Difference between 2.0/1.7/1.4

Discussion in 'Adapted Lenses' started by alaios, Mar 7, 2013.

  1. alaios

    alaios TalkEmount All-Pro

    Jan 11, 2013
    Real Name:
    Dear all,
    I would like your help how much those numbers can give differences on achieved shutter speeds and isos. As I am looking on the market for second hand lenses is very clear how much the cost increases as the number goes down. I am not sure how much more should this improvement pays off the extra money.

    This is of course a very subjective topic so please feel free to write your personal story.

  2. Mattithjah

    Mattithjah TalkEmount Veteran

    Jan 17, 2013
    Czech Republic
    Real Name:
    ...only one note from me:

    I own Jupiter 8... it is 50 F2,0. It cost 25$.
    I would like to buy small L39 mount lens Jupiter 3... it is 50 F1,5. It will cost me 200$.

    Construction of these lenses are the same.
    Jupiter 8 has slightly better contrast and sharpnes on all apertures.

    My conclusion: Jupiter 3 is not worth for me for this money...
  3. Mattithjah

    Mattithjah TalkEmount Veteran

    Jan 17, 2013
    Czech Republic
    Real Name:
    ...but it is not only shutter speed, whis is affected by lower aperture number... Lower aperture also influence character of out-of-fucus area - Bokeh.
  4. Bugleone

    Bugleone TalkEmount Veteran

    Aug 21, 2011
    An f1.4 lens can pass twice teh maximum light that an f2 lens can,...ie on extra 'stop'.

    However, in practice it does not boil down to much,...and, there are some cons with the f1.4, namely, much larger, heavier and more expensive lens and (for most lenses) mediocre image quality compared to f2.

    It's true that depth of field is slightly less with f1.4......about the only 'advantage' with the f1.4 lenses.

    Large aperture lenses (f1.4 , f1.2 & f0.95 etc) came about in the film era when there was a MASSIVE difference in image quality between 200iso and 400iso. With the advent of digital and it's incredible high iso image quality this differential is now gone completely.......

    .........And f2 lens is a much cheaper, lighter, and more sensible lens for NEX and similar systems.

    F1.7 (& f1.8, f1.9) etc were basically 'marketing' inducements in the era of film.....F1.7 is approx half a stop 'larger' than f2......so, in practice a nothing.
  5. NickCyprus

    NickCyprus Super Moderator

    Oct 11, 2012
    Real Name:
    Most lenses give better results when stopped down and not shot wide open IMO - something you should also consider (ie. my MD 50 1.7 is very good stopped down at about 2.8 - so a faster 1.2-1.4 should give another advantage here) ;)
  6. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    And in many cases to build a faster lens means that the image quality isn't as good even stopped down. Lens building is very difficult thing, even big names like Zeiss make compromises.
  7. xXx1

    xXx1 TalkEmount All-Pro

    Jan 15, 2013
    When aperture grows from 2.0 to 1.4 the shutter speed will halve. Or the ISO will halve or linear combination of these. Going from 2.0 to 1.7 will be half of that.

    The big question is image quality and artistic things (like narrow depth of field). I have a Pentax 55mm/1.8 and like it. I would gain a slightly faster and narrower depth of field with 1.4 lens but I think that it isn't worth it.

    Some faster lenses were better liked than their slower counterparts. It has mostly to do with marketing, in the old days 50mm/2.0 lens was kind of kit lens of today. That is very cheap to make.

    SMC Pentax-M 50mm F2 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database (not liked 2.0)
    SMC Pentax-M 50mm F1.7 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database (more liked)
    SMC Pentax-M 50mm F1.4 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database

    I think that from above lenses 1.7 produces best images. Would of course purchase 1.4 for occasional portrait use if I would get it cheaply but 135mm/2.5 might be better option.
  8. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    For legacy lenses, everything said is true. But for modern lenses, don't forget that the aperture is most of the times not the only difference. Lenses with brighter aperture cost more, but they often feature much better build quality, a faster or more solid AF, a much better focus ring and a generally better corrected optical formula.
  9. Grisu_HDH

    Grisu_HDH TalkEmount Veteran

    Dec 16, 2012
    Southern Germany
    Real Name:
    Never forget to consider which kind of pictures you would like to take...
    - Portraits?
    - Landscapes?
    - Makros?
    - etc. etc.
    Do you really the wide open aperture? Do you do many available light pictures?

    But first of all...
    You're talking about chosing a manual legacy lens, right?
    Have you used a manual lens before on a NEX (or an any other cameras)?
    If yes, the wide open aperture pays off!
    If no, try a cheap 2.0 or 1.7 and try it out and see if you like it and if you need more aperture!

    Best tip! Always wait for a offer that looks like good quality, don't buy a cheap 1.4 or 1.2 just to have one... the result may be scratches, fungus, dealignment...