[hkiran1]

https://www.pentaxforums.com/forums/members/51337-hkiran1/albums/5677-k7/

Hi,
I have tried to insert album photos and was not successful, so pasted a link instead.

Just bought an used K7, its near impossible to get Pentax gear in India.

I tried to take multiple shots with exposure bracketing with the picture of the building and used Luminance HDR to combine the pics,

Can any one tell me the difference between Stacking and HDR?

[donras]

Hi --- Stacking is primarily for expanding focus, while HDR is for expanding dynamic range. Both rely on taking multiple photos from the same position and combining them into one. In stacking you change the point(s) of focus, while in HDR you change the exposure(s).

Don

[donras]

Hi -- Not exactly sure, but looks like your photos have similar exposures values. You want to have some photos exposed properly for the brightest areas of the scene, and others for the darkest areas of the scene. Choose one aperture setting for all of your photos, then vary your exposure by using different shutter speeds. You could use automatic exposure bracketing to get a range of exposures, although your range from darkest to brightest seems very high, so manually choosing your exposure seems best in this case.

Don

[hkiran1]

Hi donras
Thanks for the reply. I have used Auto bracketing with 5 snaps with 1/3stop difference. I will try to increase it as 1 stop. Should i need to increase the difference in exposure in day light too while shooting landscapes or 1/3 to 1/2 is enough in good light?

My doubt with Focus Stacking is that whether the same effect can be achieved with adjusting the depth of field?

Also, does the dynamic range also increases with Focus Stacking?

Luminance

is the software which i used(Linux version) to stack those images. Tonight i will try again with increased difference in exposure.


Regards,
Harish

[donras]

Hi Harish - For the photo of the building, I suspect that a 4 stop range would be insufficient, but it depends on what you want to achieve. One way to find out is to use AV mode, set your f-stop, then determine your desired exposure for both the brightest and darkest areas of the scene, noting the shutter speed for each. If the range is larger than what can be achieved using auto bracketing, set the camera on M mode, set the same f-stop, and shoot enough photos at varying shutter speeds to cover the entire range, with 1-2 stop differences between the photos.

Generally you would be using HDR to accommodate large differences in lighting. If you just want to lighten or darken certain areas of the photograph by a stop or two, you can generally do this in post-processing. In this case it is better to underexpose slightly, making sure that the highlights are not blown out, then bring up the shadows in post.

Using HDR will generally cause some loss of overall quality -- perfect registration of all photos is generally not possible -- so I wouldn't recommend it if it's not really needed.

Don

[donras]

Hi Harish - Although HDR and Stacking are similar in that they combine a sequence of photos, they do so for different purposes, the changes that are made from photo to photo are different, and the post-processing is different. HDR is used when you want to capture detail in both the darkest and lightest parts of the scene. The camera sensor is limited in this regard, at best covering perhaps a range of 12 stops at optimum (low) ISO. HDR allows the photographer to effectively increase this range.

Stacking is used to expand the amount of the scene that is in sharp focus. This is probably most often used in macro-photography, where even high f-values such as f-22 or even f-32 are often insufficient to keep everything in sharp focus. For stacking you should typically be using the same f-value and exposure for each shot, and adjusting focus by refocusing on different parts of the subject. The intent is for the entire subject to be in sharp focus in the processed image.

You typically wouldn't use stacking in landscape photography. Using a tripod, you can use a combination of low shutter shutter speeds and large f-values, which provides a large range in which everything is acceptably sharp. In contrast, HDR can be valuable in landscape photography, although I would only use it when absolutely necessary.

Hope this helps!

Don

[hkiran1]

Hi donras,

Thank you very much for the detailed reply. I was a bit too busy due to work and study.
I have repeated the HDR according to your directions and i got a very different looking image from the last one with much more of a range. I am attaching the resultant image here. Now i am noticing colour speckles (white, red, green etc). How to avoid those and why are those speckles forming? I have used Photomatix to do the HDR.

Attached Images