Photoclubalpha

After some informative discussion on Q&A I decided to play with my macro rails last night. I was planning to stack close ups and found VF on A700 to be problematic. In the image below, the yellow roses in the back ground (on left and right) were not showing in the VF as large as the image suggests. My intent was to take the red rose and shift the focus to yellow roses and stack the two images. I could not focus on the yellows at all since I could hardly see them. Is there a solution to my situation? How do I focus on image that is outside the VF field of view?

With best regards,
Sury

Sury, David or Olaf would be able to explain this one better than most I think, (they are much more an optical expert than I), but if I was to have a guess, it's a question of distance relationships...depending on the distance from the lens to the red rose, AND the distance between the red rose and the yellow roses, (which may or may not be at the same distance either).
The red rose being so close most likely turns into a huge defocussed red blodge covering the entire field of view when you attempt to focus on the yellow roses, correct?
I think the only solution would be to move much further away from the roses and zoom in, even try using a sufficiently deep f-stop to get them all in focus together...maybe.
Greg

You can not stack such an extreme difference. To stack, you must keep the lens to subject distance fixed, and just move the camera. There is a slightly more accurate option which involves keeping the subject and film planes fixed but using a lens with internal focusing (or adding a dioptre). Moving the lens to subject distance will change scales and make stacking impossible.

David

Greg,
I expected red rose to become a blurred blob and the yellow rose to come into focus. My question was about A700 VF not showing the yellow rose in the upper right corner. Because it was a small smidgen, I could not focus on the yellow. The portion of the yellow visible in the image is much more than the amount of yellow visible through OVF. OVF is cropping the image and that made my focus shift impossible. Though not a suitable camera for closeups, A900 OVF may make this focus shifting easier is what I guess.

David,
You are right about the relationship of the lens and subject if I use focus ring to move focus. I did move the focus and of course I got different scaled images as expected which make them almost useless for stacking. I did take three images as pulling away from the image and did the focus shift with reasonable success. I am uploading those images to flickr and will post the link later.

In fact I can post them as examples of what not to do. May be we can have a subgroup where we can post examples of what not to do which could be of as much value as what to do.


My intent was to keep the focus fixed but sweep the image by moving the whole unit using the rails. When I see the red rose through OVF of the image I posted, all I see is red rose and two speckles of yellow in upper right and left. From the image you can see that the image is much wider than what I saw in OVF. I think I am being hampered by OVF Frame coverage which is 95% for A700 and almost 100% for A900, if I got the terminology right.

With best regards,
Sury

Here is the three image stack example.

With best regards,
Sury

http://www.flickr.com/photos/bigsur/set ... 872818999/

and another tangent here
Why recomposing with AF cameras is a bad idea
http://www.mhohner.de/recompose.php

sury wrote:...May be we can have a subgroup where we can post examples of what not to do which could be of as much value as what to do.
Sury

100% agree.

NevHi wrote:and another tangent here
Why recomposing with AF cameras is a bad idea
http://www.mhohner.de/recompose.php

Enlightening article. Thank you. Would the same be true with manual focus and spot selected? The lens is a MD lens
and the camera in this case is moving only back and forth, there is no angular rotation.

With best regards,
Sury