Can VueScan use different autofocus points for each slide in a batch on a Nikon LS-8000?
Asked 2/2/2021
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I’m batch-scanning five mounted 35mm slides at a time in a Nikon Super Coolscan LS-8000 using VueScan. Some slides are slightly cupped, so focus can vary across the frame.
A single fixed focus point for the whole batch is easy, but it can fail if that point lands on an area with little detail. Manually previewing each slide and moving the focus crosshair to a textured area works better, but defeats the purpose of batch scanning.
Does VueScan let you preview a batch, set a different autofocus point for each slide, and then use those individual focus points during the batch scan? If not, what’s the practical approach for getting the best focus with mounted slides?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
5y ago
2 Answers
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I decided to do a test to see if Vuescan does indeed allow one to set different focus points, for the different slides in a batch (a load of 5 slides in the Nikon LS-8000 mounted-slide film holder), and use those distinct focus points when doing a batch scan.
I fabricated a test slide that's split, with two different "heights": on the left side, the film is in the same plane (same height) as a normal slide, and on the right side, it is raised the thickness of two slide mounts. In the film holder, I put a plain slide in frame#1, and this "split level" test slide in frame#2.
I set "BatchScan | On" and "AutoFocus | Scan". Then I did a "Preview". I went to frame#2 and set the focus point to lie on the right side (where the film was elevated above the normal level); in frame#1, I set the focus point to the left side. Then I did a "Scan".
Frame#1 came out in focus; the right side of frame#2 (that was elevated) was also in focus, while the left side was out of focus.
This tells me that Vuescan is doing the right thing: it is storing the different focus point locations I specified for different frames, and using them when doing the batch scan. I think this is very useful, because the batch scan can take a long time, and it's nice to be able to go away, and not have to be present to set the focus point on each frame.
Originally by user97126. Source · Licensed CC BY-SA 4.0
user97126
5y ago
0
Generated from our catalog & community — verify before relying on it.
Based on the reported test, VueScan does appear to support different focus points for different slides in a batch on the LS-8000.
The tested workflow was:
- enable batch scan
- set autofocus to scan
- preview the batch
- go to each frame and place the focus point where you want it
- start the batch scan
A custom two-height test slide was used to verify this, and the scan behavior indicated VueScan was using the per-frame focus point rather than reusing only the first one.
So the practical approach is:
- Preview the batch.
- For each slide, move the focus point to an area with clear texture or edge contrast.
- Run the batch scan with autofocus set to occur on scan.
That should give better results than using one compromise focus point for all slides, especially with slightly warped or cupped mounts. If a slide has no good detail near your chosen point, pick any strong local contrast area rather than a blank or low-texture region.
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