WOW ! UPDATE SPEED BOOSTER BMPCC TO -> MFT on GH4 with lens control and stabilization :P

[Brian Caldwell]

performance will take a hit but not enough to warrant disregarding the fact that the system provides a half a stop advantage in speed and quite a difference in fov.  with the extra 1/2 of a stop from the bmpcc one could close down by half a stop and gain a lot more performance than the filter thickness will degrade.  

The 0.58x BMPCC Speed Booster is designed to cover an image circle of about 15mm diameter, which is slightly larger than the BMPCC sensor diagonal.  Aberration correction is extremely good within this 15mm diameter, as is the relative illumination.  However, for the GH4 4k mode you need to cover at least 17.4mm.  Assuming you don't damage your camera by trying to mount the BMPCC S.B. on a GH4, you will encounter vignetting and significant image degradation in the corners.  I do not recommend trying this.  By contrast, the new m43 XL Speed Booster will cover the entire m43 format, not just the reduced 4k crop, and you won't have any problems with image quality.  The difference between the BMPCC and XL is only 1/3 stop.

[richg101]

The 0.58x BMPCC Speed Booster is designed to cover an image circle of about 15mm diameter, which is slightly larger than the BMPCC sensor diagonal.  Aberration correction is extremely good within this 15mm diameter, as is the relative illumination.  However, for the GH4 4k mode you need to cover at least 17.4mm.  Assuming you don't damage your camera by trying to mount the BMPCC S.B. on a GH4, you will encounter vignetting and significant image degradation in the corners.  I do not recommend trying this.  By contrast, the new m43 XL Speed Booster will cover the entire m43 format, not just the reduced 4k crop, and you won't have any problems with image quality.  The difference between the BMPCC and XL is only 1/3 stop.

I think you should be more trusting of your superb optical work:) - particularly when in the context of what we're discussing here.  My personal opinion is that the advantage of pushing your bmpcc sb glass beyond its limits offers a shooter quite drastic fov imprvements for shooters of the gh4 in 4k mode who use slr glass.  And a 1/3rd of a stop gain in transmission is also a great advantage in keeping iso's lower on the gh4, or the abilty to close a lens down even by 1/3 of a stop is advantageous when it comes to feeding such densely packed pixels on the gh4.  Obviously i understand criteria for the speed boosters would have been initially to deliver an optic capable of providing as close to the full frame look on aps-c as was possible.  The original critique from reviewers would have been to compare a full frame camera vs the nex7 and the original speed booster and if the original sb for nex-ef had fallen short the sb range from metabones would have fallen flat at the offset.  

With regard to video I think the moderate drop in iq at the edges just from my experiences with the sb ultra, the bmpcc 0.58x unit and the bmcc unit, pushing them beyond their intended uses, I think the degradation (if visible) is nothing that will get in the way of story telling and the above advantages I mention I think are worth taking risk and a hit on optical quality for.  I mean ultimately the centre performance remains more or less intact.  and a change from 15mm to 17.4mm diagonal is also such a small amount, cropping the 16:9 sensor area to 1.85:1 will take the diagonal closer to the ideal.

Just my open minded, care free opinion from a video pov.  I wouldn't use such techniques for a wide landscape shot where edge performance was of importance to me - nor would I use a focal reducer in any case for such activities.  But if someone gave me a gh4 and the option of both the XL and the 0.58x unit and a limited range of lenses in the wide end for a video assignment where lighting might be on the cusp of pushing it too far I know I'd always reach for the 0.58x knowing it would do more than adequately.  conversely if i were a stills photographer looking to use a nice set of contax zeisses (the 21mm/2.8 for instance) on a gh4 for stills in full sensor mode the Xl would be my first choice since i'd be very near the same fov and performance of the 21mm/2.8 on a full frame sensor.

 

 

 

     

[Brian Caldwell]

I think you should be more trusting of your superb optical work:) - particularly when in the context of what we're discussing here.  My personal opinion is that the advantage of pushing your bmpcc sb glass beyond its limits offers a shooter quite drastic fov imprvements for shooters of the gh4 in 4k mode who use slr glass.  And a 1/3rd of a stop gain in transmission is also a great advantage in keeping iso's lower on the gh4, or the abilty to close a lens down even by 1/3 of a stop is advantageous when it comes to feeding such densely packed pixels on the gh4.  Obviously i understand criteria for the speed boosters would have been initially to deliver an optic capable of providing as close to the full frame look on aps-c as was possible.  The original critique from reviewers would have been to compare a full frame camera vs the nex7 and the original speed booster and if the original sb for nex-ef had fallen short the sb range from metabones would have fallen flat at the offset.  

