S35 MTF adapter, and although it technically dramatically increases the coverage circle, it does so at a more than minor resolution drop and doesn't seem to like very wide apertures either - and is the reason why I don't use my Digizoom more at the moment, until I test again with a S16 adapter (thought for a time I was going to buy an Ikonoskop, but changed my mind).


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#12 Macks Fiiod

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Posted 19 January 2018 - 03:59 PM

Also from the above video posted, it looks as if the Digiprimes are not producing a very good image quality on the GH4. I don't know if that is because of the lack of a prism, or if the lenses are just not sharp enough for 4K...

 

For one, the guy in that test shot the video pretty poorly by way over exposing it. I was talking to Michael Rodin on this forum and he mentioned something to the effect of digiprimes resolving up to 8k-10k, which I believe cause this glass retains a ridiculous amount of detail on only a 1080p capture.

 

Unfortunately, I don't believe they are making 2/3 sensors which shoot 8k.


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#13 Landon D. Parks

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Posted 19 January 2018 - 10:24 PM

Unfortunately, I don't believe they are making 2/3 sensors which shoot 8k.

 

I'd say more like fortunately... I'd hate to see the low light performance on that sensor with 33.1 Million pixels on a 2/3".  :blink:


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#14 Tom Visser

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Posted 19 January 2018 - 10:34 PM

took a couple of snapshots with my A7S in S35 crop... just to explain what is going on here...

 

First is a sample of a Summicron-R 90mm (non-APO) with very strong backlight, so any CA issues should be accentuated

DSC09876.jpg

 

This is the Digizoom at 17mm with a mechanical adapter, no optics in between

DSC09883.jpg

 

and again at 112mm, no optics in between - notice that the image is mostly unusable well inside of the hard vignette due to distortion)

DSC09888.jpg

 

I'll post again with a few snaps using the MTF B4 to S35 adapter


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#15 Tom Visser

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Posted 19 January 2018 - 10:45 PM

The next couple of shots are with the MTF Services B4 to S35 adapter, probably not as good performing as the B4 to S16 adapter they make, but more limited in sensor size of course.

 

This image is my best guess as to what type of coverage you would get on m43 - since m43 has a 2x crop factor, I put the A7S into FF mode and then digitally cropped in 2x @ 17mm - when you frame in 16:9 mode, you'll actually end up with a minor vignette which you can eliminate with a little bit of digital zoom or entirely by shooting 1:1

DSC09891.jpg

 

... and again at 35mm, which is the point at which I don't see any major vignette, so once framed at 16:9 should be vignette free or may even be able to go down to 32mm

DSC09893.jpg

 

The B4 to S35 adapter was actually designed to be utilized by lenses with built in tele-extenders, but since Digiprimes and Digizooms do not have this feature, you end up with this vignette, but the GH5 has some cool options to work around it if you choose to go this way.

 

At the end of the day, I don't think the quality this combination gives is something to go and seek out, but if you have the lenses already, then an interesting way to utilize them.  What would be more interesting is for someone to test the quality on a camera that actually has S16 sensor size or a GH5 1:1 HD crop using the B4 to S16 adapter.


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#16 Macks Fiiod

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Posted 19 January 2018 - 11:20 PM

I think an URSA 4.6k in crop mode with their B4 adapter is currently someone's best bet at using Digiprimes in the current era.


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#17 Ryan Constantino

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Posted 20 January 2018 - 01:43 AM

At the end of the day, I don't think the quality this combination gives is something to go and seek out, but if you have the lenses already, then an interesting way to utilize them.  What would be more interesting is for someone to test the quality on a camera that actually has S16 sensor size or a GH5 1:1 HD crop using the B4 to S16 adapter.

 

Wow! very informative. I couldn't have asked for better info. Thanks very much for taking the time to show the lenses here. Sounds fairly straightforward, I don't think the digiprimes are for me. But it's nice to learn just a little bit more about them!

Thanks again. 


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#18 Tom Visser

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Posted 22 January 2018 - 05:08 AM

Because that GH4 video was so rough and tough to garner much more information from it, I felt motivated to shoot a quick clip - still reinforces what I mentioned before, the results are soft, but can still perhaps be good enough.  Also I notice the wide end looks much worse than the tele end, not sure how that translates to the Digiprimes.  I don't think I would open up more than T3, gets a bit too hairy and do feel there's improvement in the T4 / T5.6 zone, as expected.  My gut tells me that a GH5 with the S16 version of the adapter would be an improvement over what I can do with my A7S and B4 > S35 MTF adapter.  Forgive the use of the cheap photo tripod, my fluid head is at the office.

 

 


Edited by Tom Visser, 22 January 2018 - 05:09 AM.

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#19 Macks Fiiod

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Posted 22 January 2018 - 05:17 AM

You selling the Digizoom? I'm an idiot who still shoots on a 2/3 camera.


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#20 Tom Visser

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Posted 22 January 2018 - 05:36 AM

You selling the Digizoom? I'm an idiot who still shoots on a 2/3 camera.

 

PM'd


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