Why some photos come soft

[arash_hazeghi]

I wrote a short article on my blog pointing out some issues that result in soft photos and are sometimes mistaken for focus/focus micro-adjustment. You can read it here if you are interested

http://arihazeghiphotography.com/blo...always-needed/

[Doug Schurman]

Nice job on the article Ari. The examples are very illustrative of your points.

[Andreas Liedmann]

Thanks Arash for the article , very informative . Good job all around.
Just a question , why has the dollar note a lot more contrast on RHS ? Is it just because it is just sharper in first place ?

THanks Andreas

[Joseph Przybyla]

Thanks Arash, very informative and written in easy to understand concepts and language.

[Paul Whitbread]

Atmospherics is one of the factors that gets overlooked all too often, so it'll be useful to have something to point people at. And I have say, that harrier photo is a stunner.

ps. Did you know your homepage goes to a Doetsy holding page?

[Robert Hardy]

nicely put Arash .

Rob.

[arash_hazeghi]

Thanks everyone, Andreas sharpness and perceived contrast are closely related

[john stirk]

Very informative, thanks for posting your findings, it gives me something to think about, and explains a lot of things clearly.

[Joe Subolefsky]

Great read thanks for putting it together.

[arash_hazeghi]

Thanks John and Joe

[Liam Behan]

Great Read, Thanks Arash, However I have had 3 7D2 Bodies and no matter what I did I could not get a sharp image in AI servo and at 10fps the in focus rate was only about 30%. I micro adjusted my 70-200 L IS II, 70-300 L IS and 100-400 L IS II but no improvement, except for stills and sometimes they where soft. I thought it was me making operator error, so I used my 1D4 in same situation side by side. My 1D4 was tack sharp. I have retuned the 3rd body with Canon Ireland full agreement and no argument, so maybe they know they have an issue. I plan to buy another when the original first batches are exhausted and hopefully a firmware will be released.

[arash_hazeghi]

Great Read, Thanks Arash, However I have had 3 7D2 Bodies and no matter what I did I could not get a sharp image in AI servo and at 10fps the in focus rate was only about 30%. I micro adjusted my 70-200 L IS II, 70-300 L IS and 100-400 L IS II but no improvement, except for stills and sometimes they where soft. I thought it was me making operator error, so I used my 1D4 in same situation side by side. My 1D4 was tack sharp. I have retuned the 3rd body with Canon Ireland full agreement and no argument, so maybe they know they have an issue. I plan to buy another when the original first batches are exhausted and hopefully a firmware will be released.

Hi Liam,

As I mentioned in the article despite common internet wisdom micro-adjustment is unlikely to help with inconsistent AI-servo focus issues. The lenses you used are short, so getting a sharp image should not be that difficult. If you have ruled out operator error the cameras must be defective.

I tried the 7D2 once and it struggled in my hands too. The AI-servo was not stable. I know that Doug Brown had issues with two bodies but I believe he got a third one that works OK. http://arihazeghiphotography.com/blo...-100-400-l-ii/

The phase detect AF system is extremely sensitive to the sub-mirror assembly and alignment of the micro-lenses that are used to project the light on the AF sensor at the base of the camera. A slight misalignment can cause inconsistent results in AF.

My guess is that manufacturing and/or calibration process for the lower cost cameras such as the 7D series is not as tight as the 1D/5D series that leads to this kind of inconsistent performance. The cost cutting has to show somewhere and this is one of the corners that was cut to bring the price down. To be fair, the target market for this camera is not working professionals but mostly photo enthusiasts and more advanced armatures so maybe Canon believe this level of tolerance is OK for them. You get what you pay for

[Amit Rana]

Very informative article Arash. The atmospheric refraction was an eye opener and something to keep in mind when shooting.

[Liam Behan]

Thanks for the insights Arash. As always your knowledge is brilliant. Well I received my fourth 7D2 body from Canon on Friday and I seems the AI servo is working great and the camera is very sharp over all, its a later serial number so maybe the production run has been tweaked. One question though, when doing MAFA's, live view adjustments are different to non live view adjustments!, do you think this is because of the dual pixel technology as I also noticed this with a previous 70D I had. So I used a lens align and done a non live view MFA for my 70-300 L IS - Also I have the Tamron 150-600 and a MFA on that confirms the lens is soft.

