Does the 24mm really become a 32mm with the speedbooster? If it is so, it's a problem of focal lenght, first of all. Indoor=widest possible.

@Renovatio @ala_img

Guys, to clear your minds from this mess about focal length we have special flame topic, as I remember.

General information: The Samyang 24mm 1.4 is a little bit soft at the full open (F1.4) setting. But at F2.0 (which is giving you a ~F1.4 with the speed booster) it´s fully usable. The DOF should be around the same / compareable (altough don´t forget - The speedbooster is maybe not working flawlessly any more at the full open F1.4 aperture setting! Or let´s say the image quality is MAYBE not acceptable any more). But the huge pro of the Samyang + speed booster solution is, that you can also use other lenses with the speed booster (for example the very good Samyang 35mm F1.4 or the new 16mm F2.0 lens - or older Nikkor glass). AND you also have the option to get the VDSLR editions (with the stepless apertures and fixed 0.8 pitch teeth).

But all in all this solution is also bigger, more bulky and if you get the VDSLR version (with the teethed aperture and focus ring) it´s not that nice to use for stills any more. The Nokton in comparison is not only much smaller and lighter, it´s also using a way smaller filter thread (58mm instead of 77mm - so the filter diameter fit´s better to native M4/3 lenses) and you can also focus closer (0.15m vs 0.25m). Also the quality control seems to be better (with the Samyang lenses which are also available under the Rokinon & Walimex Pro brand the quality wasn´t always top notch in the past). Not a easy choice I know.

Btw. don´t forget the Sigma 18-35mm F1.8 lens. IF it´s working good on the speedbooster it´s maybe the even better choice (because then you get a ~13 to 25mm F1.2 lens - replaces nearly all three Samyang lenses - 16mm, 24mm AND 35mm). And the Canon to M4/3 speedbooster should also come out soon (so you can also use other native EF and EF-S glass on it or the 18-35mm F1.8 with electronical aperture control. Also quite interesting I think - Especially because the Sigma is then also usable native on a 2nd body (a cheap 550D or 600D or so) as a normal AF lens ^^.

Just my 2 cents. I hope it´s helping a little bit to choose.

@Tscheckoff Thank you for interesting info about many aspects of lens, unfortunately it is steel not clear for me about DOF. What lens will provide shallowest DOF, voigt or samyang + speedbooster? This moment is very important for my project. @goanna may be it will be no so much difference, but even small difference is important for me. And yes, it would be great to look at some samples of Samyang + speedbooster.

@ala_img: Oscillian is right. The Voigtlander has the all in all shallower DOF (also because of the closer focusing range). And I think if the max. aperture and shallowest DOF is your only / primary goal, the Voigtlander is the better choice (because as already mentioned the 24mm is visibly soft wide open and more or less just usable at & above the F2.0 setting). And that softness is for sure not vanishing with the speedbooster in use. To mention it too: Yes. The 17,5mm is also soft in the corners (wide open) - But at least the centre is quite good and usable (AND as soon as you hold a Voigtlander in your hands you know why you paid that much for it - you really feel the quality). ^^

The wider angle the more DOF (more in focus) even with the same f-stop. The Samyang+booster will have the DOF of a 16mm. If you want super shallow DOF for esthetical reasons, go for a 50mm f1.4 instead. I use the 17.5mm (35mm eqv) for the feel of being more "within" a scene.

+1 on the Sigma 18-35 with a Speedbooster once the Nikon mount is out (soon!). Wonderful piece of glass that's going to replace three of my main lenses: SLRMagic 12mm, Voigt 17.5 and 25.

About the Sigma 18-35mm btw.: It´s already available here in europe (the nikon version - even at some local stores). Maybe it´s already available in your local stores too (or some online dealers already got a few one in stock). I just hope that someone will test the speedbooster soon on it. (Because it´s also my favorite future investment.)

Ala_img: When you add the 0.71x Speed Booster to a 24mm f/1.4 you get a 17.0mm f/1.0 lens. It really is a 17mm f/1.0 lens, pure and simple.

HOWEVER, the 24mm Samyang has a true focal length of 24.8mm according to my bench measurements, which means that it will become a 17.6mm f/1.0 when the Speed Booster is attached. I expect virtually zero difference between this combination and the 17.5mm Voigtlander in terms of FOV or DOF. At some point I would like to do a careful comparison.

Regarding the optical effect of the Speed Booster, it will certainly make a significant improvement in central sharpness, as it does with any lens it is attached to. In other words, the 17.6mm f/1.0 will be sharper at f/1.0 than the 24/1.4 is by itself at f/1.4. The corners should be similar to what you get at the same image height with the 24/1.4 by itself, but this would have to be confirmed by testing.