Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-22-2010, 11:08 AM - 1 Like   #16
Veteran Member




Join Date: Sep 2007
Location: USA
Posts: 1,812
Kit zooms?

Please take a look at:

Kx in Use

for lots of examples of the humble 18-55 and 50-200 kit zooms on a K-x (unless specifically noted) a lot were under very low light.

Neither lens give that much away in IQ (IMHO)
and the flexibility of having the zoom ranges
allows one to compose in the camera before the shot
- this feature is often overlooked when talking of "ultimate" lens quality and advocating primes.
(yes, primes are better in almost all tests.
But in real practical usage although one might see the difference when pixel peeping -
the difference is not that great, even if noticeable, when used for real prints or monitor display.

Also more often than not they end up being a non-ideal focal length -
and even worse the focal length needed may not on the camera -
I know because I used to shoot during film days with only primes,
when there were very few, if any, zoom lenses)

Pudding:
Shots below were on the 18-55 (Mk 1)
at wide-open aperture -
K100D

ISO400, f/3.5, 1/40sec; 18mm (hopefully EXIF still attached - PhotoBucket can mysteriously drop metadata)

Below are all on the K-x:

ISO800 f/3.5 1/50 18mm

50-200 on K-x
(both shot at 200mm - the longest end and wide open at f/5.6 -
supposedly the weakest performance of lens -
so these ought to be the "worst" samples):
Stanley Clarke w. Hiromi at Atlanta Jazz Festival May/30/2010:

ISO5000, f/5.6, 1/100, 200mm


ISO5000, f/5.6, 1/100, 200mm

In most tests the 55-300mm is supposed to be better (although PopPhoto.com tests ranks them about the same) - however the 50-200mm is considerably smaller and a bit lighter and this might make a difference (it does to me).

The 5mm difference at widest end may seem trivial - but sometimes that can have an enormous advantage - eg: the Atlanta Jazz Fest shots above - it was raining so I was very reluctant to change lenses - the 50mm can just about get the full stage for where I was - whereas 55mm would not. It was true that 200mm could only just about get 3/4 length shots - and the 300mm end would have done a lot better - but overall the trade-off of not having to change lenses and the results I got at "only" 200mm were still very satisfactory.


Last edited by UnknownVT; 12-22-2010 at 11:43 AM.
12-23-2010, 09:21 AM   #17
Junior Member




Join Date: Dec 2010
Posts: 44
Original Poster
Great, great information and examples, UnknownVT.

You make a good argument for the 50-200. As someone who spends a lot lunch breaks walking around midtown Manhattan with a G9, the smaller size seems like a plus for that lens.

Your concert shots are a strong argument for the K-x, but your discussion of low light AF performance and comparison with the G10 make a great argument for the K-r, fleshing out the comments others have made about AF performance with real world examples. I avoid flash most of the time, so the K-r AF assist lamp seems like a strong point in the K-r's favor.

VT is the US postal abbreviation for the state of Vermont, so I always read your tag as "Unknown Vermont" and then remember it's Vincent Tseng... Thanks again for the great shots and perspective.
12-23-2010, 10:18 AM - 1 Like   #18
Veteran Member




Join Date: Sep 2007
Location: USA
Posts: 1,812
QuoteOriginally posted by Taobat Quote
but your discussion of low light AF performance and comparison with the G10 make a great argument for the K-r, fleshing out the comments others have made about AF performance with real world examples. I avoid flash most of the time, so the K-r AF assist lamp seems like a strong point in the K-r's favor.
Many thanks for your kind compliments.

As you've figured, I shoot quite a bit at a very dark jazz venue.

The K-x is more than adequate - the "difficulties" that I sometimes have in auto focusing is probably due to reaching the limits of the K-x's AF ability/spec.

ISO5000, f/3.5, 1/4sec seems to be a limit for me.
AF limiting light levels are more easily understood with ISO 100 and f/1.4 (the aperture used to test dSLR AF)
so calculating backwards that's the equivalent light level:
= ISO800, f/1.4, 1/4sec
= ISO100, f/1.4, 2 secs

This is approx 1/4fc or 2.7lux
or
EV (Exposure Value) = 0 (@ ISO100)

EV=0 is only one stop above the limit of the K-x AF spec'd at EV= -1 (@ ISO100)

However AF is normally rated with a f/1.4 lens (at ISO100) -

which means that at the AF sensors with f/3.5 it is actually
-2 2/3 stops darker
which probably means I am managing to focus at 1 2/3 stops darker -
beyond the specs.... that is why I may have difficulties at times!

