[rollei_list] Re: Rolleiflex 35mm Cameras
- From: Eric Goldstein <egoldste@xxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Wed, 11 Nov 2009 17:11:14 -0500
I couldn't remember it at first, either. It is an excellent site with
a number of thoughtful articles.
Eric Goldstein
--
On Wed, Nov 11, 2009 at 10:14 AM, Austin Franklin
<austin.franklin@xxxxxxxxxxx> wrote:
> Hi Eric,
>
> Thanks for posting that link. That's Paul's (Walrus's) article/test I
> referred to earlier. He was on the Contax email list that I was on.
>
> Regards,
>
> Austin
>
>
>> -----Original Message-----
>> From: rollei_list-bounce@xxxxxxxxxxxxx
>> [mailto:rollei_list-bounce@xxxxxxxxxxxxx]On Behalf Of Eric Goldstein
>> Sent: Wednesday, November 11, 2009 10:00 AM
>> To: rollei_list@xxxxxxxxxxxxx
>> Subject: [rollei_list] Re: Rolleiflex 35mm Cameras
>>
>>
>> In addition to the two links I previously provided, more on this much
>> misunderstood concept can be found on this interesting website:
>>
>> http://toothwalker.org/optics/dof.html
>>
>>
>> Eric Goldstein
>>
>> --
>>
>> >
>> >> -----Original Message-----
>> >> From: rollei_list-bounce@xxxxxxxxxxxxx
>> >> [mailto:rollei_list-bounce@xxxxxxxxxxxxx]On Behalf Of CarlosMFreaza
>> >> Sent: Tuesday, November 10, 2009 8:43 PM
>> >> To: rollei_list@xxxxxxxxxxxxx
>> >> Subject: [rollei_list] Re: Rolleiflex 35mm Cameras
>> >>
>> >>
>> >> 1) I understand very well that if you want to keep the same relative
>> >> image size using a wide angle lens (f.e.35mm) and a telephoto
>> >> (f.e.135mm), you need to move further away the necessary distance to
>> >> compensate the telephoto longer focal length; from certain point of
>> >> view could be useful to keep in mind that even if the main subject in
>> >> the foreground has a similar size, the background will appear bigger
>> >> and closer for the telephoto image and then this "compensation" by
>> >> distance is relative and not absolute. This change for the background
>> >> perspective and relative size could be desirable or not desirable for
>> >> the image composition, but this is other issue.
>> >>
>> >> 2) I understand very well that given the similar image relative size
>> >> and keeping the same f stop for both lenses, the DOF will be similar
>> >> because the aperture is the same, f8 is always f8 for the WA lens and
>> >> the Tele lens, if the distance from the subject "compensated" the
>> >> difference for the focal length, DOF must be similar due to the
>> >> identical f stop.
>> >>
>> >> 3)For practical photography, things work different in general, if you
>> >> put a WA lens on your camera, it's because you want the WA lens angle
>> >> of view and the DOF provided by its short focal length, you have no
>> >> reason to think about the relative image size issue regarding the DOF,
>> >> and similar reasoning for any other focal length, in general you
>> >> choose the lenses for their different angle of view and the different
>> >> DOF.
>> >> Anyway, I accept that for certain marginal situations (like the lack
>> >> of the right lens for your wishes or necessities) could be useful to
>> >> know the focusing distance to the subject for two different focal
>> >> length to obtain a similar DOF for the same given f/stop.
>> >>
>> >> 4) As a regular and intensive user of a camera provided with a built
>> >> in taking lens, I know very well the issues about focusing distance
>> >> and image relative size.-
>> >>
>> >> Carlos
>> >>
>> >>
>> >>
>> >>
>> >> 2009/11/10 Mark Rabiner <mark@xxxxxxxxxxxxxxxx>:
>> >> >> Hi Carlos,
>> >> >>
>> >> >> What you're not doing when you use your DOF calculators, is
>> >> adjusting the
>> >> >> distance to maintain the same relative image size. That's the
>> >> point you
>> >> >> seem to be missing..."same relative image size".
>> >> >>
>> >> >> I suggest you read the references Eric so kindly provided.
>> >> Start by looking
>> >> >> at the chart titled "DOF for f/8, M ~= 1/20, 35mm format" at
>> >> the bottom of
>> >> >> this section:
>> >> >>
>> >> >> http://www.normankoren.com/Tutorials/MTF6.html#DOF_focal_length
>> >> >>
>> >> >> It shows total DOF for same aperture, different focal lengths,
>> >> with distance
>> >> >> adjusted to provide the same relative image size. Note the
>> >> total DOFs are
>> >> >> nearly identical for all lenses at the same aperture. Then,
>> >> ask your self
>> >> >> why... If you need help understanding that, perhaps someone
>> >> here would be
>> >> >> willing to help. But, please read the references first.
>> >> >>
>> >> >> Regards,
>> >> >>
>> >> >> Austin
>> >> >
>> >> >
>> >> > Another view of what Austin is saying might be:
>> >> > You put on a wide angle lens and you are getting more in focus
>> >> front to back
>> >> > But you also are shooting the whole house not just the front door.
>> >> > Should you back up with your longer lens to also get the whole
>> >> house you'd
>> >> > get just as much front to back as the wide did.
>> >> >
>> >> > So every time you change lenses you'd have to move back or
>> >> forward to get
>> >> > the same non zoomed in or zoomed out or cropped picture.
>> >> >
>> >> > My part is:
>> >> > At that point your depth of field would be about the same.
>> >> > Not exactly the same.
>> >> > But close
>> >> >
>> >> >
>> >> > Mark William Rabiner
> ---
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