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Thread: Fun mechanical questions for SLR's

  1. #1
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    Lightbulb Fun mechanical questions for SLR's

    Oo-ie, I been taking a closer look at the actual mechanics of my camera and I have some questions. Please berate me if I did something bad here and may harm my camera but I was just so fascinated I couldn't help myself.

    I opened up the back to look more closely at how the film is really held in and advances, etc. I decided to see what it looked like when the shutter opens.

    What I noticed is after clicking the shutter, when I advance, the shutter slids over and a different shutter comes across, just like film advance.

    Am I seeing this wrong? Is it maybe just a bar that's sliding across the shutter that makes it look like a new piece of material? If so why, what does it do? If not, and I really have a new shutter sliding into place, where is the old one going and how does it recycle, it doesn't seem like there's enough room in there for that.

    I'm utterly fascinated by this. I'm going to go hunt for diagrams of the innards but anything you wish to impart is greatly appreciated, even links to diagrams. Thanx!

  2. #2

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    Quote Originally Posted by Jess
    Oo-ie, I been taking a closer look at the actual mechanics of my camera and I have some questions. Please berate me if I did something bad here and may harm my camera but I was just so fascinated I couldn't help myself.

    I opened up the back to look more closely at how the film is really held in and advances, etc. I decided to see what it looked like when the shutter opens.

    What I noticed is after clicking the shutter, when I advance, the shutter slids over and a different shutter comes across, just like film advance.

    Am I seeing this wrong? Is it maybe just a bar that's sliding across the shutter that makes it look like a new piece of material? If so why, what does it do? If not, and I really have a new shutter sliding into place, where is the old one going and how does it recycle, it doesn't seem like there's enough room in there for that.

    I'm utterly fascinated by this. I'm going to go hunt for diagrams of the innards but anything you wish to impart is greatly appreciated, even links to diagrams. Thanx!
    Is the first one the mirror and the second one the shutter???
    Sony a7rii + Batis 2/25
    Gitzo 1530 + Markins Q3

  3. #3

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    If it is a cloth shutter, maybe it was the 2nd curtain. There are 2 curtains (cloth) and when u set shutter speed, the mech. changes the distance and hence created a windows of size, big for slow and small for fast shutter etc. When triggering the shutter, the cloth actually travels at the same speed always. It is the size of the windows which expose to light thru the len that determine the shutter speed or how much the light is entering -- speed.

    If I read you correctly... if not, maybe you can write more in detail Also, never touch the shutter, dun even think of it.

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    Well, I've been knee deep in technical information since I posted, and I'm sure someone will come along with more information, but what I've found out so far is this.

    The mirror is completely separate from the shutter curtains. Mirror flips up out of the way. The way the shutter works is there are two curtains that slide from side to side. The amount of space between them is the shutter speed. So what happens in there's one curtain protecting the film. When you press the shutter button it slides to one side and the other follows at the certain distance so an open window slides across the film. It's not all exposed at the same time, a rectangul opening (or square if a long speed) slides across the film. To really picture this think about a very short shutter speed, that window would be just a sliver. Anyway, when you then advance the film, those curtains have slid back together on the other side of the exposure window and i guess there's a small piece of plastic that ensures they are tightly closed together. So they go back to the other side. This is what I was seeing and thinking it was moving like film in one direction. It goes back and forth.

    Did that make sense? Probably a little wordy but I'm pretty excited about comprehending it clearly, lol.

  5. #5
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    Quote Originally Posted by whoelse
    Also, never touch the shutter, dun even think of it.
    Thank you, good to know. What is the reason for that?

    I did accidentally brush some skin accross one of the film rails. Should I now clean it? All I have is an optics cleaner I picked up, will that work? 'ROR residual oil remover' Doesn't say what's in it other than a little ammonia.

  6. #6
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    Quote Originally Posted by Jess
    Thank you, good to know. What is the reason for that?

    I did accidentally brush some skin accross one of the film rails. Should I now clean it? All I have is an optics cleaner I picked up, will that work? 'ROR residual oil remover' Doesn't say what's in it other than a little ammonia.
    You'll want to wipe down the rollers with soft optical cloth, or maybe some lens tissue. Thing about film-SLRs is that you have to clean out the film-chamber with a blower and a little bit of a brush every now and then, it collects dust and little particles from the film cartridge itself. Go check out the backing plate, it's the one on the hinged flap that keeps the film flat. The reel actually slides physically right across that, and any kind of dust or dirt can cause big scratches across your film reel - happened to me for a while, couldn't figure why there was this line across all my shots, grrr...

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