All Forum Comments
Comment by johnwhit posted on Woodpecker Chick at 25/05/2010 - 07:20
chris_jl wrote:
There are number of online guides to help you find the focus points and you will inevitably find people who criticize them as inaccurate for various reasons (valid and invalid). I've found http://www.zimbio.com/Digital+Cameras/articles/839/AF+adjustment+test+chart+help+Pentax+K20D helps.
I'm sorry if that isn't an amazing amount of help, but I hope it gets you started.
C
This one is very good and involves a little less construction, tripod required:giofi wrote:
I have read a lot about lenses needing focus adjustment, so I am wondering whether I should adjust focus with my K20D. Is there an easy way to determine whether a lens is front/back focusing? Is there a database of adjustments needed with Pentax lenses or are individual cameras different?
Thanks for any advice you can give me!
Giorgio
I can only say from personal experience that each are different. As far as I remember the scale is an adjustment in microns (back and forth) of the focus mechanism. I've found it varies by lens, by body and with focus distance and, for zoom lenses, with zoom. Thankfully the K20D has a memory for several lens adjustments. Also I've found it exceptionally difficult to adjust accurately for lenses with focal length less than about 28mm (any hints gratefully accepted).I have read a lot about lenses needing focus adjustment, so I am wondering whether I should adjust focus with my K20D. Is there an easy way to determine whether a lens is front/back focusing? Is there a database of adjustments needed with Pentax lenses or are individual cameras different?
Thanks for any advice you can give me!
Giorgio
There are number of online guides to help you find the focus points and you will inevitably find people who criticize them as inaccurate for various reasons (valid and invalid). I've found http://www.zimbio.com/Digital+Cameras/articles/839/AF+adjustment+test+chart+help+Pentax+K20D helps.
I'm sorry if that isn't an amazing amount of help, but I hope it gets you started.
C
http://focustestchart.com/chart.html
If you're checking a zoom lens, either go for the mid point or the most used focal length.
Hope this helps,
John
Comment by johnwhit posted on Focus adjustment on K20D at 25/05/2010 - 07:13
lol
Comment by johnwhit posted on Macro with the Bigma at 25/05/2010 - 06:51
Excellent work, I was using the DA*300 yesterday despite having a Tamron 90mm in the bag, it just wouldn't have the reach. Came away with a few keepers including this one posted earlier:
https://www.pentaxuser.com/photo/four-spotted-chaser-17638/large
Regards,
John
https://www.pentaxuser.com/photo/four-spotted-chaser-17638/large
Regards,
John
Comment by johnwhit posted on Macro with the Bigma at 24/05/2010 - 22:10
Mike-P wrote:
Sigma 70mm macro .. lovely lens, sharp as can be and my most used macro.
That was on my short list when I sold the 105mm EX but I already decided on the DA-70/2.4 Ltd at that length, the Tamrom 90mm filled the gap nicely between the DA-70 & FA-135/2.8. I'd love a DA-15/4 to complete my prime kit but at £600.... well it will have to waitSigma 70mm macro .. lovely lens, sharp as can be and my most used macro.
John
Comment by johnwhit posted on Macro lenses at 24/05/2010 - 17:16
mikew wrote:
I regard any distortion at 10mm to be part of the character of the lens. 10 mm is really quite wide for digital.
Yes, if it shows I sometimes crop a little, or just shoot at 12mm where it's virtually distortion free, it's never really showed in most of the lanscape shots I take, just architecture and the like. Good to here Adobe supporting Sigma lenses as wellI regard any distortion at 10mm to be part of the character of the lens. 10 mm is really quite wide for digital.
Regards,
John
Comment by johnwhit posted on Wide angle lens distortion at 24/05/2010 - 16:10
I believe PS CS5 has a new feature for doing exactly this, but what lenses are supported I don't know. Support for Pentax lenses?!
John
John
Comment by johnwhit posted on Wide angle lens distortion at 24/05/2010 - 15:44
Hi rob,
At that price I'd be tempted too if I only wanted the lens for Macro, it's just that I use mine as a short telephoto from time to time, so it's very much a personal choice.
Regards,
John
At that price I'd be tempted too if I only wanted the lens for Macro, it's just that I use mine as a short telephoto from time to time, so it's very much a personal choice.
Regards,
John
Comment by johnwhit posted on Macro lenses at 24/05/2010 - 15:40
Hi Rob
I prefer the Tamron to the Sigma, I've owned both, it's just a personal preference regarding OoF rendering. I prefer the build of the old FA to the DFA and the DFA has no focus limiter which puts me off it somewhat.
Regards,
John
I prefer the Tamron to the Sigma, I've owned both, it's just a personal preference regarding OoF rendering. I prefer the build of the old FA to the DFA and the DFA has no focus limiter which puts me off it somewhat.
Regards,
John
Comment by johnwhit posted on Macro lenses at 24/05/2010 - 11:06
It's hard to tell, the two cameras are giving different exposures, probably due to the difference in metering systems. I'd take the K20D and Pentax A*200 please
Comment by johnwhit posted on Pentax 200mm, Sigma 180mm tests at 24/05/2010 - 07:33
John