Bolex lenses on a Fujica ZC1000

[taki]

Has anyone used Bolex Prime lenses on a Fujica ZC1000 ? If so were they the RX or normal ones?

[Lunar07]

Has anyone used Bolex Prime lenses on a Fujica ZC1000 ? If so were they the RX or normal ones?

Use normal C-mount lenses.

[CToTheH]

sell me your zc1000. If you want I can make a trade for a canon 814 electronic

[francis]

im thinking if the camera has the standard c mount backfocus of 17.53mm then the rx lenses should be fine. the presets would give you the best quality of the bolex range of lenses

[Lunar07]

im thinking if the camera has the standard c mount backfocus of 17.53mm then the rx lenses should be fine. the presets would give you the best quality of the bolex range of lenses

And they would give you unsharp results too. Specially the ones with a focal length less than 50mm. An RX lens is designed around the fact that there is a prism between back of lens and film plane that extends the 17.52mm distance to 20.76mm. Thus the optical design is geared to correct achromatic abberations taking a 20.75mm distance into account.

You want some good C-mount lenses that are non-RX - get the Taylor Hobson Ivotal lenses (16mm, 25mm, and 50mm), and the Taylor Hobson Cooke Panchrotal 2.8" (70mm lens).

[francis]

ok i think i must be missing something. all reflex cameras that have a c mount system have a back focus of of 17.53mm. im assuming the fujica has the same backfocus as any reflex c mount camera. the actual distance in a bolex reflex c mount camera is 20.76mm. the optical distance is still 17.53mm. there is a prism there but its all optically geared to be the c mount standard of 17.53mm. if this was not true then non bolex rx lenses would not work.(im assuming from what im reading its being suggested that non bolex lenses wont work). i have used angenieux and schneider lenses on a bolex with no problems what so ever. i and others have also used switar rx lenses on elciars with excellent results. i know that the switar RX lenses have been optimised to work with the prism system i still think youll find that other lenses work well on the bolex. im thinking thet will also be backwards compatible. if you have a chance to do some tests i think thats the best way to find out. youll never realy know till you try. id say try and many lenses as you can and the more modern the glass the better.

[BK]

RX lenses from a H8 doesn't work, I have tried.

Other lenses from a Beaulieu such as a Angenieux or a Schnieder. C mount ( not CS mount ) CCTV lenses will work, I have a Cosmicar 6mm and a Fujinon zoom that works nicely on the Fujica as well as the Beaulieu.

Bill

[Lunar07]

ok i think i must be missing something. all reflex cameras that have a c mount system have a back focus of of 17.53mm. im assuming the fujica has the same backfocus as any reflex c mount camera.

Yes! Non Rex and Rex lenses have the same back focus distance. And this was explained TO YOU by ME in a different thread one week ago when you actually thought they were not the same and you incorrectly suggested the use of a spacer. This back focus distance takes into account a medium of <b>air</b> between back and film plane. So majority of lenses, with their optical groupings assume that medium is air. So they take into factor in their design to minimize <b>chromatic and spherical abberations</b> the fact that it is AIR the medium through which light is traveling between back of lens and film plane.

the actual distance in a bolex reflex c mount camera is 20.76mm. the optical distance is still 17.53mm. there is a prism there but its all optically geared to be the c mount standard of 17.53mm. if this was not true then non bolex rx lenses would not work.

While the distance is 17.52mm, light in an RX system travels via the prism NOT AIR. Which introduces diffractive chromatic abberations of its own and which extends the distance the light has to travel to 20.76mm. However, <b>light traveling via the prism suffers a chromatic abberation at the distance it travels of 20.76mm</b> when it hits the film plane. An RX lens takes these factors into consideration in designinig the optical groupings. A NON RX lens does not. In other words, both will focus light that travels a distance of 20.76mm because of the prism. HOWEVER, light focused by a non rx lens with be focused <b>achromatically</b>. This is the operative word here - ACHROMATICALLY! So, the difference bewteen a non rx and an rx lens is not the back focus distance but the ASSUMPTION of the medium through which light is traveling and the corresponding optical corrections. Each of these media introduces different diffractive and chromatic abberations. Each of these sets of lenses is geared for these different media. I hope the point is clear now.

