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What's so hard about a DIY Follow Focus?
Why hasn't anyone made a Do-It-Yourself FollowFocus system that has $100 in parts that you can get from your local RC Hobby Store? *smile*
This would be a nice thing for those that own Sony HDV cameras, DVX owners and XL1/2 users as well. Are you guys going to make me do this? The gears are simple.....If I were to piece things back together, I am sure I can build about 20 Radio Controlled Cars (gas & electric) from the parts I have. (RC Racing used to be a huge hobby of mine). I am sure the gearing would be simple using cogs from RC cars, rings and pinion gears. All that is needed is a method to mount them to a 15mm Rod system. Whoever makes the the first detailed DIY plans for this and sells them on the internet for $50 bucks should make about $15,000 in the first 45 days or so. If I don't see something soon, I am going to do it. Anybody wanna go in with me? *smile* - Shannon W. Rawls |
i wouldnt imagine it would be that hard. i dont have much experience with followfocus systems, so i couldnt build one from memory, but if i had one in front of me for reference i'm sure i could fab a copy using plastic gearing from a hobby store with $50 worth of materials.
the trick would be finding a detailed diagram of the parts in a standard follow focus, and how they interconnect (i.e. arrows and such).. or just obtaining a $500-1000 unit to use as a reference for how it should work. the any type of followfocus system is of questionable worth to people with electric servo lenses (i.e. canon IIS16x, 3x, etc etc) imho.. but that's my opinion. for full manual lenses, a $100 follow focus would be great though. |
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Dan, how did you get the piece to connect the FF to 15mm rails? Did you make this yourself?
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The one in the pic is not done by me. I only designed it and was machined for me. It is the support/mounting for the focus indicator on the rods (but I just found it another use for now)
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Nice follow focus Dan. Did it cost you under $100 in parts and labor? Have you thought about making one thats easily adaptable to different lenses thru the use of a moveable gear arm like the pro models or did you find the custom mounts for each lens a much easier/affordable option?
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Thanks Brett,
No, the cost was higher than that: the gear that goes on the lens alone was $200 (had it for over 10 years and not used it from an older follow focus for Angenieux and because of the large width, covers the large shift on the Nikkor 200mm. R/C stores have many combination of good gears for less. This one is anodized Al though. Work? four days of "brain storm" and another 3 to finish it (based on the rods mount I have) What's that worth? I found your site Brett, very nice and pro looking. Maybe one day, when I'll grow up.....Santa will get me one...... |
If this :
http://www.goldmine-elec-products.c...62&mitem=62 with a gear on the pot could replace this: http://webpages.charter.net/bartech/M_one.html they (I) would have done it already. Anyway, the idea is the same. A motor, some speed reducer and means to amount the movement (pot) The torque/speed and quietness to do WHAT is needed is what made them use what they use. The motor (alone) in that unit is over $US400 !!! machining, assembly, gear, cable, connectors, overhead and some profit ads up to 2K. Oh well... you can't fight a war with waterguns..... |
dans hourly wage.....
war and waterguns is a great comparison.....
the funny thing that i have realized recently is people like dan post often and also link to their web sites showing what and how they have created..... the others (myself included) sit back in the easy chair and admire all the creations that others have done that are similar to the comercially available versions.... the thing is, "there is no free lunch"..... the main advantage of home built is that people who have extra time and not extra cash can sometimes add to their arsenal if they build something themselves..... BUT>>>> "time IS money"..... when we want homebuilt, and we want someone else to build it for us, i see that many are shocked at what an item would cost even if we only paid the builder minimum wage ... yet you must still account for the expensive machine tool cost, endmills, blades, finishing compounds, etc.... above and beyond this is the R&D that must go into even a homebuilt project.... again we shudder at even thinking of paying anyone minimum wage to test the device and see if it is going to work- or fail after a few uses..... bottom line>>>> we all want UZIs at H2O gun prices... but unless we build it ourselves most of us are still going to end up with waterguns.... as for components, you get what you pay for..... there are some discounts to be had, but a precision machined aluminum 6061 or 7075 gear is not the same "critter" as a cheap plastic gear.... |
lo......indubitably......l
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Yes. but is that the case with a Fololow Focus?
