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Old November 26th, 2005, 01:07 PM   #1
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35mm adapter problems

my 35mm static adapter on XL1S:
ring adapter from 72mm to 55mm
2 elements +10 diottries each
GG for Mamiya RZ with Fresnels lens
5 rings UV
ring adapter from 55mm to M42
objective Zenith

I have eliminated the vignettatura, but the image is still too much dark.
which is the problem?

P.S.:
someone can post some photos of the condenser lens and of the proper GG.

in some threads I have read that someone use Aspheric Lens.
which is the difference?
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Old November 26th, 2005, 03:08 PM   #2
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in those 5 UV rings, is the glass still in there?

Any added element between the lens and camera lens will make it darker

Also, what 35mm lens do you have on there?
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Old November 26th, 2005, 03:42 PM   #3
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helios zenit 58mm, M42

the 5 UV rings are empty

but my impression that the ground glass has the tendency to darken the image ( i've also a Beattie Interscreen focusing glass, but the light resolution is the same)

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Old November 26th, 2005, 11:57 PM   #4
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What aperture or "f-stop" is the lens? It will be marked on the lens barrel close to the front end of the lens, and also on the front face of the lens. On the front face of the lens it will say:

(aperture number)/50

So for example if it says 1,5/85 that would be a F1.5 aperture lens of 85mm focal length.

In fact, what is the model number of your lens? Does it say "Helios 44" or "Helios-44M-4" or something like that? (the 'Helios' will be in Cyrillic letters)

Anyway I think most 58mm Helios lenses are F2.0. This aperture should not be too dark. Try adjusting the aperture ring. Also, some Helios lenses have a sort of stop or lock that prevents the aperture from opening any further. Set that all the way open.
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Old November 27th, 2005, 06:05 AM   #5
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i've an helios f2.0/58mm

but when I look at the image with GG is more dark. without GG there is more light.


what is the problem?


P.S.:
in my configuration there is not a condenser glass, could it be a problem?
the strange thing is that in the manual of the GG there is written that the Fresnel lenses(into the GG) increase 1,5/2 stops

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Old November 27th, 2005, 11:31 AM   #6
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Quote:
Originally Posted by Manu Pinto
i've an helios f2.0/58mm

but when I look at the image with GG is more dark. without GG there is more light.


what is the problem?


P.S.:
in my configuration there is not a condenser glass, could it be a problem?
the strange thing is that in the manual of the GG there is written that the Fresnel lenses(into the GG) increase 1,5/2 stops

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The fresnel might increase it 1.5-2 stops, but I think the light loss from most any GG is still more than 1.5-2 stops -- some light loss when using a GG is inevitable... just something you have to make up for whith more artificial light or a slower shutter. Condensor lenses should help. Remeber though that no lens can actually increase light, it can only direct it more efficiently. In any lens system, even the best of the best, there will be some loss of light, even if it's less than a percent.

note: I should say that I'm only now constructing my mini35 and don't have any first hand experience with them yet... just book knowledge and what I've read on this forum.
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Last edited by Justine Haupt; November 27th, 2005 at 12:48 PM.
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Old November 27th, 2005, 03:53 PM   #7
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Manu, the apperture of f2 is causing most of the light loss. I changed from 1.7 to 1.4 and it was an amazing diference. If you see the lenses you'll not be surprised, the lens itself is so much bigger. It's not a very big problem if you don't mind shooting with two 1000w tungsten/halogen lamps indoors or shooting with more or less sunlight outdoors.
In my experience, lighting is still an issue even with a big aperture(small number) so I just started a threas on: how to light indoor scenes with for a 35mm adapter.
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Old November 27th, 2005, 10:36 PM   #8
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You got a good point, Oscar. I wasn't thinking about how a lens designed for maximum aperture of only F2.0 will be so much darker than a more expensive lens that goes to a bigger aperture, even if that bigger-aperture lens is set to F2.0.

For example, I have a relatively cheap 50mm F1.4 SMC Pentax lens and even set at F2.0 it's much brighter than another lens I had made by Sears or maybe it was a Vivitar, max of F2.0, also 50mm.

Here's a quote from another of us dvinfo peeps who has seen this same thing: "The best way, to eliminate the hotspot, which is incidently what I have had to to, it to use a gg without any condenser, and buy very good quality fast lenses. I have been using nikons. I made the mistake of buying a fast vivitar, 24mm, and thought i had a bargin. Next to my nikon 28mm with the same apeture, the vignetting was incredible. The apeture on the vivitar, f2 was about 3mm wheras on the nikon at f2 it is about 40mm. I'm sure someone knows the reason for this on here, and this could be causing a problem for some people.

It doesn't matter how good your adapter is, without good lenses, it will always look crappy."

http://www.dvinfo.net/conf/showpost....7&postcount=26
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Old November 30th, 2005, 07:36 AM   #9
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the condenser is a PCX and aspheric lens, so is it a simple close up +4?

or with same principle but without diopter?


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