Goerz Apo/Red Dot Artar questions

[Colin Myers]

I wonder if any forum member can help with the following queries on Goerz Artar/Red Dot Artar
lenses. Does information exist which shows lens numbers related to year of manufacture?
Last year, another forum member very kindly sent me an Artar coverage table. This was extremely interesting, and closer inspection showed there to be an apparent significant difference in coverage, between ordinary Apo Artars and their Red Dot counterparts, biased towards the older lens, in focal lengths 30" and larger. This appears to be on a sliding scale , with much reduced angles of view/image circle for the Red Dot lenses as the focal length increases. I thought that the the major differences between the Apo and Red Dot lenses was in the coating. Can anyone throw any light on this? I would be most grateful for any help or advice.

[Steve Hamley]

Colin,

Goerz serial numbers by date here:


http://www.largeformatphotography.info/classic-experts.html (http://www.largeformatphotography.info/classic-experts.html)

Steve

[N Dhananjay]

Red dots are coated. Those installed in shutters at the factory were also suppoed to have their optimization tweaked for 1:10 rather than the 1:1 that is more usual for process lenses. I was unaware that they had less coverage than non-red-dots. Are you sure you were not referring to Dagors - early Dagors have more coverage than the later versions (esp. the Kern got dot ones).In general, Artars have more generous coverage than is normally assumed. Goerz suggested an angle of coverage around 45 degrees, but a 10 3/4" will cover 8x10, which suggests coverage in the range of 65-70 degrees. The story I have heaerd is that the Goerz's figures refer to the coverage angle where the APO correction holds. This would be very important for process work, but in contact printing work, the outer edges of the image circle will probably render very usable images. Hope this is of some help. Cheers, DJ

[Colin Myers]

Thanks for the info guys.
Steve, can you can throw some light on the apparent image circle anomolies. Perhaps you know where the information in the table originated?
Colin

[CP Goerz]

A former Goerz employee I believe.

CP Goerz