A Quality Issue of 18-250mm lens?

lisicai · 09-29-2008, 09:26 AM

Hi, everyone:

Though I have been using Pentax for 2 years, I am abusotely a newbie here.

Recently I bought the new Pentax 18-250mm lens from amazon. Soon I found out other than the vignetting effects, the lens will automatically slide out whenever it's pointing downwards. I had used Pentax and Sigma lens before. None of those have similar problems. Is it because the front end of the lens are too heavy? Or this is actually a quality problem so I should return the lens for an exchange?

Many thanks for your replies.

Best,

Lisi

rburgoss · 09-29-2008, 09:40 AM

That is not a quality problem. This lens as well as other extreme range zooms are known for this situation. Perhaps others may know this lens better and can tell you if I'm wrong.

OTOH, I believe this lens has a zoom lock lever, to prevent this from happening.

Attachment 19574

RB

Alfisti · 09-29-2008, 09:46 AM

Nah that's right, that's what it does. Don't use it wide open and use the zoom lock.

JohnV3 · 09-29-2008, 09:59 AM

The zoom lock only works when the lens is at it's shortest (the 18mm position). They all slide when pointed down as many posters here have stated before. I know my lens does.

egordon99 · 09-29-2008, 10:04 AM

Heck, my Tamron 28-75mm had zoom creep, and that's not exactly a "budget" lens.

It's fine, use the lock button. Now go and take pictures

forensicscientist · 09-29-2008, 10:13 AM

They don't mention this little "feature" in the ads do they?

Like others have said, its normal.

mark

Jasvox · 09-29-2008, 10:25 AM

My Tamron version does the same thing. It is the weight of the lens elements and gravity, who can fight that? Think of it, its an 18 to 250mm lens in a barrel about the same size as the kit lens, I can live with the occasional zoom creep when its pointing down. Once you get used to "locking" it when not shooting, it's not an issue at all.

As for the vignetting, just learn to find the lens' sweet spot with the aperture setting and vignetting usually isn't such a bother or issue.

Jason

lisicai · 09-29-2008, 10:30 AM

Thank you all for your kind replies. This does ease my worries alot! I am travelling New Hampshire to shoot some foliage next week. Do you guys think this would be the right lens to carry with?

Alfisti · 09-29-2008, 11:09 AM

Originally posted by lisicai

Thank you all for your kind replies. This does ease my worries alot! I am travelling New Hampshire to shoot some foliage next week. Do you guys think this would be the right lens to carry with?

In a word yes but try to avoid the extremes. So pretend it is a 21-200mm f/5.6 - f/8 lens.

Alfisti · 09-29-2008, 11:11 AM

Here are a few of my better ones with this lens .....

flyer · 09-29-2008, 11:31 AM

If those are your best, I'd hate to see the worst...Just kidding

They're kind of interesting, especially the scooter one. Nice shot.

Damn Brit · 09-29-2008, 11:50 AM

Beautiful colours in that second shot.

Venturi · 09-29-2008, 12:05 PM

Just think of it like a trombone - even the best of those slide out on thier own and they've got locks as well.

krypticide · 09-29-2008, 12:38 PM

I put a wide rubber band over the gold lettering and zoom ring, about half and half, and that adds enough friction such that the zoom doesn't creep as much. You will need to replace bands every so often due to the fact that they break down under UV light from the sun.

lisicai · 09-29-2008, 01:20 PM

I love the vivid color of all these pictures (should credit go to Pentax?) And I love the zoom range.

What Robert Capa said, "if your pictures aren't good enough, you are not close enough"...now can be addeed: "or your zoom is not enough"...I think many users will try to squeeze the full 250mm out from this lens. But anyone feel any image distortion?

09-29-2008, 09:26 AM	#1
lisicai New Member Join Date: Sep 2008 Posts: 12	A Quality Issue of 18-250mm lens? Hi, everyone: Though I have been using Pentax for 2 years, I am abusotely a newbie here. Recently I bought the new Pentax 18-250mm lens from amazon. Soon I found out other than the vignetting effects, the lens will automatically slide out whenever it's pointing downwards. I had used Pentax and Sigma lens before. None of those have similar problems. Is it because the front end of the lens are too heavy? Or this is actually a quality problem so I should return the lens for an exchange? Many thanks for your replies. Best, Lisi

09-29-2008, 09:40 AM	#2
rburgoss Veteran Member Join Date: May 2008 Location: San Jose, Costa Rica Photos: Gallery \| Albums Posts: 972	That is not a quality problem. This lens as well as other extreme range zooms are known for this situation. Perhaps others may know this lens better and can tell you if I'm wrong. OTOH, I believe this lens has a zoom lock lever, to prevent this from happening. Attachment 19574 RB Last edited by rburgoss; 10-10-2008 at 10:21 AM.

