wjlapier
Well-known
I have two 35mm lenses I just noticed that there is a difference in how I would read the markings for scale focus. Infinity at the f/16 mark on one side the distance ( in feet ) of one lens is less than 3 feet. The other is infinity on f/16 on one side and between 5 and 4 feet on the other. Is this standard for different lenses? I never noticed this or ever read anything about this. The first lens described above is the Zeiss-Opton Biogon for Contax and the other is the W-Nikkor 35/3.5 for S mount.
mdarnton
Well-known
Depth of field is basically an illusion, a measurement of how much being out of focus you are able to tolerate. Even at small openings, under sufficient magnification or on a large enough print viewed closely, it is still obvious that there is only one precise point of focus with increasing lack of focus on either side of it. At smaller apertures, this defocusing happens less quickly than at large ones, and so it APPEARS that things before and behind are sharp for some distance ahead and behind the focus point, but again, NOTHING except the single point of focus is actually in focus.
Manufacturers vary in how they define how far out of focus an image needs to be before you notice it's out of focus, and the key word here is "notice" This depends on manufacturer's standards, the print size they consider when calculating, and the viewing distance they consider appropriate for that pint size (you will notice that the picture is out of focus sooner when it is larger, or when you are closer). Given the squishiness of the variables, it's understandable that they would come to different conclusions.
Manufacturers vary in how they define how far out of focus an image needs to be before you notice it's out of focus, and the key word here is "notice" This depends on manufacturer's standards, the print size they consider when calculating, and the viewing distance they consider appropriate for that pint size (you will notice that the picture is out of focus sooner when it is larger, or when you are closer). Given the squishiness of the variables, it's understandable that they would come to different conclusions.
Dektol Dan
Well-known
101
101
Beginning photography rule #2, depth of field.
Focus 1/3 in 2/3 out. The measure of same marked on the lens works well enough for rapid shooting judgment.
That is, focus 1/3 into the subject for maximum depth of field at the chosen aperture.
101
Beginning photography rule #2, depth of field.
Focus 1/3 in 2/3 out. The measure of same marked on the lens works well enough for rapid shooting judgment.
That is, focus 1/3 into the subject for maximum depth of field at the chosen aperture.
zuiko85
Veteran
The two lens dof are calculated using different blur circles.
For a good discussion on dof search for bob Atkins dof caculator online.
For a good discussion on dof search for bob Atkins dof caculator online.
pvdhaar
Peter
Exactly, and it's not to be underestimated how this evolved over time..
Print sizes in the 1950's tended to be a lot smaller than now. Enlargements to 9 x 6 cm (ca. 3.5 x 2.3 inch) from a 35mm frame were the standard size you got from the drugstore, and that included an 0.5 cm white border on all sides. Nowadays the standard is a 15cm x 10cm full bleed print from a 1hr lab.. It's amazing how much more forgiving those oldie 9x6cm prints are compared to a 15x10 one when it comes to focus. This is reflected in the tighter DOF scales of recent lenses..
johnnyrod
More cameras than shots
I've noticed for exampled that the DoF scale on one of my Zeiss Contessa 35mm RFs needs a stop removing from it - with t he aperture set to f8, you will really only be happy about the DoF between the f5.6 marks. Their circle of confusion is bigger than mine, or film is better now than in the 1960s, or both.
Roger Hicks
Veteran
This is only a half-recollection, based on something I read many years ago, in a book that was old then, but I'm pretty sure that in the 30s Contax d-o-f scales were predicated on postcard-sized prints while Leicas were based on half-plate or even whole-plate, and were therefore that much tighter.
Cheers,
R.
Cheers,
R.
David Hughes
David Hughes
Hi,
Interesting, Contax, Exakta and Leitz all seem to agree (all mid 1930's but comparing f/9 and f/8). I didn't think so the first time I looked, then realised one was a metric scale and the other Imperial or feet.
And if we are not talking about 35mm film, a lot of contact prints were made the same size as the negative so DoF would hardy notice a lot of the time. And some of the prints were really tiny...
Regards, David
Interesting, Contax, Exakta and Leitz all seem to agree (all mid 1930's but comparing f/9 and f/8). I didn't think so the first time I looked, then realised one was a metric scale and the other Imperial or feet.
And if we are not talking about 35mm film, a lot of contact prints were made the same size as the negative so DoF would hardy notice a lot of the time. And some of the prints were really tiny...
Regards, David
wjlapier
Well-known
Couple of pics of the lenses in question. Infinity on f/16 for each lens.
Nikkorw3535at16 by wjlapier, on Flickr
Contax3528at16 by wjlapier, on Flickr
Nikkorw3535at16 by wjlapier, on FlickrContax3528at16 by wjlapier, on Flickr