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Lenswork

Lenswork

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Took the plunge and ordered a Sigma 70-200 f2.8 EX lens last week to use on my 40D. Well it arrived Friday so out i went and tried it out on the wildfowl at the local Park. Upon reviewing the pics when i got home they seemed a bit soft/out of focus. So i decided to do tests with the lens from the comfort of my lounge, I used a tripod, cable release,rule and white A4 paper. I focussed on the black line through the 6 on the rule.
I was surprised at the outcome, the shots all seemed to be front focussed.:( Worse at the wide end obviously because of the DOF, but it was throughout the focal range. The shots were between 10mm-30mm front focussing. I tried other lenses that i have, canon 50mm 1.8II and my Tamron 90mm macro, they were spot on so it wasn't the camera. So my question is, has anyone had similar probs and what was the outcome? I have e-mailed the company i bought it from and have asked for a replacement lens, I am awaiting a reply. I know that i should have gone for the Canon but funds wouldn't allow me!
Pics Test1 was f2.8 at 200mm only adjusted white balance and Test2 was at i think 80mm f4
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Sorry for the long winded thread.
 
i would ask for it to be calibrated rather than a replacement as you could get another lens with the same problem
 
hi lenswork just a thought but try this www.focustestchart.com read it then print page 18 the test card hope this helps :shake:


edit its all about the angle of the test and even the f number
 
Canon Bob said:
You have to expand on this bit please.

Bob
Click to expand...
what I meant by wider end was at the wider aperture f2.8 not wider focal length for DOF eg shallower. My mistake sorry.

prowannabe thanks for your reply, but I want one that works straight out of the box. That's what I paid for. I ve got 2 other sigma lenses and they're ok, just down to bad luck with this one maybe.

dinorock thanks for the link, i'll give it a try.
 
Focus tests should be done using a flat surface as the target point of focus. You can still have a ruler in frame to judge front/back focus but don't use an angled surface to focus on. The AF point is larger than you think, esp. on the tiny viewfinder points of the 40D and it will pick the closest point to the camera with the highest contrast which will weight the results to front focus.

The chart linked above does work better because the target point is a single line so that's the only area the AF can work with. Even better would be to cut around that section and bend it so it's at 90deg whilst the rest of the chart is 45deg.
 
I had the same issue with the same lens I bought a few months ago. Soft focus and oof more noticeable towards 200mm on closer subjects. I took it back to the shop for a refund without bothering with test charts.
People say the lens is very sharp, mine wasn't so that was good enough for me to get rid of it.
Allanoc
 
allanm said:
I had the same issue with the same lens I bought a few months ago. Soft focus and oof more noticeable towards 200mm on closer subjects. I took it back to the shop for a refund without bothering with test charts.
People say the lens is very sharp, mine wasn't so that was good enough for me to get rid of it.
Allanoc
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hi guys yeah i didnt mean not to change it ,or get it reset i just meant be sure your not doing something wrong before going back to the shop just trying to help. :shrug:
 
I've got the Sigma 70-200 f2.8 and it's pin sharp. Unlucky to get a dodgy one, but persevere if you can't afford the Canon.
 
pxl8 said:
Focus tests should be done using a flat surface as the target point of focus. You can still have a ruler in frame to judge front/back focus but don't use an angled surface to focus on. The AF point is larger than you think, esp. on the tiny viewfinder points of the 40D and it will pick the closest point to the camera with the highest contrast which will weight the results to front focus.

The chart linked above does work better because the target point is a single line so that's the only area the AF can work with. Even better would be to cut around that section and bend it so it's at 90deg whilst the rest of the chart is 45deg.
Click to expand...

