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12-16-2007, 05:45 PM   #1
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Bluriness with FA J 75-300mm f4.5-5.8

Hi.
i'm new to the forum but very psyched to have found it!
i was shooting fb with a K110D and the Pentax FA J 75-300mm f4.5-5.8. I found the lens to be very soft and not nearly as sharp as a Tamron80-210mm f4.5-5.8.

for example there's this with Tamron:
Picasa Web Albums - Joe - 2007 HPW B

this with Pentax:
Picasa Web Albums - Joe - 2007 HPW B

It very well could be operator error but i have found that the Pentax 75-300mm did not autofocus nearly as well as the Tamron.

Any recommendations or advice or areas to investigate would be greatly appreciated.

joe


Last edited by joep; 12-16-2007 at 05:46 PM. Reason: remove thumbnails
12-16-2007, 06:17 PM   #2
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I depends on some shots ... it can be soft here and there ... but can also be fairly sharp.
For a cheap lens though ... you can't expect too much.

I take my time when shooting with it ... not all come through ... but overall I am happy with it (especially with it's poor reputation).

High contrast shots are not the Pentax 75-300 strong point though ... I have had issues with CAs and purple fringing.
Just having a look at your shot though ... I haven't had issue like the one you have presented ... my poor images with mine is a hell of a lot sharper than that.

Last edited by Mechan1k; 12-16-2007 at 06:24 PM.
12-16-2007, 09:30 PM   #3
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I have a love/hate relationship with my FA-J 70-300. It _can_ be sharp. But I think you've hit the nail on the head with your assessment. I think it's perception of being soft is mostly due to AF inaccuracies, though I certainly haven't done any formal testing.

I have gotten a sharp photo[hinckc.smugmug.com] or two with it, I know the optics are capable of it. But often my experience mirrors yours.

Along the way, I wound up getting a Tamron 18-250, which I find far more reliable with the AF, though it doesn't make total sense to me why, with the Tamron being f/6.3 at the long end, and the Pentax at f/5.8. The Tamron isn't quite as long, but it's a much more useful focal length range for me and far more consistently sharp. I haven't ditched my FA-J, though. My success with the tamron also leads me to believe that it's not the body's AF system alone that is the cause of the FA-J's inconsistancies.

One thing to remember: Sports are really tough for any setup. Many have spent far more $$$ on glass and bodies and still not been satisfied. Only thing I can think of to help is to "pre-focus" at a spot. I know that makes it tough to nail the most exciting moments of the game, but you'll probably be more likely to come home with photos. Maybe split the game by quarters and alternate between pre-focus and chasing the action?

-Chris
12-16-2007, 11:42 PM   #4
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I should have posted a couple of images I have taken with it.
As mentioned ... it can produce some decent images ... but I think it comes down to lighting conditions as well.







Last time of my dog could have been sharper though ... it sometimes likes to focus on things much closer than it should.

12-17-2007, 01:08 PM   #5
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thanks

thanks folks.
do you think it would help to maybe change the autofocus to choose the center spot only? I have not changed that setting at all but think it may help.

what do you think?
12-17-2007, 03:22 PM   #6
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Setting it to center focus spot only will speed up the autofocus and also allow you to select the focus point.
12-18-2007, 05:27 PM   #7
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QuoteOriginally posted by Canada_Rockies Quote
Setting it to center focus spot only will speed up the autofocus and also allow you to select the focus point.
I find I do use Centre Focus on mine more ... I get a better shot as it does focus better this way ... otherwise I have found it likes to focus on other things (other than what I want it to)
12-18-2007, 07:21 PM   #8
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thanks, Simon. i'll give it a try.

12-18-2007, 07:33 PM   #9
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I'll try this as well. Thanks for the tip!

-Chris
12-18-2007, 10:25 PM   #10
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QuoteOriginally posted by Mechan1k Quote
I should have posted a couple of images I have taken with it.
As mentioned ... it can produce some decent images ... but I think it comes down to lighting conditions as well.

Last time of my dog could have been sharper though ... it sometimes likes to focus on things much closer than it should.
Try switching to center focusing spot only. That way you know what the camera is going to focus on.
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