1. Ben johns

    Ben johns

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    Ben
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    This might sound like a silly question but I’m deciding between two lenses, one is an f1.4 and one an f2, both 35mm. My question is f1.4 a full stop faster than f1.8 which is the fastest lens I’ve used so far. Just want to get an idea of how much extra light a 1.4 would let In.
     
  2. RichardC27

    RichardC27

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    Richard
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    Yes
  3. GreenNinja67

    GreenNinja67

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    Terry
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    1 stop = double the shutter speed therefore double the light.
     
  4. soeren

    soeren

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    Soeren
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    When it comes to the opening, not necessarily when it comes to how much more light hits the sensor
     
  5. Gaz J

    Gaz J

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    3,308
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    Gary
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    No
    f1.4 is only 2/3 stop faster than f1.8. f2 is the next full stop after f1.4.

    I guess it depends on what you’re using it for. My use would be for Astro where the extra light would mean I could reduce the exposure time would be an advantage. Others may want it for its very shallow depth of field.
     
  6. Ben johns

    Ben johns

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    469
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    Ben
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    Right ok. Well I just got a Leica m2 and on a budget for a first lens. So it’s either the 7artisans 35mm f2 or save a little and get the voigtlander 35mm f1.4.
    I’d be using the lens a lot inside so that extra stop might be helpful
     
  7. juggler

    juggler

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    4,327
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    Simon
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    If you're new to rangefinders then I'd suggest holding off the expensive one. Focusing at f1.4 will be a challenge, especially at close distances where parallax is an issue.

    disclaimer: I am utterly incompetent with a rangefinder.
     
  8. Ben johns

    Ben johns

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    Ben
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    I’m new ish, I’ve used a Ricoh 500g, I’m new to a good rangefinder, the patch on the 500g is a bit crap, on mine at least.
    I was thinking of holding off, the voigtlander is double the price
     
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  9. juggler

    juggler

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    4,327
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    Simon
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    In which case.. you know more about it than me!
     
    MatBin likes this.
  10. Dave70D

    Dave70D

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    Hi Ho Silver away !
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    The one thing that always puzzled me was, the smaller the f number=the bigger the hole/opening :confused:
     
  11. RichardC27

    RichardC27

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    The f number is a fraction of the focal length. So f1.8 on a 50mm lens = 27.77mm opening. f2 = 25mm opening, f4 = 12.5mm opening and so on

    Divide focal length by your f number and that's the size of the opening
     
    Phil V, Dave70D and MatBin like this.
  12. st599

    st599

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    1,523
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    No
    It's a fraction i.e. f/16 is a smaller fraction than f/2
     
  13. john.margetts

    john.margetts

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    Easier to understand when written correctly as f/2 with the slash as it is a fraction
     
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  14. sk66

    sk66

    Messages:
    6,240
    Name:
    Steven
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    Yes
    And when you understand that the "f" stands for "focal length," some lenses used to be marked that way. The markings on this lens are (aperture) ratio 1:1.4 and f = 50mm. Which is the same as 50mm f/1.4, and 50/1.4...

    Auto_nikkor_50mm.jpg
     
    Mr Bump likes this.
  15. Mr Bump

    Mr Bump

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    7,205
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    Paul
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    I have that exact lens on my F2 :)
     
  16. woof woof

    woof woof

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    18,391
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    Alan
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    I have one too, use it now and again on my Sony A7. It feels like it could withstand a direct hit from an Exocet.
     
  17. gunnar

    gunnar

    Messages:
    457
    Name:
    Alex
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    Yes
    F stop does not give you that information. T stop does, but lens manufacturers often don't publish it (unless they are cinema lenses), so you will have to look at independent tests.
    Lens can often be F1.4 but T1.8 or even worse.

    for example Sony's 50/1.4 is actually T1.6 https://www.dxomark.com/sony-carl-zeiss-planar-t-fe-50mm-f-1-4-za-lens-review/

    Sigma's 50/1.4 ART is T1.8 https://www.dxomark.com/Lenses/Sigma/Sigma-50mm-F14-DG-HSM-A-Canon-mounted-on-Canon-EOS-5DS-R__1009

    on the other hand Sony's 55/1.8 is also T1.8 https://www.dxomark.com/Lenses/Sony...-T-STAR-55mm-F18-mounted-on-Sony-A7R-II__1035
     
    Last edited: Oct 4, 2018
  18. Tdes

    Tdes

    Messages:
    44
    Name:
    Tony
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    Yes
    Years ago I was wrongly told that it was the area of the the blades not the area of the hole. So a f1.8 is covering less area than f8.

    Learn something new every day!!
     
  19. Steve Smith

    Steve Smith Joe

    Messages:
    9,349
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    No
    I have it too, but I can't remember which body it is currently visiting.


    Steve.
     

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