Sigma 30mm f1.4 EX DC HSM

tomcat7886 wrote in post #14200305
nice bokeh.

i think my copy has a bit of a front focus issue, thoughts?

I absolutely love this lens but I'm pretty sure my copy has a front focus issue. Either that or the 1.4 aperture is so razor thin that I can't control it to save my life! Is there any easy way to test this out?

IMAGE LINK: http://www.flickr.com/​photos/touji192/689513​0846/

touji wrote in post #14206009
I absolutely love this lens but I'm pretty sure my copy has a front focus issue. Either that or the 1.4 aperture is so razor thin that I can't control it to save my life! Is there any easy way to test this out?

Put it on a tripod and test w/ a shutter release cable and MLU with a ruler type target. It should be easy to see front focus in controlled testing.

I am dropping by this thread, though, to ask how the focus speed of the Siggy 30 compares to the 35L. Can anyone comment? I have a 5D2 and 7D, and am thinking about buying this lens for the 7D rather than buying the 35L. I'm on a kick of using the 7D a lot lately anyway.

^ I'll have to get myself a ruler then! I really hope it isn't a front focus issue because it will be difficult for me to get through all the procedures to send it in to the Sigma Japan branch!

touji wrote in post #14206920
^ I'll have to get myself a ruler then! I really hope it isn't a front focus issue because it will be difficult for me to get through all the procedures to send it in to the Sigma Japan branch!

You can use anything - a folded strip of newspaper, a set of batteries standing up at an angle... There are a lot of test targets you can print off of the internet (see TeamSpeed's home made target instructions).

touji wrote in post #14206009
I absolutely love this lens but I'm pretty sure my copy has a front focus issue. Either that or the 1.4 aperture is so razor thin that I can't control it to save my life! Is there any easy way to test this out?

IMAGE LINK: http://www.flickr.com/​photos/touji192/689513​0846/
IMG_6210 by touji192, on Flickr

Do you do "focus in the center and recompose technique" at F1.4? I think it's not advisable at wide open.

If it helps, this is how I tested mine - and adjusted the MA on my 50D.

I had this idea, then it was confirmed (with a slight tweak) by finding the same setup here on the forum, though I don't remember how I found it, or the user.

Anyway, here's what I did:

1. Got a fairly large box with some contrasty points.

2. Stacked a few DVDs (and some paper) high enough to lift that box up so that a yardstick would just fit under it.

3. Put the yardstick under the box at an angle, and lined up the 17" mark exactly with the surface of the box.

4. Set my camera up on a book at the other end of the table, so the focus point would be on the 17" mark - or it could have been on a contrasty point on the box itself, probably. I don't have a tripod, which is why I used the book.

5. Also, I measured the distance of each side of the book from the surface of the subject box. This was to ensure (as best I could) that the sensor surface remained parallel to the surface of the subject box. You want to make sure that you are shooting directly perpendicular to the subject - especially when shooting at f/1.4. I hope this makes sense in text.

I know this isn't the most scientific testing method, and it's probably not as good as some of the MA software out there, but I did the best I could with what I had. I feel like I got better results with this than I did by using a normal focus chart or shooting an angled shot of the yardstick alone. I think it helps to shoot perpendicularly at a flat surface, while adding the yardstick to determine front- or back- focusing.

Anyway, here's a photo of the setup. Hopefully this plus the description above will be helpful.

IMAGE LINK: http://www.flickr.com …/64178563@N08/6​824768122/

Jason - very nice setup! I have moved on to FoCal software, but this setup is similar to what I used before, too. Currency - with it's fine markings - makes a good test target as well.

Thanks for some example setups for the focusing!

I am not using focus and recompose, but I'm using AI Servo and holding my back focus button down but trying to snap the shot before the subject moves from the initial focus.

I've taken some great shots with the lens but a lot of times if someone is wearing a hat or they are leaning back, I'll miss focus completely. In the real life situation, it seems like I'm not getting as many keepers as I should and hopefully this test will be able to help me out a lot.

as a long time siggy 30 user, finally contributing....
its become my go to walk around lens. adding my sub as well

1

I guess I may as well post a "real life" photo, even though I was still just testing for microadjustment.

This shot is cropped quite a bit (not 100% though). No other PP other than normal sharpening with unsharp mask in DPP. Focus is on the right eye (her left). I think this is acceptably sharp at f/1.4:

IMAGE LINK: http://www.flickr.com …/64178563@N08/6​817299374/

touji wrote in post #14206009
I absolutely love this lens but I'm pretty sure my copy has a front focus issue. Either that or the 1.4 aperture is so razor thin that I can't control it to save my life! Is there any easy way to test this out?

IMAGE LINK: http://www.flickr.com/​photos/touji192/689513​0846/
IMG_6210 by touji192, on Flickr

I had 2 copies of Siggy 30mm and both were front focusing. First one was from Amazon, shipped back the day after focusing test. Second one was from Adorama and they even did pairing service for me so I can avoid having to return the lens. I guess what was acceptable to them was not acceptable for me, so I ended up shipping the lens along with my T2i to Sigma Service Center in NY. I got my lens and camera back in exactly 1 week including shipping time. Focus is now right on, however,

Looking back, I wish I had kept the lens from Amazon for calibration work instead. Although front focusing issue was more severe, that lens was extremely sharp wide open. It was out of focus at the AF target but very sharp where it was focusing. Now I gotta stop it down quite a bit to get really sharp picture. Everyone say Amazon is the way to go in terms of return policy.

Free Focus Test Charts
http://www.dphotojourn​al.com …ad-free-focus-test-chart/
https://photography-on-the.net/forum/showthre​ad.php?t=750736

This one was a pretty big crop! I have yet to find a printer to print out some charts T_T

IMAGE LINK: http://www.flickr.com/​photos/touji192/690375​6930/