its 3 gears and a cog...a plastic knob and a wheel. "ALL DONE" I have seen more complicated items for a 1/10th of the price. - Look at the complicated electronics of a UHF Diversity Transmitter and Plug-On Phantom powerred receiver (AT U100) - Look at the complicated machining AND electronics of a Ford AOD 4-speed overdrive automatic transmission - Look at the complicated construction of a Carbon Fiber Boom Pole - Look at the electronics AND complicated parts a Gas Powered 80mph offroad RC Race Car - Look at the difficult construction and preceision parts included in the Micro35 adapter - Look at this Sony VAIO 2.8GHZ Laptop I am typing on now. - Look at the electronics involved in a 16ch Mackie Audio Mixer - Look at the machining involved in a top notch professional MAC Tools torque wrench - I can go on and on. and all these are cheaper then a little follow focus. A follow focus is a chunck of metal, just as most of the items above are. At a competive price, this chunk of metal will sell just as many units OR MORE as some of the items I listed above. The preceision involved in creating a Follow Focus for a DVX100 minidv camera is not that precise and hard to do...I'm sorry, I am NOT convinced. I have used one many times. Even the gear that goes over the focus ring on the camera should NOT COST $100-$200 dollars in my humble opinion. I see more complicated bolt on-pull-over and tighten type gears all the time that costs $15.99. That is why I am perplexed as to why a Follow Focus costs so much. ...A JL Fisher Tracking Dolly or MegaCrane....I understand ...A Body Mounted SteadyCame V-16.....I understand (sorta) ...A Century Optic preceion ground glass High Definition Lens converter....I understand. But a little Bolt-On Follow focus knob costing $1100-$2100 bucks??????...Sorry, I don't get it. It's not like we're taking a hand made, hand sewn, hand measured, takes 1 week to build using 126 people @ 8hours per day: 2005 LAMBORGHINI and comparing it to a run of the mill assemply line made Hyundai Sonata here. Its a follow focus. Alls i'm sayin' is dis..........If someone comes up with a DIY way to make a follow focus that FUNCTIONS the way a follow focus should, and makes the plans availbale........they will be sittin' pretty. And I don't understand why nobody has not done this yet. People always complain about wanting an Internet Business and don't know what to do?? Well here it is...here's your opportunity. Shannon put it out there for you. That's alls i'm sayin' *smile* - Shannon W. Rawls |
Honestly I never even thought of follow focus, but after seeing the comparison, I'm with you on this one Shannon.
The price of these pieces of machinery are made that way because the people who use it can afford it. |
I ear watch-your-saying.......
Problem with DIY zis and zeat is most of this "nothing much" still needs tooling and/or machinery beyond average home maker. Plans are worth nothing if you can not make ze darn thing. Price of mass production is always less than smaller runs. How many professional focus pullers on this list? I am serious. How many? email me some pics please. How many ww? Will "zei" risk $10,000/day production and their position with a mikey mouse contraption????? ......................................................pause.......sink-a-boat-it!!!... A limited market ends up with short runs and higher (than normal) prices.... Just met a gent from LA area. He is distributor 4 "made in China stuff", we'll see...... |
In making your own, not taking over the market with your home made device.
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So my question is this: how often do you guys use focus pullers on your DV shoots? If so, do they use tape measures, or do you do the zoom-in/focus/zoom-out method to give them marks? How often do you do severe rack-focuses? Couldn't they just pull off the lens barrel?
Or is the goal to dress the camera up so it looks fancier? |
btw jbk sells follow focus for 750..lol so I guess that is like half the price what Chroziel is charging. we're getting closer..lol
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One thing about Sarena Valilis reply. That reaction goes for almost all posts on a 'Alternative Imaging Methods'
But that's what this board is about. When I'm fixing my old-timer car, of course it takes me 10 times as much time than a professional mechanic and maybe it'll fall apart in a week, but it's a lot of fun to make something yourself and it cost you nothing, most of the times. Shannon, A Body Mounted SteadyCam? I don't know about that. If you put two tripod heads on top of each other, one facing sidewards, you have the most difficult part already. Have people thought about parts of old sewing machines to use for a follow focus? |
<<<-- Originally posted by Charles Papert : So my question is this: how often do you guys use focus pullers on your DV shoots? If so, do they use tape measures, or do you do the zoom-in/focus/zoom-out method to give them marks? How often do you do severe rack-focuses? Couldn't they just pull off the lens barrel?
Or is the goal to dress the camera up so it looks fancier? -->>> For straight DV shoots with the regular lens, I wouldn't bother. On some of the things I have shot, it would be easier to have a second person doing the focus, but most of the time it's not. On the other hand, when dressing the camera up with cine lenses, I go the full monty - it's just easier to have someone else doing the focus themselves and it's easier for them to do it with an FF. We do bring the tape measure - sometimes it gets used, sometimes it doesn't. Of course, I also always bring my light meter even when I shoot DV, so maybe I'm just weird. |
poor man's follow focus
I use this on a homemade 35mm adapter, with a canon 1.8 lens.
