NikonGear'23
Gear Talk => Camera Talk => Topic started by: Bernard Delley on March 24, 2023, 10:51:11
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this is a salvage from dpreview, hope it is a fun read and encouraging in case.
Stupid enough, it came like this: Shooting the sun with 135mm f2 DC at f/2.5 in LV to protect my eyes. Handhold LV into the sun did not damage the sensor. But exposure with the shutter being closed for a fraction of a second was enough to burn a hole into the blackened super thin shutter curtain. (Insight 1, don't do this!)
It was not noticed right away. But, on short exposure times the hole produces a bright spot in always the same place of the image.
test shot of uniformly lit object at 1/320 s f/8 : orig size: full image at 25%
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view of the shutter curtain using MUP mode to get the mirror out of the way.
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I got a replacement shutter assembly for D7200 at AliExpress for 55 CHF (MH store). Soldering points show that this is a removed unit from another presumably dead camera.
I got Japanese Industry Standard (JIS) screwdrivers ( Vessel ) to avoid damage to the screw heads, especially when some amount of torque is requred. I already had tools for iPhone repair (PH 00 screwdriver and plastic spudger) and a small soft soldering tool.
The shutter is in the middle of the camera, so quite a disassembly is needed to get at it.
view of the disassembled camera, with the replacement shutter ready. The sensor is in the plastic box for dust protection.
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I used guides by Ifixit: Nikon D7100 Motherboard Replacement and Nikon D7000 Shutter Assembly Replacement . Obviously these guides match only partly for the D7200. The D7000 guide gets hasty and tired towards its end and forgets to mention the soldering altogether.
A careful layout as depicted was not quite enough with the documentation on ifixit. Insight: I should have taken a picture for every screw or part removed and put the screw then into a tray array (perhaps an ice cube tray for 96 cubes). With just the careful layout, and srews rolling a bit around, I ended spending a lot of time figuring out where exactly each part had to go back.
I did succeed at putting things together and it works. AF-fine tune has been done again and a different setting was found than before the shutter replacement. This is no wonder, AF module and bajonet kept their relative place. But the sensor goes behind the shutter assembly box, so the sensor plane differ by a few micro-meters from its previous place. With my MTF based AF-fine tune approach with sufficiently good statistical control I know fine tune values to actually better than 1 tune unit. And I have not seen it change significantly, as long as no bad treatment happened to camera or lens.
Some more detail for fun:
Some screws require a lot of torque to remove. The JIS screwdriver tip geometry allows to do this without damage to the screw head. I affixed a plastic wheel to the JIS 00 screwdriver to allow applying the torque just needed in some cases.
mainboard view. some zif sockets with open lid and ribbon cable pulled out:
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Back view of sensor assembly.
Then front side of sensor with clearly visible dust in grazing light.
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Back view with shutter assembly, still partly covered by internal camera skeleton.
Then, shutter assembly with 4 soldering connections at the ribbon protruding from the shutter. Soldering is also needed for two wires on the other side.
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If you are less impressed about handling tiny springs -- they tend to jump at you before you clearly saw where they came from -- than by soldering small connections, you have an option. Rather than soldering, you can remove two more screws and slide the shutter box open and replace the shutter curtains only.
Image below: JIS screwdrivers are non-magnetic, so screws do not budge when approached by the screwdriver. The cheap PH00 screwdriver gets easily magnetized accidentally without further ado. This can be handy to pick up tiny screws or to place them back where they should go.
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I hoped that the post was encouraging. There appears to be quite a supply of replacement shutters. I think almost anybody could do this. However, one should take my advice for better documentation and temporary storage or small parts in a mini ice-cube tray to the heart. If one skirts the soldering by replacing just the shutter curtains, one does not need the equipment for soldering.
It did not take much bravery to try this, as the camera with punched shutter was lost to begin with. The options were:
trash the damaged 7 years old camera. (continue by investing in a different camera)
sell it for parts and recover perhaps 50 $
* spend 60 $ get insight, be back with a working D7200 on success.
get it repaired by Nikon service, offer was $ 400, go on with serviced D7200.
replace it by a used camera from Ebay or Ricardo
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the pictures of replacement part offerings on the internet show that Nikon has abandoned soldering connections for the shutter assembly unit starting with model
D500, D700, D750, D800, D3
I found one ad, saying D7500 shutter is the same as D500 shutter unit.
the shutter units for D7200 D600 D610 are still with soldering connections on the ribbon.
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I was not aware that the shutter blades where that easy to melt on this series of cameras,,,
The flat cable connectors are so prone to breaking so yes take care ;)
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The trend to reduce shutter shock implied getting the tins of the curtain as thin as possible.
The sensor protector of the Z9 appears to be similar the shutter.
