Archived posting to the Leica Users Group, 2000/01/06
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]- --=====================_20304216==_.ALT Content-Type: text/plain; charset="us-ascii" At 10:29 PM 1/5/2000 -0800, Frank Dernie wrote: > > Leica Users digest Wednesday, January 5 2000 Volume 14 : Number 057 > ----------------------------- > Date: Wed, 5 Jan 2000 10:30:34 -0500 > From: Frank Dernie <FrankDernie@compuserve.com> > Subject: [Leica] Technical Pan Sharpneness & Camera Vibration > > Paul Roark asked about the effect of vibration on the resolution available > from tech pan film on a 35mm camera. > > I have never shot a test chart so I do not know resolution numbers but I am > pleased to share some observations and measurements FWIW. > > 1) I am sure that the vibration you hav e noticed is due to mirror > movements not the shutter. No. The mirror is pre-released. I wouldn't consider an SLR that didn't have this function. Focal plane shutters, from my tests, appear to have more non-offset mass to start and stop. I fear camera movement is the equal and opposite effect of this shutter movement. With the leaf shutter, I suspect that the blades on opposite sides of the lens aperture offset each other to a certain extent. I've seen comments from other shooters with leaf shutters that indicate they can get by with very light tripods (as long as there is no flopping mirror to deal with). The successful medium format leaf shutter cameras include some of the best knows makes, for example, the medium format rangefinders, Rollei TLRs and 6000 series (designed after the SL66's focal plane -- the best I've encountered), and the classic Hasselblads. > > A Hasselblad is useless for the type of > photography I do due to vibration, and it has a leaf shutter. The mirror > and darkslide etc vibration OTOH is like a grenade going off in the hand. Do you get these same results on a tripod if you pre-release the mirror? > > ... > What was particularly interesting was the time over which the vibration > contiued. It was sufficiently short for the effect to be important at > shutter speeds of 1/60 to 1/2 second but for slower speeds to be > negligible. My tests show the same thing. The oscillations are absorbed by the tripod over time. The wood and carbon fiber tripods allegedly absorb the vibration better or quicker than metal. Also, at some speeds the body's relatively efficient absorption of vibration is said to make hand held shots at some speeds with some cameras actually sharper than shots taken on (light weight metal, no doubt) tripods. One thing I sometimes do with telephotos to minimize the sharpness loss due to shutter shake is to use a strong neutral density filter. This allows me to use a speed that is long enough for the initial vibration to be a relatively small percentage of the overall exposure. > > ... > 3) the ... position of the camera on [the tripod] > ... has a large influence on measurements. My tests agree with this, at least with focal plane shutters. I've found that vibration is least where the direction of the shutter is precisely lined up with the tripod column -- and thus the tripod center of mass. This is generally the case with modern SLRs that have vertically-moving focal plane shutters. While these modern SLRs do relatively well on horizontal/landscape format shots, they are not so good with vertical/portrait format shots, where the shutter has little mass under it. With one of these SLRs, I've found that when shooting a vertical/portrait format tripod shot, I can reduce vibration by adding mass to the tripod head or camera base, such that the mass under the shutter is increased. One modified head I made that allowed this had a camera (female) bayonet (a rear lens cap) firmly attached to the head so that I could put an unused (and heavy) lens on the head to add mass (that I was carrying anyway) right where it would be most effective. It worked -- the vibration of the system was reduced. > > Very complicated Yes. As far an I'm concerned, a well designed camera for doing landscape display prints must be sufficiently vibration free that I can get all the sharpness its lens and film have to offer easily -- without having to jump through all sorts of hoops. At the wide angle end, 35 may have made the grade. (I bought a Ricoh GR1 [very good 28 mm, leaf shutter] for wide angle shots to supplement my Rollei GX.) In the moderate telephoto range, I will, at some point, just have to rent an M6 to see how it handles a 90 on a light tripod. Thanks for your experience and views. Paul Roark http://www.silcom.com/~proark/photos.html - --=====================_20304216==_.ALT Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <html> At 10:29 PM 1/5/2000 -0800, Frank Dernie wrote: <br> <br> <blockquote type=3Dcite cite>Leica Users digest Wednesday, January 5 2000 Volume 14 : Number 057<br> - -----------------------------<br> Date: Wed, 5 Jan 2000 10:30:34 -0500<br> From: Frank Dernie <FrankDernie@compuserve.com><br> Subject: [Leica] Technical Pan Sharpneness & Camera Vibration<br> <br> Paul Roark asked about the effect of vibration on the resolution available<br> from tech pan film on a 35mm camera. <br> <br> I have never shot a test chart so I do not know resolution numbers but I am<br> pleased to share some observations and measurements FWIW.