AF in Canon 7D-Is it Possible

[The_Moaner]

Hi All
I really need to sort this dillema out once and for all. I need to stop MOANING about my lens. AF in Canon 7D-Is it Possible for the focus to look good with a Sigma 17-70mm f2.8/4 IS but look terrible with a Sigma 150-500mm.

Turkeyneck (Lee) kindly met me at LLanelli Wetlands the other day and I set my camera to AUTO iso and Spot metering with spot focus on AI Servo, back button to focus. A setting I don't normally use but others do and they get good images on their 150-500mm. There is no difference to this setting in AF (focusing) to what I normally use. Non that I could see.
This lens is Brand New and was repaired by Sigma a month before Xmas. Focusing was wrong. Still wrong as far as I'm concerned.
Some images (maybe all) are noisy because of high iso that I don't normally ever use.
Anyway, have a look and pop back in here with your comments.

I need to sort this out before I commit my cash to a canon 400 f5.6 and have a 150-500 on my hands doing nothing. Maybe a letter to Sigma head office to ask what is going on with this lens?
Cheers All.

[Jonners]

Originally Posted by The_Moaner

Anyway, have a look

... where?

[squishy]

Sounds like you either have a soft copy of the 150-500, or you've got focus accuracy issues. You can find tutorials on how to adjust the AF microadjustments through google.

If the focus is slightly front or back, auto-focussed images will be slightly out of focus. Try setting it up on a tripod, and take a picture using autofocus, then without altering the framing at all, take another photo but carefully manually focus it using live view zoomed in. If the auto-focussed image looks softer than the manually focussed image, it's an AF accuracy problems.

[The_Moaner]

Sorry I forgot to post my Link--http://mrdennis.zenfolio.com/

Micro Adjust is only Good for Fixed focus lenses like 200/300/400/

Not much good for 150-500mm as then only the 500mm will be focused.
So is inoperable as far as I can see.

Surely if it is Soft Focus on lens then when Sigma supposedly fixed the focus lens in side, then it should be fine. I'm not a camera techie kind of person so most of the technikal side leaves me brain dead.

I must solve this before it drives me into the Nut-House.

Thanks for helping.

[nutmeg]

I took a look at your images and have a few questions:

How much post-processing was done and what? The green head of the mallard in particular looks like it was under exposed and lightened and the noise shows up a lot. Have you cropped the images? What size were the subjects in the originals?

Looking at your settings, it looks like you were shooting with the lens pretty much wide open for all and at some quite low shutter speeds for some. I don't have this lens, but if I recall correctly it gets far better results in good light and at f/11 or smaller.

[zan]

YOu can drive yourself mad with focussing issues, but I would suggest you get your tripod out and follow the instructions for doing the micro AF adjustment. Whether you actually adjust your lens or not is up to you, but if you follow the procedure laid out in one of the tutorials you'll be able to tell far better whether there's a real issue with the lens or if it's down to technique.

I spent about a month after I got my 7d convinced that there was a focus issue and went through the micro AF adustment with my 300mm and 300mm+1.4x converter. sure enough, there was nothing wrong with either set up, the problems were all down to me. I'm not suggesting that this is your issue, but it's definitely worth checking it out in a standardised manner before you buy a whole new lens.

[The_Moaner]

Hi Nutmeg

I was useing settings I don't ever use normally. Was told to try it out for that day as the other person with same set up gets quite good results.

Auto iso--Spot metering--Centre Spot Focus. From 0 to + 2/3rds.

I normally use iso 800 Centre Spot or Normall or the 5 cluster (as i call it).

I do understand that if speed is too low I will not get sharp images. I won't moan about that, as I understand that. As for the Dark images, I'm still trying to understand this focusing on 7D as I find it too complicated for it's own good. Canon messed up there I reckon. Trying to change from -1/3rd to + 1 stop whilst trying to catch a bird in flight etc is not easy to me as I'm use to cameras getting my image correct when I first set it up.

I agree, Mallard was slightly underexposed and some images were at iso 1600 or 3200 of which I hate useing and never normally use because of noise.

I do know that some misstakes are down to me, but not all.

If I can get Good Sharp images with my 17-70mm and other lenses, then I should get some with this 150-500mm.

Thank You for Helping me out on this--Appreciated

[The_Moaner]

Hi Zan

I have been told that the Micro Adjust is only any good with a fixed lens like 200mm or 300mm or 400mm etc. Not very Good with Tele-Lenses.

No point in useing a tripod as I do not have a remote controll.

I am driving meself NUTS. lol. Probably driving you lot Nuts as well.
I am Greatfull for all the Help from the members on here.

I must be honest here and say I don't understand this Micro AF Adjustment anyway. With my eyesight It will probably end up worse anyway, so best left alone by me.

I am going to ask one of my friends if I can use his 7D with my lens, then get him to use it on his 7D and Mine. Hopefully I'll have this sorted by end of Jan or before. With your Help and others help I'll probably stop Moaning soon. Golly, I'll have to change my name in here then.

THANKS....Dennis

[squishy]

Originally Posted by The_Moaner

No point in useing a tripod as I do not have a remote controll.

You don't need a remote control to use a tripod

[slimrbp]

I am not familiar with the lens but as has alrady been mentioned you can try out the AF against a static target.
Set the camera up on a tripod or something that will support it properly, choose a low ISO and use the autofocus to focus on a static target. To really make sure that it's all stable then use mirror lock up and as you don't have a remote release use the self timer, take a series of shots at different apertures as well.

Then review this images you should then see if the focus was accurate or not and also how the aperture impacts the sharpness to get an idea of the 'sweet spot'.

With regards to the lens being fixed, if it isn't autofocussing properly with the camera it may be that both need to go in to be calibrated together.