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10/08/2005 07:36:07 PM · #1 |
I just took a bunch of photos with my Sigma 70-300mm f/4-5.6 DL Macro Super. All of them are blurry. Auto-focus was locked in. They looked sharp through the viewfinder. There was plenty of light. Shutter speeds around 1/250 or above. Everything I took with my Pentax DA 18-55mm f/3.5-5.6 AF lens came out fine. So it's not me or the camera. Could it be that the Sigma lens is busted or just not compatible with my camera?
I'm kind of bummed. Thought I had some nice shots. |
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10/08/2005 07:39:08 PM · #2 |
Originally posted by lepidus:
Could it be that the Sigma lens is busted or just not compatible with my camera? |
Is this the first time you have used the lens with your camera?
I don't know how old the lens is, but some older sigma lenses have to be "re-chipped" to work with newer cam bodies.. |
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10/08/2005 07:42:33 PM · #3 |
Originally posted by buzzrock:
Is this the first time you have used the lens with your camera?
I don't know how old the lens is, but some older sigma lenses have to be "re-chipped" to work with newer cam bodies.. |
I've used it before and come to think of it, they were blurred too. That time I thought it was me. |
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10/08/2005 10:14:05 PM · #4 |
| Sometimes you have to give the lens a bit more "twist" when youput it on. |
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10/08/2005 10:57:29 PM · #5 |
| I think I figured out how to fix it. Ebay. Sell it and get one of the Pentax zooms designed for the *istD. |
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10/08/2005 10:58:57 PM · #6 |
Originally posted by lepidus:
I think I figured out how to fix it. Ebay. Sell it and get one of the Pentax zooms designed for the *istD. |
;) |
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10/08/2005 11:06:44 PM · #7 |
In the navy, we always used to say try a bigger hammer :-P
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10/08/2005 11:17:55 PM · #8 |
Originally posted by taterbug:
In the navy, we always used to say try a bigger hammer :-P |
That sounds like my dad. Yes, he was Navy. |
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10/09/2005 05:39:29 AM · #9 |
If the only thing in your tool box is a hammer, suddenly everything looks like a nail.
- My first boss. ;-).
edit: Ex army, not navy...
Message edited by author 2005-10-09 05:40:03.
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10/09/2005 10:48:56 AM · #10 |
Originally posted by lepidus:
Originally posted by taterbug:
In the navy, we always used to say try a bigger hammer :-P |
That sounds like my dad. Yes, he was Navy. |
That's funny, I learned that in engineering school.
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10/09/2005 10:52:03 AM · #11 |
I presume you have used a sufficient shutter speed, e.g., at least 1/focal length? Are you using a tripod?
Have you tried manual focus? You should be able to zoom in on something all the way, focus, and then zoom back out. Is it sharp then?
If it looks sharp in the viewfinder, but not in the digital copy, it might not be your lens!
Message edited by author 2005-10-09 10:53:21.
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10/09/2005 11:08:23 AM · #12 |
There are a few things you should try before concluding that the lens in malfunctioning. First and foremost, use a steady tripod, and either a remote release or the self timer. Second, shoot both wide open (max aperture) and stopped down. Third, do tests focused manually and with AF.
Do all this with a scene that has fine detail and high contrast and where you can easily judge where the focus point was. That way you can see if ANY point in the scene is sharp (including either in front of or behind the intended point of focus).
Once you've done some investigation in this manner, you should be able to tell if the lens is just generally "soft", or if it has a front- or back-focus problem, or if camera shake is coming into play on hand-held shots (works fine on tripod).
I suspect that camera shake on the hand-held shots may be a part of the problem.
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10/09/2005 11:34:49 AM · #13 |
This may seem too obvious to be plausible, but do you have a diopter adjustment next to the viewfinder? It is designed to compensate for the focal length of your eye and if it is set wrong will have the effect you described.
It would be a little slider next to or under the finder. |
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10/10/2005 06:14:32 AM · #14 |
Originally posted by nshapiro:
I presume you have used a sufficient shutter speed, e.g., at least 1/focal length? Are you using a tripod? |
Yes, shutter speeds were 1/250 and up. It was bright out.
Originally posted by kirbic:
There are a few things you should try before concluding that the lens in malfunctioning. First and foremost, use a steady tripod, and either a remote release or the self timer. Second, shoot both wide open (max aperture) and stopped down. Third, do tests focused manually and with AF. |
I'll give it a test run.
Originally posted by conglett:
This may seem too obvious to be plausible, but do you have a diopter adjustment next to the viewfinder? It is designed to compensate for the focal length of your eye and if it is set wrong will have the effect you described. |
Diopter is clear. Other lenses work fine.
Thanks guys, for all the advice. I'll keep playing with it. |
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10/10/2005 08:45:54 AM · #15 |
Originally posted by lepidus:
Originally posted by nshapiro:
I presume you have used a sufficient shutter speed, e.g., at least 1/focal length? Are you using a tripod? |
Yes, shutter speeds were 1/250 and up. It was bright out.
...snip... |
Remember that at 300mm, you need 1/300 or better, at least nominally. I don't know if the reciprocal focal length rule needs to take into account crop factors--I would guess not, but if so, you would need 1/600 on a 2x crop factor camera.
Using a tripod, self timer, and remote shutter release as Kirbic suggested will be a good test. You should also use mirror lock up if you can.
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