Thanks for the tip.
I also carried out a test using an envelope propped vertically with a battery box which had writing on and was approx 30mm thick. I focussed on the letters on the envelope but also made sure the battery box was in frame. 1st up was the sigma and guess what, the letters on the battery box were sharp but the envelope wasn't. Then i tried my 90mm macro and the letters on the envelope were sharp but not the battery box.:shrug: I'll download the test chart mentioned earlier and try again tomorrow. But i'm resigned that i may have to exchange the lens.:thumbsdown:
 
Flash In The Pan said:
Sigma :shrug:
Click to expand...

How helpful :cuckoo:

I'd definitely look at using a proper test chart but it does sound like it is front focusing. I'd also agree with one of the other replies in getting it calibrated rather than a replacement unless the shop is local and you can test the new lens you're getting there and then.
 
What.....a faulty Sigma lens is a rare occurance?

Anyway,unless test charts are what the op intends to use the lens to shoot then some real life examples of the problem would be more beneficial....
 
Flash In The Pan said:
What.....a faulty Sigma lens is a rare occurance?
Click to expand...

Your not exactly helping with a pathetic reply like you posted that though are you? What possible use was that other than to just have a go at sigma for the sake of it?

Real life examples are always nice but confuse the issue as it's harder to understand exactly what the camera has focussed on. Test charts are much more useful in diagnosing the problem, hence their name!

OP, without stating the obvious, you are using centre point focusing aren't you?
 
CraigDouglas said:
Your (sic) not exactly helping with a pathetic reply like you posted that though are you? What possible use was that other than to just have a go at sigma for the sake of it?
Click to expand...

Whereas your response added so much ;)


Anyway, I'm not going to argue with you on someone else's post. If you want to continue this please feel free to pm me....
 
I don't think it's entirely off topic to raise the QC problems Sigma seem to have. It is an issue and something that might help the OP to decide on a course of action. Get a good copy of the 70-200 and it's a great lens. Sending it to Sigma for calibration is probably the best solution and likely quicker than playing lucky dip with the retailer. Of course it shouldn't be this way but, unfortunately, it does seem to be the case at the moment.
 
pxl8 said:
Sending it to Sigma for calibration is probably the best solution and likely quicker than playing lucky dip with the retailer.
Click to expand...

I'd tend to be in agreement with that statement - There have been some reports (it's not pandemic, don't worry!) of Sigma lenses with back/front focussing issues. Sigma UK have a decently quick turn-round time for problems such as this - give them a phone or email:)
 
Phone Sigma and arrange to return it for them to check, sending it RMSD will cost you about £20 and you'll need to scan/photocopy your proof of purchase to send with it.
 
Thanks to everyone for their advice. I'm undecided now as to send the lens to Sigma for recal or have a replacement. Will wait for a reply from the internet shop i bought it off first then decide. The down side to this would be that i have to pay postage to Sigma for recal.
Anyway have downloaded test chart and have taken a few shots at f2.8 and at various focal lengths. I think they show the flaw up much better.
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IMG_0875ed1.jpg

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IMG_0876ed1.jpg

I used the centre focus point on the centre of the 'focus here' line with the camera at approx 45 degrees to the chart.
 
Send it back, it's as simple as that. If the company you bought it from don't play ball then (assuming they are in the UK) open a dispute with your credit card company (assuming you paid by cc). Regardless of whether they want to take it back or not if it's UK bought then under the Distance Selling Regulations (2000) you have seven working days from the day after that on which the goods are received to return them for a full refund....
 
Flash In The Pan said:
Send it back, it's as simple as that. If the company you bought it from don't play ball then (assuming they are in the UK) open a dispute with your credit card company (assuming you paid by cc). Regardless of whether they want to take it back or not if it's UK bought then under the Distance Selling Regulations (2000) you have seven working days from the day after that on which the goods are received to return them for a full refund....
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Thanks Flash in the pan.
Have just returned the lens to the Guernsey based company i bought it off, not really helpfull imo, can only contact them through e-mail. Even had to pay return postage £22:thumbsdown: Which they say will be reimbursed if the lens is found to be faulty.
Also just rang Sigma and they told me the lens is a grey import, so i would have to pay them for recal. Should have realised thats why the price was so low. Who said ignorance is bliss:thinking:
There is a lot to be said from buying local as i have learnt from this experience. But funds would not allow me to in this case. It was nearly £200 cheaper.
 