Don't forget for AF spec tests they use good high contrast targets
whereas I often have low to almost non-existent contrast to focus on in the dark....

So the K-x's focusing ability is actually very impressive -
of course the K-r's focus assist light would probably be a plus -
but I don't miss that often,
to want to pay the current $200 premium for a focus assist light.

EDIT to ADD:

I just realized that my exposure metering in the extreme dark is also out of the K-x official spec range:

the K-x is spec'd to EV=1 (at ISO200, f/1.4) = EV=0 (@ ISO100, f/1.4) -
this means that I am managing to meter (I use evaluative) at some -2 2/3 stops below the specs (allowing for a -2 2/3 stop loss of using f/3.5 instead of f/1.4 lens)

Last edited by UnknownVT; 12-23-2010 at 11:13 AM.
12-23-2010, 06:37 PM   #19
Pentaxian
Pablom's Avatar

Join Date: Feb 2010
Location: Jerusalem
Posts: 1,940
QuoteOriginally posted by clockwork247 Quote
there's a video on the forum that compares the 2 unit so you can see it yourself, the k-r just feels faster and because it zoom on to what it's focusing you know what you are focusing for sure, that won't happen with the k-x.

they use the same sensor so IQ should be the same

IMO the K-R is worth 100 over the k-x, if you have to get it for 100 more then get the k-x (that's just my opinion on the price).
you are talking about live view AF, that is a very specific feature that is not essential to most photographers

K-r and K-x don't share the same sensor, though they seem to perform similarly

12-24-2010, 09:23 AM   #20
Veteran Member




Join Date: Nov 2010
Location: San Diego, CA
Posts: 360
QuoteOriginally posted by Pablom Quote
you are talking about live view AF, that is a very specific feature that is not essential to most photographers

K-r and K-x don't share the same sensor, though they seem to perform similarly
that function helped alot... I'm not sure what to say.

I didn't know that they don't share the same sensor, i just assume they do because of the same size/resolution sensor built by the same company.
12-24-2010, 09:50 AM   #21
Veteran Member
Frogfish's Avatar

Join Date: Dec 2009
Location: Shanghai
Posts: 4,490
The Kr is an updated version of the Kx, similarly the K5 is to the K7, and functions of the prosumer camera have again been retained in the consumer model. It makes sense that the Kr is going to be a better camera - the only question is whether it is worth the extra $$ to pay for it.

If the difference is next to nothing (under $100) with rebating or discounts then why get an earlier model ? You can easily pick up those kit lenses for very low prices on Fleabay etc. if you need them. Go for the better camera .. it will improve every lense you put on it.

BTW if I remember correctly Pentax said that whilst the sensor in the Kr is basically the same as the one in the Kx, it has been improved upon and is so a better sensor now.
12-24-2010, 10:07 AM   #22
Ira
Inactive Account




Join Date: Mar 2009
Location: Coral Springs, FL
Photos: Gallery | Albums
Posts: 5,216
Vincent--beautiful stuff!!!
12-24-2010, 12:16 PM   #23
Junior Member




Join Date: Dec 2010
Posts: 44
Original Poster
Wow! Vincent!

Once again, fantastic information--your post made me look deeper into AF systems in general, my G9 in particular and the K-x and K-r specs. This was always kind of vague area for me, with a sense that there were some limits around which the AF started to hunt excessively or fail to lock... but no precise numbers.

Your info helps take this from magic into science... Thanks!

B&H is showing me
a black K-x w/18-55 and 55-300 for $649 (white is $715--Big premium for the color!)
White K-r w/18-55 for $669
White k-x w/18-55 and 50-200 for $569!

Following the Moore's law logic, and looking at your beautiful concert shots (and some bird shots in other threads), it really makes sense to go for the last option.

If the price is the same, I'll take a white one... if there is a big markup for color, I'll take the cheaper color.

Thanks again!

