Mini35 FAQs

These Mini35 FAQs courtesy of P+S Technik, manufacturer of the Mini35 Image Convertor.

1. Do I have to send my camera to ZGC to do some mechanical or electronic changes before I can use the MINI35 Image Converter?
2. How does the MINI35 work?
   
3. What do I basically need for a complete MINI35 Image Converter solution?
   
4. What are the additional accessories you offer?
   
5. Which cameras work together with the MINI35?
   
6. Which lens mounts are available for the MINI35?
   
7. What does the imagery the MINI35 creates look like?
   
8. What is meant by "target"?
   
9. What kind of target (ground glass) is used in the MINI35?
   
10. Can I edit the same way?
    
11. Is there a light loss using the MINI35?
    
12. How do I get started?
    
13. Is it possible to start shooting with the MINI35 right away?
    
14. Do I need a power supply for the MINI35?
    
15. Why is there an ON/Off switch on the MINI35 Image Converter?
    
16. Why is there a speed control on the MINI35 'oszi' Image Converter?
    
17. How to adjust the target oscillation speed?
    
18. What is the iris in the intermediate lens for? (only with Canon and JVC - for all the other supplied camera systems please read on anyway!)
    
19. How does the user adjusts the exposure (without affecting the depth of field by closing the front lens)?
    
20. Is it possible to adjust exposure by the camera's shutter speed? What is to be considered in this case?
    
21. What is to be considered when shooting with variable frame rates?
    
22. Why is it not recommended to adjust exposure by stopping down the front lens aperture?
    
23. When testing different shutter speeds I realised that at 1/100 sec the structural pattern of the target becomes apparent. Which shutter speed do you recommend?
    
24. When stopping down the aperture of the front lens at T4.0 or further, the structural pattern of the target becomes apparent. How can I avoid this pattern to appear on my imagery?
    
25. Is it possible to use the whole tolerance of the film lens aperture together with the MINI35?
    
26. What is the highest aperture stop I can use without getting grain from the target?
    
27. The distances engraved on the film lens's focus ring do not match to the measured distances to focused objects. Is it due to a back focus displacement?
    
28. How do I create a clean image?
    
29. Which support systems am I supposed to use with the MINI35?
    
30. Why do I need a support system?
    
31. How to use the breakout box?
    
32. Can I use a professional viewfinder with the MINI35 setup with Panasonic or Sony camcorders?
    
33. Which lenses can be used together with the MINI35?
    
34. Which lenses do you recommend to use and why?
    
35. Is it true that I have to use High Speed Prime lenses with the MINI35 and not the Standard Speeds?
    
36. Is it possible to use 16mm film lenses with the MINI35?
    
37. Does the focal length of the lens I’m using change?
    
38. Is the angle of view of the film lenses I'm using affected by the Image Converter?
    
39. Is the focal length or the angle of view of the photo lenses I'm using affected by the Image Converter?
    
40. How can I translate focal length for MINI35 in order to achieve similar angles of view compared to 35mm film, still photography and 1/3" video?
    
41. Is there a disadvantage between shooting with zoom lenses and shooting with prime lenses regarding the lens speed?
    
42. What focal length will we get using Nikkor 15mm?
    
43. Regarding stills lenses: does any of the manufacturers you support provide sets of prime lenses or do they all tend to go for the zoom lenses.
    
44. Will we have aberration of the image or any problems with black edges (vignetting)?
    
45. The MINI35 does not start ? What can I do?
    
46. Can I replace the target (ground glass) of the MINI35 if it is broken?
    
47. Is there any place other than Germany where you can buy this equipment?
    
48. Is it possible to run former versions of the MINI35 (300 series) with HDV-cameras, like the JVC GY-HD100 or Sony HVR-Z1?
    
49. Are there differences between the Canon XL1 and XL1S when using the MINI35?

1) Do I have to send my camera to ZGC to do some mechanical or electronic changes before I can use the MINI35 Image Converter?
No, there is no need for any modifications, therefore there is no need to send the camera to us.

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2) How does the MINI35 work?
The basic principle: The MINI35 achieves a mechanical and optical adaptation of 35mm film lenses to the most popular 3-CCD 1/3" DV and HDV cameras. The MINI35 is a modular system and therefore adaptable to your video camera with a compatible Connection Kit. Click here to find a list of the supported cameras.