The recent post of a Z9 failure by averity https://nikongear.net/revival/index.php?topic=10645.0 suggest that there are similar fallacies too.
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The camera inside looks like very cheap electronics. A lot of plastic, thin metal, self cutting screws that cuts into plastic etc. etc.
A F2 does not look that bad inside? :-)
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The camera inside looks like very cheap electronics. A lot of plastic, thin metal, self cutting screws that cuts into plastic etc. etc.
A F2 does not look that bad inside? :-)
The F2 has a titanium curtain that would not melt. The one in my F2 shows telltale marks on the curtain without any ill effect.
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The camera inside looks like very cheap electronics. A lot of plastic, thin metal, self cutting screws that cuts into plastic etc. etc.
A F2 does not look that bad inside? :-)
The F2 has a titanium curtain that would not melt. The one in my F2 shows telltale marks on the curtain without any ill effect.
The electronic boards look like quality boards to me, definitely not the cheap brown hard-paper boards. The Faraday screening does not need to be thick metal. It is a mostly plastic construction with appropriate screws; good for weight. The plastic engineering appears to be state of this art, not prone to the rapid embrittlement as in cheap plastic toys. What I disliked the most was the soldering on edge for the shutter ribbon.
The F2 shutter is very thin titanium. The camera geometry of this horizontally running shutter seems to imply that it is rolled. I would not want to expose this shutter to focused sun light either.
The modern vertical running shutters are descendants of a shutter appearing first in the Nikkormat camera nearly contemporary with the F2. The blades are obviously very thin, surely titanium again. maybe a little thicker, as the must not bend and hold up for hundred thousands of actuations.
Fortunately, these shutters are protected by the mirror most of the time! Canon used a black cloth shutter in F2 times, if I recall right.
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Titanium shutter: same as the Nikon F,. except for the first 1000 samples (extremely rare, from sn 6400001 up to sn 6401000), which had a cloth curtain. On the Nikon F, shutter curtain travelled horizontally, and flash sync was limited to 1/60", while on the F2 it travelled vertically (and sync was upped to 1/125"). I'll have to dig out an F2 to make sure... [EDIT: it travels horizontally on the F and F2, on Nikkorex and F3 it travels vertically and it's similar to current venetian-type shutter ]
Bernard, I confirm that the shutter curtains were thin enough to be rolled up in spools at the sides of the frame. Second curtain would unroll to cover the frame at the appropriate time, and at shutter speeds below 1/60" the whole frame would be exposed to light.
As an added bonus, including here an excerpt from my own Nikon F Identification Scheme (my own research, which predates heavily -and adds a little something- on the top work by Richard DeStoutz)
Ciao from Massimo
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The shutter of the F2 also travels horizontally, just checked.
The titanium has a structured pattern, presumably to make it stronger.
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The shutter of the F2 also travels horizontally, just checked.
The titanium has a structured pattern, presumably to make it stronger.
You are quite right, I had just corrected my statement. There was no room in the body to have two spools for winding the curtains above and below the frame!
More clarification: the F2 shutter had a Hexagon-shaped structure to make it lighter and sturdier and allow shutter speed to 1/2000" (on Nikon F it was limited to 1/1000"). Flash sync was still limited to 1/60" (even on the F3), it was only with the F4 that sync was upped to 1/250" (and top shutter speed down to 1/8000")
Ciao from Massimo
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Wow ! thanks for the interesting detail on shutters.
However the shutter of my Nikon F2, serial 7570445 (bought about 1976), definitely runs horizontally. The image below shows a curtain end reinforcement, which is visible statically when the manual winding action is interrupted. Incidentally the image was taken with AFS 60mm f/2.8 on the repaired D7200 of this thread.
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I believe remembering that the red mark at 1/80 s on the shutter dial indicates the flash sync for the F2.
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The F2 shutter is very thin titanium. The camera geometry of this horizontally running shutter seems to imply that it is rolled. I would not want to expose this shutter to focused sun light either.
The modern vertical running shutters are descendants of a shutter appearing first in the Nikkormat camera nearly contemporary with the F2. The blades are obviously very thin, surely titanium again. maybe a little thicker, as the must not bend and hold up for hundred thousands of actuations.
