tag:blogger.com,1999:blog-4731100500338248454.post8962236008170194690..comments2024-03-11T17:16:18.833-04:00Comments on artphotokebek: Focal Length vs Depth Of Field / Longueur focale vs profondeur de champRoger Gauthierhttp://www.blogger.com/profile/01690736289188945063noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-4731100500338248454.post-51470162519470792462009-12-18T15:22:20.007-05:002009-12-18T15:22:20.007-05:00Lionel, tu ne pouvais faire de compliment plus gen...Lionel, tu ne pouvais faire de compliment plus gentil. Mais alors, dans notre petite blogosphère à tous, nous sommes tous un peu comme ça, non ?<br /><br />Roger G.Roger Gauthierhttps://www.blogger.com/profile/01690736289188945063noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-66532758267235579512009-12-18T15:15:02.879-05:002009-12-18T15:15:02.879-05:00Marius and Lionel,
I will come back with some exa...Marius and Lionel,<br /><br />I will come back with some examples of my own in a few months, to show the limits. This is a strange phenomenon. I will also put emphasis on the circle of confusion, on perspective and on background blurring. Because background blurring and DOF are two different beasts also! Our collective heads are gonna split...<br /><br />•••••••••••••••••••<br /><br />Marius et Lionel,<br /><br />Je vais revenir là-dessus avec des exemples de mon cru dans quelques mois, pour montrer les limites. Que voilà un phénomène bizarre. Je mettrai aussi l'emphase sur le cercle de confusion, la perspective et le flou du fond. Parce que le flou du fond et la profondeur de champ sont aussi deux choses différentes ! Nos têtes collectives vont éclater, je le sens...Roger Gauthierhttps://www.blogger.com/profile/01690736289188945063noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-31031359734035028092009-12-18T05:58:50.208-05:002009-12-18T05:58:50.208-05:00Bonjour Roger!
merci pour ce cours magistral qui m...Bonjour Roger!<br />merci pour ce cours magistral qui m'a permis de recaler dans ma mémoire<br />les bases de la photographie.<br />On ressent une passion et une maîtrise du sujet de ta part.<br />LionelAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-74736237322301881932009-12-17T16:55:36.472-05:002009-12-17T16:55:36.472-05:00You are right, I was thinking about two different ...You are right, I was thinking about two different focal lenghts with 1:1 and 1:2 magnifications. I missed the point, thank you.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-65202397918703795162009-12-16T06:50:38.486-05:002009-12-16T06:50:38.486-05:00Marius said:
"I always wrongfully thought th...Marius said:<br /><br /><i>"I always wrongfully thought that both a 50mm and a 100m macro would have different DOFs when focusing at 30cm, let`s say ."</i><br /><br />Mmm... You may well be right, my friend! The problem is slightly different. <i>If the image magnification is constant</i> means that we make sure the dimension of a given object is the same in the lens or on the sensor.<br /><br />For example, if an object is half the size of the sensor in both cases, the DOF will be the same.<br /><br />In order to achieve that for a given object, if you change the focal length, you must absolutely adjust the focusing distance accordingly. Or crop accordingly, which is the same thing of course.<br /><br />Roger G.Roger Gauthierhttps://www.blogger.com/profile/01690736289188945063noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-14111264476995534532009-12-13T13:19:48.112-05:002009-12-13T13:19:48.112-05:00Je relirai tout ça à tête reposée...Je relirai tout ça à tête reposée...Alainhttps://www.blogger.com/profile/17588240936191844264noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-69812496699675516792009-12-13T12:31:27.183-05:002009-12-13T12:31:27.183-05:00Coucou Roger ! :o)
C'est très intéressant ! ...Coucou Roger ! :o)<br /><br />C'est très intéressant ! je vais lire tout cela à tête reposée, c'est très instructif ! MERCI ROGER et bonne journée ! :o) ***""°o.O Nancy O.o°""https://www.blogger.com/profile/06713278970113709248noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-55340285483001675822009-12-13T08:57:05.652-05:002009-12-13T08:57:05.652-05:00Wow, thank you for this. You shook my mind a littl...Wow, thank you for this. You shook my mind a little with your concise and complete lesson. It`s good to learn some more.<br /><br /><br />For instance, I knew the importance of Hyperfocal in landscapes and its relation with focal length. The funny part is that one can get the maximum depth of field without even watching through the wiefinder, but just looking at the scale on the lens.<br /><br /><br />What is new for me is the independence between DOF and focal length when focusing distance is much smaller than HF. I always wrongfully thought that both a 50mm and a 100m macro would have different DOFs when focusing at 30cm, let`s say. They`re not. I must take this into account when doing macro work and rethink the use of lens!!!<br /><br />And I must consider your calculus concern 35mm (of full frames). Talking about an APS (cropped) sensors, I think the issues stay the same, except the fact the DOF is much narrower.<br /><br />Thank you again.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-52820912118609614582009-12-13T06:20:30.053-05:002009-12-13T06:20:30.053-05:00Allô Sandra ! Si tu parles de la version française...Allô Sandra ! Si tu parles de la version française, je devrais pouvoir la publier d'ici 08h EDT aujourd'hui. Sinon, tu veux me préciser ta question ?<br /><br />Roger G. :-)Roger Gauthierhttps://www.blogger.com/profile/01690736289188945063noreply@blogger.comtag:blogger.com,1999:blog-4731100500338248454.post-30987836785342835902009-12-13T05:58:49.149-05:002009-12-13T05:58:49.149-05:00Je fais comment alorsJe fais comment alorsSandrahttps://www.blogger.com/profile/08586180311757495770noreply@blogger.com