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Thread: New lens for Pentax K7

  1. #1

    New lens for Pentax K7

    As a beginning photographer I see my direction heading towards macro.
    I have a Pentax K7 with a Pentax 18-55mm DA and a Pentax 50-200mm DA
    I was considering using extension tubes to got the inexpensive way but when you think about it, you get what you pay for!
    So I was wondering if anybody had a recommendation for a macro lens.
    It doesnt have to be a Pentax lens either.
    I have been looking at the Tamron AF 18-200mm f/3.5-6.3 XR Di II LD.
    It seems to have great reviews
    When you purchase a lens that is not of the same make as your camera, will the lens and the camera talk to each other or do you lose some of the functions?
    Any advice that will help me I would sure appreciate that

    Thanks!

  2. #2
    Moderator GrumpyDiver's Avatar
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    Manfred Mueller

    Re: New lens for Pentax K7

    First of all, I'm trying to figure out why you would want to duplicate the range that you already have with your two existing lenses; i.e. 18mm - 200mm. I suspect that optically the two lenses you already own are superior to the Tamron, as these wide-range zooms have some really wierd distortion patterns.

    Secondly, this is not really a macro lens; Tamron claims a 1:3.7 capability. A true macro is 1:1.

    The "lens and camera talk" is usually taken care of by the third party manfacturer, but there could be some "gotchas", and I am not familiar with the Pentax line, so can't comment. We have Tokina and Sigma lenses that work and communicate with our Nikon cameras, and a Samyang that does not and has to be used manually. Check with your camera retailer to find out for sure.

  3. #3

    Re: New lens for Pentax K7

    Thank you for your reply. I see shots that are extremely close up and
    I can get close in with these lenses but I would like to get in closer.
    I am just starting out so I do not know the full extent of what I can do with these lenses.
    I am learning and I practice every day!
    When I look at what equipment people are using to get these shots,
    I see that most of the time they list a macro lens.
    Thanks!

  4. #4

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    J stands for John

    Re: New lens for Pentax K7

    When you spend on a 'macro' lens you are buying convienience and if the lenses you have give you quality the extension tube is the way to maintain that. There is a proviso that if your lenses do not have manual aperture rings then you must get extension tube[s] with electrical coupling to drive the lens from the camera. Maybe not available for a Pentax camera. Photo of your lens doesn't seem to have an aperture ring, only focus?

    The cheapest and perfectly good way to achieve those closer shots is to get a moderate Close-up lens, say a two dioptre or 500mm, and use it to enable your 200mm lens to focus closer than it already does. Your lens has a 52mm filter thread so a CU lens to suit should not be that expensive. At Amazon I found a set for $10 but they are not quality items but could be useful as an introduction and if you want to go into the field then you could look to a better quality item ...It seems to me that Canon with their 500D and 250D lens would be the only sure product from some searches I've just made. If the CU lens is smaller than the front element of your camera lens you will suffer from loss of some light. Why I have edited this message to remove reference to the Popular Raynox brand. Their lenses seem to be only 49mm diameter.

    It is worth remembering that to get tight framing the solution is not always to get closer and with the 200mm lens you could well be some way back, perhaps a foot from the subject, but using the narrow angle of view of the telephoto lens to achieve trhe tight framing. There are advantages from being further back ... lighting,safety and not scaring the wee beasties.

    One side issue, you probably have heard or found you have more depth of field with a short lens than a long lens, this does not apply when doing close work. On the other hand you will have very little DoF however you go about it, short of focus stacking where you take a number of frames at different focus and the editing programme selects the sharp bits for you to compile the final shot.

    Awhile back I compiled several pages on my website on this subject which may be of interest to you.
    http://jcuknz-photos.com/HELP/HOWTOCLOSE.html
    Last edited by jcuknz; 11th June 2012 at 08:36 AM. Reason: correction and extra comment

  5. #5
    Tringa's Avatar
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    Re: New lens for Pentax K7

    Hello Langenr.

    I am fairly sure that to get what is usually thought of as true macro (ie the ratio of at least 1:1 as Manfred has mentioned) you will need a lens designed to take macro shots. I'm sure others will correct me if I am wrong here.

    Unfortunately many lens manufacturers include 'macro' in the description of some of their lenses when they they are quite a long way from achieving 1:1 reproduction.

    The only way is to check the specification of the lens.

    The shorter the focal length of a macro lens the closer you will need to be to the subject. If your interest is inanimate objects, plants or fungi then getting close is probably not a problem, though you need to consider how to illuminate the subject which could be more difficult if the camera is very close. If your interest lies more with animals then a longer macro lens may be useful.

    Dave

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