Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Sony Alpha NEX

Reply
 
Thread Tools Search this Thread
Old Sep 25, 2012, 8:09 PM   #1
Junior Member
 
Join Date: Sep 2011
Posts: 8
Default NEX-5N Manual Settings for Nadir Aerial Imagery

Hi all,

I'm new to the camera world, especially the manual settings camera world. I am using a Sony NEX-5N with the 16mm lens.
I am taking pictures from anywhere between 100 and 400 feet vertically. I have my camera pointed at nadir and I am moving at a speed of approximately 4m/sec. I am taking my pictures within an hour or two of noon so the sun is at a high angle in the sky (more than 40 degrees). I am planning to stitch the pictures together into a seamless mosaic.
What are some good settings to use so I get consistent image lighting?
I would just like some suggestions as to where I should start.
I have been using 1/500 shutter speed with a 3.2 f/stop and have been getting mixed results.

Thanks in advance!
Steve
cczeets is offline   Reply With Quote
Sponsored Links
Old Sep 25, 2012, 9:49 PM   #2
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

What do you mean by "mixed results"?

Can you post some examples?
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
TCav is offline   Reply With Quote
Old Sep 26, 2012, 10:15 AM   #3
Junior Member
 
Join Date: Sep 2011
Posts: 8
Default

Thanks for the quick reply TC,

What I meant by mixed results is that I took a series of pictures on two different days (see below). The first two were taken shortly after lunch and the second two were taken shortly before lunch on the next day. The sun angle was very close to the same (only from a different direction) and both days were clear skies. If you look at the pictures, in the first two the colors match good (particularly the roof); in the second two the colors don't match as good (particularly the roof), one is darker than the other.
The way I determined what settings to start with is I took a picture on automatic to see what the camera would use for settings, then I kept doubling the speed while halving the f/stop until the f/stop was at max. I figured that I needed the highest speed setting because of the camera moving. I also used ISO100 because that's what the camera chose. I read that ISO100 or 200 is best for bright outdoor pictures.
Like I said, I'm totally new to manual camera settings... I did some research on speed and f/stop to find that if you double the speed and halve the f/stop, then you should have the same amount of light on the sensor each time. So I used that to try some things out.
I would like to find settings that work good at different sun angles and also on overcast skies. I was hoping to get some starting settings that I could experiment with. Right now I'm just taking pictures and adjusting to see what changes. I was thrown off when I used the same settings and got different lighting between pictures (as in the below pictures).

Thanks for any help you can provide!
-Steve
Attached Images
    
cczeets is offline   Reply With Quote
Old Sep 26, 2012, 11:18 AM   #4
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

From the photos you posted, my guess is that you could greatly reduce (if not eliminate) any differences by fine tuning the brightness and saturation in post processing. Your results during overcast days might require more effort, though, but I'd try it before I made any adjustments to what I knew worked.

Don't use the building or anything unnatural to base your adjustments on; use the grass and the ground only. That's the only thing that will be constant.

I think you're there; you just need to tweak your results a little.
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.

Last edited by TCav; Sep 26, 2012 at 11:20 AM.
TCav is offline   Reply With Quote
Old Sep 26, 2012, 1:21 PM   #5
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

It's possible that the 16mm f/2.8 may be too wide for what you're doing. Is there any chance you can get higher than you are in those shots?
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
TCav is offline   Reply With Quote
Old Sep 26, 2012, 3:23 PM   #6
Junior Member
 
Join Date: Sep 2011
Posts: 8
Default

Thanks for the comments TC!

I haven't done any post-processing of imagery before.
Couple questions on that.
I am currently recording the pictures in .jpg, which I know is lossy. Should I be doing it in raw format for post-processing? Or just post-process the .jpg files? I have also been converting the .jpg files to .tif before I perform the stitching.
If I am stitching hundreds of photos together, is there a way to "batch" post-process the imagery?
Which software would you recommend for post-processing of the imagery?

Yes, I can get higher for the pictures. Should I use the same 16mm lens when I go higher, or try a different lens? If I try a different lens, which one would you recommend?


Thanks again!
-Steve
cczeets is offline   Reply With Quote
Old Sep 26, 2012, 5:00 PM   #7
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,571
Default

Stick with JPEG in the camera, for a couple of reasons. RAW Files are huge, so you won't get as many photos on a card, which could limit the length of your flights. Plus, RAW files may contain extra detail that doesn't really do you much good once you downsample to your final result, it will make post processing more cumbersome, and it may make stitching more cumbersome as well.

There are a number of programs that will do the post processing you want. Many are free and many are reasonably priced. You'll need to pick one that lets you create and manage the really big images you want to create. I can't help you there, but perhaps someone else can comment.

The 16mm lens is an ultrawide angle lens. It's wider angle of view may make stitching difficult. For instance, tall objects will always appear to be leaning toward the outside of the frame, and when you try to stitch one image with another, they may both have the same object leaning in different directions. That may be tough to reconcile in the final image. You may only be able to use about half the image (maybe less), so by flying higher, you will cover more ground with what you do get from each shot.

An alternative might be Sigma's 30mm f/2.8. It's a very good, reasonably priced lens (better than the 16/2.8 you're using)(less vignetting, less distortion, and it's sharper) and it's got a narrower angle of view.
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.
TCav is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 5:32 PM.