Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: hasselbladfan on December 17, 2011, 04:50:01 am

Title: DOF scale for H 100mm /2.2
Post by: hasselbladfan on December 17, 2011, 04:50:01 am

How is the DOF of the 100mm?

Did someone ever publish a DOF scale (for a H4D40 sensor)?

Thanks.

Title: Re: DOF scale for H 100mm /2.2
Post by: Bart_van_der_Wolf on December 17, 2011, 05:38:16 am

Quote from: hasselbladfan on December 17, 2011, 04:50:01 am

How is the DOF of the 100mm?

Did someone ever publish a DOF scale (for a H4D40 sensor)?.

Hi,

I'm not exactly sure what you are looking for. Are you looking for a comparison of the quality of defocus blur (Bokeh), or just a DOF tool that includes the wide aperture of that lens?

Almost all lenses follow the same general DOF principles, which are based on symmetrical optical designs, with regard to the amount of defocus blur (and diffraction at narrower apertures). Deviations from the general rule are caused by the pupil magnification factor as a result of the asymmetrical optical design. The mathematical outcome allways depends on your preference of the circle of confusion (COC) criterion. The COC criterion is a function of the output magnification and viewing distance requirements.

The influence of the sensor used, it's sampling density or sensel pitch, is only reflected by how accurately the blur is sampled. When your requirements call for per-pixel-sharpness (e.g. for large output which should allow close inspection), then you need to adjust your COC criterion to something like 1.5x the sensel pitch.

IOW, any decent DOF tool that allows to specify the COC criterion should answer your questions about the amount of blur. As for the bokeh, I've heard that the Fujinon designs have a less pleasant bokeh, but whether that applies to this lens as well, I'll leave that to others.

A certain amount of DOF can be restored to detail afterwards by using deconvolution sharpening. Blur caused by diffraction at narrow apertures stands the best chance of recovery, blur caused by defocus can cause more problems to restore without artifacts.

Cheers,
Bart

Title: Re: DOF scale for H 100mm /2.2
Post by: Brian Hirschfeld on December 22, 2011, 12:07:43 pm

I don't know, exactly what you are using it for, but I used this lens extensively during the end of my time with my H3Dii-39ms (which I believe has a similar sensor in terms of size 'er whatever) and all I can say is, that anywhere except from the minimum focus distance (which might be what you actually care about) even shot wide open at f/2.2  at a normal distance, a models face is fully in focus and its not an issue.

Also side note, I absolutely love the bokeh of this lens, and it almost made me keep with Hasselblad quite honestly.

Title: Re: DOF scale for H 100mm /2.2
Post by: David Schneider on December 22, 2011, 05:26:26 pm

For dof I use my iPhone app, Simple DoF.  I love it.  I have my H3d2-39 and my Canon 5dmk2 in it.  I tend to use Simple DoF in the studio to check dof on the Hassie, especially for family groups.  Spin the wheels to set f-stop, lens mm, focus point distance. 

Title: Re: DOF scale for H 100mm /2.2
Post by: Willow Photography on December 23, 2011, 09:14:31 am

I downloaded Simple DOF myself.
But if I am not mistaken, it most be something wrong with it.

It shows that with the same lens, same distance and same aperture,
a  P65 or  H4D50 has more DOF than a P40 or  H4D40.

Shouldnt it be the other way around???

Willow

Title: Re: DOF scale for H 100mm /2.2
Post by: BrendanStewart on December 23, 2011, 02:27:56 pm

If you own this lens, i highly suggest the 13mm extension tube. It's freakin' awesome i get up really close with 2.2, love it.