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07-31-2017, 11:02 PM - 4 Likes   #1
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The K1, Shift Lens and Composition Adjustment

Last evening I went out to this little cul de sac upon on a hillside over looking a little valley a couple of miles from the house. I sort of use this as a little lab, because the terrain drops off and usually I'm shooting into the sunset, the weather changes from day to day, and it works for what I'm doing. I wanted to play around with my shift lens that I was able to pickup 7 years ago - the K 28mm f3.5 Shift. It can shift 11 mm off to one side, and then rotate stopping at each clock point so that you can make a) what ever projection correction adjustments necessary; or b) re-position for stitched panoramas. According to the old lens manual, with this 28mm Shift lens, you can stitch together a resulting image that has a field of view of 110 degrees or that from a 15mm wide angle lens.

What I did was to shoot an image at the center and each clock face position, then using ICE stitch them together - resulting in [Image #1]. I wanted to see how the lens projected its shifted image on to the K1's sensor, and in particular how dark the edges would be from any shadowing within the lens itself or the camera's mirror box. I wanted to do this after sunset to really emphasis the edge shadowing if any and yes, there is some - as you can see.
  • The size of [Image #1] is 11870 x 9347 pixels. When compared to the size of the K1's sensor of 7360 x 4912, there is a lot of real estate that is added.
While I was stitching the images, post processing them and then evaluating them for additional shadowing, I started to wonder a) if you could apply the Composition Adjustment (page 71 in the K1 manual), to a shift lens that is shifted; and b) if you could - what the results would look like.

So, I went out again this evening to reshoot, this time applying the Composition Adjustment. Yes, you can add a Composition Adjustment on top of the mechanical shift from the shift lens. Yes, the resulting stitched image is larger. But, you need to think this through because there is a caveat to this. If you desire to add the maximum amount of pixels, you need to add Composition Adjustment both vertically and horizontally. Also, you need to shoot an additional image at the 12, 3, 6 and 9 o'clock positions and shift the Composition Adjustment from one side of the axis to the other side.

For example at the 3 o'clock position you need to apply 24 steps horizontally and 24 steps in the above position as well as the below position. If you break the resulting image in to the 4 quadrants -
  • the upper right quadrant will have a +24 vertically and +24 horizontally.
  • the upper left quadrant will have a +24 vertically and -24 horizontally.
  • the lower left quadrant will have a -24 vertically and -24 horizontally.
  • the lower right quadrant will have a -24 vertically and +24 horizontally.
The results are illustrated in [Image #2] - which has a "bloated" look when compared to [Image #1].
  • The size of [Image #2] is 12343 x 9848 pixels. When compared to the [Image #1] size there is an increase of 473 pixels horizontally and 501 pixels vertically. This works out to be about 10 pixels per Composition Adjustment unit.
Ok, so you get a "bloated" stitched image - what's it actually good for? Good Question! Well for that building that you are trying to straighten and you need just a bit more pixel real estate - about 5% more - you now have it. If you need to widen the image a bit, so that you have a bit more room (pixels) to correct something in post (LightRoom) - say keystoning - you have a smudge more room. If you just want a wider stitch - you now have an additional 5%.

There is one more application that is somewhat off the wall. I'm going to make another post for it, but it has to do with using Composition Adjustment in Astronomy Photography to dither the sensor - which is a noise reduction technique. I was thinking about some things last night and this would be really simple to do. - When I make the post, I'll add a link to it here...._______________________

The only downside to using a shift lens in the early evening is that you need to shoot it stopped way down, f8 to f11 is recommended in the lens' manual. It does tend to make things a bit dark. I will say, that the articulating rear screen coupled with focus peaking (at 16x zoom) becomes necessary for good focusing - especially for distant items. While I was shooting these, I found it remarkable that with focus peaking the extreme depth of field that you had at f9.



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Last edited by interested_observer; 08-01-2017 at 07:08 AM.
08-01-2017, 03:32 AM   #2
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Very cool! It would be nice if the camera could automate this just like they did with pixel shift.

Adam
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08-01-2017, 06:56 AM   #3
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QuoteOriginally posted by Adam Quote
Very cool! It would be nice if the camera could automate this just like they did with pixel shift.
In terms of automating it when used with a shift lens, it would be a bit difficult since the camera doesn't know how you are shifting the lens mechanically in order to apply the appropriate amount and direction of the shift.

However, in terms of the link to the post with the Composition Adjustment and Noise Reduction - that is extremely simple, since it is essentially Pixel Shift with an extension - but rather than shifted one pixel, you would shift say 11 pixels. I'm pegging 11 pixels, because 10 pixels should be a sufficient amount of movement to get negate fixed pattern noise and one additional pixel in order to move to an adjacent RGB pixel. So this would approach a) negate fixed pattern noise and b) pickup the additional color information from the Pixel Shift concept. Automated, you could easily pre-program an 9 shot pattern with out repeating. With this, you would essentially loose an 11 pixel frame around the entire image, but that would be a very small price to pay for the additional benefits.

This could be easily implemented and retrofitted in a firmware upgrade, across the units - even going back to the K5. If an 11 pixel movement is too precise for the older units, then use a value that they are capable of handling. If automated, I believe that the folks in the Astrophotography social group - in particular Pete-XL, StoneG and company could find it useful. The deep space object images that they are producing are just absolutely stunning.


Last edited by interested_observer; 08-01-2017 at 07:15 AM.
08-01-2017, 07:15 AM   #4
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Thanks for posting this, my 28mm shift has been sitting around too long, now I have an excuse to use it.

08-02-2017, 09:37 AM   #5
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Thank you! That' very helpful and much appriciated.
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