I had a quick look and it would appear that you are still covered by the DSR (2000) if the company is in Guernsey and if that is the case, just tell them that you are returning the goods under the terms of the DSR and want a full refund within (say) 48 hours. No need for them to check to see if it is faulty or any such nonsense.
 
Flash In The Pan said:
I had a quick look and it would appear that you are still covered by the DSR (2000) if the company is in Guernsey and if that is the case, just tell them that you are returning the goods under the terms of the DSR and want a full refund within (say) 48 hours. No need for them to check to see if it is faulty or any such nonsense.
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Thanks have done just that, but they say they will have to wait to recieve the lens first. Used Post Office to return the lens but because of weight and it going to Guernsey the PO will use Parcel force:shrug:.
 
If it is 7dayshop then under the DSR (if it applies, still checking ;)) you would have 3 MONTHS to reject the lens as they don't have any mention of the DSR in their Terms and Conditions...
 
Slightly off topic but , I have just tried to register my Sigma EX lens for the additional 2 year warranty , but it was rejected as they say the serial number I supplied did not match their list of official Sigma UK imported lens.
I bought the lens from 7dayshop 3 weeks ago and it was advertised as uk vat paid , I emailed 7day and they have just replied saying warranty is with them for 12 months , so it looks like grey imports despite saying UK vat paid .
 
rusty said:
Slightly off topic but , I have just tried to register my Sigma EX lens for the additional 2 year warranty , but it was rejected as they say the serial number I supplied did not match their list of official Sigma UK imported lens.
I bought the lens from 7dayshop 3 weeks ago and it was advertised as uk vat paid , I emailed 7day and they have just replied saying warranty is with them for 12 months , so it looks like grey imports despite saying UK vat paid .
Click to expand...
Confirms what Sigma told me. So what does paying vat on the lens gain you:shrug: Nothing as far as warranty is concerned.
 
I accept that if I import a lens from Hk and do not pay import duty/vat that Sigma will not support the warranty and any support has to be through the supplier but I was not aware this was the case from 7dayshop spec as they say UK vat paid .
I have emailed them for clarification and await a reply , I am mindful to return the lens asking for a refund unless they can show me that I knew I was buying a grey import duties not paid .
 
UK VAT paid in that context just tells you that you will not pay any VAT to import from Guernsey to the UK mainland, this is prepaid for you.

It's nothing to do with whether its a Grey or not.
 
Flash In The Pan said:
If it is 7dayshop then under the DSR (if it applies, still checking ;)) you would have 3 MONTHS to reject the lens as they don't have any mention of the DSR in their Terms and Conditions...
Click to expand...
Thanks to everyone who's taken the trouble to give advise
Handy to know incase they come back at me with some bu*****t. I've used them before but have had no cause to return anything. It shows how good a company are by the way they handle their customers problems. Hopefully it will be resolved quickly.
 
I had the VAT issue with my first 70-200 VR, the seller couldn't/wouldn't supply a VAT invoice, so I sent the lens back. If 7Day state VAT paid then they should be able to supply you with a VAT invoice, which in theory would get you full Sigma UK cover.

It may explain why they were flogging off a load of returned Sigma lenses on Ebay recently, when they should have been covered by a manufacturer's warranty.....
 
Flash In The Pan said:
I had the VAT issue with my first 70-200 VR, the seller couldn't/wouldn't supply a VAT invoice, so I sent the lens back. If 7Day state VAT paid then they should be able to supply you with a VAT invoice, which in theory would get you full Sigma UK cover.

It may explain why they were flogging off a load of returned Sigma lenses on Ebay recently, when they should have been covered by a manufacturer's warranty.....
Click to expand...

