Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-07-2008, 05:36 PM   #1
Veteran Member
vievetrick's Avatar

Join Date: Sep 2006
Location: Easthampton - Massachusetts - USA
Photos: Gallery
Posts: 5,175
Does K20 (high ISO)+ F4 lens = no need for 2.8

Just thinking today about something and wanted some input from K20 users. I do not have a K20 or a DA,FA,F 300 F/4 but I started wondering. For sports action we always talk about having big glass. I have a Sigma 70-200 2.8 and love it. I wonder with the bodies improving noise results in high iso's will it matter if I have the 2.8? Will I be able to get away with the F/4 while shooting at say ISO 800-1600-3200 or better? Maybe wishful thinking but any K20 users willing to try an experiment? Take some sports shots in a gym on the field (in low less the great light) at F/4 with the hight ISO.

04-07-2008, 05:42 PM   #2
Veteran Member




Join Date: Feb 2008
Location: Toronto
Posts: 3,915
i don't have a K20D, but there's no replacement for fast glass
04-07-2008, 05:53 PM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,401
Note that high ISO and image capability are only 1/2 the equation, what about low light shots.

Faster glass equals better focusing performance, and the abilility to add a TC to get length when needed.

It will never be relplaced by High ISO, and note, high ISO quality is a very fickle thing. what was good on the *istD 4+ years ago is now deemed unacceptable.

Soon everyone will scream for ISO100 quality shots from ISO6400, and then you will be back in the same point about asking for faster glass.

I view high ISO as a work around solution to a problem, and also a somewhat artistic medium. It is not preferred, but what must be to get the shot
04-07-2008, 05:56 PM   #4
Pentaxian
Arpe's Avatar

Join Date: Sep 2006
Location: New Zealand
Photos: Gallery | Albums
Posts: 4,346
Have a look here for some I've posted here. Rugby in the rain with the 70-200/2.8 plus 1.4x TC. Exif all there. I can have a dig around for some higher ISO ones if you want, those 3 only go up to 1100.

Using my istDs I have taken them at ISO 3200 at the end of a dark wet day, and I have one of my favourites from it. So i guess the K20D will be even better!

04-07-2008, 06:01 PM   #5
Veteran Member




Join Date: Mar 2007
Location: Boston, PRofMA
Photos: Albums
Posts: 3,053
With dSLRs, smaller f stops also = better DOF...
I'm still having problems adjusting after using P&S cams for so long where f/2.8 has nearly everything in focus. I used SLRs before the P&S but that was too long ago :-)
04-08-2008, 08:23 AM   #6
RaduA
Guest




QuoteOriginally posted by vievetrick Quote
Just thinking today about something and wanted some input from K20 users. I do not have a K20 or a DA,FA,F 300 F/4 but I started wondering. For sports action we always talk about having big glass. I have a Sigma 70-200 2.8 and love it. I wonder with the bodies improving noise results in high iso's will it matter if I have the 2.8? Will I be able to get away with the F/4 while shooting at say ISO 800-1600-3200 or better? Maybe wishful thinking but any K20 users willing to try an experiment? Take some sports shots in a gym on the field (in low less the great light) at F/4 with the hight ISO.
Hi, Vievetrick!

I have the K20D and FA 50/f1.4 and I always prefer working the aperture down rather than ISO value up. Sure it depends on what you want to do and like Kenyee said before me DOF is an important aspect. But what I just have to tell you is that K20D + decent lens has at ISO 100-400 an enormous level of detail and no noise what so ever. So for me the ideal combination is to keep the ISO under 400 and the f value between 2,8-5,6 to "sharpen" up the lens a bit. Even at f2 and bellow you can use the center portion and crop from the margins with good results for portraits. Otherwise you could do more than decent shots at ISO 800-1600 (especially if you don't print very large formats). It all boils down to what you expect from that particular shot.

Radu
04-08-2008, 10:05 AM   #7
Veteran Member
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by vievetrick Quote
but any K20 users willing to try an experiment?
There are trillions of ISO comparisons out there, including my own...