It fits right in with the under $200 total cost . shallow depth of field on minidv for less than $200. http://www.tabletools.com/tabletools...strongboy.html |
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There are screwdrivers that have a 90° twist. The mechanism is very precise. This should easily be converted in a follow focus similar to Dan's.
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Dan did you draw that?
Oscar: Interesting idea! I'm not sure how much it would help though. It would certainly allow you to adjust the focus manually but I'm going to want to use a focus puller (either attached by wire or wireless) farther away from the camera (moving shots etc). |
Wireless lens controls is a whole other ball of wax from a mechanical follow focus. There have been a few systems built from RC technology, one of them even became the industry standard for Steadicam back in the 80's. However the degree of precision required to adequately follow focus with repeatable marks is pretty sophisticated engineering. As we all know, RF is prone to interference (the higher-end wireless focus systems use microwave) and the data stream is pretty high to ensure good response. It's one of those things that if it were mass-produced, it could be made fairly cheaply, but it isn't, so it isn't.
Here's a clip of my wireless lens control system in action that our own Chris Hurd shot when he was visiting me on set while in town for a trade show. |
Oh indeed! That's why I'm thinking about going the "tethered via a wire" route. Infrared could also be used. It would at least be easier than RF!
Nice clip! |
Good deal Aaron. Hardwired lens controls were the original deal (the third image down on this page shows one, along with a lot of great other images of the late great Panaglide system) but for obvious reasons have been superceded by radio systems. But hardwire is much cheaper and easier to build, and will work fine. If this is to be used with a stabilizer, try to use the most flexible cable you can between the motor and the controller.
Also remember that to be useful, they must allow the user to repeatably hit a mark by turning the knob to a fixed position, as opposed to a zoom control type of arrangement that can drive the lens in one direction or another. I forget the distinction, but I believe the first type is called a positional servo. Best of luck with your project! |
Awesome pictures! =D
That's actually the only part that troubles me - making the dial make repeatable marks. That and how to calibrate the thing for different lenses. Anyway, it's on the backburner until my anamorphic stuff works it's way out! I'm definitely going to be looking around at parts though! |
FYI, Aaron, the simpler versions of this sort of system require the user to dial in the end limits for a given lens manually. You have one knob for each end (close and far), and you start with them both in the middle.
Turn the focus knob to the close focus end. Turn the close focus adjustment until you reach the end of the barrel, thus setting close focus. Turn the focus knob to the far end. Adjust the far end limit all the way to the other end of the lens. The lens is now calibrated. This is obviously a slower system than the automatic calibration on the Preston but also a lot cheaper. |
Charles,
With recent advances in computer and electronic controls, wouldn't it seem like a relatively straight forward thing to build an Vari-Zoom controller with follow focus capability? If the Vari-zoom had a way to record what the first focus setting was, what the final focus setting was, and the speed to move between them, then the operator would just have to initiate these settings to perform the desired rack focus. Sounds like a pretty easy thing for a LANC controller with a little onboard memory. Am I daff in thinking that electronic capability could completely replace all this external equipment? I know of your background and experience, so please be gentle bursting my bubble. |
Patrick,
It's good to think about stretching the boundaries, and modern tech can indeed sometimes replace the tried-and-true. What you describe is pretty easy, and the XL2 has this sort of feature built-in. However, being able to rack between two preset points is a limited feature at best. Let's assume we are talking about pulling focus for a 35mm optical system here, since it is far more critical than a straight-up DV setup. I'm talking about the Mini35, the Micro35, or any of the DIY systems that allow one to use 35mm lenses on a DV camera with the resulting shallow depth of field. Since most folks are fond of shooting with the 35mm lens wide open to minimize the DoF, the challenges of pulling focus are just the same regardless of whether there is a Panaflex or a Panasonic behind that lens. Last night on set we were shooting a two-camera setup, and the B-camera was asked to do a take by themselves. To kill time, I watched our veteran B-camera assistant pull focus during the take. His eye was constantly scanning the two actors, whipping to the lens barrel to check the lens marks, back to the actors heads, down to their feet to reference floor marks, etc. etc. Very intense process, lots