50D micro adjustments............. why the big difference

[hus]

Ok just a question regarding these micro adjustments.
The other day I finally got my Tamron 17-50 non VC and did the usual micro adjustment and the lens is dead sharp on +/- 0 which is great news.
My Tamron 70-200 f2.8 seems to require +16 to give me nice sharp pictures no worries but when I put that lens on my sons 400D (no micro adjustments) the thing is dead sharp.

I also put on a sigma 70-200 f2.8 and that requires only +4 adjustment.
First why is the 50D so fussy about these lenes and secondly since the Tamron is so far out should I get it calibrated to my camera so I don't have to have such a big correction for the lens.
Or should I just have the corrections dailed in and not worry about it


Cheers all

[Meumerke]

The only worry I have is at which FL did you apply the adjustments? A tele zoom might need + 4 at FL 200 mm and -1 at FL 70 mm (just using an example). If your tele needs the same correction applied over the whole FL than you're OK.

[hus]

All done at 200 mm at f2.8, I assumed once they were done at 200mm then the rest would fall in place.

[Meumerke]

All done at 200 mm at f2.8, I assumed once they were done at 200mm then the rest would fall in place.

It could be alright for this lens. Just check at various FL. I did several tests with my D7000 / Sigma 150-500mm. It would front focus at 150mm and backfocus at 500mm. Because I use this lens 99% of the time at 500mm, I concentrated on getting it right there.

[Tricky]

Definitely check to see if different micro-adjustments are required at different focal lengths. There could be significant differences at (say) 70, 120, 150 and 200.... or they could all be the same.

I've found zoom lenses the hardest to 'microadjust'. I've generally had to pick a compromise adjustment setting or, where I tend to use a lens mostly at one end of it zoom range, I've biased towards the adjustment required at that end.

[Tricky]

Re-reading your post, I was also going to comment on the different settings that you mention for different lenses. The required adjustment is a combination of how far out your body is out and how far out your lens is. Both could be within manufacturing tolerances (say +/- 5), but if they go in the same direction you could end up needing a 10 adjustment.

With the particular adjustments mentioned, it could (as an example) be the result of:

50D body being -6
Your son's 400D is +10
Tamron 17-50 being +6 (ie perfect match when mated to the 50D body)
Tamron 70-200 being -10 (ie needs +16 adjustment when mated to 50D, yet perfect match when mated to your son's 400D)
Sigma 70-200 being +2 (ie needs +4 adjustment when mated to 50D)

Prima facie the Tamron 70-200 may seem like its out of whack, but it may only be a little outside manufacturer's tolerance. If it can be made to focus properly using micro-adjust then there's no problem, that's what this facility is for. There is no advantage in getting the lens itself re-calibrated.

[hus]

Thanks for the feedback, will be checking at different FL, but even though the Tamron 70-200 needs the biggest correction, it produces really sharp images than what I get with the sigma.

[arthurking83]

Also: This may apply more so to the 70-200mm than the 17-50mm, but I would also check the micro adjust requirements at different focused distances too.

That is, say at 200mm check the micro adjust differences if you focus at something at 2m away and then try again at 10m away. Obviously you may need a different subject at 10m if the subject at 2m is very small.

But if you're using this lens generally at 10m or more and you're getting spot on focus at 10m and you've micro adjusted the lens to suit a distance of 2m, then there is the possibility that at 10m the lens will now misfocus.

[LJG]

Most of my lenses were OK, but I had issues with hitting the focus with my 150-500. I checked and set it with a focus chart in the backyard but it was hopeless in the field at roughly 3 times the distance. So I set out and found a vertical pipe with a joint up high and securing bolts all the way around. I moved away to roughly the distance I am usually away from my subjects (birds) and set up the tripod with remote shutter. I went out to 500mm, focussed on one point, changed micro adjustments at 5 a time, then uploaded into DPP, pixel peeped at 100% and then fine tuned the micro adjustment and set it to the sharpest and clearest image. The setting was completely different than using a focus chart in my backyard. Remember also that your 3rd party lenses are reverse engineered, so may well be out slightly. I could never get my Sigma 150-500 to take sharp images on my 450D, but with micro adjustment on my 50D it is at an acceptable level. My other lenses are all fine, it was mainly the big Sigma that was giving me the irrits. Since using this method my shots are acceptably sharp from about 5 metres to as long as 50 metres. On long shots (infinity) it is no good, but I don’t use it for landscapes anyway haha

[William]

Is this Micro adjusting a new thing on newer Cameras ? I dont and cant do it on my 30D and it seems to focus very well with anything I put on the front of it . I dont remember it happening on the old Film SLR's either , Time for a stupid question , Why !! Whats happened ?

[hus]

Here are the results from both lenes, not really sure which one to use. The distance in this test is roughly the distance my subjects are.
I took shots at different adjustments and then had a look at 100%.
Here are the reults of the sigma

[hus]

Below is the result from the Tamron

[hus]

Also looking at these I was wrong about my Tamron needing such a big correction and the sigma seems slightly sharper than the Tamron

[Bennymiata]

It seems ot me that perhaps you need some negative adjustment on the Sigma, rather than positive adjustment.
The more positive you give it, the worse the image becomes.

Glad I got a 60D, and have never had any problems with my lenses, which are a mixture of Canon, Sigma and Tokina.

[OzzieTraveller]

G'day Hus

Great item for discussion - I read it with interest
There have been other threads along similar lines [not to worry - you're not the 1st to ask this Q]
The article below may interest you too ...
http://www.canonrumors.com/tech-arti...d-other-myths/

Regards, Phil

[hus]

Glad I got a 60D, and have never had any problems with my lenses, which are a mixture of Canon, Sigma and Tokina.

At first I thoght it was a great feature, but now it seems more of a curse as the thing always plays on your mind if you can improve it any further.
Will do some more tests with negative dialed in and see what results I get

[hus]

Here are the Sigma minus results

[hus]

Here are the Tamron minus results

[hus]

It seems both lenes seem sharper without any correction, the object was about 7m away from the camera, at the same level and set at f2.8.
Also it seems the Sigma is sharper than the Tamron but the colour looks better using the Tamron.

My question is do I use the Sigma and for the little bit of sharpness or use the Tamron to get the better colour ?