How does the MINI35 works: The chip size (image field) of your digital video camera is artificially enlarged by an intermediate projection, therefore transferring the 35mm lens characteristics (e.g. angle of view and depth of field) to the video camera.
The deciding point is the two stage configuration: The image, drafted by the film lens is projected onto an oscillating ground glass, called target. This target is in the same position, as the film plane in a 35mm film camera. For this reason the scale of reproduction, as well as depth of field and angle of view show the "film like quality", similar to a 35mm film camera. In a second step this real image is resized and projected onto the CCD - video chip. Since this is just a linear squeeze of a two-dimensional image all optical characteristics, like depth of field and angle of view stay the same.
This means that the video chip is not the place of image creation (this is the target!),
but of image recording.

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3) What do I basically need for a complete MINI35 Image Converter solution?
For a complete solution the following items are necessary:
1) The MINI35 Image Converter basic unit.
2) A compatible lens mount for the film or photo lenses, you like to shot with.
3) The compatible Connecting Kit for the digital video camera, you want to use the Image Converter with.

We explicitly recommend the use of a remote switch in order to guarantee an easily operated start and stop of both, camera and Image Converter simultaneously. Corresponding switches are available from P+S Technik, ARRI and other suppliers. For further information please refer to [Link: TecDoc: RS-Switch]

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4) What are the additional accessories you offer?
Additional accessories, like different lens mounts, a complete shoulder set (including a shoulder pad, hand grip extensions and hand grip with an ON/OFF switch), 15mm rods for the prepared light weight support and a case for your MINI35 system are available. Other very helpful accessories for the MINI35 are the matte box and follow focus systems, which allow the focus puller to work professionally with focus and filters, etc.
Further on we offer the MINI35 Breakout Box which provides video outputs for a quality viewfinder and additional monitoring. From here power is distributed to the Image Converter, camera and various accessories. By using a professional battery system you will prolong operation time. The battery system together with the viewfinder is the perfect upgrade for extensive shoulder shots as the viewfinder can be adjusted for eye height and the battery holder helps to balance the system.

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Every Connecting Kit contains everything needed to attach the corresponding camera to the MINI35 (i.e. Intermediate lens, Plate/Support bridge for fixing the camera on the MINI35, battery adapter, lanc/non-lanc cable). For a current list of supported cameras, please click here.

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6) Which lens mounts are available for the MINI35?
The following lens mounts are available and easily changed (even on set) for the MINI35:
* PL Mount
* Panavision Mount
* BNC-R Mount
* Nikon Mount
* Canon Mount (EF mount)
* Contax Mount
* Leika R Mount

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7) What does the imagery the MINI35 creates look like?
Basically the MINI35 makes a limited depth of field possible for 1/3" video cameras as up to now it was applicable only in connection with 35mm film. Thereby the MINI35 enables film-makers to use limited depth of field as another creative instrument for shooting on video. At the same time the targets structural pattern affects the image comparably to a light soft-focus and low-contrast filter and adds a film grain-like effect to it. In contrast to a textbook-perfect, hard and clean digital video, the MINI35 generates images, appearing more lively and softer. Altogether the look and feel is similar to the imagery you are used to from 35mm film.

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8) What is meant by "target"?
The "target" is the core of the Image Converter. It is a specially ground optical glass, similar to a ground glass used in viewfinder systems of film cameras. The image, drafted by the film lens, is projected onto this target and in a second step captured by the CCD-chips of your digital video camera. In order to blur the target's structural pattern, it is set into an oscillation movement.

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9) What kind of target (ground glass) is used in the MINI35?
The target, used in the MINI35, is a specially ground optical glass, that minimizes light loss.

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10) Can I edit the same way?
Yes. You can edit the same way you are used to.

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11) Is there a light loss using the MINI35?
Yes, for the MINI35 you can assume a light loss of 1.2 stops. Since the light loss is not linear this is the "worst case" value.

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12) How do I get started?
Since shooting with the MINI35 is similar to shooting with film we recommend you test the complete setup in detail in order to familiarize yourself with your Image Converter and its specific features! For setup details please refer to the User Manual.]

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13) Is it possible to start shooting with the MINI35 right away?
Yes, this is possible, but since shooting with the MINI35 is similar to shooting with film, we recommend to test the complete setup in detail in order to familiarize with your new Image Converter and its specific features! Please mind the necessity of checking back focus.
For setup details please refer to the User Manual.

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14) Do I need a power supply for the MINI35?
Yes, you need a power supply to run the motor of the MINI35 for the oscillation of the target. There are different possibilities for power supply.
1) Basically you can use the standard DV brick batteries, that come with your digital video camera. Corresponding battery adaptors are delivered with each Connecting Kit.
2) The usage of our "Breakout Box" provides the possibility to generate one single power supply for both, camera and Image Converter in connection with professional battery systems like Anton Bauer, PAGlok, Sony V-Mount and IDX. For further information on the "breakout box" please also refer to TecDoc68: Breakout box.

