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Discussion in 'Nikon Chat' started by transition, Sep 25, 2017.

  1. transition

    transition Member

    In my early topic I asked about the meanings of the letters and numbers around the periphery my lens. You gentlemen replied with some helpful information. If I can find it again I'll note each comment.
    In the meantime and in a similar vein I would like to know more about the particular aspects of lenses. In saying that it is a question of explaining to me what exactly each set of letters actually mean.
    For example, AI, does the A stand for Automatic and the I for indexing or have I got that completely wrong, please?
    On my original Nikon FE there was a ring with a probe which slotted into, what I think were called "rabbits ears" on the lens itself? What was the purpose of this coupling together, please?
    Is this system still used on digital cameras, please?
    Is there a book which would explain quite simply how todays cameras work?
    What makes two similar lenses with similar, for example zoom ranges, so different in price?
    I realise my questions will seem very basic but that is the stage I am at.
    Thank you,
  2. PeteRob

    PeteRob Well-Known Member

    The naming of lenses is manufacturer dependent. There is bound to be guide for nikon naming somewhere on the internet - wikipedia is always worth a look. Nikon made a decision early in the days of autofocus to try to keep their lens mount whereas Canon decided to start with a clean piece of paper and start with a new one. Nikon jumped through lots of hoops to try and keep compatibility with mechanically operated lenses while the trend has proved to favour electronically controlled ones. This makes cross-compatibility rather a minefield. I don't know which current Nikons support mechanical linkages for aperture control and autofocus but I'd consider these "old technology".

    Today's cameras "work" exactly like old cameras work. Aperture and exposure time are set to allow a controlled amount of light to fall on the sensor. The sensitivity of which can be set frame by frame. Other handling aspects like focus are automated and image stabilisation allows handholding at greater exposure times than woukd be possible without. The output is a digital negative that can be developed in or out of camera. In camera processing produces a jpg file that can be seen on a computer with commonly available software such as web browsers.

    As with everything quality costs. To make photography (always an expensive hobby) more accessible there are lower cost cameras and budget lenses that work well if looked after. If you want more robust equipment and wider apertures (more glass), faster focussing, etc. then the price is higher.
  3. nimbus

    nimbus Well-Known Member

    AI stands for Aperture Indexing, the means by which the camera recognizes the aperture of the lens in use.

    The Rabbit's Ears or claw connected to a corresponding part on cameras that pre-dated the AI system and enabled the metering to recognize the aperture. Such functions are carried out electronically on modern cameras so the ears are non-functioning on modern cameras. The AI system does allow some Nikon digital cameras to meter in some modes with such lenses, it is done by setting the lens details in the camera menu system.
  4. cliveva

    cliveva Well-Known Member

    as to lens costs, firstly to produce the best lens,in the grinding/polishing, a lot of skill and time is required, i.e. grind, measure, grind, remeasure,etc, etc. cheaper lens elements are machine ground to within a given tolerance, which is wider than that used for high a quality lens. Then they are coated with expensive films to reduce flare, chromatic aberration and improve light transmition. They are built with more expensive metal bodies, less are made, so development costs are greater per unit manufactured. I'm sure there are more reasons:rolleyes:
  5. AndyTake2

    AndyTake2 Well-Known Member

    The material the lens is made from also changes the price. Fluorite glass and other exotics cost far more to manufacture than the standard stuff, and even that varies a lot.
    It's a bit like the glass on wrist watches.
    Some are made of a standard glass, some are made of sapphire.
  6. El_Sid

    El_Sid Well-Known Member

    Do you mean a ring around the lens mount? That is part of the Ai system, there was a prong on it which engaged with a ridge protruding on any Ai lens, the 'rabbit ears' were not involved at any point, this is the system fitted to the FE and it's manual brother the FM. The rabbits ears were an earlier version of aperture coupling and engaged with a prong/lever that hung down from the viewfinder prism housing. Unlike the Ai system the aperture range had to manually indexed by turning the aperture ring to maximum and minimum once the lens was mounted and the prong engaged. If your camera had a prong hanging from the prism then it wasn't an FE but something earlier.

    Yes and no... Certain high end digital bodies, such as my D7000, do indeed still have the AI coupling ring which allows use of the metering system in M and A modes with manual AI lenses. I can't remember when the AI ring was reintroduced but models in the D3xxxD5xxx don't have it and nor do the early models (anything pre D300 I think). It was only reintroduced, I suspect, in response to complaints from Nikon owner with manual, often top end, lenses which required either the use of a secondary light meter or the 'sunny 16' rule. I have a feeling that Nikon will try and phase it out again...

    Again the prongs have no use, indeed early lenses with or without the prongs won't fit at all as they foul on the camera's Ai coupling lug. Generally any pre-Ai lens in original condition will probably not fit on a digital body.

    If you mean the controls etc. there are 3rd party guides which give more in-depth explanation of the camera controls and how to set them up correctly for various situations, generally based on actual use. The problem sometimes with user manuals is they are written by the people who make the cameras rather than by people who actually use them - this can occasionally mean assumptions are made about the users knowledge that may not be true...

    If you mean the actual nitty gritty about how sensors work, how image processing works etc I imagine there may be though how simple they are likely to be I couldn't say...

    Design, glass quality, dimensional accuracy, quality control tolerances, construction materials, AF motor design & build, batch size etc etc...

    I just replaced my 55-300mm with the rather more expensive 70-300mm which is larger, heavier, less flimsy and has faster AF so you do get what you pay for. Similarly I also have a Canon 55-250mm and the professional model 70-200 F4L and while the 55-250 is a nice lens, reasonably quick focusing and above average in IQ it pales by comparison to the L lens which is extremely sharp, has very high resolution and is astonishingly fast focusing - which it should do for a lens that 3 or 4 times the price of the 55-250...
    Last edited: Sep 26, 2017
  7. Learning

    Learning Ethelred the Ill-Named

    [PEDANT MODE] Fluorite is not glass; it is crystalline. [/PEDANT MODE].
    Some day such a mode will exist. I hope that it is not too embarrasing.
  8. AndyTake2

    AndyTake2 Well-Known Member

    Not in the slightest - I learn something every day.
  9. transition

    transition Member

    Thank you Gentlemen. You have been most helpful.
  10. GeoffR

    GeoffR Well-Known Member

    Sorry but AI stands for Automatic Indexing as opposed to the previous system of manually indexing lenses when mounting them by selecting minimum and maximum aperture to let the camera know the lens aperture range.
    Learning likes this.

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