| review: Zeiss Sonnar 135mm f/4 Telephoto Lens (appr. € 80,- second hand) |
This Zeiss objective was designed in the 1930s by Dr. Ludwig Bertele and built in the 1960s and regarded as the theoretically maximum possible in 135mm objectives.
Well, mordern designs with new glasses are faster now but they are not sharper.
This telephoto lens is sharp to the edge of the frame (at least of my 8.6mm CCD frame).
But at f/4 (fully open) it tends to introduce a little vignetting.
So I normally stop it down to 5.6 which is still reasonable fast for astrophotography.
With RGB filters there is slight chromatic aberration in red and blue while the green is sharp when staying in unfiltered focus.
This is the version with 42mm screw and hence I can easily adopt it to my filter wheel giving just the correct distance to the CCD.
The M42x1 thread is also known as 'universal screw mount' and was used on Pentax, Praktica, Mamiya/Sekor, Yashika and many other brands.
The flange-to-film distance is 45.5mm and hence too long to screw it directly to a CCD camera.
The Starlight Xpress cameras come with a tube adaptor for that.
Check the thickness of your filter wheel including adaptors if you want to use it with M42 objectives.
Example Photo of the Coathanger Cluster
The Zeiss was stopped down to 5.6 to decrease vignetting.
Image was taken with Starlight XPress HX916 without IR-blocking filter.
Slightly Unsharp Mask was applied.
The halos arround the stars show the chromatic aberration because I did not refocus the RGB frames.
Conclusion
This lens is a very good (and cheap second hand!) lens for wide field CCD astrophotography.
Use the search tool on this site to find more astro photos taken with it:
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