Why Sweep And Stitch?

[Joanna Carter]

Thanks Joanna, yes I have used Manual exposure but of the scenes I was trying to capture the DR was too great-that was the problem I couldn't overcome

I've been inveigled into teaching some sessions at our local photo club over here. It's been a very interesting challenge, especially having to do it all in French. Not only have I learned an awful lot of "photographic" French, I've also had to learn how to teach techniques I do automatically.

What is relevant here is to get to know the DR of your camera and use it to best advantage.

e.g. I have a Nikon D810 and always shoot in RAW. Nikon claim a 14 stop DR and, yes, it is possible but you do have to work to get that range.

To start with, I learnt that you should always expose for the highlights and recover the shadows in post processing. So the first thing I did was to shoot a sheet of textured white kitchen roll, taking a series of photos, incrementing the exposure by ⅓ stop each time, until the over-exposure markers started showing as being irrecoverable in DxO.

By doing this, I found that I could expose at 2 ⅔ over without blowing the highlights. So, now, I will find the "right" exposure by taking a spot reading on the highlight area and then manually adjust that upwards by 2 ⅔ stops.

This helps give you the widest possible range of shadow detail; in my case, realistically, I could retrieve around 9 stops below the "standard" exposure, without introducing too much noise in the deeper shadows.

Since what you see on the back of the camera is an "on the fly" jpeg image, which doesn't have the same DR as the RAW, things will look horrendously under-exposed. Don't panic! This is normal.

When you bring in your RAW images for stitching, you need to make sure you start with a flat, neutral setting. Then you need to recover the shadows on the darkest image, then do exactly the same adjustment to all the others.

You might need to make slight adjustments to some of the layers after stitching them in Photoshop but, on the whole things should be reasonably even.

Anyhow, that's what I do

 

[Digital Finger]

thanks Joanna, OK well I always shoot RAW anyway and although Im never going to be organised enough to do such tests I know from experience how much I can' reasonable expect to pull back from the highlights clipping on the camera histogram, Ive got pretty good at it.

The main problem with canon is that actually it doesn't pull up the deep shadows at all well, which is why I have got pretty good at guestimating how far I can ETTR without losing the highlights as I really need exposure in the shadows.

I have to admit I haven't actually tried a pano with my 5DsR , the last time I tried was with the 5D2 which for my money was crap at shadows, the got really noisy really fast, I I am still judging what I expect by that yardstick

I shall have to try with my current camera. I have tended to try it at the coast here when the sun is in full view and consequently the shadows in the tree line tend to be a long way off what I can salvage

}anyhoo, thanks for the suggestions- I guess I'll have to go out not and give it a go


What are your thoughts about tripods? I know I would always use one for multiple exposures but with panos there's maybe no point as far as I can see without a levelling head or similar, which I don't have or want -- so I'm going to ditch it altogether as I can possibly get results not far off hand holding, or am I mad? (we'll see I guess)

 

[AggieDad]

I stitch multiple images to create a single image that shows a broader field of view than can be accomplished with my camera and lenses.

A 10mm lens on an APS-C sensor camera will have a field of view of about 99 degrees (or about 121 degrees on a 35mm camera). Move up to a 35mm lens with a crop-sensor camera and the result is a mere 37-degree FoV. To capture the broad expanse of a mountain range or the desert in West Texas, I find I want an image of some 140 to 160 degrees width.

There is no doubt that doing a letterbox crop creates an image shape that can be considered a panorama – we might think of any image with 2.5:1 or greater width to height ratio as panoramic. But doing so does not create the broad scope that can be achieved with several images and some stitching.

With today's cameras and software, a stitched photo is easy, and it can be done handheld. Just use manual settings, hold your camera steady, and make sure you overlap your shots by about 25%. I urge you to give it a try.

 

[Andy Puttbach]

There is another reason for shooting a stitched pan over cropped letter box, lens choice. By shooting a multi image pan I can control the angle of view of each frame by the lens I choose. What does this do for me? If I shoot a landscape with an ultra wide angle the background is minimized in relation to the foreground. In effect making mountains or buildings look smaller then they actually are when I look at the scene with my eyes. If I use a normal or longer lens it cuts the angle of view and has the effect of increasing the objects in the background. You can see examples of this in any 101 discussion of lens length. Of course if I use a longer lens I now need more frames to cover the intended pan area. I have been shooting this way for awhile. My taste is to use a 50mm to 100mm on a crop sensor to get the effect I want.
When processing multi frames I also find it useful to process each frame separately in Lightroom then stitch and then process the whole pan again. It helps a lot with exposure issues from shadows and sun.