Ha, if only this was true of the F2AS I bought new back in 1978. In the first year it, according to the techo that rebuilt it, "tore the rivets out of the shutter". In the third year the shutter again self destructed shortly after I put an MB-3 on the camera. During this period I would have averaged 5 rolls of film per week ie approximately 10k frames per year...hardly a serious workload for a flagship unit. The poor electronics, 4* resistor rings consumed so far, well that's another rant :(
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The Nikon FE2, FA and early FM2 where the first Nikon cameras with a very fast 1/250 sec flash sync speed. The shutter blades had to be very strong and lightweight to move so quickly, the only suitable material at the time was titanium. The shutter blades were very thin and stiffened by thicker sections in a honeycomb pattern. Later Nikon found a way to make aluminium shutter blades which were strong and light enough. Aluminium is cheaper and easier to work, so Nikon switched to them for later FM2 cameras and all subsequent cameras. These shutters don't have the honeycomb pattern. It's possible that if very strong concentrated light is focused on the shutter, and the shutter is black so absorbs most of the heat and the melting point of aluminium alloys is relatively low, it could burn a hole in the blades. However, I wonder if Nikon now uses some kind of plastic for shutter blades as the hole in the shutter blade looks more like melted plastic, or maybe aluminium melts like that too?
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The sad story about the burned 'shanding' unit of the Z9 does NOT refer to a traditional shutter curtain. The sensor shield is just comprised of tiles made of lightweight plastic and its purpose is to prevent ingress of dust and dirt to the sensor. The Z9 user can opt for the protective shield being activated as the camera is switched off, or deactivate it all together.
By the way, I noticed earlier that the terminology here in the thread is confusing and really leads to mixing up a true shutter [curtain] and the protective shield of Z9, as the Z9 does not have any mechanical shutter at all.
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The Nikon FE2, FA and early FM2 where the first Nikon cameras with a very fast 1/250 sec flash sync speed. The shutter blades had to be very strong and lightweight to move so quickly, the only suitable material at the time was titanium. The shutter blades were very thin and stiffened by thicker sections in a honeycomb pattern. Later Nikon found a way to make aluminium shutter blades which were strong and light enough. Aluminium is cheaper and easier to work, so Nikon switched to them for later FM2 cameras and all subsequent cameras. These shutters don't have the honeycomb pattern. It's possible that if very strong concentrated light is focused on the shutter, and the shutter is black so absorbs most of the heat and the melting point of aluminium alloys is relatively low, it could burn a hole in the blades. However, I wonder if Nikon now uses some kind of plastic for shutter blades as the hole in the shutter blade looks more like melted plastic, or maybe aluminium melts like that too?
Delrin, a high quality plastic, melts at 175 C, aluminum at 660 C and Titanium at 1668 C. I just cannot believe that the shutter blades of the D7200 would be plastic. By hand feel its foil thickness is between 12.5 micro meter and 50 micro meter. Contrary to the household aluminum foils, shutter blades feel like spring blades. -- Molten metal foil can look like this burned hole. -- Each D7200 shutter curtain has 4 blades, while the Z9 protective shield appears to have 3 tiles. - I just discovered the pictures of the Z9 sensor shield further down the in the "Z9 Failure" thread: it is definitely plastic tiles, much thicker, on a single curtain. -- I seem to remember that the Nikonos III shutter was mentioned to be made from aluminum, vertical running. This shutter goes to 1/500s . I still have my Nikonos III, Each curtain is a single blade. The surface structure is more like the rough side of aluminum foil, however blackened.
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Pure Aluminium melts at 660 C, but it is usually alloyed to improve strength and other properties. Most Aluminium alloys melt at significantly lower temperatures, some lower than 500C.
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Does the color of the material matter here? Kitchen aluminum foil is shiny silver and reflects most of the light, whereas the shutter curtain is almost black and isn't very reflective.
When I tried to burn the piece of paper using a hand glass when I was in the junior high, I used a piece of black paper. A piece of white paper of the same material was slower to catch the fire, if I remember correctly.
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Yes, there are many different alloy's with different temperature properties, not a fixed value. Shutter-blades are subject to very high forces so a lot of engineering has gone into material testing,,,
Shiny and reflective blades, would definitely cause issues regarding light bouncing back and forth between the shiny sensor surface and the blades.
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Whilst we might not suffer melting of the aluminium shutter blades, I suspect high temperatures may detrimentally alter the temper of the material and cause buckling of the blade.
In a quick'n'dirty experiment this sunny morning, I cut some 30x40mm sections from a screw-top wine bottle capsule and applied some concentrated sunlight. This aluminium was 0.22mm thick, painted black and quite stiff to bend. Focussing a 8x12cm planoconvex lens on the black surface generated enough heat in a minute to cause slight buckling and obvious annealing of the alloy. Bringing out the big gun (35cm diameter lens from an old 5x7 enlarger) had the second sample heat up in seconds...again no melting but visibly distorted and very soft to bend. So I guess that despite there being no visible damage to an aluminium shutter, overheating may still cause significant issues.
Further to Erik's point about temperature properties, I had a chat with a friend who provides tech support to the bottle closure industry. He stated that the coating/printing on the caps is baked at a maximum of 185deg C as touching even 200 degrees would reduce the temper of the aluminium to the point where it can not be used to shape the cap. So there would appear to be some quite narrow margins in getting aluminium to behave in the manner required.