[arash_hazeghi]

Liam, micro-adjustment only applies to phase-detect AF with the AF sensor. Live view AF is though contrast detection with the imaging sensor. There is no micr-adjusemnt for that.

[Liam Behan]

Thats what I thought, in you older guide to MFA you use eos utility in live view what would you now do.

Cheers
liam

[arash_hazeghi]

Thats what I thought, in you older guide to MFA you use eos utility in live view what would you now do.

Cheers
liam

The guide is correct but I think you are confusing live view method with live view AF.

In Live view mode you can either focus with the image sensor, this is called contrast detect or "live view AF". MA does not apply to this mode. You can also use phase detect or "quick mode" AF which uses the AF sensor. This is what you need when doing micro-adjust.

best

[Liam Behan]

Great Arash, Thank You Very Much!

Liam

[Liam Behan]

Hi Arash, me again!

I just noticed on the 7D2 I cannon select Quick Mode Phase Detection, so I went to the manual and it says, - During Live View shooting and movie shooting, the AF control method (phase-difference detection with the image sensor or contrast detection) switches automatically depending on the lens type and function used such as magnified view. The AF speed may therefore change greatly and focusing may take longer -

But it fails to say what AF method uses phase or if you can lock it to that? My 6D has Quick AF as did my 70D


Liam

[arash_hazeghi]

Hi Liam,

you are right. With the 7D2, the image sensor can also perform some crude form of phase detection using the dual-pixel technology but this method is to compliment the contrast detection. It is quite slow and doesn't provide subject tracking like AI-servo. Unfortunately it seems like with the 7D2 you cannot force the camera to use the main AF sensor in live view mode like the other bodies, so you cannot use LV for micro-adjustment. you have to take photos at each setting and compare them manually.

BTW, I wouldn't spend too much time on MA. As I mention in the article the reason most photos come out soft is operator error, poor conditions or both rather than focus adjustment.

Best

[Liam Behan]

Hi Arash,

i have been been doing the comparison method slower but works. You ar also correct on why photos come out soft,
Sorry I went off topic.
Liam

[arash_hazeghi]

Thanks everyone who read the article and left comments on my blog

[Richard Stern]

Great article. Here in NS this Winter, where the outdoor temp. has been -5 to -20 deg. C. for about 6 weeks now, the atmospheric refraction effect around the car, where the inside temp. is around +18 deg. C., is almost continuously so severe that it makes using the car as a blind almost impossible, as focus hunting and inaccuracy is almost continuous with any lens.. You have to get out and move several metres from the car's "heat envelope" to minimize it, which defeats the purpose of the blind. An alternative is to open the car windows for about 20 minutes in the hope that the temperatures will partially equalize enough to minimize the effect. I was pleased to see that you mentioned this effect, but thought I would mention this extreme example of the phenomenon.

Richard

[arash_hazeghi]

Hi Richard,
That's right. When shooting from a vehicle on a cold day my suggestion is also to roll down the windows turn off the heater and drive for at least 15 min. The inside of the car will become cold and uncomfortable but you can often reduce the heat shimmer from the vehicle itself.

best

[David Stephens]

Great article. Here in NS this Winter, where the outdoor temp. has been -5 to -20 deg. C. for about 6 weeks now, the atmospheric refraction effect around the car, where the inside temp. is around +18 deg. C., is almost continuously so severe that it makes using the car as a blind almost impossible, as focus hunting and inaccuracy is almost continuous with any lens.. You have to get out and move several metres from the car's "heat envelope" to minimize it, which defeats the purpose of the blind. An alternative is to open the car windows for about 20 minutes in the hope that the temperatures will partially equalize enough to minimize the effect. I was pleased to see that you mentioned this effect, but thought I would mention this extreme example of the phenomenon.

Richard

I'm in Colorado and routinely shoot from my car-blind in temperatures from 100 F to -15 F. Humidity is relatively low here, so all I do is roll down the driver's side window and set the heater low. Here's one that I shot from the car Saturday, with snow and temperature in the teens F:

Immature Bald Eagle Flies By by dcstep, on Flickr