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fujinon-tv c-mount lenses?

RichA

New member
Does anyone have any experience with these? Are they good lenses? Specifically thinking the 25/0.85 looks interesting.
(that 5.6mm rear protrusion is worrisome!)

http://www.rmaelectronics.com/specsheets/CF25L.pdf
I've got a Fujinon 25mm f1.4 and it is very sharp at f4 and below. It is a 1" lens and there is some vignetting, but not complete vignetting like you see with wider angle or smaller sensor lenses.

http://www.pbase.com/andersonrm/cmount_lenses_on_panasonic_g1

P.S. Want a really fast c-mount lens? Expensive, but better than $2500 for a slower Schneider.

http://cgi.ebay.com/Fujinon-TV-lens...nses?hash=item33550a3b1a&_trksid=p3286.c0.m14
 
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pentacon6

New member
I used to purchase a 35mm f 1.7 in a fair price. However, the back ring needs some machine to fit in to the adapter. But I am really sure that it is fully covering the sensor.
 
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Vivek

Guest
I use a few Fujinon-TV lenses (25 and 50mm f/1.4). Both are superb.

The 25/0.85 is a special lens. I considered it for a long time but never bought one because of the rear element protrusion which makes it useless for use on a G1. I have no doubt that it is a true f/0.85 lens.

I have never seen anyone using (pictures) of it on a G1. So, whoever is buying these are hoping for a future camera that would allow them to use it.

This lens is discontinued.

I do have a generic 25mm lens that is marked f/0.85. I think it is a Senko 25/0.95 which is marked wrong by an over enthusiastic lens assembler. Real aperture is more like f/1.1.
 
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loa

Guest
Thanks Vivek. Guess that protrusion is a deal-breaker. Thanks so much for the help!

RichA: 0.7 - wow! I'd certainly be curious to shoot a few through that..
 
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MrAdrenalin

Guest
Hi Vivek,

I would love to se some pictures with the 50mm f1.4 fujinon TV-lens att different f-stops showing its rendering and bokeh. Thinking of using one as a portrait lens so those kind of pictures would be highly appreciated.

Best regards,
Magnus
 
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Vivek

Guest
Will do, Magnus. It will take a week or so. It does need a modification (the easiest to do) to fit a c-mount adapter to get to infinity. I will show the modified lens as well.
 
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MrAdrenalin

Guest
Looking forward already to it and thank you for the extra treat with the modification. :)
What c-mount adapter would you recommend for it. I will be using it on an Olympus E-P1.
 
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MrAdrenalin

Guest
Do you by the way know how much of the sensor in the G1 and E-P1 is being used during movie mode? Is it the same area as when shooting stills in 16:9? I have bought a 12.5-75mm fujinon with constant f1.2 and looking forward to test it when I get my E-P1.
 
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Vivek

Guest
I have no interest in videos (it is out of my league and interest). I am very serious about street photography and G1 fits the bill very well since its introduction. It is an extraordinary versatile and very useful camera. This is after ~ an year of constant use and is not an exaggeration.

The E-P1 is not for me and if the GF-1 does not an EVF, it is not for me (though it appears that it would be without the swivel TFT screen). I do not care about the looks, logos and colors (well, black isn't a color. ;)).

Anything I have posted/post (re: lenses) here pertains to the G1 and just because the G1 shares the m4/3rds mount, it would, by extension, apply to the E-P1 or GH1, etc.
 
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dcouzin

Guest
Does anyone have any experience with these? Are they good lenses? Specifically thinking the 25/0.85 looks interesting.
(that 5.6mm rear protrusion is worrisome!)
I don't understand why the 5.6 mm rear protrusion is worrisome. 9.6 mm with the thread. The flange focal distance for a C-mount lens is 17.52 mm. So there is 17.52-9.6=7.92 mm clearance between the rear lens surface and the image, provided there's nothing but air between them. The G1 has some glass over the sensor. If the thickness of glass is x mm, and the refractive index of the glass is 1.5, then the glass reduces the airspace by x/1.5. Vivek mentioned in another strand that the thickess of filter glass over the G1 sensor is about 9 to 10 mm. Then assuming 10 mm of glass right against the sensor, there's still about 1.25 mm of airspace between the protruding rear element and the filter glass.

More worrisome is the fact that there's a pile of glass over the G1 sensor and the C-mount lens is optically corrected for air between it and the image plane. A Bolex RX type lens is optically corrected for a 9.5 mm thick glass pane (prism) somewhere between it and the image plane. The corrections of these two types of lens are very different and each situation requires the appropriate lens in order to make sharp images at the widest apertures. Long ago I wrote two articles on the RX/C compatibility question: 1976-78; 1987. In order to appraise the G1 situation, whether it's RX-like or more nearly C-like, we need good dimensional information. rmaelectronics.com provided accurate dimensions for the Fujinon lens. Does anyone have accurate dimensions for the G1 camera, especially for what's above the sensor?
 
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Y.B.Hudson III

New member
an element wider than 21.6mm±, and deeper than 5.75mm± (measured from the c-mount flange) will not fit the G1...due to the design of the light box baffles...all this apprehension could be alleviated if you actually had a G1 in your hands...zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz...
 
