Having problems with a Sigma DG 28-300mm 3.5-6.3 lens - just not quite right in focus.

[ChrisMadog]

He everyone,

I have a Canon 450D (Rebel I think in the US) dating back to 2009.
The Canon 18-55mm lens won't focus and it looks like the Flex Cable has died so I've got one on order.

I have a Sigma DG 28-300mm 3.5-6.3 lens and while it works, the image quality just isn't 'quite right'. It always seems to be that little bit fuzzy.

Has anyone found some little bit of 'magic' to get it right ?

Kind regards,

Chris

[ChrisMadog]

Thank you for your reply 🙂

I now understand Front/Back focus and I will check mine tomorrow. I suspect it is doing one or the other and now I'm itching to find out which 🙂

I do understand Depth of Field and I often use ADF in landscape shots.Other times I go manual to get the result I want.

However, thank you for the in-depth explanation.
While I am a photo enthusiest, I certainly need to learn more 🙂

Lind regards,

Chris

[ebiggs1]

" As always, I find your false and condescending assumptions to be offensive. "

Easy solution.    Stop reading them!  I wish you would.

[ebiggs1]

"I now understand Front/Back focus and I will check mine tomorrow."

Please, let me know how this goes.

[ChrisMadog]

@ebiggs1 wrote:

"I now understand Front/Back focus and I will check mine tomorrow."

Please, let me know how this goes.

---

I checked the focus this morning and found that the lense focusses in front of the focus point, so front-focusing

I've checked the camera settings and threre is no way to adjust or compensate for it apart from manually focusing.

At least I now know what is happening. Thank you.

Kind regards.

[Waddizzle]

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@ChrisMadog wrote:

@ebiggs1 wrote:

"I now understand Front/Back focus and I will check mine tomorrow."

Please, let me know how this goes.

---

I checked the focus this morning and found that the lense focusses in front of the focus point, so front-focusing

I've checked the camera settings and threre is no way to adjust or compensate for it apart from manually focusing.

At least I now know what is happening. Thank you.

Kind regards.

---

How many test shots did you take?  I suggest taking at least a dozen.  If you took the test shots indoors, try taking another set of test shots under different lighting conditions, preferably sunlight.  

What did you use for a test target?  Did you use a tripod?  What focal length and aperture did you use for the tests?  At what distance was the test target?

I ask all of these questions because it is all too easy to get inconsistent results.  You want to take several test shots, and take an average of all of the results.  Hopefully, the various test shots are somewhat consistent, and not all over the map, sometimes in front, sometimes in back, sometimes dead accurate.

[ebiggs1]

Chris,

"...threre is no way to adjust or compensate for it apart from manually focusing."

If front focus is true, it is simple, just because you are aware of what is happening.  I remember you said you have an older Rebel?  So, it won't have focus adjustment.  So, you need to do it yourself.  It can be as simple as 'focus and reframe'.  Takes a second or two!  Probably not the best for action shots but with practice ..............

The main point to remember, if it is focus misalignment, something in the photo will be in sharp focus.  If nothing is in sharp focus, you probably need to look else where.

[RobertTheFat]

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ebiggs1 wrote:

Chris,

"...threre is no way to adjust or compensate for it apart from manually focusing."

If front focus is true, it is simple, just because you are aware of what is happening.  I remember you said you have an older Rebel?  So, it won't have focus adjustment.  So, you need to do it yourself.  It can be as simple as 'focus and reframe'.  Takes a second or two!  Probably not the best for action shots but with practice ..............

The main point to remember, if it is focus misalignment, something in the photo will be in sharp focus.  If nothing is in sharp focus, you probably need to look else where.

---

Does any Rebel have focus adjustment? That would be news to me!

"It can be as simple as 'focus and reframe'"? What's simple about that? If the lens front-focuses, how would you even find something to focus on? I'd say that "with practice" the OP will simply learn to hate the lens!

On a more serious note, is this a case where the Sigma dock would be helpful? Is the lens worth the trouble and expense of that solution?

[ebiggs1]

Robert,

"What's simple about that?"

Oh my, you people that are so dependent on automation.  You guys should have grown up when we had none.  If you can't figure out how to make that work, you picked the wrong hobby.

I don't think the Sigma DG 28-300mm 3.5-6.3 lens is a dockable lens.  I don't remember that either.  I don't remember if any Rebel has focus adjustment either since I haven't used one much since I got rid of my XTi's.  But I bet his doesn't.

I do remember the Sigma DG 28-300mm 3.5-6.3 lens is just an average lens at best.  This may be all it can deliver and not focus misalignment at all.  You can't expect everything in a 10:1 zoom lens.

[kvbarkley]

Unless the T7i has it, no Rebel has/had AFMA.

[ChrisMadog]

---

 

Oh my, you people that are so dependent on automation.  You guys should have grown up when we had none.  If you can't figure out how to make that work, you picked the wrong hobby.

......

---

Oh dear - the "I'm so freakin' smart" people are here !
Stand your ground everyone - they may go away.

Okay, I'm an amateur photographer who likes to take photos and try to preserve memories.

I don't and won't claim to know much about photography but, ... and here is where I am different to those who put crap on people they think know less than them, ... I want to learn.

I had a pentax 1000 back in the 70's - fully manual, but it got stolen and I couldn't afford to replace it.
I don't brag that I could drive that camera and I don't put crap on others that may not be able to either.

I've got a Canon 500 in a drawer somewhere but I couldn't afford to take lots of photos with the development costs, so it is in the drawer. Nor did I want to develop the films either - I don't have time. My electronics business is way more important.

But, I do like taking photos.

If you can't talk to people without resisting the urge to try to prove you are better than someone else, don't post.

If I can't get anything better out of the lens and it's because of some factor that you know about, simply and respectfully say so. You don't need to denigrate anyone or say how good you are to do that.

I'm not stupid and I don't deal well with people who insist everyone else is 'stupider' than they are. We are here to help each other and putting people down, even serreptitiously, is not the way to do that.

Regards,

Chris