Now, last time you suggested in a different thread that one can use a spacer to swtich non rx and rx lenses on an RX system because of the different back focus distances. I replied to you that this is not true and no spacer will work because actually there is NO difference in the back focus distance. The difference is in the medium itself through which light has to travel. Apparently you had done your research. However this throws serious doubts on your tests. Because till a week ago you actually thought that non rx lenses and rx lenses have different back focus distances.

Taki asked a pointed question. The answer should be pointed. Not the sort of hit and miss approach that you talk about. For God's sake Francis, months ago you talked about a spacer that allows 16mm RX lenses to be used on an H-8 Rex camera. When I asked you about the specs you answered: "Well, experiment with different spacers." 8O I mean, this is so random - and it spreads ideas in a chaotic manner.
Also, why should ANYONE suggest that he gets an RX pre-set lens to use on a Super8 camera when a NON RX lens with a clickable aperture ring will do fine and produce results if collimated correctly? At a fraction of the price and with comparable quality. A Switar non rx lens for example. Instead of fighting the laws of physics. Specially when C mount lenses are everywhere in sight.

[francis]

well your tone is a bit bitchy but i will give you the benefit of the doubt. just because you tell me something in another thread doesnt mean what you say is correct. as for what i said about the spacer...

it was in reference to the bolex ds8 camera. the film plane is closer to the lens mount. i was confusedabout this so i showed a local cinematographer. we did some rough handholding and noticed that if a 16mm camera lens was held about a cm from the bolex things started to focus up. did i get a spacer cut? no. i dont need one yet. you want the specifics then you get me the cash and ill have one cut for you or you get one cut yourself. i made an observation and reported it.

im browsing the net here with people writing more or less that the distance between the film plane and lens mount on a reflex and non reflex bolex is different. that would mean the lens is focussing at a different place. i will confirm this with the local bolex people. they are in the know so why not ask them and end this, right?

[Evan Kubota]

"im browsing the net here with people writing more or less that the distance between the film plane and lens mount on a reflex and non reflex bolex is different."

Sorry, that isn't true. RX lenses and non-RX lenses both have the same standard C-mount flange focal distance (17.52 mm). As Lunar07 pointed out, the reflex lenses are calibrated for glass behind the rear element, not air. The focus markings are placed differently as a result, since the prism affects the refraction of light passing through. AFAIK it's theoretically possible to get a reasonable focus on extreme closeups using RX lenses on a non-RX camera, but only at higher f/stops. It will never focus to infinity.

The f/stop markings are also off if you use an RX lens on a non-RX camera, since the RX lenses have 1/2 stop or so compensation built in for the light loss due to the prism.

[taki]

I will be carefull of RX lenses less then 50mm on the Fujica as Lunar07 warns. Is the 50mm "on the limit" so it might work if not wide open? (I have a nice 50mm Schiender RX )

As an aside, I have used a 12mm non RX on the bolexRX and not had focus problems due, I think, to the large depth of field.

I didn't know that the RX lenses let in more light as well, as Evan said. I have just been metering at the adjusted 1/80 th instead of 1/60 when at 24fps. I will adjust further when I use my non RX 75mm on that bolex. I will keep an eye out for the Taylor Hobson Ivotal lenses. That zoom on the ZC1000 is just too heavy, not to mention, if you can shoot with primes, better off doing so.

[francis]

i emailed a bolex specialist and got this back.

Dear Francis, the rule is that on a reflex camera you need to use
lenses
marked Rx (or Dv) on prime lenses of focal length 50mm or less. Longer
focal
length lenses marked Rx etc. may be used on both Rx and non-rx cameras
as
the depth of the focus plane is big enough on these lenses to make up
for
the actual back-focus difference. The only long focal length lens
actually
marked Rx I can think of is the 75mm Switar in it's various forms.
The only way round using Rx lenses on a non-rx camera is to reduce the
lens
aperture 2 or 3 stops. The other problem is that when checking focus on
a
non-rx the ground glass image might look in focus but when projected it
will
look unsharp.
Hope this is of help, all the best, Andrew


as for an ivotal, i do have one id like to get rid of. i beleive its the 50mm though. let me know if its what you might want.