Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-27-2010, 11:20 AM   #1
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Pentax DA 16-45 Focus issue and poor overall quality

I have bought a DA 16-45 lens and would appreciate your comments.

My K20D kit lens was the 18-55 II. It was faulty and was replaced but I have never been happy with the edge performance, so I bought a second hand DA*16-50mm. This got damaged in the post and has caused me 3 months of hassle. I had an issue with this lens too that it would not focus at infinity at wide angle and the focus light would therefore just flash. Prior to today I had thought this was SDM related and could not happen on a screw-drive lens.

Seeing a DA16-45 second hand and knowing that it is highly regarded, I bought it and today tried it out. I am very disappointed. It won't focus at infinity at anything under 20mm on my K20D. It just makes a slight whirr as it tries to focus. Moving the quick shift ring makes no difference and I can only take a photo on Manual! Anyone else had this on screw-drive?

The image quality too seems very poor. I have posted three unsharpened highest quality JPEGs here taken with a tripod and no SR and I would appreciate feedback.

Centre - seems OK to me. Focus was on the distant buildings. Manual focus as Auto Focus was impossible.


Left very poor CA around white pillars. Metal lamp post has purple fringe.


Right looks very poor to me. It is the same distance as the main focus point.


The image in total appears here...
http://i816.photobucket.com/albums/zz88/tigershoot/IMGP6140.jpg

02-27-2010, 11:31 AM   #2
Pentaxian
Swift1's Avatar

Join Date: Sep 2009
Location: Oregon
Photos: Gallery | Albums
Posts: 3,921
I had a 16-45 with the same problems. I had to send it in to get repaired and the repair tech removed 2 shims from behind the mount. Works perfect now. Cost $100 though.

With the K20 you may be able to adjust focus to correct it. I don't have a K20 so I don't know.

If you are able to return it to the seller you may want to. It is a great lens and well worth the going rate but if you get a bad copy it's not worth the repair costs.


Swift1
02-27-2010, 11:51 AM   #3
Pentaxian
Mike.P's Avatar

Join Date: Mar 2008
Location: South Coast .. UK
Photos: Gallery
Posts: 1,737
WOW .. thats weird.

Is that La Marina?

BTW .. my 16-45mm is nothing like that, Santa Pola harbour.



La Marina Beach.


Last edited by Mike.P; 02-27-2010 at 11:57 AM.
02-27-2010, 12:09 PM   #4
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Original Poster
It is La Marina. I wish I could say it's La Marina in pin sharp focus but it seems like it was take during one of our frequent earth tremors!

02-27-2010, 12:11 PM   #5
Pentaxian
Mike.P's Avatar

Join Date: Mar 2008
Location: South Coast .. UK
Photos: Gallery
Posts: 1,737
Ah, we have a house just up the road from where you took the pics.
Was coming out in a couple of weeks but we had to cancel otherwise you could have tried mine.
02-27-2010, 12:17 PM   #6
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Original Poster
Have you not just sold yours to someone in Switzerland - or did you have two? I got mine via the UK forum Classifieds.
02-27-2010, 12:18 PM   #7
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Henry, TN
Photos: Gallery | Albums
Posts: 2,878
Seems time to look into a focusing issue with the body rather than multiple lenses.

H2
02-27-2010, 12:25 PM   #8
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Original Poster
I cleaned the contacts in case they were causing an issue. My brother has a DA16-45 and I used this only a week ago with no problem. I use/have used on this body a DA55-300, DA50-200, two different 18-55 IIs and a Sigma 10-20 all with no focussing issues. It's only happened on the DA*16-50 and this DA16-45mm.

02-27-2010, 12:26 PM   #9
Pentaxian
Mike.P's Avatar

Join Date: Mar 2008
Location: South Coast .. UK
Photos: Gallery
Posts: 1,737
QuoteOriginally posted by tigershoot Quote
Have you not just sold yours to someone in Switzerland - or did you have two? I got mine via the UK forum Classifieds.
I had 2
02-27-2010, 01:35 PM   #10
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by tigershoot Quote
Seeing a DA16-45 second hand and knowing that it is highly regarded, I bought it and today tried it out. I am very disappointed. It won't focus at infinity at anything under 20mm on my K20D.
I'm confused. Won't focus at infinity, or won't focus at 20mm? the later is *way* shorter than the minimum focus distance; of course it won't focus that close. Not sure what that has to do with infinity, though.

QuoteQuote:
The image quality too seems very poor. I have posted three unsharpened highest quality JPEGs here taken with a tripod and no SR and I would appreciate feedback.
Did you use the 2-second timer? Looks like a bit of shake in there, presumably from the mirror slap. Also, did you use a hood? Have a filter mounted? No and yes answers respectively could be contributing factors.

