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01-07-2011, 11:43 PM   #1
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K-x vs. K-r long high ISO exposures

Hello all! And excuse my poor english.
I joined this forum because I'm looking for a new camera, that will replace my old Canon 350D. I'm not a fanboy of a brand and I wish a new Pentax camera.

Here are the features I'd like it to have:

- low noise at long exposures, because I'll use, occasionally, the camera at astrophoto (I own a Celestron 130EQ).
- good LiveView viewing, because at astrophoto is necessary to view the focus correctly.
- I'll use the camera normally, photographic speeking.

From the sensor point of vue, I saw that K-x is better than K-r (see screenshots). Unfortunatelly, the complete review for K-r is not available on dpreview, to compare all the features (including high ISO). But I compared K-x with 1 D Mark IV and the sensor have the same high ISO IQ.
Also, I looked the samples taken with K-x and K-r (see dpreview) and K-x seems to beat K-r at the quantity of noise at different ISOs.

Anyway, there is a problem I noticed:
. Not so big difference, but still exists. Through the viewfinder

So, in my country, the K-r body has the price of the K-x kit (18-55 included). What should I choose?

Thank you in advance.

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Last edited by ursamajor; 01-08-2011 at 02:26 AM.
01-08-2011, 04:27 AM   #2
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As I'm owner of a K-x, and a K-7, I find the K-r better than either of those two, unless you need a quiet shutter, which is the hall mark of both the k-7, and the K-5.

I'd go for the K-r, if I didn't already have the K-5! The focus assist light on the K-r is very helpful in bad light, and the faster focusing is a boost, both in 'normal' and 'live view' mode - some also feel the focus indicator light in the viewfinder essential - I don't :-)!

You probably can get a used kit lens for next to nothing on EBay, or similar sites.

You compare the K-x with the EOS 1D Mark IV, which is like comparing a VW Beetle with a Jaguar - not fair in any way, as the 1D is a very expensive camera costing close to ten times as much!
01-08-2011, 05:31 AM   #3
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Thank you for your answer. I understand you, but probably, you use the cameras for general shootings/purposes. I specified that I'll use for astrophotography, too. And I saw that, in terms of noise, the K-x's sensor is better, essential thing in astrophoto.
I compared the K-x with 1D, in terms of sensor, not price or features. I can compare it with Canon's 500D or 550D, or Nikon's D3000/5000, but they are too expansive, too, for the offered performance.

PS: another pic from HERE.
I think there is a big difference of details.
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01-10-2011, 04:17 AM   #4
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Please, tell me if you can, in terms of autofocus, is K-x comparable with my old Canon 350D or better, or maybe not? Thank you.

01-10-2011, 08:31 PM   #5
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QuoteOriginally posted by ursamajor Quote

I specified that I'll use for astrophotography, too. And I saw that, in terms of noise, the K-x's sensor is better, essential thing in astrophoto.
A few pertinent things you might like to consider:

- The K-r has an inbuilt intervalometer, basic albeit probably adequate for general astro work. Acquiring similar add-on functionality for K-x (and or some other brands/models) would only add extra cost and, possible limitations and~or unwanted complexity; such as:
gentLED Camera Remote Control

- To me, probably the major drawback of K-x, and sadly now K-r too, is their basic lack of a PC type port! That limits the otherwise decent-performing affordable camera models from much useful expansibility for use in "non standard" work such as astro, macro, etc. Grrr....

- K-r reportedly permits some useful control re: disabling the dreaded DFS (Dark Frame Subtraction), whereas with K-x you're stuck with it's hard-coded restrictions.
Can be Bad Thing™.

- K-r supposedly sports improved LiveView operation (mfgr spiel, IIRC), as well as having a 21st century screen resolution for it. So although still not what could be called good~usable in the field, it is (in my experience) worthwhile at a pinch over K-x which was next-to-useless in that.

- Regarding your concerns about lower noise etc., in K-x; as owner of both models (and a natural born sceptic) I take that, and all the "slightly better IQ in..", "look at the cute numbers and graphs we can make" gabble in the 'reviews' out there with copious grains of salt.

YMMV on that but just remember, there are almost as many great astro works taken with quite humble and alleged "poor IQ and Noisy" DSLR models of every brand out there than there are stars in our home galaxy.

"Astro" isn't even a Category on Pentax Gallery either:
PENTAX Photo Gallery
Neither is well represented on Flickr:
Astro photography Pentax - Flickr: Search

Hmm.... but don't let me give you the feeling that you might be backing a wrong horse, let's continue to assess...

QuoteOriginally posted by ursamajor Quote
I compared the K-x with 1D, in terms of sensor, not price or features. I can compare it with Canon's 500D or 550D, or Nikon's D3000/5000, but they are too expansive, too, for the offered performance.
Exactly. Cost is not a sensible metric to qualify any camera, and particularly not in the areas of criteria that you specified.
The law of diminishing returns ensures that, which seems to be your primary yardstick in defining your non-allied shortlist.

Otoh; I hope you don't get too blinded by cutesy sensor graphs and overlook capabilities like availability of features and inexpensive 3rd party accessories that can make or break a good productive experience in an off-beat specialty field such as semi-serious astro hobby.

