Lens Repairs?

jdarrough · 02-22-2008, 03:53 PM

I have an SMC Pentax 100-300mm Zoom lens which is being used with my K100D. I wanted to know what other think about determining if the slight blur when at 300mm is due to a lens element being out of alignment, or what. What test can be performed to find out? In fact, what test can be performed for any lens for that matter?

Thanks to you Guru's of all things Pentax. I have had an ME Super for almost 35 years, and was thrilled to get the K100D but it sure is different!

Regards to all, Jim in Oregon

(200+ pix of the eclipse last night!)

Adam · 02-22-2008, 05:35 PM

Thread moved to the appropriate section.

Thanks!

wlachan · 02-22-2008, 05:39 PM

The Pentax 100-300 are known (2 versions at least) to be not very sharp toward the long end. I have never used this lens so have no idea how bad they are but should yours had misalignment, there is no way to recalibate even by Pentax. That's just how Pentax lenses are designed and made, unlike some other brands their lenses could be re-aligned through a few screws (like Tamron).

jdarrough · 06-06-2008, 03:27 PM

And where might that be, Adam? I would like to read responses if I can find my messages.

Tom M · 06-06-2008, 03:34 PM

Originally posted by wlachan

That's just how Pentax lenses are designed and made, unlike some other brands their lenses could be re-aligned through a few screws (like Tamron).

I wouldn't make such a blanket statement.

clawhammer · 06-06-2008, 04:32 PM

If it's the power zoom version (FA 100-300 f/4.5-5.6), then it being soft at the end is just a fact of life with that lens. It's not a very good lens, and is 'soft as a pillow' at the long end.

Some of the best places for lens info/reviews are this site's lens review database, the K-mount Page, Stan's Pentax reviews (Pre-digital lenses only), and to a lesser extent photozone.de. If you look around those pages, you'll find the 100-300s aren't traditionally the best lenses, with the power-zoom version a particular stinker.

If you're looking for a better xx-300 lens, the newest sigma and Tamron 70-300's are good for their price (~150), and the new Pentax DA 55-300 is turning out to be a winner.

roy · 06-06-2008, 06:32 PM

Originally posted by jdarrough

What test can be performed to find out? In fact, what test can be performed for any lens for that matter?
(200+ pix of the eclipse last night!)

put it on a tripod. most problems are not the lens or camera at 300mm but are user faults. use the 2 secound delay and a remote if you have one..

jdarrough · 06-12-2008, 09:28 AM

I know about user error. Been taking photos for 40 years. I am using a tripod. I think it's the lens, as it is not the high end ones. My FA zoom is 35 - 85 and is much sharper. Thanks for your help!

02-22-2008, 03:53 PM	#1
jdarrough Junior Member Join Date: Jan 2007 Location: Springfield, OR Photos: Gallery Posts: 29	Lens Repairs? I have an SMC Pentax 100-300mm Zoom lens which is being used with my K100D. I wanted to know what other think about determining if the slight blur when at 300mm is due to a lens element being out of alignment, or what. What test can be performed to find out? In fact, what test can be performed for any lens for that matter? Thanks to you Guru's of all things Pentax. I have had an ME Super for almost 35 years, and was thrilled to get the K100D but it sure is different! Regards to all, Jim in Oregon (200+ pix of the eclipse last night!)

02-22-2008, 05:35 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Thread moved to the appropriate section. Thanks! Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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02-22-2008, 05:39 PM	#3
wlachan Veteran Member Join Date: Sep 2006 Location: Canada Photos: Albums Posts: 2,625	The Pentax 100-300 are known (2 versions at least) to be not very sharp toward the long end. I have never used this lens so have no idea how bad they are but should yours had misalignment, there is no way to recalibate even by Pentax. That's just how Pentax lenses are designed and made, unlike some other brands their lenses could be re-aligned through a few screws (like Tamron).

06-06-2008, 03:27 PM	#4
jdarrough Junior Member Join Date: Jan 2007 Location: Springfield, OR Photos: Gallery Posts: 29 Original Poster	And where might that be, Adam? I would like to read responses if I can find my messages.

06-06-2008, 03:34 PM	#5
Tom M Veteran Member Join Date: Aug 2007 Location: Lincoln Park, NJ Photos: Gallery Posts: 780	Originally posted by wlachan That's just how Pentax lenses are designed and made, unlike some other brands their lenses could be re-aligned through a few screws (like Tamron). I wouldn't make such a blanket statement.

06-06-2008, 04:32 PM	#6
clawhammer Veteran Member Join Date: Sep 2007 Location: Logan, Utah Photos: Gallery Posts: 971	If it's the power zoom version (FA 100-300 f/4.5-5.6), then it being soft at the end is just a fact of life with that lens. It's not a very good lens, and is 'soft as a pillow' at the long end. Some of the best places for lens info/reviews are this site's lens review database, the K-mount Page, Stan's Pentax reviews (Pre-digital lenses only), and to a lesser extent photozone.de. If you look around those pages, you'll find the 100-300s aren't traditionally the best lenses, with the power-zoom version a particular stinker. If you're looking for a better xx-300 lens, the newest sigma and Tamron 70-300's are good for their price (~150), and the new Pentax DA 55-300 is turning out to be a winner.

06-06-2008, 06:32 PM	#7
roy Inactive Account Join Date: Sep 2006 Location: D/FW area, Tx. Photos: Gallery Posts: 1,710	Originally posted by jdarrough What test can be performed to find out? In fact, what test can be performed for any lens for that matter? (200+ pix of the eclipse last night!) put it on a tripod. most problems are not the lens or camera at 300mm but are user faults. use the 2 secound delay and a remote if you have one..

06-12-2008, 09:28 AM	#8
jdarrough Junior Member Join Date: Jan 2007 Location: Springfield, OR Photos: Gallery Posts: 29 Original Poster	I know about user error. Been taking photos for 40 years. I am using a tripod. I think it's the lens, as it is not the high end ones. My FA zoom is 35 - 85 and is much sharper. Thanks for your help!

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