12-24-2010, 12:48 PM   #24
Veteran Member




Join Date: Sep 2007
Location: USA
Posts: 1,812
QuoteOriginally posted by Ira Quote
Vincent--beautiful stuff!!!
Thank you Ira for your very kind words.

It had just occurred to me -
not to take anything away from the new K-r
(it's early days for the K-r - I'd wait for the price to drop)
but the twin lens kit for the K-x is one of the best bargains around
at about $550-70.

It is just about the cheapest yet one of the top combinations for very low light work -

people may laugh at the two kit zooms for low light work......
but the proof of the pudding....

I've posted this in my thread: Kx in Use
and I'll paste it here:

I went back again last night to my low light venue....

ISO5000, f3.5, 1/25, 18mm
as usual it was not that well lit in there except stage center -
look at my favorite low light subject - the pianist to the left of the frame
dark enough for ya?

and almost as if he were deliberately challenging/teasing me -
he was wearing a baseball cap -
which put his face in the shadows almost all of the time!

ISO5000, f/4, 1/13, 50mm (using the 50-200) this shot was actually grossly under-exposed (the shutter speed should have been about 1/4 sec) - I had to bring up the brightness on this shot quite a bit -

There was still focusing difficulties - but once I figured to focus on the rim of the cap peak it was fine.......

drummer in the shade -

ISO5000, f/4.5, 1/15, 95mm

Of course as usual there was plenty of playing off stage from the audience area:

ISO5000, f/4, 1/5, 20mm

Not everything was nice and sharp - quite the contrary -
there were lots of shots that showed plenty of subject movement -
I mean we're talking about shutter speeds of 1/15 down to about 1/4 sec
and these musicians move a lot during play....

ISO5000, f/4.5, 1/13, 80mm -
I was lucky to get this shot, and the movement kind of adds to the pic.

Even at stage center, light can be a challenge - the hat peak puts the face in the shade - shot with +2/3 stop compensation - then post process to bring up the facial details sacrificing some burnt out highlights like the hands.

ISO5000, f/4.5, 1/15, 43mm.

Last edited by UnknownVT; 12-24-2010 at 04:18 PM.
01-12-2011, 11:28 AM   #25
Junior Member




Join Date: Dec 2010
Posts: 44
Original Poster
And the winner is....

We have a winner.

I decided on the k-x.

Discussed it with my wife and... she said I should get a k-5! She likes the shutter sound. I guess I really have no choice!

Thinking about lens options now.
01-12-2011, 12:00 PM   #26
Veteran Member




Join Date: Sep 2007
Location: USA
Posts: 1,812
QuoteOriginally posted by Taobat Quote
I decided on the k-x.

Discussed it with my wife and... she said I should get a k-5! She likes the shutter sound. I guess I really have no choice!
K-5?

WoW!
I am just so green with envy.....

Congrats, I hope you really enjoy the K-5 -
and please show us some results.

Last edited by UnknownVT; 01-12-2011 at 03:05 PM.
01-12-2011, 01:59 PM   #27
Veteran Member




Join Date: Nov 2010
Location: San Diego, CA
Posts: 360
QuoteOriginally posted by Taobat Quote
We have a winner.

I decided on the k-x.

Discussed it with my wife and... she said I should get a k-5! She likes the shutter sound. I guess I really have no choice!

Thinking about lens options now.
just get a K-5 body and start getting some zoom, best option IMO, the pentax prime are great, but i always see prime as a novelty VS zoom is more of a work horse, you get the horse 1st lol.
01-12-2011, 03:27 PM   #28
Veteran Member




Join Date: Sep 2007
Location: USA
Posts: 1,812
QuoteOriginally posted by clockwork247 Quote
just get a K-5 body and start getting some zoom, best option IMO, the pentax prime are great, but i always see prime as a novelty VS zoom is more of a work horse, you get the horse 1st lol.
What a sensible outlook -

I agree - for ultimate-ultimate quality primes are the way to go - to squeeze every last single drop of IQ out.

But for real practical usage zooms are just more flexible - and for most normal general photography there isn't that much difference.

That however is a very emotive issue for some of us here
where we can debate to a stand-still the de-/merits of the 18-55 kit zoom for example - some really do consider it close to, if not, rubbish - whereas others (like me) actually quite like ours and get quite presentable/satisfactory results...... of course it's all opinion.

