View Full Version : Grubb objectives - Who knows more than VM?

Steven Tribe
17-Dec-2009, 15:10
In front of me is a classic double pill-box patent single aplanatic Grubb landscape objective. Bought for experiments, as the achromat lens has gone. According to VM, the early series (A - E) are related to the objective type: A meaning Petzval, E meaning the single aplanat, that is, the one I have. But mine, apart from the serial no. 1686 has the clear engraving A6! There is no way this could have been a Petzval earlier in its life as the two part barrel, internal extension, are complete. Anyone have any ideas as to the significance of the letter/number code?

17-Dec-2009, 15:17
I don't know anything about Grubb lenses,
except that some were made in Ireland,
and I'd quite like to repatriate one,
and make some pictures with it here.

Is that an odd idea?

Steven Tribe
17-Dec-2009, 15:32
A very good idea! There was a real Polish made lens from before 1914 on the site a few years ago - but no-one from Poland bid! I think the Grubb family went (returned?) to England later and continued in Engineering. This lens was certainly made in Dublin in the late 1850's. I'll post some pictures when I have some good light over the weekend. The adjustment of the first pill-box is quite different than other designs I have seen. The barrel lacquer still reflects all lamps which makes artificial lighting almost impossible.

17-Dec-2009, 15:36
Very good, would like to see it-

You know, they were better known for telescopes, producing the biggest refractors in the world?
Photographic lenses must have seemed like a sideline...


Steven Tribe
19-Dec-2009, 02:58
Here are a few photos of the Grubb - a kind of striptease, showing the ways of changing how it is put together to change the F value. The description given in VM actually quite accurate - but perhaps the pictures will help comprehension it certain helped me.

Photo 1 is its normal mounting/transport position. The front pill box has a mounting sleeve and a loose washer at the base.

Photo 2 shows the way the whole front section can be pulled out of the main barrel. This section has two tracks (note the screws holding the rail(s) in other photos too). Friction will keep it in any position (different f values?) but also has a turn locking system at the very end.

Photo 3 shows how the whole front section can be removed. The barrel still has an F baffle.

Photo 4 shows the various pieces split up completely.

Still very interested in hearing from anyone who has an alternative suggestion of the letter/number coding of early Grubbs?

19-Dec-2009, 03:16
Thanks for postng those Stephen,
and well done for figuring out what it does-