SX-70 FAQ
Contents
1. exposure works perfectly If there is a lot of bright light close to the camera even if it does not enter the lens it may influence the electronic exposure control which may need some compensation If the contrast of the motive is greater than the film can take you may use the control to select which part of the picture is exposed correctly If you shoot a bright flower in front of a dark background you may dial into the dark so the flower is not overexposed as the automatic decides on average measurement Q When I want to use a flashbar to brighten up a counter light shot the SX 70 refuses to flash creating a silhouette How come A Fill in flash operation is not possible with certain early models see list above Q How does exposure control work with flash 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html tp A Shutter speed is fixed aperture is based on focused distance max 20 ft 6 5 m Baz writes I moved back towards a regular operation of camera when on flash mode Now the riddle is how much in stops a SX70 mine is a Alpha 1 model 2 closes with the decreasing of focusing distance The answer when fiddling with those little devices that won t stick back in place The follower cam has two parts one move toghether with focus knob the other is a little flat thing hinged to the follower operated by a second little solenoid via a flat spring and this second sol is located over the big on2. you re done go back in the dark pull the cassette out pull out the strip of metal and pop the cassette back in the camera The top sheet now ejects normally developing your multiple exposure Why would anybody go to all this trouble Well in my case I was working with a 3D ray tracing program back in the late 80s I wanted a quick way to view the program s 24 bit output but the company hadn t gotten any 24 bit displays yet So I saved a separate 8 bit indexed file for each of the Red Green and Blue channels hacked the color look up tables to display linear red green or blue and photo composited on the SX 70 by displaying each channel in turn and doing a multiple exposure Hocker Object by Eric Graham Object Scene and Photo by Marcus Brooks Scene and Photo by Marcus Brooks Objects and Scene by Ken Offer Objects and Scene by Ken Offer Photo by Marcus Brooks Photo by Marcus Brooks For grins I m attaching some example shots In the plane photo you can see where my cheater slipped out onto the film The Newton s cradle shot on the left is a joke I played on the photo lab I was also shooting 35mm negatives so I thought it might be amusing to have one positive image on the film I just reversed the order of the 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html tp 10 sur 11 color palettes Q What is the purpose of the four contacts at the rear of the flashbar slots of Sonar SX 70 camera
3. SX 70 FAQ http www chemie unibas ch holder sxfaq html Frequently asked Questions about the SX 70 e How to open close the SX 70 e Where do I get a user s manual for my SX 70 e Where are the batteries How do I replace them e What happens when you press the red button e How does exposure control work How much does the camera stop down with distance in flash mode e Can I use type 600 film in a SX 70 camera e How to disassemble a SX 70 e Flashbars FAQ e What is the purpose of the two hole socket at the right side of the SX 70 e How to make double multiple exposures with a SX 70 e What is the purpose of the four contacts at the rear of the flashbar slots of Sonar SX 70 cameras e How to make very long timed exposures e Who still repairs SX 70 cameras Q How to open close the SX 70 A POLAROID SX 70 LAND CAMERA Opening and closing Q Where do I get a user s manual for my SX 70 1 sur 11 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html tp 2 sur 11 Q Who still repairs Polaroid cameras A Call Polaroid s customer service to get a free copy or look at their online SX 70 user s guide Q Where can I buy Time Zero SX 70 Film and flashbars for my old One Step or my folding SX 70 camera A From the Polaroid web site Time Zero has been dead for a long time Now and then one surfaces on ebay but they are ver
4. apacitor at 1024pf I thought 270 or 220 might be best but they were all overexposed I found that changing the resistor does not do what I intended I am not sure if this is an RC combination I am beginning to think the resistor may be part of a meter calibration circuit Perhaps one day I ll find a schematic I also tried the conversion on an Alpha series model 1 not Sonar I could not get good results at all This makes no sense to me yet since the exposure control module is the same part as the sonar models I will try it again some day with smaller capacitors and see if I can get into the correct range I wonder if anyone has had good results with trying to convert a non sonar camera It seems to be there should be no difference in the late model cameras Oh well It took me a while to figure out how to remove the shutter housing from the camera It is difficult on the Sonar model because the cover has additional clips at the top on each side and not only on the bottom You have to be more aggressive to spread the sides of the cover to release the clips No screws were involved Also it is not necessary to remove or open the Sonar the unit at all Here are some hints for your site To remove the leather from an SX 70 use HEAT Don t try to just pry it off I use a hair dryer and a small flexible putty knife When desoldering components don t bother trying to use a plunger type vacuum desoldering tool These just make a mess and require to
