Sigma 50mm 1.4 large image cricle?

Can't seem to find any answer about the Sigma 50mm 1.4 image circle size. Looking at the back of this lens I wonder if using it with a shift adapter one can get good results.

The Canon 90mm and 45mm ts-e image circle is 58.6mm. Physically comparing the 90mm ts-e back end to the 50mm Sigma the later appears smaller, but I know image circle isn't determined by eye balling the lens. Anyone got the data to answer this question?


Thanks in advance!

I am not sure what the image circle is, but you do realize that you will lose infinity focus, right?

hxpham wrote in post #9732831
I am not sure what the image circle is, but you do realize that you will lose infinity focus, right?

why lose infinity focus?

abdul10000 wrote in post #9732845
why lose infinity focus?

Because you are increasing the flange distance (by adding an adapter)... unless you were positioning to use the lens on the new Samsung or micro fourth thirds cameras (where there is space enough to mount a shift adapter and retain the original mount distance).

To address your initial question, I have both the S50 and the 90TSE on hand, so I popped them out of the bag and held them up to the wall (in a darkened area). I don't have a ruler, or work-bench to really sort it out, but the image circles look pretty similar in size... the Sigma projecting obviously bigger than the 43mm diagonal it needs to safely cover a 135 format frame (makes sense considering the vignetting is so low on the lens).

EDIT: I just tried the 85/1.8 and the 30/1.4. The 30/1.4 is clearly projecting an image the smallest of the four (just checking!), but most telling is the 85/1.8 which doesn't project as large as either the Sigma 50 or the 90TSE.

Chez Wimpy wrote in post #9732912
Because you are increasing the flange distance (by adding an adapter)... unless you were positioning to use the lens on the new Samsung or micro fourth thirds cameras (where there is space enough to mount a shift adapter and retain the original mount distance).

So its like using an extension tube? Makes me wonder how do people using a Zoerk adapter with medium format lens for example use this combination to take architectural pictures with no infinity focus?

Chez Wimpy wrote in post #9732912
To address your initial question, I have both the S50 and the 90TSE on hand, so I popped them out of the bag and held them up to the wall (in a darkened area). I don't have a ruler, or work-bench to really sort it out, but the image circles look pretty similar in size... the Sigma projecting obviously bigger than the 43mm diagonal it needs to safely cover a 135 format frame (makes sense considering the vignetting is so low on the lens).

Very interesting. I am not sure I understand how you did the test. Your looking through the lens from which side, the back, while having the lens front element face the wall?


Thanks for the feedback!

abdul10000 wrote in post #9733615
So its like using an extension tube? Makes me wonder how do people using a Zoerk adapter with medium format lens for example use this combination to take architectural pictures with no infinity focus?

The distances for medium format lenses/cameras is longer than that of 35mm DSLRs, so infinity focus is retained with an adaptor.

hxpham wrote in post #9735044
The distances for medium format lenses/cameras is longer than that of 35mm DSLRs, so infinity focus is retained with an adaptor.

Thanks, so medium format lenses are designed for a longer space which the shift adapter does not effect like with 35mm lenses. Too bad there are no medium format lenses with large aperture like with 35mm lenses.


I guess I have to email sigma about the image circle of their lens.

For infinity focus, you could try buying the Pentax version instead and adapting it to fit EOS mount...but you'll have to see how that affects the image circle.

abdul10000 wrote in post #9733615
Very interesting. I am not sure I understand how you did the test. Your looking through the lens from which side, the back, while having the lens front element face the wall?

I took out the lenses, uncapped both ends, focused about 3 meters in (to an area of my apartment with lighting) and just held them out from a dark wall about 44mm... or realistically until their image projection came into focus. This was not precise because my camera obscura really needed a fully illuminated scene (a drop cloth or something around the lens to allow me to see the finely detailed edges of the image circle) and a mounting board to hold them still. I also don't own a ruler! The Sigma and the TSE 90 were both obviously larger than either my 85/1.8 or my 30/1.4 (positively diminutive in comparison)

abdul10000 wrote in post #9737983
Thanks, so medium format lenses are designed for a longer space which the shift adapter does not effect like with 35mm lenses.

The good news with digital is the sudden surge of mirror-less camera with shorter (even shorter than rangefinder) flange distances that allow the incorporation of tilt-shift adapters. The micro-four-thirds cameras already have these devices for a number of legacy 135 format lenses, and the Samsung NX, with its APS-C sized sensor, looks to be the best platform yet for this kind of photography... at least until Sony gets their product to market. The only problem with EF mount lenses is that, to date, no adapters have supported the electric protocol necessary for (AF and) stopping down the aperture. The only way to shoot stopped down is to engage the DOF preview button on a Canon camera, and un-mount the lens in that position. Not a pretty work-around in the field.

There is one other option however....
http://www.luminous-landscape.com …ameras/hartblei​-cam.shtml
and this is probably the best way to test the imaging potential of the Sigma 50/1.4 without going through too many hoops. The only caveat (besides the insanity of dropping tens of thousands on the rig + digital MF back :cool being that the 50/1.4 doesn't have the greatest corner resolution on FF stopped down (the 50/1.8 will beat it in the f5.6~f8.0 range) so for FF sensor shifting purposes, I guess having the featureless sky at the top edges of the frame would be the best bet. For ASP-C sensors though, it might be no worse than the TSE 90 results shifted on a FF camera... with tilt at f1.4!! Interesting idea for sure.