^^^^^^^^^^^^^^^^^^^^^^^
OMG This is getting worse, hope that i didnt recieve one of those lenses. My confidence in this company is getting lower by the minute:shake: Surely they wouldn't send out returned lenses as new.:shrug: Saying that, the box it was in was a bit battered and bruised.:eek:
 
Lenswork said:
^^^^^^^^^^^^^^^^^^^^^^^
OMG This is getting worse, hope that i didnt recieve one of those lenses. My confidence in this company is getting lower by the minute:shake: Surely they wouldn't send out returned lenses as new.:shrug: Saying that, the box it was in was a bit battered and bruised.:eek:
Click to expand...


Naww, I doubt very much they would do that, it looks more like they dump their warranty return stuff via Ebay it's more likely just down to good ol' Sigma qc
 
Had an email from Sigma who state if seller of lens can provide import duty & vat payment forms then they will honour Int 1 year warranty but not extended to 3 yrs .
 
dinorock said:
hi lenswork mike here again found this lens test on youtube seems to contradict the other tests but says 90% of all lens returns are user error :bang: see what you think http://uk.youtube.com/watch?v=HS0hlQ9lSps
ps hope this helps
Click to expand...

Thanks dinorock. I've had a look and i seem to have carried out my tests in a very similar manner. Main difference is that i used a cable release and not the self timer. I'm satisfied that i carried the tests out ok.
Heres a couple of pics i took on Friday with the lens straight out of the box. They were taken with a 40D focus set to A1 servo the shutter speeds were 1/640 and 1/800 with an aperture of f2.8 at 200mm focal length. I was approx 15ft away from the seagull. Focus was on the seagulls head. The pics are appalling
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IMG_0792ed.jpg

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IMG_0791ed.jpg

These were shot in raw and resized and converted to jpeg, not good at all.
 
Lenswork said:
Thanks dinorock. I've had a look and i seem to have carried out my tests in a very similar manner. Main difference is that i used a cable release and not the self timer. I'm satisfied that i carried the tests out ok.
Heres a couple of pics i took on Friday with the lens straight out of the box. They were taken with a 40D focus set to A1 servo the shutter speeds were 1/640 and 1/800 with an aperture of f2.8 at 200mm focal length. I was approx 15ft away from the seagull. Focus was on the seagulls head. The pics are appalling
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IMG_0792ed.jpg

2
IMG_0791ed.jpg

These were shot in raw and resized and converted to jpeg, not good at all.
Click to expand...
just a question really but why are you shooting at 2.8 with a shutter speed of 640sec, slow the shutter speed down ,up the f number, see what happens .sorry it took so long to answer ,im doing other things on my computer .:bonk:



damn missed yah o well keep trying
 
dinorock said:
just a question really but why are you shooting at 2.8 with a shutter speed of 640sec, slow the shutter speed down ,up the f number, see what happens .sorry it took so long to answer ,im doing other things on my computer .:bonk:



damn missed yah o well keep trying
Click to expand...

As i was testing the lens i wanted to freeze the subject so that i could compare shots, thats why i shot at a high shutter speed. I thought that there would be less chance of blur. I dont expect the lens to be sharp as a sharp thing, but, i would like it to be able to take reasonably sharp pics wide open.
That was one of the reasons i bought the lens was for the F2.8 aperture, i want to try a bit of sports.
I was trying it out at various aperture settings and they are not much better to be honest, as my tests proved to me.

On a different note.
That youtube link you sent, one thing confused me. After the test when they were reviewing the test shots they put the images through light room where they sharpened them.:shrug: Surely if you are testing the quality of the lens you should judge those images straight from the camera with no post processing? Am i missing something here? I know that all images could do with a bit of sharpening, but, when you are specifically looking at image quality from the lens, surely it should be as shot!
Am i right or wrong on that assumption.
 
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