5. cts electronic flashes to a flashbar socket Q What is the purpose of the two hole socket at the right side of the SX 70 A The camera can be triggered by shorting the two contacts which happen to be the same contacts that go to the red button internally Q How to make multiple exposures with a SX 70 Marcus Brooks writes The trick is to defeat the little hook thingy that shoves the film into the rollers See the notch on the back left corner of the cassette Cut a strip of thin steel that just slides into that notch on top of the film maybe 3 16 wide and 1 5 inches long and bend it into a cross section something like the following I cut the strip out of the lifter spring from an old cassette I guess I made the 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html 9 sur 11 ramp angle about 45 degrees Its height should match the depth of the notch in the back of the cassette so the vertical skirt is restrained by the back wall It s easier to do than to describe You start with the cassette already loaded in the camera In total darkness pull the cassette back out of the camera and slide this device into the slot with the bent part down and snugly against the back of the cassette Then put the cassette back in the camera Instead of ejecting the top sheet as usual the hook should now ride up over the ramp and slip along the top Now take as many exposures as you want When
6. e and a half stop plus minus when full turned right or left this allow a finer tune of exposure Every mark puts a variation of about a half stop plus minus Q Can I use type 600 film in a SX 70 camera A The SX 70 time zero film has a speed of 125 ASA whereas the 600 has guess 600 ASA e The 600 Film has four little plastic nubs at the bottom that prevent them from being loaded in a camera designed for type 600 film You can either trim them off with a knife or use the following method Thanks Pat One can use a piece of exposed film or the plastic cover off a pack to load it without removing the tabs Hold the sheet under and slightly beyond the pack while loading it The idea is to have something smooth that covers the tabs as the pack is inserted Remove the sheet once the pack is in far enough and off you go e Now you have the problem that the film is four times too fast which is more than what you can compensate with the exposure control Even if you turn it 3 sur 11 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html fully into dark your pictures will still be overexposed There are two ways to correct this o A temporary solution Reduce the incoming amount of light Affix glue tape clip a 1 stop neutral grey filter in front of the lens and set the lighten darken control 1 5 stops to darken This will also darken the View in your finder Use a coated filter to get best results Remembe
7. e that move the shutter The second solenoid hangs the two blades of shutter iris in a certain position and thus determinates the effective aperture according to the different positions of focus dial In few words when I press the red button first the main solenoid closes shutter mirror raises the main sol opens shutter the second sol stops the back travel of blades to a position if necessary the main sol disengages the second sol devices the shutter closes the mirror goes flat again the shutter remains closed until I depress the red button All this when I m on flash operations I was able to fix the crucial position manually closing the shutter blades by pushing on the white plastic swinging arm with a little screwdriver and pressing on the spring of the second solenoid with another The shutter holds and when you move the focus knob you can see the iris closing and opening Then shining a light from viewfinder and putting a ground glass over the lens I could take a measure of how much light passes through lenses when varing distance here a table stating the start aperture as f8 at infinity f8 at 2 meters 8 0 8 at 1 meterA f11 0 5 v at 0 6 meter 16 0 6 at 0 4 meter 22 0 3 at 0 3 meter 32 0 3 another table with fixed stops f8 at infinity fll at 2 meters 16 between 1 and 0 6 meter 22 between 0 6 and 0 4 meter at 0 5 I guess 32 between 0 4 and 0 3 meter The lighter darker knob puts a variation of about on
8. ew mods on my camera the pictures appear better exposed than before with the standard SX 70 film I feel the color and contrast is a bit better and perhaps the film is a bit sharper too Overall I like the new Platinum film I hope that the new film does not leak the white development paste that the old film did that was quite annoying In order to use the new 600 Platinum film Polaroid 32 I had to trim the center two tabs protruding from the bottom corner of the film magazine it s on the bottom of the side that you insert first into the camera The center two tabs which are barely noticeable will catch on the spring mounted on the bottom of the camera which holds the magazine up in the film bay Otherwise there are no other obstructions or differences that I have noticed If I like the camera enough I will build the flash adapter I think the camera is really worth it Thanks for posting such great information Georg I found it very helpful and I like my SX 7 more for it Keep up the good work Tony Wong 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html 7 sur 11 HWS i 3 Vy ok s 7 r Ls lt JUUN Jim Meyers writes have a few old SX 70 cameras and I love to experiment I could not resist trying the electronic modification to convert some of my cameras to 600 speed I found that the Sonar OneStep converts the best I had to use a 150pf capacitor Since I originally measured my c
