Computar Process 305 mm f 9

[fujinonA]

I'm looking for some info on this lens.
Is true that this lens has an IC of 655 mm?
I would like to know if this lens focused at infinity give me the same spec..
Thanks

 

[Nick Zentena]

Do the math. To hit 655mm you would need 95degrees of coverage.

Here is a thread on the LF forum on a shorter version claiming 95 degrees of coverage.

http://largeformatphotography.info/lfforum/topic/501537.html

 

[fujinonA]

Thanks , I have noticed , also this one:

http://www.largeformatphotography.info/lfforum/topic/498719.html

"......210mm Computar, 456mm

240mm Computar, 523mm

300mm Computar, 655mm

Though not tested the 270mm Computar should cover about 590mm......"

How is it possible?

 

[fujinonA]

I forgot to say that in the thread they don't say if the lens is focused at infinity or if these lenses are optimized at 1:1 (like the old Apo Nikkors in barrel).

 

[sanking]

I forgot to say that in the thread they don't say if the lens is focused at infinity or if these lenses are optimized at 1:1 (like the old Apo Nikkors in barrel).

For my tests the Computar lenses were focused at 100-150 feet.

Computars, when you can find them new in their original box, have a spacer ring that allows optimizing for close work or for infinity. Bascially, you use the spacer ring for close work, eliminate it for infinity.

How is such coverage possible? Well, the lens does what it does. I have four of these lenses (210mm, 240mm, 270mm and 305mm) and they are great performers, much better in terms of coverage than even the legendary wide angle Dagors.

Sandy King

 

[fujinonA]

Thanks Sandy,
I was looking for this one http:

//66.218.71.225/search/cache?p=computar+305&toggle=1&ei=UTF-8&b=11&u=www.largeformatphotography.info/lenseslist.html&w=computar+305&d=8D3A5ABFEC&icp=1&.intl=us

infact the spec list of the 305 it comes with an IC 482 mm but it's always better to write if a lens is optimized at 1:1 .
Thanks again

 

[tim atherton]

I'm looking for some info on this lens.
Is true that this lens has an IC of 655 mm?
I would like to know if this lens focused at infinity give me the same spec..
Thanks

yes, at infinity and at f22. At f32 it will give you somewhat more.

It will cover 12x20 with 2 or 3 inches of rise/fall

 

[sanking]

yes, at infinity and at f22. At f32 it will give you somewhat more.

It will cover 12x20 with 2 or 3 inches of rise/fall

That is also my experience. The Computar 305 f/9 covers 12X20 with about three inches of rise and fall. Of course you have to stop down to f/45 or f/64 to use the lens all the way to the edge of the field, but even at the extreme edge the lens gives very respectable results for contact printing, which is what most people do with 12X20 negatives. I have not actually tested the resolution but I estimate it to be about 15 lppm at the extreme edges at f/64.

Just to repeat something that I have said before on another forum, Apo-Kyvytars appear to be the same lens with similar coverage to the Computars. A few Kowa Graphic lenses are also of similar design and coverage, but the great majority are not. I mention this because there have been a number of auctions on ebay for Kowa Graphic lenses in which the seller claims the lens is same as the Computar. This may be true, but in most cases it is not, so buyer beware.



Sandy