Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Sony Alpha dSLR / Konica Minolta dSLR, Sony SLT

Reply
 
Thread Tools Search this Thread
Old Oct 25, 2006, 5:44 AM   #1
Junior Member
 
Join Date: Oct 2006
Posts: 2
Default

Hello all,

I have had the Minolta 7D for over 8 months now and have had the Sigma 24-70 f2.8 EX DG DF lens for about 6months. However, after finally buying an M42 adapter for a few of my Carl Zeiss Jena lenses, I have realised that my Sigma lens should be producing far superior images to what it is doing now.

After doing a bit of research, I have only come across one person on the internet that has had problems with this particular Sigma lens on the 5d and 7d; such being sharpness and general connectivity. Has anybody else got the same problems such as level of sharpness and constant lens disconnections? (By disconnections i mean when the camera doesn't recognize that you have a lens installed.)
My main problem is that my images for landscape images aren't sharp at all. I have tried every combination possible and still cannot get a sharp image.

If I use this same lens on my Minolta 7 and 700si, my sharpness is fine.

Can anybody please shed some light on this lens? It would be greatly appreciated as Sigma itself can only say "sorry, send the lens in." It would be pointless to send this lens in if there was nothing wrong with it and that's how the image quality is supposed to be.

Thank you in advance
Elek

elek is offline   Reply With Quote
Sponsored Links
Old Oct 25, 2006, 8:59 AM   #2
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

If you've got the same problems with the same lens on two different bodies, I'd send it to Sigma and let them take a look at it.

The camera not recognizing that a lens is attached could be something as simple as dirty contacts (so, you may want to clean the lens mount contacts).

But, it could also be a symptom of a lens issue. Sometimes, Sigma has to rechip lenses for better compatibility, too (upgrading them to newer firmware), since they sometimes miss something in the protocol between the camera and lens (how they communicate).

This is a relatively common problem with older Sigma lenses (needing to be rechipped to work with some newer cameras), since they didn't license the lens mount technology and missed features that were implemented by a camera manufactuer later in newer bodies. This is not limited to KM (you see the same problems reported by owners of other models like Canon DSLRs with some Sigma lenses). Most lenses from other manufacturers won't have these kinds of issues (apparently, they do license the lens mount technology).

Again, this is usually an issue with older Sigma lenses. But, it's not that unusual to see problems reported with newer Sigma lenses from time to time, too -- requiring a trip back to Sigma to get sorted out. I've even seen some reports that Sigma has asked camera owners if they'd consider letting them send their camera body and lens to Japan to try and get them working right.

But, I'd be inclined to send them just the lens (since, I don't recall anyone else reporting any major issues with the 24-70mm on a KM body). It may just be defective (or they may have newer firmware available and can easily rechip it for you).



JimC is offline   Reply With Quote
Old Oct 28, 2006, 12:16 AM   #3
Junior Member
 
Join Date: Oct 2006
Posts: 2
Default

Check this thread



http://forums.dpreview.com/forums/re...ssage=20573991
hassert is offline   Reply With Quote
Old Oct 28, 2006, 1:09 AM   #4
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

I missed that one. lol

My favorite walk around lens for an old Nikon body I have was always a cheap old Sigma 35-70mm f/3.5-4.5 "Zoom Master" with noisy focusing. But, it took sharp photos with good contrast and color. The gears finally wore out it in though. So, it would grind a bit from time to time until you switched to MF and moved the focus some. Then the AF would work OK again for a while. But, it was used a lot (thousands of images), so I got my moneys worth out of it. lol

I haven't tried any Sigmas on my KM 5D yet. But, the 70-200mm f/2.8 EX series lenses are highly regarded by most KM DSLR owners that have them. So, not all Sigma lenses have issues, and they can rechip some lenses for better compatibility.

I'd send a lens with an issue back to Sigma and let them take a look at it.
JimC is offline   Reply With Quote
Old Oct 29, 2006, 2:36 AM   #5
Junior Member
 
Join Date: Oct 2006
Posts: 2
Default

Thank you both for your input.

