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

ChrisMadog
Contributor

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

22 REPLIES 22

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.

EB
EOS 1DX and 1D Mk IV and less lenses then before!


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?

Bob
Philadelphia, Pennsylvania USA

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.

EB
EOS 1DX and 1D Mk IV and less lenses then before!

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

 


 

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


@ChrisMadog wrote:

 


 

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.

 

 

Regards,

Chris


Please, accept my apologies for some of the replies.  I have no idea what that one remark you singled out was all about.  Back in the day before auto focus lenses were invented, the entire concept of front/back focusing was entirely non-existent.  All lenses were manual focus, and you had focusing aids in the viewfinder.

 

 

 

In today's world, some camera bodies have the capability to compensate for lenses that have focusing systems that may not be precisely calibrated for your camera body.  The fact that a given lens and a given camera may not be a match made in heaven is usually a reflection of manufacturing tolerances than manufacturing defects.  

 

Canon's Rebel camera bodies do not offer AFMA, Auto Focus Micro-Adjustment, but the camera bodies with ##D or #D model numbers do offer this feature in two basic forms.  First, AFMA allows the camera to recognize the type of CANON lens that you have mounted on the camera body, but it cannot distinguish between one serial number or the next.

 

Second, Canon camera bodies make no attempt to recognize third party lenses, which is probably for the best.  Third party lenses may sometimes fool the camera body into thinking that they are a specific Canon lens model, but sometimes the camera body may think the third party lens is one model, and at other times another model.  This confusion can only lead to errors over the long run, and Canon seems to have washed their hands of it by not recognizing third parry lenses, at all.

 

 

As for your immediate issue, I strongly suggest taking as many test shots as practical.  You should expect to get inconsistent results from one test shot to the next.  The problem is determining and distinguishing whether or not, or how much, the inconsistentencies are a result of lens performance or testing errors.  The best assumption to make is that inconsistencies in test shots is a result of testing flaws, and not the lens.  This perspective should force you to become more meticulous and accurate with your test shots, thereby reducing the sources and causes of out of focus shots.

 

What can you do about a lens that front or back focuses?

 

With a Canon Rebel body, there is very little that you can do, because they lack AFMA.  Seeing how today's auto-focusing DSLRs lack the viewfinder manual focusing aids, your options in that direction are limited, too.  You have some not so pretty choices to make.  

 

Keep using the lens, and trying to compensate for its' focusing behaviors.  Buy a new camera body with the AFMA feature, which has its' limitations because you're using a third party lens and the body may not always correctly recognize it.  Or, you could sell the lens.

--------------------------------------------------------
"The right mouse button is your friend."

Hi Waddizzie,

 

No need to apologise. It's all good in the end.

 

What you have said is what I needed to find out. Thank you.

I can't afford a new camera body but maybe in the future if I can find a job again. Anyone need an electronics Tech ?? LOL
People don't fix things, they throw them away these days and buy a new one 😞 ... and who wants to emply a 60+ year old these days ?

 

I will try to compensate for the lens until the flex cable arrives to fix the 18-55mm Canon lens.
I've got a Canon 70-300mm lens too but I need a new front lens part for it - mould is growing between the two pieces of glass. It's not a great lens but it would do if I had to but as I said, I need a front lens assembly for it.

 

Thank you again. You were very clear with what you said. 🙂

 

Kind Regards,

Chris

"I'm not stupid and I don't deal well with people who insist everyone else is 'stupider' than they are."

 

Chris this is an open public forum.  You are free to take or ignore the advice posted here.  Most of the comments are meant to help but you may not like some of the answers.  Nobody claimed that made anybody " 'stupider' ".  Some folks write posts about which they have no practical experience with.  It is up to you to decide which will benefit your situation.  I don't think anyone insists on anything!

 

BTW it is, surreptitiously.

EB
EOS 1DX and 1D Mk IV and less lenses then before!

First off a lens is what a lens is. It can not change after it is manufactured.  It can't get any sharper or any less.  It can suffer from alignment issues.  Only Sigma is likely able to perform this adjustment.  I have never used this Siggy in question but I can tell you lenses with a zoom ratio of 11 to 1 are never going to be the sharpest tack in the box.

 

Now for focus adjustment.  Like I stated you can not make it any sharper.  This adjustment simply moves the pin point focus distance.  If this is off, something in your photos will still be in focus. Just not where you thought.

 

Lastly is user technique.  How you are actually using the lens.  In other words it could be you and not the lens.

 

"I'm at a loss as to what to do."

I do have a extra question for you.  Was the lens ever real sharp and has this happened recently?

EB
EOS 1DX and 1D Mk IV and less lenses then before!

"a lens is what a lens is"

 

That was my thought as well but I was after a means where I could do something about it.

I can understand focus problems when zooming but even at 28mm and F3.5 it just doesn't have "it".
A handy lense while I await the flex cable for the Canon 18-55mm but I've always wondered why it was nowhere near as focussed.
To answer your question, "Was the lens ever real sharp and has this happened recently?" - it has always been this way since I have owned it.  I bought it second-hand.

 

The problem was bought to light when I woul;d focus on someones eyes for a photo and it would never be quite in focus.
I'd love to have the money for a really good lense but I'm not in that position due to health problems in the past.

I've heard of doing focus adjustments but how is this done ?
My camera is one of the early EOS 450D - bought in 2009.

 

Thanks for the reply and kind regards.

 

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