My own experience is that the K20D is about 1/3 stop better in noise than the *istDS if one prints out images to the same size. After all, the new sensor cannot use more light as it isn't bigger. So even after 4 years, the *istDS noise performance is still ok.
04-08-2008, 02:36 PM   #8
D W
Veteran Member




Join Date: Mar 2008
Location: Hogtown, ON, Canada
Posts: 329
There are always situation when one ponders: If I only had an extra 50mm longer or 1mm wider or 1 stop faster.

04-08-2008, 03:56 PM   #9
Veteran Member
Miserere's Avatar

Join Date: Sep 2007
Location: Boston
Photos: Gallery
Posts: 1,994
QuoteOriginally posted by D W Quote
There are always situation when one ponders: If I only had an extra 50mm longer or 1mm wider or 1 stop faster.
I've had many a girl say that to me. Such is Life...
04-08-2008, 04:00 PM   #10
Veteran Member




Join Date: Feb 2008
Location: Chicagoland
Posts: 338
I don't think f4 + high iso will ever really be a replacement for fast glass. No matter how smooth your sensor is a high iso, there are things that just can't be replicated without the large aperture.
04-08-2008, 04:20 PM   #11
Veteran Member
aegisphan's Avatar

Join Date: Nov 2007
Location: New Mexico
Posts: 815
QuoteOriginally posted by Miserere Quote
I've had many a girl say that to me. Such is Life...
, definitely not 1 stop faster.
04-08-2008, 05:39 PM   #12
Pentaxian
Arpe's Avatar

Join Date: Sep 2006
Location: New Zealand
Photos: Gallery | Albums
Posts: 4,346
The problem with f2.8 is of course the narrow DOF. If you're focus is a tad off then there goes the picture. F4 I suppose gives you a little bit more leeway.
04-08-2008, 06:41 PM   #13
Veteran Member
vievetrick's Avatar

Join Date: Sep 2006
Location: Easthampton - Massachusetts - USA
Photos: Gallery
Posts: 5,175
Original Poster
QuoteOriginally posted by falconeye Quote
There are trillions of ISO comparisons out there, including my own...

My own experience is that the K20D is about 1/3 stop better in noise than the *istDS if one prints out images to the same size. After all, the new sensor cannot use more light as it isn't bigger. So even after 4 years, the *istDS noise performance is still ok.

I think you are correct in one way or another. I guess it was wishfull thinking. I have to laugh though at your comment Falconeye " A trillion" come one I already spent to much time on the internet a trillion pictures could take awhile to review
04-09-2008, 03:13 AM   #14
Veteran Member
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,863
QuoteOriginally posted by vievetrick Quote
I have to laugh though at your comment Falconeye " A trillion" come one I already spent to much time on the internet a trillion pictures could take awhile to review
I may have skipped some numbers while counting...

There are many, esp. in my German forum where the "photo engineers" have tested and argued K20D noise from every possible angle. Looks like K20D comes out slightly better than *istDS/K100D and those slightly better than K10D. It is actually hard to determine because noise reduction is always different and noise can always be traded for detail. So, an MTF-based noise measure would be required to know for sure.


As for 2.8 vs. 4.0 ... it is just one stop and 1/2 stop better noise plus possibly 1/2 stop better SR could do the trick.

On the other side, as others have said here: bigger is always better

My personal sweet spot is a diameter of 75mm for any length. More doesn't fit anymore.
04-10-2008, 12:47 AM   #15
axl
Inactive Account




Join Date: Mar 2007
Location: Nove Zamky, Slovakia
Photos: Gallery | Albums
Posts: 7,181
One thing that will stay always different is DOF. f4 will never be f2.8 ...
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!
f/4, iso, k-mount, k20, pentax lens, slr lens, sports, users
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lens implications of high ISO bodies? Nass Photographic Technique 11 09-16-2010 01:47 PM
K-7 high ISO vs K20D high ISO supa007 Pentax DSLR Discussion 72 05-10-2010 04:24 PM
High iso jpgs GX20 (k20) 1600-6400 burnie Pentax DSLR Discussion 3 01-17-2010 12:39 PM
K20 high iso opinions!! COULDBE2 Pentax DSLR Discussion 4 07-03-2009 04:39 AM
High ISO quality of K20 lol101 Pentax News and Rumors 56 02-07-2008 03:44 PM



All times are GMT -7. The time now is 12:29 AM. | 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