Rank Taylor Hobson lenses

[brucep]

I have just acquired a 3 1/2 inch f4 and a 6 inch f4.5 Ental II pair of lenses, but the aperture settings confuse me and I hope someone can explain them to me.

The 3.5" f4 has these aperture settings 1 2 4 8 and 16 and the 6" has two sets of markings. The first set is exactly the same as the 3.5", but above those markings in the same window it has 30 25 20 15 10 and 5 so the number sequence is reversed to the first set.

Can anyone enlighten me as to what these settings are?

Thanks
Bruce

[Dan Fromm]

Its an English thing. I have a Dallmeyer enlarging lens with a similar aperture scale.

1 = wide open (time * 1 to get correct exposure)
2 = 1 stop down (time * 2)
4 = 2 stops down (time * 4)
and so on.

I'm not sure about the others.

[brucep]

Having looked at it more last night, I now believe the second markings are the aperture diameter. I wonder if this lens was designed as a process lens.
Does anyone know if Ental II were used as process lenses?
Anyhow the glass is immaculate so I'll try and mount it and see how it performs
Bruce

Sent from my X17 using Tapatalk

[Dan Fromm]

The VM wavers a bit on design types, says that longer Ental IIs were heliar types. Shorter ones may be tessar types. Go count reflections.

Process lenses? Not likely, Ental IIs are too fast for that.

[IanG]

I've use a few Ental enlarger lenses and they were superb quality, very well made, not far off the best available now.

An enlarger lens doesn't really need an f-stop aperture scale, the relative exposure scale is far easier, I'm surprised few other companies used it. The biggest customer for these lenses was the UK military, after WWII every medium sized and upwards Naval ship, and similarly Air Force and Army bases had their own photographic department usually with De Ver 54 and later 54a enlargers a range of TTH or Ross lenses.

You're second lens indicate it may also have been sold or used for some other purpose as well, the field of applied photography was quite large, it still is and is an area most here don't know about. A glance at Langford's Applied Photography book would be an eye opener :D and things have advance a lot since then.

Ian