of "computational power". And a lot of human judgement as well, that "fuzzy logic" thing that involves anticipating where and how a person will move instead of chasing them once they get there. It reminded me for the umpteenth time how much respect I have for great focus pullers and what an art it is to be able to estimate distances down to mere inches from alongside the camera. Incidentally, my assistant uses a Panatape, a sonar-based system that reports the distance with a readout right by the lens; however, he uses this as one of his tools to estimate focus, never relying by at as gospel. To get back to the scenario you described: to be able to automate a rack focus would rely on the two subjects to be fixed, i.e. not alive! If your foreground subject is off by a few inches when you trigger your pre-programmed rack, you will end up with a soft shot. So you reprogram the end stop and try again. This time he's back on his mark, so the shot is still soft. In other words; all the electronics out there can't replace the judgement and response of a human being who can pull focus. You need to be able to react instantly and intuitively. As far as the actual controller, it really does require a mechanism that simply duplicates the effect of having one's hand on a gear-driven knob that delivers repeatable, direct results turning the lens to be really effective. The body mechanics sort of demand this. Even with commercially available mechanical follow focuses, most assistants I know have very defined preferences. For instance, they may love the feel of the Arri but dislike the Chrosziel; love the Panavision but have issues with the Arri etc. And those are all high-end systems with little or no backlash, torque etc. Hope this makes sense. |
>>>>>>>>>>In other words; all the electronics out there can't replace the judgment and response of a human being who can pull focus. You need to be able to react instantly and intuitively<<<<<<<<<<<<<
For now. But, With all due respect, I am just about to further demonstrate the opposite (using the 35 image converter instead of an Arri or another film camera) and the focusing system I have made. Hold your thoughts for a second and follow this rationale: Scenario: Camera to actor 6 ft. Lens 135mm. Aperture 2.8. DOF a few inches. Actor is on the mark never moving his feet. Actor is "arguing" and leaning back and forth. Not much, but just enough to drive the first AC crazy. He can't say what he has in mind, for that would be his last day on the show...... (he got used to it anyway, so it don-hurt-no-mo...) (BTW, this is a dirty OTS and he is leaning on a diagonal line not straight on the optical axes of the lens !!!!) Panatape or digitape shows the first AC (at best and if aimed at his face and never reading the BG as he leans in and out) the very precise distance of 5' 8" to say 6'3". Marks on the lens: 5' , some 30deg later a 5.5 and some other 20 deg further the 6' and so on.... There is no indication of 5.8 and 6.3. So... where is that 5.8 and 6.3??? But the first AC knows all that and he is taking marks (on the white donut eyeballing the viewfinder) during rehearsals. Action is slightly different from rehearsals (faster/slower pace, more dynamic, etc) Rolling focus in and out with action on a lens that has no marks whats-oh-ever for the amount of movement in the field has nothing to do with science. Is pure educated and polished by practice intuition or second nature. There is no time to read distance and conform the lens. By that time, the action is long gone. INSTINCT IS ALL it takes (for now)! So, I second your respect for this skill. Good? As good as many years of eyeballing distances can get a pro. Perfect? Nope. Scenario 2: Kid on a swing. Same 135 (or let's be reasonable here and pick an 85) Average swing movement? Let's say 5 ft. Camera on dolly coming from 25 to 15 ft diagonal. The take is 30 seconds long. Infinite combinations of positions between camera and the kind's position on the swing lead to the ultimate nightmare for the first AC. Mark zeat. Rehearse zeat. Panatape zeat. I have just done "zeat" (not only in the clip I am on the swing) but actually dolly-ing in on 135mm from 12 to 5 ft while a matchbox was swinging from the kitchen light via dental floss thread. Clip is kinda long to post, but "zeat" (and other shots such as following a soap bubble and sprinkler water jets on 135mm at 2.8) might as well have been the reason behind the Canadian' Academy to award me the Gemini for tech achievement. Now, obviously the question: if is soooooo good, why is it not in use? Answer: a premature views discrepancy between my initial business partner and I, lack of promotional funds as well as FEAR of first AC's that ANY new-kid-on-the-block using the device could replace their polished skills and positions led to the current situation. Film (for which it was designed) is going down and for 35mm image converter is way too expensive. I will shoot further tests to demo the above but I will knot waste my time anymore to make a point. Not worth it. Just for the luve-of-it. nil homini naturae sine magno labore dat (for all of us: der aint no free lunch) I am not playing S M R T here but is fun and that's all I remember from first year in HS of latin. (they took it of the qurikulim after zeat.) so... don ask fo-mo. No humans/animals were harmed during any of the above real and fictional takes. Casualties: soap bubbles...,.... water on the ground (oh well...and the DV tape....;-)< (Just entertaining my virtual friends here......hey?(a'la'Canada) |
