Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-18-2014, 09:27 AM   #1
Site Supporter




Join Date: Oct 2013
Photos: Gallery | Albums
Posts: 259
need a better lense

When I purchased this K-30 I bought it with a tameron 70-300 which i returned due to horrible purple fringe. I replaced it with the sigma 70-300 apo-dg macro, which proved to perform much better. However it certainly could be sharper. Granted this was a budget lens I realize this. I would like to buy a fully compatible Pentax lens for this camera, as I would expect to get better results. I shoot mostly nature photography, and quite often, even though what i see in the viewfinder is very sharp, what comes out on the sensor is not, especially when checked at 100-200%.

Can anyone suggest a Pentax zoom, with similar reach that could be sharper for say $1000.oo.

I know thats asking a lot for the price
I have considerd that possibly the sensor in the camera may be miss adjusted, due to the viewfinder being sharp and the images not. but then what one sees in the viewfinder is so small it's hard to tell.

I would certainly love to step up the quality of my shots.

Thanks to all.

DeWolf

01-18-2014, 09:41 AM   #2
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Oregon
Photos: Gallery | Albums
Posts: 10,286
At that price range look at the DA*60-250

There is also a Sigma 100-300 f/4 which gets good reviews but I have no experience with it myself.
01-18-2014, 09:41 AM   #3
Site Supporter
boriscleto's Avatar

Join Date: Dec 2009
Location: Liverpool, NY
Photos: Gallery
Posts: 12,290
The DA 55-300 is well below your budget, the DA* 60-250 might be available used for around $1000.

Another possibility is the FA* 80-200/2.8. There is one on eBay right now at $1089 BiN.
01-18-2014, 10:08 AM   #4
Pentaxian




Join Date: Apr 2007
Location: Oklahoma USA
Posts: 1,475
I don't have the Tamron or Sigma, but in general the Tamron seems to have a good reputation for being sharp, but with purple fringing on the long end particularly, while the Sigma seems to be known for being a little soft at the longer lengths. Basically longer lengths are a challenge for almost all lens designs.

I will say that you're expecting a lot because of 16mp - especially at 200%! Realistically if most of us had examined our 35mm film to the same degree back in the day, most of those classic SMCT primes wouldn't have looked so great either. My 55-300s (all 5 of them, where they're not defective) look better at 100% on 10mp than on 16, and I'm betting they would have been spectacular on my K100. Nobody (well, almost) shot 500 resolution test images on kodachrome like I've done with the 55-300s on my dslrs.

My suggestion is to look at your images very, very carefully for consistency across the frame at every focal length and focusing distance - obviously expect stronger results in the center than the edges, but look for consistency in the corners and edges. If you've got that, understand that you might need to buy a lot more copies of another model before you find it again.

Also, it might be too late if you've sent it back, but consider using software, possibly a couple of different packages, to compensate for the Tamron purple fringing, and then look at the net results vs. the Sigma. Sure, it's annoying to have to use software to fix that, and it's not just plain fair that you can't buy the new and improved Tamron 70-300 in Pentax mount (ugh.) But unless you get a Nikon you're going to be stuck with that situation more often than you'd like. I'd say Canon too, but I'm still miffed over the FD situation, and I can't stand that whole smaller-than APS thing they've got going :-)


Last edited by tibbitts; 01-18-2014 at 10:39 AM.
01-18-2014, 10:29 AM   #5
Veteran Member




Join Date: Jul 2009
Location: London
Posts: 856
The DA* 300? Not a zoom of course, but I would have thought ideal for nature photography, not least because it's WR.
01-18-2014, 11:24 AM   #6
dms
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 1,550
With your lens at the closest focusing distance and wide open manual focus (MF) on a ruler angled in front of the lens. Is the number you focused on sharper than those closer or farther away? If not the shims for the screen are likely wrong/send out for Pentax service. If yes then use the lens in manual focus on a scene (best on a tripod and stopped down about 3 stops) and check the sharpness. That will tell you what the lens can do! And then do comparison of AF and MF. The AF may need adjusting. If you get a $1000 lens and the focus is way off it will be little/no better than a $200 lens.
01-18-2014, 11:47 AM   #7
Site Supporter




