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Old Aug 8, 2010, 2:38 AM   #1
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Default Pentax 28mm f3.5 Shift Lens

I have been wondering about this lens for a couple of years. I have come across a couple, with reasonably hefty prices. Between the price and the effects of the cropped sensor, I always came to the conclusion that it would not be wide enough, and thus passed. Well, I came across one that was in mint condition and was reasonably priced, and something overcame me (could not have been LBA - I though that I was over it) - I bought it.

Well, the lens is heavy - very heavy metal and glass - as in real glass. The front element is large and absolutely perfect. Its construction is - heavy, flawless, very mechanical in terms of the shifting mechanism and then there is the rotational mechanism, along with the aperture(s) and focusing. Built like a limited lens.

I have done several stitched landscapes, figuring out how to use it - and then how to stitch the results together. Figuring out how to use it was simple. Stitching the results together was a bit more tricky, since all the packages assume a common nodal point, and by shifting the lens from one side to the other, the software "sees" that and throws up all over you.

You need to use a tripod, set everything up, shift the lens over with the dial. Take the first picture. Then you rotate the entire lens barrel to move the shift over to the other side, and shoot that frame. Thus you have about a 10% overlap. Initially I stopped there - but then what you want to do is to crank the lens back to the middle and shoot a middle frame, so that you have something to tie all the results into (the left shift and right shifted images).

One utility will not touch it. Another has problems with it, but with the right settings, will accept it. Another, once I had the three frames rather than 2 worked well with the results.

It has actually turned out to be a fun learning experience. The lens is sharp. It was designed for film, and it does work well on digital. I am still in the process of figuring out all of the nuances.

I want to try it on architecture and just see how narrow it is with the crop factor. I am being optimistic. From what I see, I think it may be alright.

Anyway the sky was difficult here, and I am trying to figure out how everything works. This is f8, and I am think that it needs to be stopped down more. Some more learning is in order....

So here is the first set of stitched results...

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Last edited by interested_observer; Aug 8, 2010 at 2:41 AM.
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Old Aug 8, 2010, 2:44 AM   #2
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While I was shooting this, I also took a set of bracketed images - 5, of the middle frame, just to see how it went. Turned it into an HDR (just used what ever the utility processed - with no adjustments).

What I would like to do is to have this fully across the entire shifted and stitched frame. I am working on this - after yesterday, I thought that I would just not push things along as hard.

Actually, this is a very accurate representation of the view. The sky was difficult.... but this caught it very well.

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Old Aug 8, 2010, 2:51 AM   #3
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... and just to put things in perspective, up above is the day time view of the area I have been practicing in for a while, trying to catch everything together. Here is a stacked image using the DA 10-17 of a sunset with the iridescent blue sky along with the valley lights (a couple of months ago).....

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Old Aug 8, 2010, 3:08 AM   #4
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As I wrote before, you have the shift from the center to one side. You also are able to rotate the entire lens barrel, 360 degrees, so that you can roll the shift say from the left side over to the right side.

But you can also, stop in 30 degree increments, so if you do not get the shift axis right, you get this. Which also means that you can in 6 or 7 shots, build a very nice square result stitched together.

This was actually my first attempt, with shooting the lens. The sky is tricky with this lens in terms of the shift and how the light is handled - I think....

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Old Aug 8, 2010, 12:46 PM   #5
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Very interesting - I've always wanted to play around with one of these lenses, but (like you) am not willing to venture much capital on one.

Doing HDR panoramas isn't as difficult as you would think - if your software can stitch it, it'll work. The HDR part is the easy part of the exercise. The times I've done it I did the HDR first, then stitched (I just used CS4 to stitch).

Have fun with it - you are making me jealous.
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Old Aug 8, 2010, 10:50 PM   #6
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I have done a number of successful HDR panos just rotating the camera around the nodal point over the last couple of years (especially with the new tripod). The shift lens is a bit different in that the bulk of the lens shifts off the optical center up to 11mm to one side. In doing this the optical path changes, so that you have less of a direct straight line path from the front lens face to the sensor. Also, the straight line path is not really perpendicular to the sensor face, so I am wondering about the angle of inclination as the light strikes the individual photo pixel - and its not uniform across each one - as the angle changes across the sensor face. This acts almost as another aperture (be it a lot larger), and I have seen this affect already (and I like it, I just want to apply it in a very uniform way). I am getting some additional ideas based on what I am seeing here, and maybe start trying some of them out - heck the film is free....

So where I am going with this, is that in my way of thinking, there is the potential of less light getting to the sensor when shifted as opposed when centered (or not shifted, or shifted just slightly). Therefore I am thinking that when shifted there is the potential of essentially having a smaller aperture or effectively a high f stop. This I think could possibly lead to a very uneven exposure. However, a number of sites addressing panos via shift lenses, show stunning stitched images. So, I am either over thinking this, or still in the very early learning stages - and probably both are true. I am also thinking that I have been essentially shooting directly into the sun, and shifting off to either side, so I am just aggravating the problem. I need to switch to another location, to try some things out.

Folks have been using these for a long time on film, and at least 10 years digitally, very successfully. So this is nothing new, maybe I am just letting the engineer in me go to the extreme here.

Also, I am seeing and reading that the lens acts better when really stopped down (and it tops out at f32) - and possibly severely stopped down. In that I have been doing sunsets, the light is already pretty low, and f8 is pretty small. f16, f22, f32, I am not really seeing as anything nearing reasonable, since I tend to be up around 30 seconds already. But - giving it a try, who knows.

Take a scroll down to "Shifting for Panoramas" on this link...
... I know that this can be achieved via the nodal route, too.


Last edited by interested_observer; Aug 8, 2010 at 11:13 PM.
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Old Aug 12, 2010, 5:36 PM   #7
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cool lens you got there, mind postin a pic of it?

I enjoyed your shots, looks like youre getting the hand of things
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Old Aug 12, 2010, 9:16 PM   #8
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Hi NM,

I am not the best product photographer around, but since there are some excellent shots on the web, here are some links...

Here is a description of the lens, from Bojidar Dimitrov's Pentax K-Mount Page ...
Here are some additional images from the web...
In this image, you can see the extended "hole" that extends off to the side, so that as the lens is physically shifted, the light path shifts as well.
Now this is a 67 version 75mm, but I am putting it here because it really shows how the entire lens is shifted off to one side.
I think that we all can enjoy this image!!!!
The lens itself just shifts to one side. In order to get the other side, the lens turns 360 around, so you would turn the lens 180 degrees and then image the other side (left, twist 180, right, shift back to the center and then take the center shot). Also, if your interested - here is the users manual...
... hope you enjoyed it...


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Old Aug 14, 2010, 7:24 PM   #9
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never heard of something like this before. Atleast not with this style mechanism. thanks for the info
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