Calling all photographers!

    Evening people!

    I have had the pentax kx for a while now... bought it with the standard kit lens and a 55-200mm one. Now i really want something a bit faster... a really good portrait lens perhaps?. Was wondering if any one could recommend certain lenses that would go well with the kx... and possibly wont cost me an arm and a leg? Have been waiting on some deals to come on here.. but all the lens deals tend to be nikon/canon :(.

    Thank youuuu in advance for any help!


    I have no idea and I agree that the lenses/cameras seem to be Nikon/Canon but ask in this thread as well and there may be someone to give you a bit of help.
    I don't know that a new lens would be 'faster' though. What exactly do you mean? Do you want to take family pics? Anyway - there's some knowledgeable people around that may turn up.


    Well there's faster in a few ways. First could be Autofocus (if it's not … Well there's faster in a few ways. First could be Autofocus (if it's not in body), but the main and most likely one is the F stop, the lower it is, the faster the shutter speed you can use as it lets more light in (simple explanation). I know for Canon the 50mm F2.8 is popular.

    The OP says he's looking for a faster lens!!

    See you learn something every day. I thought a lens was just a lens and the camera did all the work.
    Thanks for the info dcx

    Yes hottoshop you are right.
    Like the other month when I discovered that the unit of optical power, the Diopter, is used by underwater and then by photographers in general to descibe a magnifying lens as 'a diopter'.

    It would help if what I typed wasn't randomly lost by the site. Try again. There seems to be an idea that a fast lens is one that acommodates a fast shutter speed - pro lenses are fast!! Or, I have seen that 'fast lenses; let through more light!!

    Clearly, physically a lens cannot be faster, as it is a fixed structure that alters the direction of the passage of light which travels sufficiently rapidly that the effect of the lens upon its speed is irrelevant.

    How wonderful that when I clicked on Submit this site took me to Search. I must stick with firefox.

    So a faster shutter speed!!!!! Back to 'a faster lens accommodates a faster shutter speed ' as i said ^^^

    Stick a piece of glass ( let's call it a lens!) in the path of light and the wavelength alters hence the speed but it doesn't matter as the speed is so great that the difference cannot be detected by a camera.

    Not your fault that there is no notion of SI units for photographers. Not my fault either. Look the sites - they need to start talking in proper units and proper scientific parameters and definitions and then they will all know what they are talking about! ATM it is mayhem.

    My usual trick of dozing off and not because of the ^^^^^^^^^^^^^^^^^^ I hasten to add !

    Bottom line for me is that this is all way above my limited brain capacity so I'm bowing it.

    Actually reading through your posts again I think I can get a slight grasp of what both of you are putting forward. That though is where my input finishes.

    Interesting subject though and thanks both for the info, expanded knowledge and all that.

    Did the OP get his/her answer ????? You decide..........................

    OP ??

    'Faster Glass' as its know will always be more expensive.

    The glass in the lens is of a higher quality and usually there is a lot more of it

    What you mean is you want something with a bigger aperture to allow more light in so the shutter doesn't need to stay open as long to capture an image thus eleminating motion blur or the need for a tripod.

    So I would guess you are wanting to take piccys in lowlight or of sport/action.

    This unfortunetly as a rule comes at a cost.

    I take it your 50-200mm is around the f5.6 mark? Struggle with cloudy days or inside?

    It all depends on what you are going to take photos of, how much reach do you need etc?
    The other definition of a quick lens will amount to the Motor used in the autofocus ring housed in the lens itself, how much does the lens hunt for the focus sweet spot? But if you are any good at manual focusing ( a lost art these days if you ask me) then you can save yourself a packet by buying some of the older lenses with high quality optics but slower motors for autofocusing.

    Original Poster

    Thanks for the response guys! im sorry for not being clear... what im after above all is a very shallow depth of field. Like i mentioned something that can take nice portraits by focussing on the subject and blurring the background. My kit lens goes down to f3.5 and is actually not that bad... have taken some pics with good blurring effect... but im after something faster i.e. with a lower f-number so i can get even shallower depth of field.. while ideally still retaining good sharpness (on the subject).

    Celticsun:Im still very new to photography and wouldnt mind trying manual focus.. i think the pentax kx has a lil indicator for when it thinks the image is in focus.. which might be helpful if it means im saving a few quid. Ive heard the old super-takumar are excellent.

    Was thinking of going for the "m42 super-takumar 50mm" what do you guys think?
    Edited by: "Frankenstein" 6th Aug 2010

    Any lens with an aperture of 2.8 or less should fullfill your needs.

    Be aware when buying second hand lenses especially older models that the optics need checking. If possible take a photo of something bright (like the sky) or a piece of paper. You are looking for dust or mould growing in the lens on the optics. These will appear as small or large black dots when viewed at 100% crop

    F2.8 is only half a stop faster than F3.5, I'd be looking at something below F2 for a decent wide aperture prime if you can find something suitable in your price range unless you're wanting a very compact lens.


    A better quality 2.8 will give better BOKEH than a lower F-stop.

    And anything below 2.8 limits your lens options

    Not all true, aside from bokeh being subjective and being very good on some of the F1.4 lenses generally a wider aperture lens stopped down will perform better than a similar lens at the same aperture wide open. In addition, a wider aperture lens will give more options for shallower depth of field and importantly will give higher shutter speeds in low light. The latter is one of the main reasons I use wide aperture primes because even with F2 and F2.8 zooms, I still need to be able to squeeze more light in. For longer focal lengths and zoom lenses F2,8 is generally as wide as you can go however in the portrait/normal range there are plenty of choices.


    Sorry I should have been more clear, I was specifically commenting on the range of lenses available albeit very limited for the OP's Pentax.

    The choice of sub 2.8 is pathetic in the pentax compatable range. If the OP had a nikon or canon mount they'd be laughing!

    Shallow DOF and a wide AP within a budget if it was a Canon i'd say 50mm 1.8


    Shallow DOF and a wide AP within a budget if it was a Canon i'd say 50mm … Shallow DOF and a wide AP within a budget if it was a Canon i'd say 50mm 1.8

    Then do what i did and exchange it for a 60mm macro after 6 months, seriously that lens is amazing


    NP, my lenses are all cheaper ones so F3.5-5.6/ Would love a nice F2.8 or … NP, my lenses are all cheaper ones so F3.5-5.6/ Would love a nice F2.8 or 1.8 but they can cost thousands for some of them. Can get a 50mm F2.8 for under £100 used, but fixed zoom isn't much use it a lot of circumstances.

    Prime lenses are great, I wasn't sure but my 60mm hasn't been off the body for about a year now. Granted it's not great for birds/motorsport etc. but as a walk around lens I have been impressed with it, it certainly makes you think about our pictures more
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