Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-28-2013, 12:31 PM   #1
Veteran Member




Join Date: Jan 2010
Location: Durham, nc
Photos: Albums
Posts: 887
K-30 and Tamron 28-75/2.8

So I've been playing around with my K-30 with my Tamron 28-75 f/2.8. I love this lens, but it was unusable on my K-x because of the front focus issues. I've been using it almost exclusively on my K-01, until now. With the arrival of the K-30, I was able to adjust the focus on a per-lens basis. It's still not perfect, but it's better.

I first adjusted the focus so that at 75mm a nearish subject was correctly focused. I used a focusing chart and bright daylight, and it took -10 to adjust out the majority of the front focus.

Then I tried the same tests at 28mm, and it turned out that I needed -5 for 28mm at the same range. Although, 28mm was more forgiving, at -10 it was only slightly back-focused.

Neither of these, however, were the correct setting. I say this, because at -5 or -10, the camera would not focus to infinity at 75mm. I took 5 photos (with a target two miles away) at each adjustment setting and at both 28mm and 75mm. Ignoring the front/back focus for close objects and concentrating on infinity is the only way to properly adjust this lens, it seems. It took -7, and that's nicely between the -5 and -10 that the extremes need for close distances too.

It's not perfect, Live View still gets a sharper image, but it's the closest I can get with this lens and CDAF. So, this lens will likely always reside on my K-01. It's unfortunate too, because it would make a great lens for shooting stage productions and ballroom dance events, if it weren't for the focus issues. I get much better results cranking the ISO and shooting stage events with my Promaster AF 100mm f3.5 Macro, or getting in closer and using my FA50-1.7

Still, the lens is at least usable on the K-30 now. Not reliably so, but usable. Still want to snag a Tokina ATX Pro and see if that does any better...

Charles.

10-28-2013, 12:39 PM   #2
Veteran Member
Andi Lo's Avatar

Join Date: Jul 2008
Location: Halifax, Nova Scotia
Posts: 2,925
When I had this lens it has minimal FF/BF issues and I dont think the issue made it unusable. However it might be because I chose to prioritize the 75mm setting. At 28mm, normal shooting distances you'd still get a fair bit more DOF than at 75mm. It's less likely that you'll shoot it at 28mm up close than 75mm.

Was it perfect? I'm not sure, but my results was sharp at 2.8 in most conditions, that's all I need to know.

Or I might have gotten a better sample, I'm not sure.

My current Nikon copy seems the same, a bit off at certain distances when peeped, but when used normally the IQ is still extremely good and is my most used zoom lens, just like it was in pentax.
10-28-2013, 01:24 PM   #3
Veteran Member




Join Date: Jan 2010
Location: Durham, nc
Photos: Albums
Posts: 887
Original Poster
Mine has been unusable on the K-x, with no lens adjustment. It's completely usable in LiveView, and now that I own a K-30, it's mostly usable. It still struggles with distant subjects in dim lighting -- often misfocusing with CDAF, but correctly focusing in live view. (Which is odd as hell).

I'd like to say it's my backup lens, on my backup body (K-01), but honestly, it's my most-used lens on my most-used body. The K-30 is a wonderful camera, but I find myself using the K-01 with this Tamron much, much more.

Charles.
10-28-2013, 02:42 PM   #4
Veteran Member




Join Date: May 2012
Posts: 698
QuoteOriginally posted by ChopperCharles Quote
Mine has been unusable on the K-x, with no lens adjustment. It's completely usable in LiveView, and now that I own a K-30, it's mostly usable. It still struggles with distant subjects in dim lighting -- often misfocusing with CDAF, but correctly focusing in live view. (Which is odd as hell).

I'd like to say it's my backup lens, on my backup body (K-01), but honestly, it's my most-used lens on my most-used body. The K-30 is a wonderful camera, but I find myself using the K-01 with this Tamron much, much more.

Charles.
What do you gain by using the K-01 instead of the K-30? I would think the K-30 in live view should behave exactly the same as the K-01, so using it in live view should be just as good as using the K-01. The K-01 is after all just a K-30 with the viewfinder and PDAF removed. Or am I missing something?

10-28-2013, 06:13 PM   #5
Veteran Member




Join Date: Jan 2010
Location: Durham, nc
Photos: Albums
Posts: 887
Original Poster
The K-01 I use more because I find it more enjoyable to use. I just feel more creative with it in my hands, and because of it's smaller size I tend to take it with me more often. The feel of the camera and the menu options are all completely intuitive to me, and I seem to take better pictures with it. I enjoy working around its limitations.

I actually think I enjoy my K-x more than my K-30. It too has a better feel, from menu options to size and heft and button placement. But I'm delving more and more into astro photography, and a K-30 and GPS unit (for star tracker functionality) is about the same price as a quality motorized equatorial mount, but with the added benefit of weather sealing, front/back focus adjustment for my other lenses, a better sensor, and WAY better live view. On paper it makes sense that it's the better camera. In my hands, I find I don't feel as creative. I feel like I'm posing as a "real" photographer by using such an advanced sexy camera, and that i have to justify it by taking awesome pictures. Which inevitably means I don't. At all. but with the K-01, I don't care. It's a fun camera, and nobody takes me seriously when I use it -- least of all me -- which means I get better photographs of people, and just generally enjoy myself more. It's less intimidating to other people, and less intimidating to me too

Charles.
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!
28mm, 75mm, events, focus, infinity, k-01, k-30, k-50, lens, pentax k30, pentax k50, stage
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-30 + Tamron 28-75, focus seems off ChooseAName Troubleshooting and Beginner Help 11 07-09-2014 06:04 AM
For Sale - Sold: Tamron 28-75/2.8 AndrewShirley Sold Items 2 04-15-2012 09:32 AM
For Sale - Sold: Tamron SP AF 28-75 mm f/2.8 and Tamron 90 mm f/2.8 macro lens Vantage-Point Sold Items 5 03-22-2012 03:35 PM
K-r and Tamron AF 28-75 f2.8 lens LSUDAN Pentax K-r 2 12-03-2011 12:03 AM



All times are GMT -7. The time now is 11:35 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