9. h the SX 70 and you expose the shutter will open for 15 20 seconds during this time if you simply open the front panel i e as if to load film then you interrupt and shut down the exposure circuits without closing the shutter A This will then keep the shutter open until you close the panel again which should then eject the film A If the film will not immediately eject then simply fire the exposure button again and it will A Simple hey A This should be carried out with the camera on a tripod for obvious camera shake reasons Q Who still repairs SX 70 cameras Vintage Instant in Amsterdam repairs SX 70 and other Polaroid cameras and sells 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html Spare parts Someone called Fastcat99 offers SX 70 repairs on ebay Instant Photographic Repair in New Jersey USA phone 1 973 831 8616 This address was given by a reader I don t know anything about this company If you know other companies that repair SX 70 cameras please let me know 11 sur 11 11 01 2012 17 41
10. modified pack to insert freely By the way I was able to use a pocket knife blade to carefully pry off the retaining ring over the light sensor and change the filter without removing the front cover much easier when dealing with a Sonar model or one with screws holding the cover on Laird Kelly O Another solution Modify the exposure electronics for 600 ASA The key component is the capacitor of the exposure integration circuit If this capacitor replaced by one four times smaller that would correspond to a four times faster film Jerry Rebold writes I boldly modified my SX 70 to use 600 film The suggestion to change the capacitor to one that s 4 times smaller worked like a champ Here s how It would have been simple on the manual focus models but on the Sonar the focusing mechanism prevents the shutter housing from popping off as shown on your page even though mine isn t screwed on from the back So I ground a good quality jeweler s screwdriver to fit the square recess screws that hold the shutter housing and found it was not too difficult to remove them they self thread into plastic so they were not overly tight You can get to the back of the circuit board after you 4 sur 11 11 01 2012 17 41 SX 70 FAQ 5 sur 11 O http www chemie unibas ch holder sxfaq html A carefully trim the heat staked fin that holds the end of the board with the light sensor and B unsolder 7 soft flat tabs bent over the board at
11. o much heat Desoldering braid works the best and with the least damage Make tools from wooden sticks for prying pressing pins etc They don t scratch the camera Best regards The cause of the overexposure problem was shutter drag A slight amount of drag does not cause problems when used with Time Zero film but will cause problems 11 01 2012 17 41 SX 70 FAQ http www chemie unibas ch holder sxfaq html tp 8 sur 11 when converted to 600 speed This variable is why the mod works well on some camera and not so well for others A good cleaning of the shutter assembly clears up most of the problem I found on all the models I converted that I had to substitute a clear filter for the tinted photo cell cover The cameras now take beautifully exposed photos with 600 speed film without having to dial in compensation for normal lighting Jim Meyers There are at least three different electronic circuits which work on the same principle but have different capacitor values This modification requires good electronics and mechanical skills The flexible printed circuits Polaroid uses in the SX 70 disintegrate when they are heated too much while soldering Be aware that you may destroy your camera when you try this modification George Q Anybody knows how to open a SX 70 A See the article How to disassemble a SX 70 Camera Flashbars FAQ I have added an article about Flashbars that includes schematics for an adapter that conne
12. om the scanner Tony Wong writes I would like to give you some feedback about your update information for converting an older SX 70 to use the newer 600 speed film I have a Sonar model and the modifications described worked well I have taken about 20 pictures with the new mods and they came out great Enclosed is a sample of the pictures I took First I started at the beginning by removing the main body and roller assembly this I did not need to do I should have started with section C 11 01 2012 17 41 SX 70 FAQ 6 sur 11 http www chemie unibas ch holder sxfaq html the shutter housing Everything Marty Kuhn described is pretty much the same I replaced both the resistor and capacitor since the resistor measured about 275 K ohm which means it drifted about 18 a bit much for my preference The only comment about choosing a replacement component is the capacitor should be as small as possible since there is a recess in the housing a bit wider than a resistor and about 2 resistors deep The capacitor I bought was too tall After I replaced the components I had to paint the whole area black Both sides of the circuit board around the photo diode were painted black On my SX 70 Sonar the circuit board was held in place by soldered connections for the shutter release button LED and a plastic tab melted down to provide a cheap lock down I had no screws holding my circuit board From the pictures I have taken with the n