Join Date: Oct 2013
Photos: Gallery | Albums
Posts: 259
Original Poster
QuoteOriginally posted by jatrax Quote
At that price range look at the DA*60-250

There is also a Sigma 100-300 f/4 which gets good reviews but I have no experience with it myself.
read the reviews on the DA*60-250, and certainly seems like the best option for me. Question is, will the internal motor work on the K-30, or will it revert to the cameras focus motor?

DeWolf
01-18-2014, 11:54 AM   #8
Site Supporter




Join Date: Oct 2013
Photos: Gallery | Albums
Posts: 259
Original Poster
QuoteOriginally posted by dms Quote
With your lens at the closest focusing distance and wide open manual focus (MF) on a ruler angled in front of the lens. Is the number you focused on sharper than those closer or farther away? If not the shims for the screen are likely wrong/send out for Pentax service. If yes then use the lens in manual focus on a scene (best on a tripod and stopped down about 3 stops) and check the sharpness. That will tell you what the lens can do! And then do comparison of AF and MF. The AF may need adjusting. If you get a $1000 lens and the focus is way off it will be little/no better than a $200 lens.
tried that in the beginning. the number i focus on is sharper than the rest, but its not sharp. I have warranty time left and may send it in for a going over.
As far as 200% pixel peeping, I have considered, after a LOT more practice, marketing through online stock photo sites. Who I have been told check photos at 200%. Granted this venture is more of a passing thought than a serious reality, but I thought it best for me to get the best I can afford, providing the camera or the operator are not the ones at fault
So yes, I will have to rule those out completely, and possibly send the camera in.

DeWolf

01-18-2014, 12:07 PM   #9
Site Supporter




Join Date: Feb 2011
Posts: 4,892
QuoteOriginally posted by dewolf Quote
When I purchased this K-30 I bought it with a tameron 70-300 which i returned due to horrible purple fringe. I replaced it with the sigma 70-300 apo-dg macro, which proved to perform much better. However it certainly could be sharper. Granted this was a budget lens I realize this. I would like to buy a fully compatible Pentax lens for this camera, as I would expect to get better results. I shoot mostly nature photography, and quite often, even though what i see in the viewfinder is very sharp, what comes out on the sensor is not, especially when checked at 100-200%.

Can anyone suggest a Pentax zoom, with similar reach that could be sharper for say $1000.oo.

I know thats asking a lot for the price
I have considerd that possibly the sensor in the camera may be miss adjusted, due to the viewfinder being sharp and the images not. but then what one sees in the viewfinder is so small it's hard to tell.

I would certainly love to step up the quality of my shots.

Thanks to all.

DeWolf

The Pentax 55-300 is better than the Sigma.

I like the Tamron 70-200 the best out of the 70-200 options, and it's within your $1k budget, but at 300mm the Pentax 55-300 will do better than the Tamron cropped (assuming you have enough light to shoot at F/8, etc).

The 60-250 is nice but above your budget. I like the DA*300 even better than the 60-250 but it's also above your budget.
01-18-2014, 12:11 PM   #10
dms
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 1,550
Looking at other photo's on the net at 200%, or in general seems pointless.

As money is not very limiting, get an inexpensive to moderate cost very sharp lens so you know what the camera is capable of!

50mm moderately fast lenses are generally very sharp. I usually suggest a used Pentax 50mm f/1.7 m lens. About $50 from KEH for example. Or get a new 50mm Pentax lens.

