Northwinds
Posts: 15
Location:
Registered: 16 Jan 2011
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maybe a noobie question on exposure
Posted: 20 Apr 2011 at 18:20 GMT
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Ok I should probably know better but I've been taking some panos recently with my Canon 7D and my Sigma 4.5mm fisheye lense.
That part is all good - 3 shots at 120 degree intervals on my nodal ninja - 1 straight up zenith shot and 2 or 3 for nadir patching.
Now here's the problem:
I keep the 7D set to Manual exposure and make sure every exposure is right in the middle, but when it comes to patching the nadir shots in their exposures are way off with the rest after they're patched.(PTgui)
This might be pretty basic but ......anyone?
Thanks in advance.
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Smooth
Posts: 3774
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 18:45 GMT
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Northwinds said: I keep the 7D set to Manual exposure and make sure every exposure is right in the middle
I assume you are NOT changing the exposures between images within each panoramic set? All must be the same. Of course you need to shoot fast enough to allow for changing light.
My second thought is that you haven't mentioned White Balance. You must use a manual white balance and keep well away from AWB. Same is true for ISO stay away form all things auto.
Next thought is to make sure you are not allowing light through the view finder by using the view finder cap or by covering it. Light entering the chamber from reverse is a bad thing.
Regards, Smooth 
www.omnipix.com.au
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Northwinds
Posts: 15
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Registered: 16 Jan 2011
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 19:02 GMT
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Thanks - great suggestions but I don't think that's it!
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Smooth
Posts: 3774
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 19:13 GMT
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Northwinds said: Thanks - great suggestions but I don't think that's it!
Well, it's very hard to answer on something without seeing the files. Upload them so we can see. It can only be so many things ....
Regards, Smooth
www.omnipix.com.au
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Northwinds
Posts: 15
Location:
Registered: 16 Jan 2011
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 19:44 GMT
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I think I may have figured it - been reading several other posts here on exposure - when I mentioned earlier that I was essentially shooting manual but making everything 0ev - could this be the problem?
Thanks.
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mediavets
Posts: 1980
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 20:42 GMT
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Northwinds said: could this be the problem?
Thanks.
Yes.
Andrew
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Northwinds
Posts: 15
Location:
Registered: 16 Jan 2011
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 21:50 GMT
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So would suggestions like using the histogram to compare shots be the best way forward?
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tturner
Posts: 218
Location: Dallas,TX, United States
Registered: 28 May 2006
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 21:56 GMT
updated: 20 Apr 2011 at 22:15 GMT
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NW,
Are you changing the exposure between shots? If so then that is your problem. Keep the same shutter & f-stop for the entire pan.
Regards,
TTurner
edit: sorry, missed that Smooth already mentioned that.
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Doug Aurand
Posts: 3282
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: maybe a noobie question on exposure
Posted: 20 Apr 2011 at 23:03 GMT
updated: 20 Apr 2011 at 23:04 GMT
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Northwinds said: Now here's the problem:
I keep the 7D set to Manual exposure and make sure every exposure is right in the middle, but when it comes to patching the nadir shots in their exposures are way off with the rest after they're patched.
TTurner is right.
If you are saying you manually keeping the exposure in the middle of the Meter Scale and that involves a different shutter speed each time, that's your problem
All the shots have to be at the same settings; same ISO, same f/stop, same shutter speed.
I shoot between 5 and 8 photos, bracketed in each position, for HDR blending and the exposures of the brackets have to be exactly the same at each position.
But I disagree with Smooth about the White Balance
With super wide lenses, like your 4.5mm and my 4.88mm, and so much overlap, I find PTGui has no problem with blending the White Balance. While narrower lenses can cause the White Balance to be specific to a much smaller area like a lamp could cause.
Hope that helps
Doug Aurand
Albuquerque, NM
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Smooth
Posts: 3774
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: maybe a noobie question on exposure
Posted: 21 Apr 2011 at 6:17 GMT
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Doug Aurand said: But I disagree with Smooth about the White Balance
Disagree all you like Doug, but as usual you're wrong. Don't continue to push your low budget, take a guess - bad habits on to others learning.
You sprouting or reaffirming what has already been clearly stated doesn't add anything to the thread either.
Smooth
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hindenhaag
Posts: 729
Location: Netherlands
Registered: 7 Mar 2010
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Re: maybe a noobie question on exposure
Posted: 21 Apr 2011 at 7:34 GMT
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Hi NW,
best thing as Smooth already asked for is to upload the files.
Anyway, Did you already try exposure correction in PTGui? >advance, >Exposure / HDR
Heinz
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Northwinds
Posts: 15
Location:
Registered: 16 Jan 2011
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Re: maybe a noobie question on exposure
Posted: 21 Apr 2011 at 8:01 GMT
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Thanks all for your comments - I think it was a fundamental misunderstanding on my part!
I'll try shooting a new pano either today or tomorrow and get back with the results.
many thanks!
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Pete Loud
Posts: 397
Location: United Kingdom
Registered: 14 Oct 2006
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Auto white balance ?
Posted: 21 Apr 2011 at 10:50 GMT
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On outdoor panaos I use the same white balance settings, in the conversion from Raw.
On indoor panos, where there are many different types of light sources, I use auto white balance and let PTGui blend them. I don't have problems with it.
Here is an example of an indoor scene with Auto WB. It has daylight, incandescent lights, florescent lights, even mercury lights.
www.peterloud.co.uk/photos/Newcastle/Grainger_Mar...
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Smooth
Posts: 3774
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: Auto white balance ?
Posted: 21 Apr 2011 at 12:13 GMT
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Pete Loud said: On indoor panos, where there are many different types of light sources, I use auto white balance and let PTGui blend them. I don't have problems with it.
So what is your point here Peter? Your camera happens under some circumstances to get the white balance correct under certain lighting situations. Cameras are notoriously bad at correct white balance under artificial light. One of the main things you will read on any quality camera review is the white balance "issue" under certain lighting situations.
OK, so you and Doug or even I can get acceptable results using AWB in some lighting circumstances and what differences there are can be dealt with with PTGui blender. This still doesn't make it right or optimal and definitely shouldn't be passed on as an accepted method to somebody learning. People should learn the correct procedures from the beginning.
The fact is, AWB is not the correct setting for panoramic shooting. You might be able to get away with it, sometimes. But you are taking a risk. Just as it isn't correct to use different shutter speeds or apertures between shots when you are attempting to make a single converged panoramic photograph.
Anyway, I'm not interested in a "Zzzzz Doug" argument. I've tried to explain the way it should be done to Northwinds. People take short cuts everyday and it typically reflects in the results.
Regards, Smooth
www.omnipix.com.au
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Pete Loud
Posts: 397
Location: United Kingdom
Registered: 14 Oct 2006
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Re: Auto white balance ?
Posted: 21 Apr 2011 at 12:24 GMT
updated: 21 Apr 2011 at 12:25 GMT
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Smooth
"Your camera happens under some circumstances to get the white balance correct under certain lighting situations."
That virtual tour had three examples where Auto WB worked well under varied light types, how many more do you want to see?
Here's another half dozen, or so.
www.peterloud.co.uk/photos/SEAsia_07-08/BQ2.html
Want any more?
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