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dcouzin

Guest
an element wider than 21.6mm±, and deeper than 5.75mm± (measured from the c-mount flange) will not fit the G1...due to the design of the light box baffles...all this apprehension could be alleviated if you actually had a G1 in your hands...zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz...
If it doesn't fit, it doesn't fit. You wouldn't want to Dremel a millimeter off the light box baffles, would you? (Read here what Kubrick did to mount his f/0.7 "Barry Lyndon Lens".)

But how does the optical concern detailed in my second paragraph disappear by having a G1 in one's hands, or by snoring? What's the point in mounting an ultrafast lens on a camera if extra glass (or lack of extra glass) between the lens and the sensor renders the lens very unsharp wide open?
 
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loa

Guest
What's the point in mounting an ultrafast lens on a camera if extra glass (or lack of extra glass) between the lens and the sensor renders the lens very unsharp wide open?
Well that was kind of the point of the thread. I was wondering how they work. Now I know...

Thanks for your input everyone!
 

woodmancy

Subscriber Member
an element wider than 21.6mm±, and deeper than 5.75mm± (measured from the c-mount flange) will not fit the G1...due to the design of the light box baffles...all this apprehension could be alleviated if you actually had a G1 in your hands...zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz...
Are you going to sleep as you write this - could be low blood sugar :mad:

Keith
 
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Vivek

Guest
Well that was kind of the point of the thread. I was wondering how they work. Now I know...

Thanks for your input everyone!

There is no substance in that quote at all. None of the users (of superfast lenses) said that the rendition is "soft".

Let him go pick on the Noc folks (Leica board), then we will see some substantive results. ;)
 

Y.B.Hudson III

New member
D@ cousin... I suggest the scientific method; that you p@y the tuition...get your hands on a G1 and some f@st lenses...find a brick wall, and then report back...
 
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dcouzin

Guest
There is no substance in that quote at all. None of the users (of superfast lenses) said that the rendition is "soft".
This seems to be a rejoinder to my: "What's the point in mounting an ultrafast lens on a camera if extra glass (or lack of extra glass) between the lens and the sensor renders the lens very unsharp wide open?"

If no one here has noticed that the wide open imaging is unsharp with either the RX-type ultrafast lenses or the standard C-type ultrafast lenses then one possible explanation is that the pile of glass over the G1 sensor is around half way between the 0 mm thickness appropriate to C-type lenses and the 9.5 mm thickness appropriate to the RX-type lenses. "Splitting the difference," half of a very noticeable error might not be very noticeable.

Another possible explanation is that the users of ultrafast lenses here have lax standards of sharpness. Post #91 (from Photomorgana) in the "A superfast normal on the G1" strand shows two pictures made with the 26mm f/1.1 Macro Switar RX lens. The one shot at f/1.1 is, in my opinion, grossly unsharp. Look at the lower eyelid hairs in that picture! The one shot at f/1.8 looks pretty sharp (in the 1 megapixel JPEG posted).

You can object that I'm applying unreasonable standards of sharpness. I think not. It is a long tradition in photographic lens design that the sharpness at full aperture be judged against the sharpness at the next few apertures. If the f/1.1 image is that much weaker than the f/1.8 image the lens design is not regarded as succesful. But I've had experience with the 26mm f/1.1 Macro Switar RX lens used on a Bolex H16 RX camera where the f/1.1 to f/1.8 sharpness difference is nowhere near as great as in Photomorgana's pictures. So it's not the lens's fault. Perhaps the G1 does not have anywhere near 9.5 mm of glass over the sensor.

Another long tradition is to expect more image from more sensor while still expecting a less absolutely sharp image upon the larger sensor. For a nice example consider how Zeiss rates its cine lenses. Lenses for 16 mm cinema (diagonal 12.7 mm for Zeiss) are rated at 20, 40, 60 cycles/mm. Lenses for 35mm cinema (diagonal 30 mm for Zeiss) are rated at 15, 30, 45 cycles/mm. So the expected absolute sharpness of the lenses for 35 cinema is just 75% of that for 16 cinema, but since the 35 mm cinema frame is (linearly) 235% the of the 16 mm cinema frame the net comparison is (linearly) 177%. For digital photography it is the pixel count, not the sensor size, which should determine the expected sharpness of the lenses. The 12 megapixel G1 sensor is comparable to the sensors on the RED electronic cinema cameras which are using Zeiss lenses made for 35 mm cinema. Surely more image should be expected from the G1 sensor than from a 16 mm film frame.

Traditions can be trashed if you wish. Photomorgana's f/1.1 image can be called "sharp" if you wish. Have fun on eBay, because no one will be designing and manufacturing lenses for such tastes.
 
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Vivek

Guest
A non user of any of the things being discussed is analyzing what is posted and projecting some conclusions without having any clues about the issues involved.

Who is having "fun" on eBay, btw?!
 

woodmancy

Subscriber Member
A non user of any of the things being discussed is analyzing what is posted and projecting some conclusions without having any clues about the issues involved.

Who is having "fun" on eBay, btw?!
Can't really say that I have had fun on eBay. It's useful, but nondescript in terms of fun.

Keith
 
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