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Anyone seen that f1.0 / 50mm lens before??
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PostPosted: Wed Aug 13, 2008 4:57 pm    Post subject: Anyone seen that f1.0 / 50mm lens before?? Reply with quote
Quite some time ago I aquired that lens made by famous UK lens maker DALLMEYER (Ok, ok, it is not M42 but M64), and I wondered if anyone has seen that before?





PostPosted: Wed Aug 13, 2008 5:23 pm    Post subject: Reply with quote
Never Shocked Have you tested it? It seems with the big mount it should project a large image circle. It is non-retro focus correct?


PostPosted: Wed Aug 13, 2008 5:26 pm    Post subject: Reply with quote
Funny that it only stops down to 5.6

It seems to have been intended to do 1:1 reproduction.

I have something thats somewhat in this line, a Bausch&Lomb 8 1/4" (210mm)/f:4.5 also marked 1:1 and that only stops down to f/8

So what sort of lens is it thats designed for 1:1 and large aperture with no need of smaller apertures ?

My guess is something that is for photographing a flat field, so no need for DOF, under low illumination, fairly close to the subject.

Some sort of document reproduction - maps ? blueprints ?


PostPosted: Wed Aug 13, 2008 6:40 pm    Post subject: Reply with quote
I've never seen that lens, actually the most of those ULTRA-MICRO-MAKRO-lenses.
I am more interested in the result obtained by this lens or any super fast lens.

Those chip-mask copying lenses do have very FAST speed and fewer F-stops,
since those ULTRA lenses are sharpest at the wide open anyhow.


PostPosted: Wed Aug 13, 2008 8:09 pm    Post subject: Reply with quote
Interesting glass! An f1.0! Wow!
This high speed and the fact that it just stops down to f5.6 make me think that it was surposed to be used for x-ray or screen shots.


PostPosted: Thu Aug 14, 2008 12:22 am    Post subject: Reply with quote
I don't know this lens, so here are some guesses.

luisalegria wrote:
It seems to have been intended to do 1:1 reproduction.


Not necessarily. 1:1 is the common notation for F/1.0 in Europe.

luisalegria wrote:
So what sort of lens is it thats designed for 1:1 and large aperture with no need of smaller apertures ?

My guess is something that is for photographing a flat field, so no need for DOF, under low illumination, fairly close to the subject.

Some sort of document reproduction - maps ? blueprints ?


I think Luis is right. I have seen similar lenses used in old photocopy machines. The large aperture was needed because of the low sensitivity of the materials used at the time. Of course, 50mm doesn't make senses for a full lettersize copy machine...

Cheers!

Abbazz


PostPosted: Thu Aug 14, 2008 1:04 am    Post subject: Reply with quote
Found a little info here http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=155


PostPosted: Thu Aug 14, 2008 3:03 am    Post subject: Reply with quote
Hahaha, it is Klaus's site. He is an OP.


PostPosted: Thu Aug 14, 2008 7:04 am    Post subject: Reply with quote
maddog10 wrote:
Found a little info here http://www.macrolenses.de/ml_detail_sl.php?ObjektiveNr=155


BIGGRIN...at least I know now that someone uses my site...

@koji: thanks, yes it is indeed

@abbazz: I don't think that 1:1 means f1.0, it usually denotes the magnification a lens has been made for (or is optimal for) i.e. in this case mag. 1x and a 1:1 reproduction ratio. Quite unusual focal length for that indeed.

@all others: I am not sure about the X-ray machine comments, that could indeed be, since these phosphorus screen emitted very dim light, so as to photograph and/or display them, "super lumen" lenses were used, some f0.75 so I would guess that would be the best guess....


PostPosted: Thu Aug 14, 2008 9:28 am    Post subject: Reply with quote
Very Happy Didn't even notice it was yours!

Just did a couple of searches and it came up.


PostPosted: Thu Aug 14, 2008 11:06 am    Post subject: Reply with quote
You'll notice only on that start page, but google usually directy you directly either to the macro or special lenses (sub-)pages.


PostPosted: Fri Aug 29, 2008 11:01 pm    Post subject: Reply with quote
kds315* wrote:

@abbazz: I don't think that 1:1 means f1.0, it usually denotes the magnification a lens has been made for (or is optimal for) i.e. in this case mag. 1x and a 1:1 reproduction ratio. Quite unusual focal length for that indeed.


Hi Klaus,

I disagree with you on that one. Looking at the text on the lens it would seem most unlikely to me that it would list name, focal length and intended magnification rather than name, focal length and aperture. On the aperture scale the maximum aperture is listed as just 1, not 1.0. I'm wondering if it would make sense in a 1:1 magnification lens to have a larger front diameter than back.

Anyway, I noticed a small difference between our examples. Mine is slightly narrower between the aperture ring and the rear male thread, the diameter is the same for the thread and the barrel up to the aperture ring. Does yours have a removable ring around it? And yours has its serial numbers on the back of the flat bit on the rear whereas mine has one on the retaining ring around the rear lens and the other on the aforementioned narrower bit of the barrel.
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