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Arsat N 35 / 2.8 Shift - some questions
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PostPosted: Wed Aug 07, 2013 1:52 pm    Post subject: Arsat N 35 / 2.8 Shift - some questions Reply with quote
Hi all, after a remission of the MF-lenses virus I have been struck again - my latest affliction being an Arsat N 35 mm f/2.8 shift lens, which I bought at a fairly good price (at least I hope). I fits snugly on my Nikon D600, but I have got some questions left.

It is a shift-only lens (which is fine with me, since perspective control is what I mainly want) with a max. reach of 11 mm in one direction. Which direction depends on the way you rotate the lens - it rotates on the mounting flange, that has a small window showing different numbers depending on the angle of rotation. So it goes 11 mm up or down, or any which way, giving the following indications on the rotation ring:

0° and 180° - 11
30°, 90°, 150°, 210°, 270°, 330° - 8
60°, 120°, 240°, 300° - 7
In view of the values I presume these figures have got some relation to the max. amount of shift, although I can't find any logical /mathematical correlation between these values and the rotation angles. Anybody got an explanation? (Just curiosity, it also functions without my knowing why)

A second issue has to due with sharpness loss and light fall-of when shifting. Focussing on the center of my viewer image with no shift, my focus goes off once I start shifting the lens (which I understand, instead of the optical center the lens border is rensponsible for the image formation on my focal plane) but I am not sure how to deal with this issue. Refocus? Choose a smaller aperture? The latter seems preferable, but on shifting my image already gets quite a lot (2 - 3 stops) darker.

I would like to have some more info about the ins and outs of this type of lens - and of the Arsat's standing in the shift-world. Shift-only lenses are hardly discussed anywhere, it's all about tilt-shift. So I would be grateful for some answers, hints and info.

A photo of the lens, 11 mm shifted upwards, 0° rotation.




PostPosted: Wed Aug 07, 2013 2:07 pm    Post subject: Re: Arsat N 35 / 2.8 Shift - some questions Reply with quote
bobcominitaly wrote:
Anybody got an explanation?


The height (~24 mm) of the sensor is less than the width (~ 36 mm) which is less than the diagonal (~43 mm).


PostPosted: Wed Aug 07, 2013 5:13 pm    Post subject: Re: Arsat N 35 / 2.8 Shift - some questions Reply with quote
Hi,

bobcominitaly wrote:
Arsat N 35 mm f/2.8 shift lens


I had this about 10 years ago, used it on a manual film body (slide film). I wasn't that pleased with the sharpness or light falloff, but I have to admit this was when I was starting photography, so my technique must have been more flawed than it is today Smile Also it may have been that my copy was not perfect (though mechanically it was very robust)

When I found a Nikkor 28mm/3.5 relatively cheaply I jumped at the chance and sold the Arsat. Am using it from time to time (mostly when traveling) on a D700.

As sichko explained, you can shift more when shifting up/down versus left/right before hitting severe light falloff. Imagine how the image circle shifts on the sensor to visualize it.

Below is my fave pic I took with the Arsat but I had to crop it to 2/3 of the original size because the sharpness was so bad at the border of the image.



One trick I like to do with shift lenses is to take panoramas by taking a pic shifted to the left and another shifted to the right; it is enough to lay the pictures on top of each other in Photoshop, no need for panorama software. For instance like this (Nikkor 28mm/f3.5 on D700):



AIUI in principle you should shift the camera and keep the lens in place, instead of the other way round, but I think it only makes a difference when there are objects close to foreground. At least I haven't had any ill effects with my landscapes despite being sloppy.


PostPosted: Wed Aug 07, 2013 7:46 pm    Post subject: Reply with quote
@Sichko: Iam still trying to figure out the differences in these numbers. Does it mean that if a shift on the landscape side (24 mm) of the focal plane is 11 mm, then on the portrait side (36 mm) it is 8 mm, and on the diagonal side (43 mm) it is 7 mm? If so, at least I know what it means, although the use of these figures remains a mystery.

@hmallat: thanks for your reply and comments (although not too encouraging, but that is the nature of the game: any cheap old mflens is a potential diamond that may turn out o be a piece of glass). And thanks for your photo's - especially the first one (where in the Netherlands was it taken?) gives me an idea of what to expect. Couldn't I get the same perspective with a 50 mm and no cropping?


PostPosted: Thu Aug 08, 2013 4:33 pm    Post subject: Reply with quote
bobcominitaly wrote:
I am still trying to figure out the differences in these numbers.


Have a look at the PC-Nikkor 35mm manual, especially page 11 (Maximum Permissible Shift). Of course "permissible" means in this context that beyond that amount of shift the image deteriorates beyond a standard defined by Nikon instead of it being some absolute limit.

http://www.nikonusa.com/pdf/manuals/archive/PC-Nikkor%2035%20mm%20f-2.8.pdf


Quote:
@hmallat: thanks for your reply and comments (although not too encouraging, but that is the nature of the game: any cheap old mflens is a potential diamond that may turn out o be a piece of glass). And thanks for your photo's - especially the first one (where in the Netherlands was it taken?) gives me an idea of what to expect. Couldn't I get the same perspective with a 50 mm and no cropping?


Well, since you have the lens already, use it and see what you think of the results. Your experience may differ from mine, I may have had a dud copy.

Shift lenses aren't so important with digital as they were on film because we can do perspective correction afterwards without that much loss of quality, but I like to use a shift lens when I have the patience needed for operating it Smile ... but yes, the images I posted could have been taken with a normal lens and manipulated with photoshop or panorama software.

That pic was taken in central Amsterdam, I forget the exact street but it was in an area which had many wonky buildings.
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