QuoteQuote:
Right looks very poor to me. It is the same distance as the main focus point.
In which case, there's no particular reason to expect it to be in focus. I doubt the focus field on this lens is *that* curved. EXIF is mostly gone, and I didn't see if you said what aperture you used, but if it's wide open or close to it, DOF as well as inherent edge softness could be limiting you more than you think.

Since you say you focused manually, no point worrying about checking AF calibration. Although I would wonder just how good a job you did. Also, at distances as great as this, I'd expect atmospheric humidity and haze to take a toll on contrast and sharpness.

All of which to say, while the image here is understandably disappointing, it's a bit hard to pin down what might be going on, because actually, there's quite a few things I see here that could be combining none of which have anything to do with the lens' sharpness per se. You'd want to do some better controlled tests.
02-27-2010, 03:02 PM   #11
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Original Poster
Hi Marc

When I am talking about 20mm I mean the focal length. Under 20mm the lens just won't focus at infinity.

The shot is at F8 at 250th/sec. There is no camera shake as otherwise the centre would be blurred too. 250th at this focal length on a tripod is easliy fast enough. Mirror slap would affect the centre as much as the edge too.

I had a brand new Multi Coated UV filter on and the light was behind the camera front element. The link to the full size image can be ignored as it seems that on my account you cannot zoom in anyway. This was taken today and it was very clear.

Thanks for your input.

Last edited by tigershoot; 02-27-2010 at 03:09 PM.
02-27-2010, 03:18 PM   #12
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by tigershoot Quote
When I am talking about 20mm I mean the focal length.
Ah, I should have figured that out. Sorry. Hmm, quite odd - but definitely sounds like a defect.

QuoteQuote:
The shot is at F8 at 250th/sec. There is no camera shake as otherwise the centre would be blurred too.
Well, I think there is - that was my point. Unless the CA on the center crop is just making me *perceive* it as camera shake.

QuoteQuote:
I had a brand new Multi Coated UV filter on
OK, that accounts for some of the softness compared to what the lens is capable of, then. As does the (assumed) lack of hood - even if the direct light source is behind you, there is a ton of reflected light in a scene like this. Try it without the filter but with a hood, and using the 2-second timer.

QuoteQuote:
This was taken today and it was very clear.
Unless you live on the moon, atmosphere always affects the image at long distance. Whether or not you can see haze, there is always some particulate matter as well as humidity - both of which can affect contrast and sharpness.
02-27-2010, 03:21 PM   #13
Junior Member




Join Date: Dec 2008
Location: Alicante
Posts: 37
Original Poster
Just to confirm. It did have a hood on. My manual focus technique is to focus until I see roof tiles in the distance start to shimmer with a sort of moire effect. It works fine this way with my manual lenses. I am surprised a new filter would affect image quality - I find this disturbing.
02-28-2010, 03:09 AM   #14
Pentaxian
Mike.P's Avatar

Join Date: Mar 2008
Location: South Coast .. UK
Photos: Gallery
Posts: 1,737
QuoteOriginally posted by tigershoot Quote
am surprised a new filter would affect image quality - I find this disturbing.
Unless its a very high quality filter on there (Hoya pro) I wouldnt use it.
I have them on my lenses but they come off when I shoot.
03-01-2010, 10:18 AM   #15
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
QuoteOriginally posted by tigershoot Quote
I am surprised a new filter would affect image quality - I find this disturbing.
You're putting an extra piece of glass in front of a well-designed lens. Of course it's going to affect IQ. Filters should be used when you need the specific effect they create - polarizing, ND, etc - but you pay for that in some degradation. How much depends on how well-designed the filter is - the more expensive the better, in general. Since there doesn't appear to be any need for an special effects, you basically got nothing in return for the degradation.
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!
focus, focus issue, hand, image, issue, k-mount, lens, pentax da, pentax lens, quality, screw-drive, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Poor upload Image Quality TGregory Site Suggestions and Help 13 11-09-2011 10:09 PM
K-x shake - camera issue or poor technique? Edwin13 Pentax DSLR Discussion 23 05-21-2010 01:07 AM
Help...Very Poor Video Quality JesseY Video and Pentax HDSLRs 5 12-20-2009 12:08 PM
Poor Quality Photographs elvis35to05 Photographic Technique 11 01-02-2009 10:12 AM
Poor Build Quality of Pentax 540-fgz rsi1986 Pentax Camera and Field Accessories 32 12-07-2008 01:46 PM



All times are GMT -7. The time now is 07:08 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