In the early days of zooms (35mm film SLRs) the Zoom-Nikkor 43-86 mm f/3.5 was enormously popular among pros - because of its flexibility -
but this the retrospective take:

" This beautifully built 43-86 mm zoom lens was immensely popular in the early Nikon years, although image quality admittedly was poor. Thus it served to give zooms a reputation of bad quality that tenaciously survives even to this time. However, many people are unaware that Nikon replaced the first 9-element version with a markedly improved new 11-element design in 1976. The last optical version had serial numbers starting at 774 071 and continued into the AI epoch. I have used it extensively with or without a close-up lens and it really gives good results stopped down to f/8 or so. Even with the newest design, pincushion distortion is a bit on the high side compared with modern lenses so the 43-86 shouldn't be used for architectural photography. Moreover, its bokeh isn't great. In fact, it is terrible! Easily the worst of all Nikkors in this aspect. "

So that used to be the trade off between quality and flexibility - yet many pros chose to use it.... shows what the test bench may reveal - often is not carried over to print - especially newsprint!

Having said that we are very fortunate with advances in computer design, automation and use of specialized optical materials - there are now quite affordable and reasonable quality zoom lenses for APS-C dSLRs (smaller sensor lenses are easier to design and produce). Of which I would count the 18-55mm kit zoom - I realize there will be some that will disagree - but I am quite happy with my results like in post #16 above....... and in the thread: Kx in Use
01-12-2011, 06:20 PM   #29
Site Supporter




Join Date: Nov 2008
Location: Minneapolis
Photos: Albums
Posts: 588
QuoteOriginally posted by clockwork247 Quote
just get a K-5 body and start getting some zoom, best option IMO, the pentax prime are great, but i always see prime as a novelty VS zoom is more of a work horse, you get the horse 1st lol.
That's odd, I take a huge portion of my photos with a normal-length prime, and only pull the zooms out for wildlife.

Everyone will have a different process, a different way of seeing the scene. It is hard to know what you will like until you get out there and do a lot of shooting.
01-12-2011, 06:38 PM   #30
New Member




Join Date: Jan 2011
Posts: 20
The DA55-300mm is not a bad lens at all. Sure it doesn't have the SDM function and is a bit noisy as driven by the body's AF motor, but it does the job quite well. When I had a K10D I also chose the DA17-70mm and DA55-300, primarily after reading tests and reviews on a few Pentax lenses. The two of these covered a decent comprehensive range, and also they exhibited minimal distortion at either end of their focal lengths. After having a Pentax branded 18-250mm with significant distortion at the 18mm range, I decided to pay more attention to this in particular in reviews before choosing a lens, and these two did well.
The Sigma 18-250 HSM DC lens is not bad for such a range as controls distortion well, but is not very fast f3.5-6.3, and I am skeptical about build sometimes as have had to return mine under warranty for jamming mid way through the zoom range and have heard other stories of issues with some Sigmas. Ideally, if looking to get into shooting more than just basics, I think it is good to have two decent range covering lenses, and one general superzoom for the occasions you want to run around 'light' and need a lens to do everything.
Reply

Bookmarks
  • 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!
advice, camera, canon, dslr, k-r, k-x, lens, photography, sense, system
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lens shade incompatibility! 18-55mm vs 18-55mm WR PALADIN85020 Pentax SLR Lens Discussion 2 11-07-2010 07:56 PM
Why No Twin Kit lens optin for Pentax K-X White (18-55mm & DL 55-300mm) ajaya Ask B&H Photo! 8 06-01-2010 10:12 PM
Large format twin reflex lens, can you split? telfish Pentax SLR Lens Discussion 6 03-04-2010 02:34 PM
DA 18-55mm AL II vs DAL 18-55mm (kit lens) vs DA 18-55mm WR rustynail925 Pentax SLR Lens Discussion 10 01-08-2010 02:06 PM
18-55mm WR compared to the original 18-55mm kit lens HogRider Pentax SLR Lens Discussion 19 11-26-2009 12:01 PM



All times are GMT -7. The time now is 05:22 PM. | See also: NikonForums.com, CanonForums.com 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?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top