| View previous topic :: View next topic |
| Author |
Message |
ray_parkhurst
Joined: 20 Nov 2010
Posts: 325
|
 Posted: Fri Mar 30, 2012 7:03 am Post subject: |
 |
|
| Babylonia wrote: | | Within the same PDF catalogue you can find handy lists for choosing the best lens for a certain usage, as they list the minimum pixel sizes of sensors that the lenses are matching, enlarging factor and image circle. See page 36 and 37. |
Cool list. This was exactly the sort of info I was hoping for when I started this thread: info on lines of lenses that offer high quality alternatives for macro around 1x and that may have been more "modernized" than the ones I'd been seeing. Thanks to all for sharing this.
It also seems with this info I've come full circle versus my very first post on the forum, which was to ask for help in adapting the 95mm Printing-Nikkor I had just purchased. The mounting solution I finally found was the Rodenstock Modular Focus unit, which has adapters for various mounts but the base mount is M45x0.75, the same as the Printing-Nikkors. I see in the Linos literature that their Inspec 60mm and 100mm lenses also have the M45.0.75 mount and they recommend the MF unit to mount them!! It turns out that the 95mm and 105mm Printing-Nikkors were used in a number of industrial inspection applications, so the M45x0.75 mount may have been a standard developed for inspection lenses. A couple of the Tominon E36 lenses I've purchased came with various adapters from their M39 mount to M45 as well, so they may have been used in the same applications. All very cool stuff...
Ray |
|
| Back to top |
|
 |
Peter De Smidt
Joined: 05 Jan 2012
Posts: 154
|
|
| Back to top |
|
|
ray_parkhurst
Joined: 20 Nov 2010
Posts: 325
|
| Posted: Fri Mar 30, 2012 3:06 pm Post subject: |
|
|
Looks like the image circle is a bit too small, only made for 2/3" sensors...Ray |
|
| Back to top |
|
|
Yann E.
Joined: 22 Feb 2012
Posts: 184
Location: France
|
| Posted: Mon Apr 02, 2012 7:35 am Post subject: |
|
|
| seta666 wrote: | I remember having "hot-spot" issues with a Tamron SP 90/2.5; reason being the rear element was flat so light was bouncing back from the sensor to lens and back againg to the sensor. When closing the aperture you would see a blue spot but at wide apertures you would just notice a loss in contrast
Regards
Javier |
| Babylonia wrote: | As for the later Tamron SP 90/2.8 model several years back already at the website of Tamron they had written information that for digital use they specially had changed the coatings of the rear lens elements to avoid hot spot problems (as good as it gets). It was their designation to "Di" naming in lenses, that it was optimized for digital usage. How good (or bad) lenses are in practice is asking to experience of many users.
|
Having owned and used both lenses extensively in the field, I'd say the hot spot was actually a rare occurence with the 2.5/90 under natural light, unless there was a highly reflective element in the picture and close to the optical axis. It was a bit more frequent with flash.
I never experienced any hot spot with the 2.8/90 DI, be it under natural light or with flash, with or without highlights in the optical axis.
BUT considering the 2 lenses have a totally different construction & optical layout, it is difficult to tell wether the improvement comes from the coating or the completely different design...  |
|
| Back to top |
|
|
ChrisLilley
Joined: 01 May 2010
Posts: 680
Location: Nice, France (I'm British)
|
| Posted: Mon Apr 02, 2012 8:45 am Post subject: |
|
|
| Yann E. wrote: |
BUT considering the 2 lenses have a totally different construction & optical layout, it is difficult to tell wether the improvement comes from the coating or the completely different design... |
I suspect the design at least as much as the coatings.
Tamron 52B 90mm f/2.5 is 8 elements in 6 groups; the last element seems to have an almost flat surface. (Manual focus, magnification 0.5x, has aperture ring).
Tamron SP AF 90mm f/2.8 Di is 10 elements in 9 groups with a convex face towards the sensor. (Autofocus, mag 1.0x, no aperture ring).
 |
|
| Back to top |
|
|
seta666
Joined: 19 Mar 2010
Posts: 786
Location: Castellon, Spain
|
| Posted: Mon Apr 02, 2012 1:23 pm Post subject: |
|
|
| ChrisLilley wrote: | | Yann E. wrote: |
BUT considering the 2 lenses have a totally different construction & optical layout, it is difficult to tell wether the improvement comes from the coating or the completely different design... |
I suspect the design at least as much as the coatings.
Tamron 52B 90mm f/2.5 is 8 elements in 6 groups; the last element seems to have an almost flat surface. (Manual focus, magnification 0.5x, has aperture ring).
Tamron SP AF 90mm f/2.8 Di is 10 elements in 9 groups with a convex face towards the sensor. (Autofocus, mag 1.0x, no aperture ring).
|
You can see in the drawins the 90/2.5 has a flat rear ellement; you won't see any digital lenses with a flat rear ellement as it is the cause of light bouncing back into the sensor. Problem was more eviden with high contras scenes and with small apertures; that was the reason I sold it
_________________
http://www.flickriver.com/photos/seta666/
www.macrosmuymacros.com |
|
| Back to top |
|
|
Peter De Smidt
Joined: 05 Jan 2012
Posts: 154
|
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