I have looked at the link provied and I conducted the test myself with the batteries, (different objects for me.) I tried at first with the Sigma 24-70mm and focused on the front object. It did capture it but it wasn't sharp at all. I then tried it with a Carl Zeiss 50mm on M42 mount and the picture came out remarkably better than the Sigma. However, it still could have been a bit better.

I have had my Minolta 7d sent in for CCD censor realignment and when I received it back, the pictures were sharp, colours vivid. However after time this slowly started to dissapear, only slightly though. I have had a look on the net about this and they have said that there are three screws on the bottom of the camera that adjust the ccd position that come loose. Mine doesn't have this? Is it possible to test whether your CCD censor is in the right position?

Thank you once again.
Elek
elek is offline   Reply With Quote
Old Oct 29, 2006, 6:55 AM   #6
Senior Member
 
cope's Avatar
 
Join Date: Jun 2003
Posts: 718
Default

The screws are under the bottom rubber pad. Some have reported good luck with DIY adjustments, but some found that they only made things worse.
cope is offline   Reply With Quote
Old Oct 29, 2006, 11:31 AM   #7
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

If you're seeing the problems with the lens on both the 5D and the 7D, along with "lens not attached" errors, that sounds like it's more likely to be a lens problem to me (problems with the same lens on two different bodies).

KM used a 50mm f/1.7 to calibrate the Autofocus. Do you have another lens you can try with the cameras?

One way to check them real quick is to stagger some boxes, books, CD/DVD Cases, or similar items on a table.

Then, shoot the middle item and see if the ones just in front of it and just behind it are softer.

For example, this quick test I did using a 100m f/2 with my 5D last year using a few of my wife's books, focusing on the book in the middle (no comments on the books please). :-)

If the book in front my focus point would have been sharper, the camera would have been front focusing. If the book behind it would have been sharper, it would have been back focusing. It looks close enough to me (especially since light was low).

Full Size Image:

http://www.pbase.com/jcockfield/imag...3/original.jpg

JimC is offline   Reply With Quote
Old Oct 29, 2006, 3:48 PM   #8
Senior Member
 
bernabeu's Avatar
 
Join Date: Jan 2005
Posts: 990
Default

print this from the attachment:

(shoot at a 45 degree angle)

Last edited by bernabeu; Jun 27, 2015 at 4:24 PM.
bernabeu is offline   Reply With Quote
Old Oct 29, 2006, 4:22 PM   #9
Senior Member
 
cope's Avatar
 
Join Date: Jun 2003
Posts: 718
Default

This is the text from Minolta:

[align=center]KM 5D/7D Front/Back Focus Test[/align]


The AF system might be causing the focus to shift in front or behind the subject. You can do a quick test to determine this. We recommend photographing three cereal boxes or similar items (cake mix, etc) on your kitchen table. We recommend these because they provide a flat plane with fine detailed print that make focusing and determination of focus point easier (the back of the box might be the most detailed).

Place one box in the center of the table make sure it is parallel to the camera's image sensor. Place another box parallel to the first box and in front of it about 1 inch in front and slide to the right to so that you can see most of the first box. Place the third box 1 inch behind and parallel to the center box and move it to the left. Framing all three, you should be able to see most of all three boxes. Use center focus to focus on the middle box. Take a shot with a shutter speed of at least 60 and lens aperture at the widest opening. Observe the shot. Is the center box the sharpest and the front and back boxes un-sharp? Is the front or back box sharper than the center box or is the sharpness of the front or back box nearly equal to the center box? If the very first case, the center is sharpest, the camera is OK. If either the front or back is sharper, the camera needs adjustment.
cope is offline   Reply With Quote
Old Oct 29, 2006, 4:33 PM   #10
Junior Member
 
Join Date: May 2006
Posts: 29
Default

Well I did test my KM5D with 50/f1.7 for focus shift and from photos I have taken in church. I was trying to get a good picture of a person in front row and with different appertures I was constantly getting second row of people in focus and my subject which I was focusing on (spot focus - face) was out of focus. So I think my camera has back focus problem.....or is it lens problem? But I noticed similar thing with my Tamron 28-300 especially with range 200 to 300....for me it is hard to get subject in focus in that range even with f8. So that point out that my camera may have problem....??? hmm ...now what is the solution...???
Steve101 is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 7:32 AM.