With regard to video I think the moderate drop in iq at the edges just from my experiences with the sb ultra, the bmpcc 0.58x unit and the bmcc unit, pushing them beyond their intended uses, I think the degradation (if visible) is nothing that will get in the way of story telling and the above advantages I mention I think are worth taking risk and a hit on optical quality for.  I mean ultimately the centre performance remains more or less intact.  and a change from 15mm to 17.4mm diagonal is also such a small amount, cropping the 16:9 sensor area to 1.85:1 will take the diagonal closer to the ideal.

Just my open minded, care free opinion from a video pov.  I wouldn't use such techniques for a wide landscape shot where edge performance was of importance to me - nor would I use a focal reducer in any case for such activities.  But if someone gave me a gh4 and the option of both the XL and the 0.58x unit and a limited range of lenses in the wide end for a video assignment where lighting might be on the cusp of pushing it too far I know I'd always reach for the 0.58x knowing it would do more than adequately.  conversely if i were a stills photographer looking to use a nice set of contax zeisses (the 21mm/2.8 for instance) on a gh4 for stills in full sensor mode the Xl would be my first choice since i'd be very near the same fov and performance of the 21mm/2.8 on a full frame sensor.

 

 

 

     

I do appreciate your open minded spirit about using optics beyond their design intent.  But just to be clear about what happens in this case - using the 0.58x Speed Booster on the GH4 in cinema 4k mode - I plotted some MTF curves below.  As you can see, the performance is great over the whole BMPCC format, but if you go beyond that the performance falls off a cliff.  I'm  very cautious about all of this because a few users have purchased the BMPCC S.B. with the intention of using it on a larger format, only to be disappointed with the results.  This is why this particular Speed Booster has always been advertised as being BMPCC-specific, and has "BMPCC" engraved on it.

[jonpais]

When I shoot, I almost always frame the subject to the left or right of center, so the vignetting and drop in resolution wouldn't be worth it for me. I suppose I am willing to sacrifice a touch of sharpness for a wider FOV though, as I would choose the Speedbooster XL over the Ultra any day. At the end of the day though, I think color is more important than mere MTF values. 

[richg101]

 

Either you've been over engineering your lenses, or I'm tired and confused:)    I just checked sensor specs and based on sizes of the bmpcc sensor and the area used on the gh4 (UHD, 16:9 mode) I'm seeing a pair of different corner reference points on your chart.  obviously that steep droop towards the farthest edge of the field is still there, but with the two reference points moved to the sensor horizontal edges based on what I'm seeing from the sensor data then things look a lot more promising on both the gh4 and the bmpcc..

Just to clarify, your Y axis is the horizontal and not the diagonal isnt it?  if so, the new pink line I've added shows 6.25mm from sensor edge (bang on the edge of the bmpcc sensor's 12.5mm width), and the orange line plots the edge of the gh4 sensor area used in 4k 16:9 mode (15.65mm pickup area width).    

   

 

[Brian Caldwell]

 

Either you've been over engineering your lenses, or I'm tired and confused:)    I just checked sensor specs and based on sizes of the bmpcc sensor and the area used on the gh4 (UHD, 16:9 mode) I'm seeing a pair of different corner reference points on your chart.  obviously that steep droop towards the farthest edge of the field is still there, but with the two reference points moved to the sensor horizontal edges based on what I'm seeing from the sensor data then things look a lot more promising on both the gh4 and the bmpcc..

Just to clarify, your Y axis is the horizontal and not the diagonal isnt it?  if so, the new pink line I've added shows 6.25mm from sensor edge (bang on the edge of the bmpcc sensor's 12.5mm width), and the orange line plots the edge of the gh4 sensor area used in 4k 16:9 mode (15.65mm pickup area width).    

