Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
05-07-2010, 10:47 PM   #1
Inactive Account

Join Date: May 2010
Posts: 3
Need advice for the choice of a main lense

Hi everyone,
I’m looking for a prime lense to put on my pentax k-x.... and the more i look at my options, the more i’m confused...

So here is my situation; i take most of my picture when i travel... mostly in third wold country with great landscape (i do a lot of hicking). I want to take great picture of my trip... but i’m not travelling to take pictures (so i won’t carry alot of lenses, i won’t change lense multiple time during the day and i not carry a tripod).

When i bought my k-x i figure that the best fit for my needs was a Tamron 18-250... but now i start to be a little bite worry about the slow speed (f) of that lense.

So now i’m looking for a lenses that will be on ly camera most of the time... and keep the 18-250 for the sunny days where i expect to meet some wild life (otherwise i do not really need a long lens)

So here are my options:
Tamron 18-50 f2.8
Tamron 28-75 f2.8
Sigma 17-70 f2.8-4.5
Or keep only my 18-250....

i will like not to mist any low light shot because i have the wrong lens... I know that a 17mm is great for landscape... but i do have access to a software that could make landscape picture out of multiple shots (ie:Ptgui)

What will you do if you were in my situation???
Thanks for your help


Last edited by ben_mtl; 05-07-2010 at 10:55 PM.
05-07-2010, 11:14 PM   #2
hcc's Avatar

Join Date: Nov 2009
Location: Brisbane, Australia
Photos: Gallery | Albums
Posts: 3,526
I would not worry about the "slow speed" of the DA18-250mm, and most Pentaxians do not "keep the 18-250 for the sunny days ". You already have a K-x and a DA18-250mm: I suggest that you spend some time with your K-x and DA18-250mm before buying any new lens.

When I travel, my K-7 and DA18-250mm constitute my basic travel kit. They fit nicely in a small top loader bag. I don't worry about the weather. The only time the DA18-250mm does not perform well outdoor is at night. During day time, the DA18-250mm is perfect whether it is sunny, cloudy or rainy, and it works fine for sunset and sunrise. Indoor, you use the flash when needed.

I shoot outdoor a fair amount and the only situations when I need a faster lens is when I shoot before sunrise and after sunset: I bought a fast prime (f1.4) just for that purpose. Everything else: the DA18-250mm can handle...

Have fun, enjoy your DA18-250mm and leanr to use it....
05-07-2010, 11:38 PM   #3
Veteran Member
sterretje's Avatar

Join Date: Dec 2008
Location: Roodepoort, South Africa
Photos: Gallery | Albums
Posts: 3,534
I also suggest that you practice ('at home') with your current combo and find out where it limits you in low light. I'm not sure about the specs of the lens (what is the max aperture; 3.5?), but a 2.8 might not give you very much compared to e.g. 3.5.
I'm always disappointed where low light actually starts; it's always earlier than I would think.

As you have a Kx with its great high iso performance (hearsay), just yank the ISO one or two steps when it gets to lower light conditions.

PS for your information: the word 'prime' in your opening paragraph is confusing In photography, it is used to indicate a lens with a single focal length (e.g. 50mm).
05-08-2010, 12:20 AM   #4
Veteran Member

Join Date: Feb 2010
Photos: Gallery | Albums
Posts: 971
first of all, the options you've listed aren't prime lenses... so i'm not sure which type of lens you are actually trying to consider. also, stitching multiple shots is very useful, but in the heat of the moment, it is very useful to have a wide angle lens when available.

if i was going on that trip, i would keep the 18-250 (great IQ for a super zoom btw), and get a DA 21 or better yet a DA 12-24. Two lens, that's it. get a tripod for night shots =P

05-08-2010, 07:34 AM   #5
Inactive Account

Join Date: May 2010
Posts: 3
Original Poster
Sorry for the confusion... i should have used the word “main” lens (ie: the lens that I’m using most 80% of the time), instead of prime.

I found a couple of website where they show nice graph about the different spec / limitation of the lens

So for example if i look at my Tamron 18-250 vs the Sigma 17-70
Based on those graph, my inexperienced eyes are saying that i should decrease the speed of my 18-250 if i want better IQ... and in all cases the Sigma 17-70 will give me better pictures...

That is what the charts are telling me... but will i really see a difference in real life?!?!?
05-08-2010, 07:43 AM   #6
Site Supporter
SpecialK's Avatar

Join Date: Dec 2006
Location: So California
Photos: Gallery
Posts: 14,849
Based only on focal length, the 17-70 is (almost) the widest, and (almost) the l longest. Great image quality as well. I may buy one when my 18-50 dies.

Next choice would be the 18-50 because of the wide end. The 28-75 is an excellent lens but not really wide enough for the city. (I also may buy one when my 18-50 dies :-)
05-08-2010, 08:10 AM   #7
Veteran Member
Mechan1k's Avatar

Join Date: Jun 2007
Location: Sydney, Australia
Posts: 2,889
The Sigma 17-70 is a good all-round lens for travelling.

The image quality is good as well. I'd like to get one myself ... I have the 17-35 and the 28-70 Sigma lenses ... and they are huge ... I'd like to just downsize a bit. Albeit losing a little speed on the long end (although the 28-70 f/2.8 is soft at wide apertures at 70mm anyway.) But to go to one lens will be fine for me. I keep seeing some nice images from the 17-70 (even a friend has it in Canon mount ... and his images are nice indeed with it. He loves his version as well.
05-08-2010, 08:41 AM   #8
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by sterretje Quote
I also suggest that you practice ('at home') with your current combo and find out where it limits you in low light. I'm not sure about the specs of the lens (what is the max aperture; 3.5?), but a 2.8 might not give you very much compared to e.g. 3.5.
Like most variable aperture zooms, the 18-250 is only f/3.5 at the very widest end. By the time you get to "normal" territory, it's f/4 or f/4.5.

Given the OP already has the 18-250, what I'd probably do is keep it and use it most of the time outdoors, but keep a small prime in the pocket also for use in low light situations. It wouldn't be a lot of lens changing - just pop the prime on when heading indoors somewhere that you plan to stay and shoot a while. Even though it's not an overly popular lens, I'd be thinking about the M35/2 for this purpose. Assuming you're OK with manual focus, that is - but if your only experience with MF is with slow zoom lenses designed for AF, then you haven't really *experienced* MF. With a lens actually *designed* to be focused manually, it's not as hard as one might imagine.

Other possible choices would be M28/2.8 to get a somewhat wider view for less money (under $100 rather than over). Or, if you just absolutely have to have AF, the DA40 would a reasonable choice, or the FA35/2 if you can find one and don't mind spending considerably more.


  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
f2.8, k-mount, landscape, lense, lenses, options, pentax lens, picture, slr lens, tamron
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Advice for KX kit lens choice... TOUGEFC Pentax DSLR Discussion 24 05-28-2010 08:14 PM
Advice about buying the K-7 and lense Eetu Pentax DSLR Discussion 15 02-16-2010 03:35 AM
Lense pick quick advice acarpov Troubleshooting and Beginner Help 7 09-02-2009 09:39 AM
Newbie advice on lense shifter Troubleshooting and Beginner Help 8 01-14-2008 01:00 PM
Need advice on lense, and how did i do.. ABCWinter Pentax DSLR Discussion 3 01-01-2008 07:16 AM

All times are GMT -7. The time now is 09:19 PM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]