09-29-2008, 10:30 AM	#8
lisicai New Member Join Date: Sep 2008 Posts: 12 Original Poster	thank you! Thank you all for your kind replies. This does ease my worries alot! I am travelling New Hampshire to shoot some foliage next week. Do you guys think this would be the right lens to carry with?

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09-29-2008, 09:46 AM	#3
Alfisti Veteran Member Join Date: Mar 2007 Location: Toronto (for now) Posts: 1,748	Nah that's right, that's what it does. Don't use it wide open and use the zoom lock.

09-29-2008, 09:59 AM	#4
JohnV3 Senior Member Join Date: Jan 2007 Location: Phoenix, AZ USA Posts: 165	The zoom lock only works when the lens is at it's shortest (the 18mm position). They all slide when pointed down as many posters here have stated before. I know my lens does.

09-29-2008, 10:04 AM	#5
egordon99 Inactive Account Join Date: Dec 2006 Location: Outside of Philly Posts: 1,561	Heck, my Tamron 28-75mm had zoom creep, and that's not exactly a "budget" lens. It's fine, use the lock button. Now go and take pictures

09-29-2008, 10:13 AM	#6
forensicscientist Pentaxian Join Date: Jun 2008 Location: DFW Texas and Michigan - I commute :) Posts: 1,012	They don't mention this little "feature" in the ads do they? Like others have said, its normal. mark

09-29-2008, 10:25 AM	#7
Jasvox Veteran Member Join Date: Oct 2007 Location: Melbourne, Australia Posts: 3,107	My Tamron version does the same thing. It is the weight of the lens elements and gravity, who can fight that? Think of it, its an 18 to 250mm lens in a barrel about the same size as the kit lens, I can live with the occasional zoom creep when its pointing down. Once you get used to "locking" it when not shooting, it's not an issue at all. As for the vignetting, just learn to find the lens' sweet spot with the aperture setting and vignetting usually isn't such a bother or issue. Jason

09-29-2008, 11:09 AM	#9
Alfisti Veteran Member Join Date: Mar 2007 Location: Toronto (for now) Posts: 1,748	Originally posted by lisicai Thank you all for your kind replies. This does ease my worries alot! I am travelling New Hampshire to shoot some foliage next week. Do you guys think this would be the right lens to carry with? In a word yes but try to avoid the extremes. So pretend it is a 21-200mm f/5.6 - f/8 lens.

09-29-2008, 11:11 AM	#10
Alfisti Veteran Member Join Date: Mar 2007 Location: Toronto (for now) Posts: 1,748	Here are a few of my better ones with this lens .....

09-29-2008, 11:31 AM	#11
flyer Veteran Member Join Date: Jan 2008 Location: Ste-Anne des Plaines, Qc., Canada Posts: 2,013	If those are your best, I'd hate to see the worst...Just kidding They're kind of interesting, especially the scooter one. Nice shot.

09-29-2008, 11:50 AM	#12
Damn Brit Guest	Beautiful colours in that second shot.

09-29-2008, 12:05 PM	#13
Venturi Veteran Member Join Date: Mar 2008 Location: Tulsa, OK Photos: Gallery Posts: 2,636	Just think of it like a trombone - even the best of those slide out on thier own and they've got locks as well.

09-29-2008, 12:38 PM	#14
krypticide Veteran Member Join Date: Dec 2007 Photos: Gallery Posts: 1,079	I put a wide rubber band over the gold lettering and zoom ring, about half and half, and that adds enough friction such that the zoom doesn't creep as much. You will need to replace bands every so often due to the fact that they break down under UV light from the sun.

09-29-2008, 01:20 PM	#15
lisicai New Member Join Date: Sep 2008 Posts: 12 Original Poster	I love the vivid color of all these pictures (should credit go to Pentax?) And I love the zoom range. What Robert Capa said, "if your pictures aren't good enough, you are not close enough"...now can be addeed: "or your zoom is not enough"...I think many users will try to squeeze the full 250mm out from this lens. But anyone feel any image distortion?