Also when on the Pentax teat; Trust me, it sure isn't easy chasing up those non common essential bits and pieces that other brand owners take for granted and find readily available, inexpensive. eg. You can always throw a dart blindfolded at eBay and almost guarantee to hit Accessory X & Y to fit Canikon, yet same parts to suit Pentax often becomes a lottery draw. (when and if they're even available to fit the brand)

So when doing your homework make sure all t's and i's are crossed and dotted there too.
At very least, prepare to be a patient slugger and grinder as well as improviser where possible. Frustrations are often the norm, not the exception and mechanical and similar aptitudes are highly valuable.

In the real world <boring_cliché> Availability of cheep cheep s/h "primes" </boring_cliché> just ain't gonna help the person who dares tread much beyond the circle in their photographic interests and endeavours.

Thus Pentax too, must stand on merit. And merit isn't defined by a single-entity ability or aesthetic.

And... if you've made it this far, then by now you probably realise that I am warning that Pentax ownership is mostly a survivalist game (local callow fanboys and chronic LBAddicts excepted). Good luck.

HTH.

.R.

"Corporations may manufacture products, but what consumers buy are brands." -- Naomi Klein, No Logo
01-10-2011, 09:08 PM   #6
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QuoteOriginally posted by ursamajor Quote
Please, tell me if you can, in terms of autofocus, is K-x comparable with my old Canon 350D or better, or maybe not? Thank you.
Caveat: I've never owned a 350D;
However, it seems like that might be an apples and oranges comparison in a way because, should it not depend on what IS lens one might bolt onto the Canon?

Some of their IS/USM lenses are mind-boggling in their AF performance, unlike Pentax where an "old" or cheaper market screw-drive body largely determines the result, an ancient 350D clunker would surely get a new lease of life when married to esp. something of modern or L grade calibre.

A fairer test would be a shootout between 350D + IS and and K-x + SDM lens, ie. lenses of respective equivalent vintages and size.
And in that contest, I think I'd prefer to have my $$$ on Canon anyday -- for both speed and accuracy.

Otoh; Overall K-x suits all needs and expectations in AF for me. Which I suppose could be less stringent than that of most users, although I am fairly dependent on it too for vision impairment reasons.
And Fwiw; in general use so far K-r appears to be at least equal, if not marginally better at some AF duty. (Take that as one-person subjective though.)

HTH.

.R.
01-10-2011, 11:37 PM   #7
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I think there probably is very little difference between then IQ of the K-x and K-r for practical purposes in genral photography -
but as you have more critical applications - have you seen this thread?

K-x is king for long exposures and astrophotography! ( 1 2 3 ... Last Page)

This obviously started before the K-r came out - but there are a number of astro-photographers there who seem very experienced.

I am not too sure if HighISO is actually used for very long exposures -
they tend to use stacking.....
but it's best that you read the thread and use your own judgment
- you might also want to PM some of them to ask more pertinent questions.

There is also this thread:

K-r vs. K-x in high ISO performance

As for direct comparisons:

There has been a thread in the K-r forum:
anyone did Kx to Kr?
take a look at Post #18
the links to the direct comparison photos seem to show that there was very little difference between the new K-r and K-x.

The referred direct comparison photos thread was by devorama:
K-r vs. K-x ISO samples (or return of the ISO flower!)

The direct links to devorama's side-by-side ISO flower comparisons

All sizes | high-key_ISO_elevator | Flickr - Photo Sharing!

All sizes | low-key_ISO_elevator | Flickr - Photo Sharing!

All sizes | grey_ISO_elevator | Flickr - Photo Sharing!

If anything the K-x may be just a bit better than then K-r - especially on the last grey elevator ISO series - but that could be just down to slight focus differences.

This seems to be born out by the K-x and K-r test images at Imaging-Resource.com - as you have already shown a crop of.

Pentax K-r Digital Camera Samples - First Shots - The Imaging Resource!

Pentax K-x Digital Camera Thumbnails - Full Review - The Imaging Resource!
01-11-2011, 12:09 AM   #8
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Thank you, Hypocorism.
Like a non-english speaker (I'm romanian), I had difficulties to understand some parts of your post. Some expressions are beyond my understanding, but I understood the overall message.

An intervalometer is good for timelapse recording, not necessary for astrofoto (through the telescope). More than that, I always protected my shutter. I don't need to stress the shutter, by making thousands of captures for few minutes of film. More than a intervalometer I need long, clean, detailed long exposures, possibly at high ISO. I have already my chinese remote controller for Canikon & Pentax and I believe that's all I need for astro/long exposures.

Concerning the comparison between AF of 350D and K-x, I reffered to the kit lenses, not luxury lenses. I never "played" with a Pentax, but the urban legends/myths reminds about poor AF of Pentax cameras.

PS> can you tell me precisely what the PC-like port do? And can you be more specific concerning Dark Frame Subtraction. Thanks.

Thank you too, UnknownVT, for the links.


Last edited by ursamajor; 01-11-2011 at 12:45 AM.
01-12-2011, 07:32 AM   #9
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OK, my choice is... K-r white! Oops, I'll be a pentaxian.
I've allready ordered it! 603 euros.

Last edited by ursamajor; 01-12-2011 at 12:17 PM.
01-13-2011, 08:03 AM   #10
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QuoteOriginally posted by Hypocorism Quote
- To me, probably the major drawback of K-x, and sadly now K-r too, is their basic lack of a PC type port! That limits the otherwise decent-performing affordable camera models from much useful expansibility for use in "non standard" work such as astro, macro, etc. Grrr....
Does the PC port serve some other purpose that I'm not aware of? It's only to fire an external flash, right? In which case you can get a hotshoe to PC adapter for $11 from FlashZebra.
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