Then you will now what an optimum lens can do. Zooms by their nature cannot be as sharp as a really sharp prime lens.
01-18-2014, 12:25 PM   #11
Pentaxian




Join Date: Apr 2007
Location: Oklahoma USA
Posts: 1,475
QuoteOriginally posted by dewolf Quote
tried that in the beginning. the number i focus on is sharper than the rest, but its not sharp. I have warranty time left and may send it in for a going over.
As far as 200% pixel peeping, I have considered, after a LOT more practice, marketing through online stock photo sites. Who I have been told check photos at 200%. Granted this venture is more of a passing thought than a serious reality, but I thought it best for me to get the best I can afford, providing the camera or the operator are not the ones at fault
So yes, I will have to rule those out completely, and possibly send the camera in.

DeWolf
I'm not sold on the ruler thing, because it assumes that any focus deviation will be consistent between very close distances and infinity. Not all lenses behave that way - they might need a -10 adjustment at one focus or focal length setting, and +5 at another.

I've never heard about this 200% criteria, but before you act on that, you should investigate it further. There aren't a lot of lenses that are going to look sharp at 200% on 36mp, no matter what you pay for them, and if agencies rejected pictures based on that, they wouldn't be accepting a lot of images. It doesn't make sense to me that they would check a 36mp FF sensor at 200% and also check a 12mp APS sensor at 200%.

You might want to post crop examples here of what you consider "not sharp."
01-18-2014, 12:36 PM   #12
dms
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 1,550
There are other considerations such as focus shift--but most importantly you need to know what you see in focus on the screen is in focus!

Using the ruler only tests the correctness of the screen shimming. Once that's good you do the next step. But if you cannot rely on the manual focus you have lost the primary/best focusing method to use as a standard to compare AF to. (Yes you also have live view but that is not generally useful when taking a shot.)
01-18-2014, 03:04 PM   #13
Site Supporter




Join Date: Oct 2013
Photos: Gallery | Albums
Posts: 259
Original Poster
QuoteOriginally posted by dms Quote
There are other considerations such as focus shift--but most importantly you need to know what you see in focus on the screen is in focus!

Using the ruler only tests the correctness of the screen shimming. Once that's good you do the next step. But if you cannot rely on the manual focus you have lost the primary/best focusing method to use as a standard to compare AF to. (Yes you also have live view but that is not generally useful when taking a shot.)
by screen I am assuming you mean viewfinder. But shimming?
Did some research on focus shift in ref to stops, and will do some tests with that tomorrow when I have light again.

DeWolf
01-18-2014, 03:57 PM   #14
Site Supporter




Join Date: Oct 2013
Photos: Gallery | Albums
Posts: 259
Original Poster
using a high intensity lamp I shot the following.

240mm F5.6 manual focus,
240mm F8 manual focus
240mm F8 auto focus
100% crops
is this helpfull

DeWolf

Last edited by dewolf; 06-01-2016 at 08:10 PM.
01-18-2014, 05:55 PM   #15
dms
Site Supporter




Join Date: Aug 2011
Location: New York, NY
Photos: Gallery
Posts: 1,550
Yes shimming, The viewfinder should show the same focus as what the screen "sees." To do that the screen is adjusted till they are within spec.

Moving the sensor forward or backward (which Contax I believe tried for AF) is not easy/viable, nor is moving the mirror relative to the prism, so the screen is shifted by shims. But there is some tolerance, and it may be off. That's what I argue is the first/most basic thing to check. And then go to the AF from there.
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!
btw, camera, dog, filters, hood, image, iso, k-mount, lens, noise, pentax, pentax lens, quality, sensor, shots, slr lens, thanks, time, viewfinder
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
finding a better lense than Sigma AF 100-300mm f/4 EX DG HSM APO NSX167 Pentax SLR Lens Discussion 12 12-07-2012 03:31 PM
Need a new lense for portraits mmeckel Pentax SLR Lens Discussion 60 04-10-2012 07:10 PM
Need help finding a lense dndcdr Pentax SLR Lens Discussion 13 12-18-2011 03:48 PM
Need help picking a wide angle lense Moggman Pentax SLR Lens Discussion 21 03-14-2008 06:16 PM



All times are GMT -7. The time now is 01:54 PM. | See also: NikonForums.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