13. r the L D control returns to zero when you fold the camera o NEW An easy way to modify the SX 70 to use 600 film To use 600 film in a SX70 camera simply remove the 4 protruding black pieces of plastic from the leading edge of the pack of film With no film in the camera remove the front cover of the camera the one that surrounds the lens This is done by gently easing outwards the housing sides nearest to the bottom hinge I do this with my thumb nail so no crowbar work needed Once the cover is removed you can then pop out the neutral density filter from the inside of the cover Replace with a similarly thin piece of clear plastic Re fit the housing insert film turn the exposure compensation to its darkest setting and enjoy the results Each time the camera is closed the exposure compensation dial will reset to the neutral position An irreversible modification can be done to fix this by means of cutting off the plastic tongue at the top right hand corner of the name plate I must stress that this is advise only and is totally done at your own risk both in terms of any possible resulting personal injury or damage to equipment O Laird Kelly writes I think I found an easier modification Since the tabs on the 600 pack catch on the flat spring on the bottom of the film compartment I used a pair of bent nosed hemostats any needle nosed pliers slim enough to fit would work to crimp the corners of the spring thus allowing the un
14. s A The contacts give handshaking information to attached flash units This especially important if the flash unit is powered from the battery in the camera s film pack because it cannot focus or eject pictures and recycle the flash at the same time It also makes sure the shutter button is blocked until the flash is ready Flash socket top view from rear of camera 1 flashbulb 5 2 flashbulb 4 3 Power supply from Flash IC 6V 4 flashbulb 3 5 flashbulb 2 6 flashbulb 1 7 connect to GND for flash mode camera 8 GND The contacts with are opposite to the respective contacts 1 voltage when focusing shutter button slightly depressed 2 voltage when taking shutter button fully depressed 7 voltage when camera unfolded 8 voltage when camera focus not in park position Also see the article 636 Flash for SX 70 Sonar for further explanation of how the contacts can me used name link09 If anyone out there repairs services modifies SX 70 and other Polaroid cameras I d gladly put your address and e mail on this page Q How do I make very long timed exposures Since exposure is controlled by the electric eye covering the light sensor leads to longer exposure times with a maximum of 30 seconds 1 minute If this is not long enough for you you can extend exposure infinitely using the following method Thanks Gavin Blake when you are in a low light situation wit
15. the other end After using solder wick to get rid of most of the solder a long needle was used to pry up the tabs while unsoldering under a 20X industrial microscope It s a bit awkward working with all the parts strung together but the board hinges up to give access to the back side with the resistor and capacitor They were painted over but with a little acetone and scraping and an ohmmeter I determined that the resistor is indeed 330K but the capacitor measured 1100 pF not the 740 pF shown on your page I first tried replacing the 330K resistor with 82K but the pictures were still way too light So I restored the 330K resistor and replaced the capacitor with a tiny 270 pF one from Radio Shlock and voila a 600 speed SX 70 We used a small ceramic disc of unknown specs from our junk box To do it right use a NPO or COG type less sensitive to temperature changes like Digi Key cat no P4930 or BC101BCT 50 volts 270 pF COG type They cost less than 15 cents Here s how www rwhirled com identified my SX 70 The complete serial number you entered is 5d940853525 Your camera has the Alpha 1 shutter design with the Alpha K focus wheel Your camera is probably an SX 70 Sonar OneStep The serial number itself is 8535 Your camera was made on April 9 1979 during the A shift Jerry Rebold P S I experimented with the new black amp white 600 film it s cheaper and here s the first successful pic The out of focus look is fr
16. y expensive and usually the image quality due to age is worse then TIP Color shade film Q Where are the batteries How do I replace them The battery is built into each film pack It is a laminated mercury free 6V zinc carbon battery Newer TIP films contain a Lithium battery Please recycle the battery Q What happens when you press the red button A The shutter closes The fresnel mirror is unlatched and springs up in front of the viewing mirror On its back is the taking mirror which reflects light from the lens to the film The electric eye in the front of the camera measures the light and sets aperture and opens the shutter according to the calculated values The exposed picture is ejected through a pair of rollers that break a pod with chemicals that start development Mirrors flip back to idle position THE SX 70 EXPOSURE CONTROL Look at the beginner s guide frequently made mistakes page Q How does exposure control work A The SX 70 contains a set of electronic circuits that use the data of an electronic light sensor in the front of the camera to calculate aperture and time of exposure Note that light is not measured through the lens TTL A dial at the front of the camera lets you change the picture to brighter or darker Usually there is no need to change this dial Note that the dial springs back to neutral when the camera is folded If you are photographing in a low contrast contrast environment the automatic
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