RE: A Macro Lens Question
Hi Rob again , your tests proove to be very valuable. 2 photos from you tell more than a lot of written words ;-) thanks Markus >>To provide an example I just produced a pair of shots at f5.6, >>one with my >>A50/1.2 + tube and the next with my A50/2.8 macro lens, nothing >>changed but the >>lenses: >> >>http://members.ozemail.com.au/~audiob/temp/IMGP2269.jpg 50/1.2 >>http://members.ozemail.com.au/~audiob/temp/IMGP2270.jpg 50/2.8 Macro >> >>Cheers, >> >> >>Rob Studdert >
Re: A Macro Lens Question
On 27 Apr 2005 at 16:52, Godfrey DiGiorgi wrote: > I can't help but feel that the quality of the two pictures presented > are somewhat exaggerated given that you're comparing a dedicated 50mm > macro lens vs a 50mm f/1.2 lens. I suspect that you'd see much less > difference with the far more commonly used 50mm f/1.7 or f/2 lens. The advantage in using these two lenses was to present an exaggerated or worst case scenario to make most obvious the differences. Also these two lenses were both next to me at the time, it only took a few seconds to do so I did it. :-) Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: A Macro Lens Question
Since I asked the original question, allow me to jump in, not so much to Rob's defense (he can do that himself) but from my perspective. I don't mind that the effect is a bit exaggerated as it better shows what's happening when using a dedicated macro v a regular lens. I recognize that there will be differences to a greater or lesser degree depending on a number of factors, but just to ~see~ Rob's point in such a clear way was very helpful. Shel > [Original Message] > From: Godfrey DiGiorgi > --- Rob Studdert <[EMAIL PROTECTED]> wrote: > > To provide an example I just produced a pair of > > shots at f5.6, one with my A50/1.2 + tube and the > > next with my A50/2.8 macro lens > > I can't help but feel that the quality of the two pictures presented > are somewhat exaggerated given that you're comparing a dedicated 50mm > macro lens vs a 50mm f/1.2 lens. I suspect that you'd see much less > difference with the far more commonly used 50mm f/1.7 or f/2 lens. > > Godfrey
Re: A Macro Lens Question
--- Rob Studdert <[EMAIL PROTECTED]> wrote: To provide an example I just produced a pair of shots at f5.6, one with my A50/1.2 + tube and the next with my A50/2.8 macro lens I can't help but feel that the quality of the two pictures presented are somewhat exaggerated given that you're comparing a dedicated 50mm macro lens vs a 50mm f/1.2 lens. I suspect that you'd see much less difference with the far more commonly used 50mm f/1.7 or f/2 lens. Godfrey
Re: A Macro Lens Question
Quoting Jack Davis <[EMAIL PROTECTED]>: > Rod, > Sorry if this has been asked, but was the 1.2 lens > also set to 2.8? > He tells you in the text you quoted that both were at F5.6 > --- Rob Studdert <[EMAIL PROTECTED]> wrote: > > To provide an example I just produced a pair of > > shots at f5.6, one with my A50/1.2 + tube and the > > next with my A50/2.8 macro lens This email was sent from Netspace Webmail: http://www.netspace.net.au
Re: A Macro Lens Question
Yes. I recall Minolta once sold a special lens for three dimensional close up work, with variable/adjustable field curvature that would allow that kind of "negative" field curvature when needed. Their typical example was a photo of a rack of billiard balls. Their uncommon and expensive 24mm VFC (variable field curvature) that had good close-focusing results because of a floating element... Andre
Re: A Macro Lens Question
On Apr 27, 2005, at 7:48 AM, mike wilson wrote: Isn't a macro lens designed for flat field work? If so, wouldn't a regular lens used with an extender, a bellows, or helicoil focusing device, be a better choice for 3D objects, such as close-ups of flowers or small objects? Or maybe close-ups of not so small objects? Yes, most dedicated macro lenses are flat field corrected. If the primary point of interest is in the centre of the frame you might get away with a non-macro lens pretty easily but the point is that the generally distorted plane of focus on the subject side of most non-macro lenses can become a problem at macro distances. It certainly would be no better for 3D objects, a flat field lens will generally record any object in close focus with less optical distortion. In addition, I suspect the curve of the plane of focus in the non-FF lens will be the "wrong way". In other words, if focussed correctly in the centre, the curve of plane of focus will move back towards the lens towards the edges of the frame. In most macro pictures, one would want the plane of focus to move away from the lens as it moves towards the sides. I think... Yes. I recall Minolta once sold a special