Lacerta Coma Corrector 2" for up to f/4 Newtonian Telescopes - Aplanatic 4-element GPU Design
Optimised for fast-ratio f/4 - f/5 Newtonian Reflectors / Dobsonians etc. with a 2” focuser.
This large, 4-element coma corrector has been designed by famous optical engineer, Pal Gyulai (Hungary) who became known for his very high quality oil spaced apochromatic telescopes.
It has been optimised for telescopes with focal ratios slower than f/4 (i.e. f/4, f/5, f/6 etc), so we wouldn't recommend to use it with Newtonian telescopes with focal ratio faster than f/3.75...
It will still work with f/3.75, but it won't give such perfect image as with f/4, of course, but it might still be a considerable solution when the price compared to a Paracorr of Winne.
It doesn't introduce any additional spherical aberration into the system like some cheap, 2-element coma correctors would do, and therefore it produces finer stars and clearer, more detailed structures of galaxies, nebulae, etc. (see comparison photos)
Working distance: 55mm from the stop ring, which is at the beginning of the M48 thread.
Diameter: 2 inch (50.8mm)
Overall length: 100mm from M48 connection
Diameter front lens: 43.4mm
Image circle: 40mm (this is the max. diagonal size of the sensor for which the image will be still corrected)
ATTENTION, the optimal working distance is dependent on the focal length and non-linear!
F = 600mm, working distance = 51.66mm
F = 800mm, working distance = 53.66mm
F = 1000mm, working distance = 55.0mm
F = 1200mm, working distance = 54.66mm
from 1500mm, working distance 54,60mm
visual use: Here the working distance is far more tolerant, and does not need to be kept as accurate.
We recommend the visual sleeve with M48 thread: M48508 (coming soon to 365Astronomy...)
To see the difference between the 4-lens GPU and probably the best 2-element (Baader) coma corrector, you should open the following two images in two separate windows or tabs and then "blink". Note the fine planetary nebula at the center of the picture and the limiting size (kind permission ONLY for Teleskop-Austria by Burkhard K. from Bondorf)
Evaluations with CCD Inspector software (for professionals):
Comparison photos with the same software for similar (but 2-element) coma correctors: