Sigma 85 1.4 DG with 7d, is it a bad copy?

Discussion in 'Canon EOS' started by bhavesh, Nov 14, 2010.

  1. Hi,
    I've heard great reviews of sigma 85 1.4 DG, i know i was not going for 1.2 L in near future so decided to buy it from Hong Kong.
    It looked decent at first but as i brought it home and tested it for a few shots i found it very soft. 1.4 was almost not usable in 8 out of 10 shots. the lens was getting good sharpness only after 3.5, which is not the case with most of the other photographers who use this lens currently.
    It is quite fast even in low light but misses focus 5 out 10 times, is it the problem of 7d or85 1.4?
    I'm hereby posting some test shots please let me know what do you think of it.
    00XgEv-302033584.jpg
     
  2. how can i upload more pictures in one post?
     
  3. 100% crop of the image in above post
    00XgF4-302037584.jpg
     
  4. one more image @ 1.4, 1//160
    00XgF8-302039584.jpg
     
  5. 100% crop of above image
    00XgF9-302041584.jpg
     
  6. at many times the issue is that it focuses at some other point only than the 'red' dots that it shows in the view finder.
    PS : Hight ISO Noise reduction was on in my camera, during above shots.
     
  7. Sigma lenses often have front- or back-focusing issues and need to be calibrated to your camera. Sharpness does indeed look not that hot... I hope yours is just a bad copy and Sigma will sort this out. I had high hopes for this lens, too.
     
  8. Sigma and focusing issues go hand in hand... just do a search. They seem to be more plagued with focus issues on Canon equipment, probably something in trying to decipher the Canon focusing system. If you can, return it for another copy. You'll find lots of people send to Sigma for "adjustment" and never get things sorted out.
     
  9. First: why are you testing focus at 1/160th and ISO 800? Are these hand-held shots? Since such tests don't involve aesthetics, put the ISO back down where it belongs, use a tripod (to keep things in a fixed position), and use your flash. Those shots look underexposed, and softened by the high-ISO nature of the exposure. That's no way to evaluate the lens!
     
  10. I agree with Matt. Use tripod or test during daylight to achieve fast speeds. I can tell you that Sigma 85 is sharper than 85L (at least my copy) so first eliminate user error. If still soft then I would exchange it.
     
  11. Have you tried the micro focus adjustment feature of your 7D? I don't have the Siggy but my EF 85 1.8 USM and 50 1.2L USM focus accurately and quickly on my 7D. No problems in low light. Unless you have problems with other lenses, your focus problems are due to the Sigma.
    Try the spot AF mode and see if you can increase the precision of target acquisition. The larger points could be touching something brighter or more contrasty in front of or behind your target. If it consistently misses and locks on something else, you need a micro focus adjustment. I've read many guys need to really max out the MFA to compensate Sigma primes.
     
  12. Matt's right. Use tripod, low ISO and I'd shoot something with better detail than a table and add more light if possible. Dull room light and even slight underexposure kills apparent detail. Using the middle focus point only is the most accurate option but as we're not focus testing here just use manual focus and live view 10x the get it right.
     
  13. Hi, can anyone help me.. how to do micro focus adjustments on 7d for my 85 1.4. i'm completely new to the concept. Can anyone send a link or explain from scratch?
     
  14. Perhaps my standards are low, but given that the shot is at ISO 800, handheld, with the DOF that comes with 85mm 1.4, I guess I am not all that sure there is a problem here. Maybe I am alone?
     
  15. I'm not sure either and that's why it's worth testing better.
     
  16. Hi, can anyone help me.. how to do micro focus adjustments on 7d for my 85 1.4. i'm completely new to the concept. Can anyone send a link or explain from scratch​
    Bhavesh, have you tried going out of your house and taking some real world pictures with the lens? If not try it and share your results after that. If issue continues then exchange the lens.
     
  17. Professional camera shops can usually adjust the focus of an auto focus lens if they have both the lens and camera. I have a Canon 7D and a few Sigma lenses, the 10-20mm and the 150-500mm. So far I have not had any problems with the auto-focus and the lens have been better than I expected.
    Jim
     
  18. Hi, can anyone help me.. how to do micro focus adjustments on 7d for my 85 1.4. i'm completely new to the concept. Can anyone send a link or explain from scratch?​
    Don't you have the camera's manual?
     
  19. The screw on the edge of the table is the only variation in the pattern.
    So it grabbed the focus point.
    Using that many focus points result in random focus from any lens. Use a single focus point or center with assist points.
    I have not seen any issue with focus on my Sigma 85mm F1.4 and 5D II
     
  20. New results, i clicked some pictures in broad day light with shutter speed more than 1/2000 and 4 out of 10 shots were not on target @ 1.4 here are the details
    00Xh35-302805584.jpg
     
  21. 2nd one not sharp at all..
    00Xh36-302807584.jpg
     
  22. 100 % crop of above picture (picture 2)
    00Xh37-302809584.jpg
     
  23. this one too missed the target, picture 3.. will upload more pics soon what do you say? should i change the lens?
    00Xh3A-302809684.jpg
     
  24. 100% crop of above picture
    00Xh3B-302811584.jpg
     
  25. one more example, picture 4, 1.4, 1/4000, iso 500
    00Xh3E-302813584.jpg
     
  26. 100% crop of picture 4
    00Xh3F-302813684.jpg
     
  27. Were the other 6 images sharp? Can you post an example? The lens is very sharp at 1.4 but don't forget that at 1.4 DOF is very shallow so it's easy to miss.
     
  28. @ Ilya,
    1) the images that i just posted earlier are sharp enough at 1.4?
    I'm confused, is this result due to my inability to shoot correctly at shallow depth of field or my lens is not upto the mark?
    here is the sharpest image @ 1.4
    00Xh3p-302819584.jpg
     
  29. 100% crop of the sharpest picture
    00Xh3s-302821584.jpg
     
  30. If this is your sharpest photo then I suspect there is a problem with the lens. Do you have any other bodies to try it on? You could probably use microadjustment feature of the 7D to see if it will cure the problem but in any case I would try to exchange it. 100% crop of one of the test images I made with it at 1.4. As you can see it's tack sharp.
    00Xh4S-302825584.jpg
     
  31. Try taking photo using the AV setting, you should have only one focal point, that close to the subject you depth of field is only a centameter or two at most.
    http://www.dofmaster.com/dofjs.html
    Jim
     
  32. My first ever lens was a Sigma 28-90 or something like that with a Canon film body Eos 300 I think. For 2 years of my daughters life most of the shots are OOF and I thought it was just me. Then I found PN and asked what lens to buy -> 50mm 1.4 -> amazing in focus photos.
    I'd never touch another Sigma.
    A little off subject but hey ho.
     

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