Dan:
Also with due respect--I'm having a hard time following you. I re-read the thread to see if you already referenced this device--perhaps you have been discussing it in another thread that I haven't seen. And can you explain what you mean by "zeat"? If you have developed a system that can accurately pull focus under the situations you describe, I applaud you and would still encourage you to actively pursue development, regardless of the issues you describe. I have several friends who have pioneered radical film equipment and faced the various battles you describe. Yes, AC's will tend to resist things that "undermine" their skill level but mostly if they don't work or are unreliable, or difficult to use. But that doesn't mean there isn't a place for it. I worked with a prototype system that required an actor to wear a sensor like a wireless mike, and transmitted distance back to the camera. It was in a rudimentary form, and it seemed to me to be delivering confusing information, but one day that might come to market. Preston Cinema's Light Ranger system is also occasionally in use for difficult shots like the swing scenario you described, but it is reportedly a bit cantankerous to work with. <<Film (for which it was designed) is going down and for 35mm image converter is way too expensive.>> It's pretty clear that high end HD has already embraced a 35mm sized image sensor (Genesis, D20, Dalsa). Certainly the Mini35 is not cheap compared to the cameras it is attached to (then again, those cameras are amazingly sophisticated for their price, so that is the wild card, not the adaptor), but perhaps one of the hard-working DIY crowd will eventually come out with a commercial version. Don't get me wrong, I'm interested in new technologies myself. I think a device like you describe would be pretty handy--for certain situations. But since you have a pretty good understanding of the process, I'm sure you'll also agree that pulling is much more than just keeping a subject in focus; many shots will require pulling between two characters with specific timing and at specific rates that are entirely up to the assistant to determine based on his judgement, the dialogue, the energy of the scene, etc. Sometimes they will calculate splits to hold two characters in partial or full focus; sometimes they will opt to roll the focus a little bit deeper so that the foreground person is just inside acceptable focus so that the background person can be as sharp as is possible--or vice versa. Again, all of this is based on human judgement and cannot be duplicated by any device that says "show me the subject, and I'll keep it in focus". |
Thank you for you re Charles.
By "zeat" I mean "that". The system does not pull focus by itself. It is a visual indicator for the first AC. In very short: two tiny CMOS/CCD (surveillance type) on the sides of the MB counter rotate in sink with the lens of the film camera. Wherever the images overlap, that is where the focus is. The first AC could not care less, if the actual distance is 6.2 or 6.3 or anything else. As long as the images overlap on his monitor (wireless) he can use his FIZ (as he normally does) to operate the focus ring on the lens and SEE what he is doing on the monitor without guessing the distance. As for "split" focus, all he needs to do is keep the two images NOT perfectly overlapped by equal amounts (hence his actual focus being in the middle) carrying both actors within the DOF of a certain lens (more or less subject to distance, focal length and aperture setting) An encoder on the focus ring reads the movement of the lens and “translates” this movement into a circular counter rotating movement for the two CMOS cameras. Calibration to a lens takes one minute and is based on three points (plus infinity which is the same for all lens - the two CMOS are parallel at this starting point) >>>>>>>Again, all of this is based on human judgment and cannot be duplicated by any device that says "show me the subject, and I'll keep it in focus".<<<<<<<<<<< I agree with you on this. The device itself does not do the job for the focus puller. It is up to him to actually pull focus, BUT: this time he can be right on (to the very inch) at any given time on anything that can be photographed. (including but not limited to FIRE, WATER, SMOKE, MIRROR REFLEXIONS, SMALL OBJECTS (relative to the frame size) and other "hard to get" the least to say situations. You can see some pics and clips here: http://dandiaconu.com/gallery/Oustanding-Technical-Achievement Charles, my email is on the website if you need it. Sorry to go off topic for all that are not interested. |
Very interesting Dan. So essentially, this is based on the rangefinder focusing principle--the assistant dials the lens until the two images of the desired object overlap, right?
