I've begun playing with image stacking for DoF as outlined in these forums lately. I'm using Bridge then Photoshop PS5 & a robust laptop (windows) with 4 GB of memory. When I stack several photos (9 photos in most attempts), I get a strange blurry "frame" around the edges of the photo when completed. I've uploaded an example of this.
I'm stacking the photos as layers in PS, the using EDIT/AUTO ALIGN LAYERS, then EDIT/AUTO BLEND LAYERS & checking "stack images" and checking "seamless tones & colors".
I'm shooting with a 5Dii & Sigma 150 macro lens, although that should not matter, as no evidence of this "frame" is present in any of the raw images.
The blurry edge is because changing focus changes focal length (nearer focus results in greater magnification) - at least with every lens I've paid attention to - so in the process of aligning the images some of them need to be rescaled. The end result is that you end up with a little blurry border.. just crop it off (and remember that that happens.. so you can leave room in your compositions in the future).
You might want to download a free trial of Helicon and compare the results you get with that compared to those of Photoshop. I've had much better results with Helicon although must admit that I haven't given CS5 much of a try.
I'd also consider looking at Zyrene Stacker as well. Both programs have thier strengths and weaknesses, depending on the user and the shots.
I think Floris is correct about the focal length changing. One apsect about how modern internal focal length lenses work is that as the focal distance changes, so does the focal length. A 180 mm macro is going to be 180 mm when focussed at infinity, but may be as low as 120 mm (2/3)'s when closed focussed to 1:1.
Also, for an object as large as this and from the angle shot at, you probably need more than 9 images to handle the edges.
Discussion
3 repliesI'm stacking the photos as layers in PS, the using EDIT/AUTO ALIGN LAYERS, then EDIT/AUTO BLEND LAYERS & checking "stack images" and checking "seamless tones & colors".
I'm shooting with a 5Dii & Sigma 150 macro lens, although that should not matter, as no evidence of this "frame" is present in any of the raw images.
Any ideas on what might be causing this?
I think Floris is correct about the focal length changing. One apsect about how modern internal focal length lenses work is that as the focal distance changes, so does the focal length. A 180 mm macro is going to be 180 mm when focussed at infinity, but may be as low as 120 mm (2/3)'s when closed focussed to 1:1.
Also, for an object as large as this and from the angle shot at, you probably need more than 9 images to handle the edges.