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15) Why is there an ON/Off switch on the MINI35 Image Converter?
As specified in FAQ #2 [How does the MINI works] the image generated by the 35mm front lens is projected in a first step on a ground glass-like target. In a second step this image is resized by a relay lens system to the smaller-sized video chip.
The target itself carries a structural pattern to visualize the image created by the front lens. If the target is motionless, this pattern is stamped on the image and appears like some kind of dirt on the lens.
In order to blur this structural pattern the Image Converter has to be switched on. The target starts oscillating whereby the structural pattern appears in a film grain-like manner.

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16) Why is there a speed control on the MINI35 'oszi' Image Converter?
As specified in FAQ #2, the image generated by the 35mm front lens is projected in a first step on a ground glass-like target. In a second step this image is resized by a relay lens system to the smaller-sized video chip.
The target itself carries a structural pattern to visualize the image created by the front lens. If the target is motionless, this pattern is stamped on the image and appears like some kind of dirt on the lens.
In order to blur this structural pattern the target is set into an oscillating movement, whereby the structural pattern appears in a film grain-like manner.
The speed control now diversifies the targets oscillation frequency. This provides the opportunity to eliminate disturbances or interferences caused by high shutter speeds or to achieve different grain effects, also depending upon the iris opening of the front lens. [FAQ Einfluss der Frontblende auf den grain effect]
For information on the right adjustment of the target speed please consult TecDoc No. 69: PRO35_adjust Target-Speed.

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17) How to adjust the target oscillation speed?
For information on the adjustment of the target's oscillation speed please consult
TecDoc No. 69: PRO35_adjust Target-Speed.

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The intermediate lens of the Canon and JVC Connecting Kit each with is equipped with an iris. However this iris only serves to light reduction. This offers the opportunity to shoot in bright environments with a wide opened front lens aperture (in order to obtain a narrow depth of field) without overexposing the video cameras CCD-chip. Therefore the Image Converter's iris is comparable to a variable ND function. But there is no influence on depth of field, because the light source relating to this iris is not a three-dimensional environment but the two-dimensional image on the target, which obtains just one focus plane. That is why the depth of field isn't influenced by the Image Converter's iris.

For all the other supplied camera systems (Sony and Panasonic) the reduction of light, described above, is obtained with the aid of the internal aperture of the video camera. In this case there is no influence on the depth of field as well.

In summary: For a camera setup with the MINI35 Image Converter the aperture of the front lens serves to adjust the image's depth of field; the iris of the intermediate lens and accordingly of the video camera only serves to adjust exposure.

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1) Use the ND function of your video camera or
2) Use a ND filter in front of the film/photo lens to decrease the light, entering the system

We do not recommend increasing the shutter speed of the camera in order to control exposure. In this case please consider, that the visibility of the target's structural pattern changes and might cause disturbance or interferences in your image. Although it's possible to eliminate these interferences by adjusting the speed control of the target. For further information please refer to TecDoc No. 61 and TecDoc No. 69.

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20) Is it possible to adjust exposure by the camera's shutter speed? What is to be considered in this case?
When decreasing the shutter speed of your camera in order to control exposure please consider, that the visibility of the target's structural pattern changes and might cause disturbance or interferences in your image. Please refer to TecDoc No. 61 and TecDoc No. 69.

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21) What is to be considered when shooting with variable frame rates?
When decreasing the shutter speed of your camera in order to shoot at variable (higher) frame rates, please consider, that the visibility of the target's structural pattern changes and might cause disturbance or interferences in your image. By adjusting the target's speed control it is possible to eliminate these interferences. For further information please refer to TecDoc No. 61:PRO35 variable framerates.

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In order to control exposure it is more advantageous to use the Image Converter's or camera's ND function.

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23) When testing different shutter speeds I realised that at 1/100 sec the structural pattern of the target becomes apparent. Which shutter speed do you recommend?
We recommend the use of standard shutter speeds with the current version of the MINI35. For further information please refer to TecDoc 61: Variable Framerates high shutter speeds and TecDoc No. 69: PRO35 adjust Target-Speed.