Will this system work beyond a certain distance, such as a super-telephoto image like someone running at the camera on a 600mm or longer (seen in full figure or wider)? In the scenario you described, where the camera is dollying in as the subject is on the swing, isn't it still pretty tricky to pull focus using this method--I would guess it takes a bit to guess where to stop and reverse each end of the "swing" since it changes each time, due to the camera getting closer. Certainly I can see the advantage when using a still camera lens with poor markings, or how an inexperienced assistant could achieve better results with this perhaps more intuitive system...like I said, very interesting. I'll have my assistant check this out; he was actually one of the designers behind the Panatape so I'd be curious to see his reaction to something like this. |
>>>>....dials the lens until the two image....>>>>
Yes. >>>>Will this system work beyond....<<<< Yes again. Replacing the middle tube with a longer one (increasing thus the base of the triangle) and replacing the lens on the CMOS with longer focals (set of primes to match the Zeiss primes, yes, they are interchangeable and have their own tiny MB, no filters though) longer focals can be helped: (I have just uploaded another picture with the lens kit) (same album, last picture) Longest lens I had it calibrated was 250mm and gave focus to the first AC (that was checking it out) whatever he aimed the camera at.( way beyond measuring tape's range: trees, street signs and people on the sidewalk.)When that was OK, I got it up on the camera as you saw in the pics. >>>>....it takes a bit to guess where to stop and reverse each end.....<<<<<< Please watch the first clip 5 years... (on that page) With each swing, the movement decreases. Not a lot, but IT DOES. It takes about 90 sec for it to settle. I have been rehearsing my "moves" for over two hours. (practice) (I have pulled focus before a few times by eye and tape and marks on Zeiss and Panavision. Without it, I failed miserably with all the marks that I could have even wanted under my nose and the "moves" practiced for a while.... Lens marks are not linear. The movement is accelerated towards close focus. A "rhythmic" back and forth will not do. Have some fun (in a break) if you get the chance with your assistant and see. Have him see that clip first, please, so he knows the set up. Is the easiest set up ever. A tennis ball and dental floss. Swing it two-three-five feet or whatever the ceiling allows. Lens 50mm wide open. Distance 5?-6? ft. On axis (not diagonal as I have done it). Free to use panatape/cinetape. Have him hold focus longer than 10 seconds. (done it for 2 minutes)Look through the viewfinder. You be the judge. If you could get it on tape to see how many times during one swing he will be soft (behind or ahead)….. but that would be too much trouble. (I have done it though) Thank you for checking the site. |
BTW,
If the above is successful, next is having two balls, 8-16 inches apart from each other (diagonal on the ceiling) and also 8-16" apart at different heights (one edging the bottom frame and the other one the top of the frame. Camera is locked. No pan, no tilt. Shift focus from one to the other at will or by request. At different heights, they will have different oscillation (frequency). When this one is mastered, dolly in (out) while they swing. (I did not do the last one myself, but I did shift from the "real thing" to its reflection in a mirror (some 4 ft away from the real thing) while dolly-in). Next is the same ball describing a circle....smaller and smaller (I used a candle for a "dramatic effect") Oh well, the list is long, but the fun is worth it. |
FF knob
Hi,
Just a stupid question in between all this die-hard technotalk :) I'm planning to make my own FF together with the micro35 (when is that guide coming?! :), and would like to know from one of you pros: how far do you normally turn a FF knob from one focus end to the other? Is it one turn, multiple turns, or isn't there really a standard? I was looking for lenses (nikons) today for my future micro35 and already figured out I need MF since there focus ring turns much farther from end tot end and much smoother than AF. Thanks, Steven |
Some FF units have two speeds, most only one.
You should be able to cover infinity to close focus on your Nikon lens in one hand turn (or a bit less) MF have that range spread over 200 deg (more or less) . Find a larger dia. gear to mount on the focus ring of the lens, so when engaged to your FF, the hand knob will rotate about 300 deg. Do not get stuck with the above figures. Any alternative ratio that you can find works for you is BEST. I am glad you pursue it. |
I have a separate viewfinder on my (double DV) 35mm adapter, with DOF and nice focusing circle in the middle. It has almost the same lens as the adapter itself. I wounder if it is possible to make a follow focus that simultaneously focus both lenses. Maybe a wire between them or something. (they are a bit apart and parts of the adapter between them)
If someone has a suggestion...(putting all my bets on Dan) |
"Almost the same lens" spells trouble.
If they do not rotate in sink (via gear) you do not see what you record! Infinity (as well as close focus) should be identical for both, same as here: http://images.google.ca/images?q=rolleiflex&btnG=Search&hl=en&lr=&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial_s any size gear will do: http://www.care2.com/c2c/photos/view...DER%20LENS.jpg (make sure there is no backlash and not too tight if you use gears) Otherwise, O-rings on bearings will do just as fine. Cross the O-ring (as figure eight) so it does not slip and add a thin plastic sheet in between to cut the friction. Good luck. |
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