lens for three dimensional close up work, with variable/adjustable field curvature that would allow that kind of "negative" field curvature when needed. Their typical example was a photo of a rack of billiard balls. Most macro lenses are corrected for flat-field work because, in the greater scheme of things, corner to corner sharpness and correction for copy work and other small, flat-art objects is their priority. For three dimensional objects, flat-field correction is less important ... more focal length is more important so that you have working distance for proper lighting and better perspective. A 200mm lens is brilliant for 35mm format cameras, a 90-135mm lens is equally great for 16x24mm DSLRs. Godfrey
Re: A Macro Lens Question
> In addition, I suspect the curve of the plane of focus in the non-FF lens > will be the "wrong way". In other words, if focussed correctly in the > centre, the curve of plane of focus will move back towards the lens > towards the edges of the frame. In most macro pictures, one would want > the plane of focus to move away from the lens as it moves towards the > sides. I think... That'd be my thoughts, too, Mike... Fred
Re: A Macro Lens Question
> To provide an example I just produced a pair of shots at f5.6, one with > my A50/1.2 + tube and the next with my A50/2.8 macro lens, nothing > changed but the lenses: > http://members.ozemail.com.au/~audiob/temp/IMGP2269.jpg 50/1.2 > http://members.ozemail.com.au/~audiob/temp/IMGP2270.jpg 50/2.8 Macro Excellent examples, Rob - really answers the question, I'd say. Fred
Re: A Macro Lens Question
On 27 Apr 2005 at 8:21, Jack Davis wrote: > Rod, > Sorry if this has been asked, but was the 1.2 lens > also set to 2.8? No, both were set (mechanically using their aperture rings) at f5.6. Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: A Macro Lens Question
Rod, Sorry if this has been asked, but was the 1.2 lens also set to 2.8? Thanks, Jack --- Rob Studdert <[EMAIL PROTECTED]> wrote: > On 28 Apr 2005 at 0:33, Rob Studdert wrote: > > > On 27 Apr 2005 at 7:16, Shel Belinkoff wrote: > > > > > Isn't a macro lens designed for flat field > work? If so, wouldn't a regular > > > lens used with an extender, a bellows, or > helicoil focusing device, be a > > > better choice for 3D objects, such as close-ups > of flowers or small objects? > > > Or maybe close-ups of not so small objects? > > > > Yes, most dedicated macro lenses are flat field > corrected. If the primary point > > of interest is in the centre of the frame you > might get away with a non-macro > > lens pretty easily but the point is that the > generally distorted plane of focus > > on the subject side of most non-macro lenses can > become a problem at macro > > distances. It certainly would be no better for 3D > objects, a flat field lens > > will generally record any object in close focus > with less optical distortion. > > To provide an example I just produced a pair of > shots at f5.6, one with my > A50/1.2 + tube and the next with my A50/2.8 macro > lens, nothing changed but the > lenses: > > http://members.ozemail.com.au/~audiob/temp/IMGP2269.jpg > 50/1.2 > http://members.ozemail.com.au/~audiob/temp/IMGP2270.jpg > 50/2.8 Macro > > Cheers, > > > Rob Studdert > HURSTVILLE AUSTRALIA > Tel +61-2-9554-4110 > UTC(GMT) +10 Hours > [EMAIL PROTECTED] > http://members.ozemail.com.au/~distudio/publications/ > Pentax user since 1986, PDMLer since 1998 > > __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
Re: A Macro Lens Question
Perfect - a picture is worth a thousand words ;-)) Shel > [Original Message] > From: Rob Studdert > To provide an example I just produced a pair of shots at f5.6, one with my > A50/1.2 + tube and the next with my A50/2.8 macro lens, nothing changed but the > lenses: > > http://members.ozemail.com.au/~audiob/temp/IMGP2269.jpg 50/1.2 > http://members.ozemail.com.au/~audiob/temp/IMGP2270.jpg 50/2.8 Macro
Re: Re: A Macro Lens Question
On 27 Apr 2005 at 14:48, mike wilson wrote: > In addition, I suspect the curve of the plane of focus in the non-FF lens will > be the "wrong way". In other words, if focussed correctly in the centre, the > curve of plane of focus will move back towards the lens towards the edges of > the > frame. In most macro pictures, one would want the plane of focus to move away > from the lens as it moves towards the sides. I think... Yes, if I'm interpreting what you wrote, consider the plane-of-focus on the subject side to appear like a section of a sphere (that's an oxymoron if I've ever written one :-) with its centre behind the camera. So effectively the DOF will appear more shallow at similar apertures when using a non-flat field corrected lens, you can see this effect in my sample images (just posted). Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: A Macro Lens Question
