The need for speed! Aero-Ektar

[John Kasaian]

It was between a Dallmeyer Pentac and an Aero Ektar on the field of ebay honor and the Aero Ektar won---or rather I won the Aero Ektar as the Pentac blew right out of my budget. My interest in these lenses is for night photography using a 5x7 camera (an Agfa-Ansco Universal) Any barrel lens for under $40 isn't too bad a deal I figure, and I've got a lensboard with a big honkin' hole the beast may or may not fit.I suppose I'll have to make a concrete and lead box to keep it in (or do I need a permit from the nuclear regulatory conmmission?) but aside for being a fast lens and perhaps loosing a few stops due to staining from the effects of hot glass (though this one sems pretty clear from the pictures---I've seen some that look like the color of tea) I don't really know much about the things. My main concern is will it illuminate a 5x7 gg? I know they were designed to cover 5x5, but do they have mechanical vignetting to limit coverage? I'm not too concerned about the corners being mushy. Any thoughts? Ideas? Suggestions?

[Frank Petronio]

I usually made aperture adjustments by holding the lens between my thighs. It was fine. And kids with three arms make great assistants.

I don't know about the coverage. IMHO the only reason to use it was at f/2.5, it didn't do that great stopped down, it just seemed muddy. So wide open the coverage may not be that... large.

[domenico Foschi]

Frank, holding such a lens between your thighs seems to me an unncessary risk.

[Per Madsen]

Frank, holding such a lens between your thighs seems to me an unncessary risk.

The Thorium glas in the lens is an Alpha emitter.

You have to eat the lens to get any significant radiation damage.

Goggle for "Thorotrast" for an example of Thorium used as a contrast
medium for brain blood vessel examinations with long term consequenses.

http://en.wikipedia.org/wiki/Thorotrast

[John Kasaian]

The Thorium glas in the lens is an Alpha emitter.

You have to eat the lens to get any significant radiation damage.

Goggle for "Thorotrast" for an example of Thorium used as a contrast
medium for brain blood vessel examinations with long term consequenses.

http://en.wikipedia.org/wiki/Thorotrast

The blood vessels in my brain could probably use the help!

[Struan Gray]

The Thorium glas in the lens is an Alpha emitter.

You have to eat the lens to get any significant radiation damage.

It's the gamma from the daughter products that you need to worry about. Michael Briggs is the man to read:

http://home.earthlink.net/~michaelbr...aeroektar.html

[Carsten Wolff]

I second Struan's suggestion. I've still got a 7" Aero Ektar; it reads 100 counts/sec through the back..... it's not going anywhere near my face even via a GG..... you may argue only a dosimeter gives you a porper idea; that'll be the next step.
Get HP5 instead.

[Michael Heald]

Hello! I pl.ayed with an Aero Ektar for a while for 4x5 astrophotography. It covered at f2.5 without any problem, but I'm not sure about 5x7.
The main problem I had was with chromatic aberration. I spent a lot of time testing it and to get pinpoint star images, I had to stop down to f5.6. Best regards.

Mike

[Michael Heald]

Hello! I forgot to mention that the yellow tends to clear when you point it at the sun for a while. Of course, don't leave it out when the sprinkler comes on like I did. It tends to ruin all the hard work put in to make the lens better!

Mike

[Per Madsen]

It's the gamma from the daughter products that you need to worry about. Michael Briggs is the man to read:

http://home.earthlink.net/~michaelbr...aeroektar.html

I forgot about the daugther products.

What is the normal decay chain for Thorium ?