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In order to control exposure (i.e. when light is too intense like in bright daylight) without affecting the depth of field, we recommend to use the iris of the Image Converter. [FAQ INTERNE BLENDE].
If this ND function is insufficient and the image remains overexposed anyway, closing the film lens iris may not offer the required limited depth of field or may project too much grain on the video image. Two possible remedies:

1) Use the ND filter of your video camera or
2) Use a ND filter in front of the film/photo lens to decrease the light entering the system

We do not recommend to increase the shutter speed of the camera in order to control exposure. In this case please consider, that the visibility of the target's structural pattern changes and might cause disturbance or interferences in your image. Although it's possible to eliminate these interferences by adjusting the speed control of the target. For further information please refer to FAQ#20 and TecDoc No. 69: PRO35_adjust Target-Speed.

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25) Is it possible to use the whole tolerance of the film lens aperture together with the MINI35?
We advise not to use the whole tolerance of the film lens aperture together with the MINI35. Stopping down the aperture of the front lens at T4.0 or further unveils the structural pattern of the target.
In order to control exposure (i.e. when light is too intense like in bright daylight) without affecting the depth of field we recommend to use the Image Converter's iris, FAQ#19.

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26) What is the highest aperture stop I can use without getting grain from the target?
We recommend to avoid stopping down the front lens aperture further than T4.0.

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27) The distances engraved on the film lens's focus ring do not match to the measured distances to focused objects. Is it due to a back focus displacement?
Yes. You have to adjust the back focus at the Image Converter. For the adjustment please refer to the User Manual.

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28) How do I create a clean image?
For creation of a clean image please consider the following items:
* Back focus adjustment - a step by step guide is to be found in the User Manuel.
* adjust the target's oscillation speed - please refer to TecDoc 69: Target speed.
* control the camera's shutter speed - please refer to TecDoc 61: Variable Framerates high shutter speeds.
* do not stop down the front lens further than T4.0
* Try setting the camera to manual mode and limit the gain to 0 db or even –3 db

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29) Which support systems am I supposed to use with the MINI35?
* By default the MINI35 is prepared for the use with 15mm light weight support (15mm rods not included!)
* The bottom plate of the MINI35 is also prepared for accession to 35mm bridge plates and therefore applicable with 15mm and 19mm heavy duty support.

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30) Why do I need a support system?
* In order to stabilize your setup
* Offers the possibility to connect accessories like matte box or follow focus to your MINI35 setup

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31) How to use the breakout box?
Please refer to TecDoc No. 68: Breakoutbox -In-Out.

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32) Can I use a professional viewfinder with the MINI35 setup with Panasonic or Sony camcorders?
Yes, this is possible! Using the breakout box (TecDoc No. 68: Breakoutbox -In-Out) provides the option to connect a Sony DXF 801 b/w professional viewfinder (PAL/NTSC). For further information please refer to TecDoc No. 68: Breakoutbox -In-Out.

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Furthermore the following lens mounts are available and can be used with the corresponding lenses:
* Panavision Mount
* Nikon Mount
* Canon EF Mount
* Contax Mount
* BNC-R Mount
* Leica Mount

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34) Which lenses do you recommend to use and why?
The following lenses work perfectly with the MINI35:
* Zeiss Master Primes
* Zeiss HS Primes
* Cooke S4
* Zeiss Ultra Primes
You always have to keep in mind, that you have a light loss of 1.2 stops with the MINI35. The faster the lens, the more light is left for exposure! Over and above a wide opened front aperture creates a smaller depth of field.

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35) Is it true that I have to use High Speed Prime lenses with the MINI35 and not the Standard Speeds?
No, it is not true that you have to use Zeiss High Speed primes. The advantage of the HS lenses is the fact, that with a T 1.3 the HS lenses have a bigger aperture and accordingly a smaller depth of field than standard speed lenses. Although you can use other lenses, i.e. Ultra Primes or photo lenses: It is important to check each lens before shooting, because you never know what could happen. That is what camera assistants do before shooting with film cameras and it should be the same before shooting with a MINI35 and film or photo lenses.

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36) Is it possible to use 16mm film lenses with the MINI35?
The MINI35 is developed for the use with 35mm film lenses, that expose the whole N35 Academy format. Since 16mm lenses are styled for smaller frame sizes, vignetting problems may occur. As a rough guide 16mm lenses, whose rear lens is as large as a one €uro coin should work. But if you decide to use 16mm lenses, please test it before shooting!

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37) Does the focal length of the lens I’m using change?
No, the focal length of the lens does not change. It stays the same!