On 28 Apr 2005 at 0:33, Rob Studdert wrote: > On 27 Apr 2005 at 7:16, Shel Belinkoff wrote: > > > Isn't a macro lens designed for flat field work? If so, wouldn't a regular > > lens used with an extender, a bellows, or helicoil focusing device, be a > > better choice for 3D objects, such as close-ups of flowers or small > > objects? > > Or maybe close-ups of not so small objects? > > Yes, most dedicated macro lenses are flat field corrected. If the primary > point > of interest is in the centre of the frame you might get away with a non-macro > lens pretty easily but the point is that the generally distorted plane of > focus > on the subject side of most non-macro lenses can become a problem at macro > distances. It certainly would be no better for 3D objects, a flat field lens > will generally record any object in close focus with less optical distortion. To provide an example I just produced a pair of shots at f5.6, one with my A50/1.2 + tube and the next with my A50/2.8 macro lens, nothing changed but the lenses: http://members.ozemail.com.au/~audiob/temp/IMGP2269.jpg 50/1.2 http://members.ozemail.com.au/~audiob/temp/IMGP2270.jpg 50/2.8 Macro Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
Re: Re: A Macro Lens Question
> > From: "Rob Studdert" <[EMAIL PROTECTED]> > Date: 2005/04/27 Wed PM 02:33:18 GMT > To: pentax-discuss@pdml.net > Subject: Re: A Macro Lens Question > > On 27 Apr 2005 at 7:16, Shel Belinkoff wrote: > > > Isn't a macro lens designed for flat field work? If so, wouldn't a regular > > lens > > used with an extender, a bellows, or helicoil focusing device, be a better > > choice for 3D objects, such as close-ups of flowers or small objects? Or > > maybe > > close-ups of not so small objects? > > Yes, most dedicated macro lenses are flat field corrected. If the primary > point > of interest is in the centre of the frame you might get away with a non-macro > lens pretty easily but the point is that the generally distorted plane of > focus > on the subject side of most non-macro lenses can become a problem at macro > distances. It certainly would be no better for 3D objects, a flat field lens > will generally record any object in close focus with less optical distortion. In addition, I suspect the curve of the plane of focus in the non-FF lens will be the "wrong way". In other words, if focussed correctly in the centre, the curve of plane of focus will move back towards the lens towards the edges of the frame. In most macro pictures, one would want the plane of focus to move away from the lens as it moves towards the sides. I think... mike - Email sent from www.ntlworld.com virus-checked using McAfee(R) Software visit www.ntlworld.com/security for more information
Re: A Macro Lens Question
Shel, I think (perhaps wrongly) that when you take a regular lens and put it on extender, bellows or any other such device, you essentially enlarge the middle portion of the image circle thereby achieving your magnification. The macro lens is designed to sustain such an "abuse" and still give you excellent resolution. So, from resolution point of view, it seems macro lens would prevail. And it seems to me that in macro shooting, resolution is quite important factor... Personally, I've found that working with converters wasn't good enough from resolution point of view, while working with extension tubes was too cumbersome on the field. So I bought a macro lens, and I am very happy about this very purchase. -- Boris
Re: A Macro Lens Question
On 27 Apr 2005 at 7:16, Shel Belinkoff wrote: > Isn't a macro lens designed for flat field work? If so, wouldn't a regular > lens > used with an extender, a bellows, or helicoil focusing device, be a better > choice for 3D objects, such as close-ups of flowers or small objects? Or > maybe > close-ups of not so small objects? Yes, most dedicated macro lenses are flat field corrected. If the primary point of interest is in the centre of the frame you might get away with a non-macro lens pretty easily but the point is that the generally distorted plane of focus on the subject side of most non-macro lenses can become a problem at macro distances. It certainly would be no better for 3D objects, a flat field lens will generally record any object in close focus with less optical distortion. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
A Macro Lens Question
Isn't a macro lens designed for flat field work? If so, wouldn't a regular lens used with an extender, a bellows, or helicoil focusing device, be a better choice for 3D objects, such as close-ups of flowers or small objects? Or maybe close-ups of not so small objects? Shel