   

 

Hi Rich:

Your numbers would be for the horizontal dimension of the format, not the diagonal.  My numbers indicate the full diagonal dimension.  According to my data, the diagonal (corner-to-corner) of the BMPCC sensor is 14.32mm, and the diagonal of the GH4 Cinema 4k crop is 17.4mm.

[richg101]

hahahaha.  it would appear i was (and am) tired and confused.  I've been looking at mtf's for an anamorphic (with 3 charts for points of reference on the vertical plane rather than a single diagonal).  My Y fields have been horizontals of late.

on the subject of speed boosters...

What are your opinions of this upcoming kipon medium format focal reducer?  There's been heated debate as to whether it's worthwhile or not.  Are you of the belief that if a focal reducer is designed and manufactured within a typical budget for consumer sale and with enough focal reduction to present the exact same fov it can replicate exactly the look of the lens fitted to its original format?

 

for instance..  If you had a 80mm/2.8 planar and took a photo on a 645 frame of full 56mm width, then took that same 80mm lens and put it on a focal reducer with enough magnification change to compress that same image circle onto a 24mmx36 frame, would the two render the fov/depth of field exactly the same?  or would you expect the dof rolloff to render differently?            

[Brian Caldwell]

hahahaha.  it would appear i was (and am) tired and confused.  I've been looking at mtf's for an anamorphic (with 3 charts for points of reference on the vertical plane rather than a single diagonal).  My Y fields have been horizontals of late.

on the subject of speed boosters...

What are your opinions of this upcoming kipon medium format focal reducer?  There's been heated debate as to whether it's worthwhile or not.  Are you of the belief that if a focal reducer is designed and manufactured within a typical budget for consumer sale and with enough focal reduction to present the exact same fov it can replicate exactly the look of the lens fitted to its original format?

 

for instance..  If you had a 80mm/2.8 planar and took a photo on a 645 frame of full 56mm width, then took that same 80mm lens and put it on a focal reducer with enough magnification change to compress that same image circle onto a 24mmx36 frame, would the two render the fov/depth of field exactly the same?  or would you expect the dof rolloff to render differently?            

For anamorphic you may want to do a conventional MTF vs frequency chart for a number of selected field points.  For example, when designing anamorphic lenses for Arri Alexa 4:3 I normally use seven field points:  (0,0), (0,8mm), (0,11.88mm), (6mm,0), (8.91mm,0), (6mm, 8mm), and (8.91mm,11.88mm).  Due to the strange asymmetrical aberrations a plot of MTF vs image height can be pretty confusing.  I suppose you could do three separate MTF vs image height charts; one for X, Y, and diagonal planes, respectively

Regarding medium format focal reducers, IMO the main problem is that medium format optics tend to be big and slow, and their optical correction is often ho-hum.  So, for example, if you take a Hasselblad 80/2.8 and add a 0.7x focal reducer you get a 56mm f/2.0 lens with merely average optical correction.  Certainly not something that would set the world on fire, and it would pale in comparison to a Zeiss 55/1.4 Otus, and would probably have a hard time keeping up with a 55/1.8 FE.  In principle you should be able use a focal reducer to match the FOV and DOF the same, assuming you use the same rectangular shape for both formats.  However, the newer 135 designs by Zeiss, Sigma, etc. are so good that you might as well buy one of these instead of going with an adapted medium format solution.  

[geppoitaly]

hi to everyone, and thanx to mr.  Caldwell for reply and explanation.

at this time only photo 4k 25p crop works well with sigma 18-35 f1.0 :p yess f1.0 (some weird crop starts by panasonic ?)  and all  the anamorphic format 4:3 3:2 1:1 e 16:9

and also after firmware download removed and closed-new firmware my speedboster 0,58x ef-bmpcc can auto focus hihiihi

 

p.s. v2.40 firmware have only few copyright improvements , than dont update if you want jaylbreak your adapter in future

[geppoitaly]

ciao. now i have the 0.64x and no hit the shutter filter in still and is way better than 0.71 but vs pal 4k photo mode in 0,58x without any aberration !? mmm its a hard comparison. and top for 4:3 and less for anamorphic

[Michele]

Hi I still  did not understand if on my gh4 with SP ef-bmpcc I will have autofocus and stabilization. I use canon efs 17-55mm and canon ef70-200 f2.8 . can anyone help understand? thanks a lot