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For further understanding: In principle every 35mm film lens draws a round image onto the film gate of a film camera (most 35mm film lenses draw an image diameter of 30mm in order to expose S35 formats as well as N35 formats, although a diameter of 27,2mm suffices to expose the N35 formats). This film gate or an accordant format mask cuts out the framing as desired.
For the MINI35 it's nearly the same: The fore part of the Image Converter is designed simular to a N35 film camera: The film lens draws a round image onto the Image Converter's target, which is in the same position as the film stock in a film camera. In a second step a 27,2mm image circle (remember: this is satisfactory for N35 formats!) is then squeezed to the diameter/diagonal (6 mm) of the 1/3" CCD-chip. The CCD-chip then serves as a quasi format mask and cuts out the framing according to the CCDs size.
In conclusion, it is safe to say that the CCD-chip defines what is recorded by the video camera!

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39) Is the focal length or the angle of view of the photo lenses I'm using affected by the Image Converter?
The focal length of your photo lenses is not affected by the MINI35.

Stills Photographers: Compared to still photography the angle of view changes (gets smaller!). In order to choose the right focal length for a desired angle of view please refer to [FAQ: Translate Focal length].

Cinematographers: If you are used to shoot on film lenses, you can handle a photo lens the same way like a film lens. I.e.: on the MINI35 the angle of view (as well as the focal length and depth of field) of a 50mm photo lens is the same as of a 50mm film lens! Differences remain in order to the handling (i.e. focus).

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40) How can I translate focal length for MINI35 in order to achieve similar angles of view compared to 35mm film, still photography and 1/3" video?
In order to achieve same angles of view with the MINI35 please use the following factors starting from
* 1/3" video; 4:3 [Standard lens: 7 mm]: Factor: 4,6
* N35 film 4:3 [Standard lens: 32 mm]: Factor: 1* 1/3" video; 1:1,78 [Standard lens: 5,9 mm]: Factor: 4,2
* N35 film; 1:1,78 [Standard lens: 25 mm]: Factor: 1* Stills Photography full format [Standard lens: 48 mm]: Factor 0,67Please note: The standard focal lengths are based on a vertical visual angle of 28°

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41) Is there a disadvantage between shooting with zoom lenses and shooting with prime lenses regarding the lens speed?
Yes, the disadvantage is the speed of the different lens types. Due to the optical design of zoom lenses you usually get less light through a zoom lens to the chip, compared to a prime lens. The loss of light can be handled by opening the lens's iris or putting up more light sources. We recommend to use prime lenses, because you always have to keep in mind, that there's a light loss of 1.2 stops with the MINI35. The faster the lens, the more light is left for exposure! Over and above a wide opened aperture creates a smaller depth of field.

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42) What focal length will we get using Nikkor 15mm?
It will be also 15mm! But please note: The angle of view will change in comparison to 35mm still photography. For further information please refer to FAQ#40.

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43) Regarding stills lenses: do any of the manufacturers you support provide sets of prime lenses or do they all tend to go for the zoom lenses?
They do both, zoom lenses and prime lenses. But Nikon seems to be the only manufacturer that still produces photo lenses with real mechanical focus adjustment. Other lenses are manufactured with auto focus function which is of no use with our products. But it is possible to find used prime lens sets in very good condition of Canon and other lens manufacturers.

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44) Will we have aberration of the image or any problems with black edges (vignetting)?
No, if you use the recommended lenses you won't have any such problems! If you use other lenses please test them before shooting!

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45) The MINI35 does not start ? What can I do?
Background: The MINI35 starts when the VTR signal goes to LOW Level on the lanc/nonlanc connector. Some cameras do not go to LOW Level when pushing the VTR button. We do not know whether this is a typical problem for a certain camera model or only for some single cameras.
Solution: Connect a remote switch (like "RS switch" (#20499) from P+S Technik) to the MINI35 Image Converter (3-pin Fischer). Then you can start the camera (VTR) and the MINI35 simultaneously. This is the method preferred by most DPs. Alternative switches are available from ARRI ("RS-4") and other suppliers.

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46) Can I replace the target (ground glass) of the MINI35 if it is broken?
When the target of the MINI35 is broken, you will have to send the MINI35 to us and we will replace it then.

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47) Is there any place other than ZGC where you can buy this equipment?
While P+S Technik has several dealers world-wide, ZGC is the exclusive dealer for the Americas.

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48) Is it possible to run former versions of the MINI35 (300 series) with HDV-cameras, like the JVC GY-HD100 or Sony HVR-Z1?
Sorry, but it is not possible to use former versions of the MINI35 together with HDV-cameras due to an other movement of the target (oscillation for the 400 series - rotation for former series) and modified Connecting Kits. Newer Canon XL camcorders are adaptable anyway.

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49) Are there differences between the Canon XL1 and XL1S when using the MINI35?
With the XL1S, you can use the slow shutter without Canon lenses. Also, the XL1S chip is more sensitive to light – an advantage when using the MINI35.

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