<br> <br> 1) I am sure that the vibration you hav e noticed is due to mirror<br> movements not the shutter.</blockquote><br> No. The mirror is pre-released. I wouldn't consider an SLR that didn't have this function.<br> <br> Focal plane shutters, from my tests, appear to have more non-offset mass to start and stop. I fear camera movement is the equal and opposite effect of this shutter movement. <br> <br> With the leaf shutter, I suspect that the blades on opposite sides of the lens aperture offset each other to a certain extent. I've seen comments from other shooters with leaf shutters that indicate they can get by with very light tripods (as long as there is no flopping mirror to deal with). The successful medium format leaf shutter cameras include some of the best knows makes, for example, the medium format rangefinders, Rollei TLRs and 6000 series (designed after the SL66's focal plane -- the best I've encountered), and the classic Hasselblads.<br> <br> <blockquote type=3Dcite cite> A Hasselblad is useless for the type of<br> photography I do due to vibration, and it has a leaf shutter. The mirror<br> and darkslide etc vibration OTOH is like a grenade going off in the hand.</blockquote><br> Do you get these same results on a tripod if you pre-release the mirror?<br> <br> <blockquote type=3Dcite cite>...<br> What was particularly interesting was the time over which the vibration<br> contiued. It was sufficiently short for the effect to be important at<br> shutter speeds of 1/60 to 1/2 second but for slower speeds to be<br> negligible.</blockquote><br> My tests show the same thing. The oscillations are absorbed by the tripod over time. The wood and carbon fiber tripods allegedly absorb the vibration better or quicker than metal. Also, at some speeds the body's relatively efficient absorption of vibration is said to make hand held shots at some speeds with some cameras actually sharper than shots taken on (light weight metal, no doubt) tripods.<br> <br> One thing I sometimes do with telephotos to minimize the sharpness loss due to shutter shake is to use a strong neutral density filter. This allows me to use a speed that is long enough for the initial vibration to be a relatively small percentage of the overall exposure.<br> <br> <blockquote type=3Dcite cite>...<br> 3) the ... position of the camera on [the tripod]<br> ... has a large influence on measurements.</blockquote><br> My tests agree with this, at least with focal plane shutters. I've found that vibration is least where the direction of the shutter is precisely lined up with the tripod column -- and thus the tripod center of mass. This is generally the case with modern SLRs that have vertically-moving focal plane shutters. While these modern SLRs do relatively well on horizontal/landscape format shots, they are not so good with vertical/portrait format shots, where the shutter has little mass under it. With one of these SLRs, I've found that when shooting a vertical/portrait format tripod shot, I can reduce vibration by adding mass to the tripod head or camera base, such that the mass under the shutter is increased. One modified head I made that allowed this had a camera (female) bayonet (a rear lens cap) firmly attached to the head so that I could put an unused (and heavy) lens on the head to add mass (that I was carrying anyway) right where it would be most effective. It worked -- the vibration of the system was reduced. <br> <br> <blockquote type=3Dcite cite>Very complicated</blockquote><br> Yes. As far an I'm concerned, a well designed camera for doing landscape display prints must be sufficiently vibration free that I can get all the sharpness its lens and film have to offer easily -- without having to jump through all sorts of hoops. At the wide angle end, 35 may have made the grade. (I bought a Ricoh GR1 [very good 28 mm, leaf shutter] for wide angle shots to supplement my Rollei GX.) In the moderate telephoto range, I will, at some point, just have to rent an M6 to see how it handles a 90 on a light tripod.<br> <br> Thanks for your experience and views.<br> <br> Paul Roark<br> <a href=3D"http://www.silcom.com/~proark/photos.html"= eudora=3D"autourl">http://www.silcom.com/~proark/photos.html<br> </a></html> - --=====================_20304216==_.ALT--