help with a crazy idea - rayxar 50/0.75 and lumix lx1....

[orangealpaca]

I recently bought a rayxar 50 / 0.75 lens out of old x-ray imaging equipment, in the hope that i could mount it on my gf1. i held it as close as i could get - it is an interesting lens - saturated and so very fast (1000th sec in the late afternoon shadows). although dirty and abused, it is still in pretty good condition for having some fun. It takes shots at about 40cms (no focussing ring) when held as close to the sensor as I can get it (the black sensor shield or image cropper gets in the way of putting it any closer to the sensor - probably luckily for me!) Extreme narrow depth of field as expected.



I am wondering - if i were to mount this lens almost on top of a digital sensor, whether i could get infinity focus? When i hold a piece of paper in front of it it seems I can get infinity focus at about 6mm from the back glass of the lens. Does this make sense? Or are some lenses made so that you can never get infinity focus?

If so, would it be possible to perhaps hack up my lovely old lumix lx1 (with cracked lens, hence the gf1) and possibly possibly mount it to read on the lx1 sensor? I could make up a holder that would allow me to pull it in and out to focus.... (i have a medium lathe and tools - I am a jeweller and metalsmith - all do-able mechanically - just wondering optically?) this is all assuming i can re-arrange the electronics within to make room of course....



Yes - craziness.... But why? It would make a great evening indoors camera - it is SO bright. It could open up all sorts of lighting possibilities.... And it would be fun, of course!

Really i just want to know if optically this might be possible - then i will start looking at the mechanics and electronics possibility-or-not....

In thanks,
Sean.

[Spotmatic]

[orangealpaca]

thanks spotmatic!

it all makes sense.... if only it were so easy with not buying stupid weird camera gear....

[orangealpaca]

....and just to show that I am not a complete fool (only half), i opened up my lx1 last year to replace a broken gear in the zoom drive (the crack in the lens, later found, unfortunately happened at the same time).

I believe that when I get the lens components out, that there might be enough room to mount the rayxar lens end close enough to the ccd to give infinity (supposing my naive hopes of such an optical possibility are true....)
the repair manual grab shows where the sensor lies, behind a filter at the end of the lens assembly....








Any suggestions as to the possibility of this from an optics point of view would be greatly appreciated!

Cheers.

[Scheimpflug]

[orangealpaca]

yes - the shutter - it does seem to be located within the lens group.... and it is listed in the manual as being a combination mechanical and electronic.

and yes to keeping everything connected in order to have signals going out. just really not sure about the shutter system....

maybe i will have to suck it and see. i will try to search and see if anyone has pulled something like these apart.

thanks for your thoughts Scheimpflug!

[ylyad]

Re infinity, it really depends on how the lens is designed as this depends on the distance between lens and film. Apparently, 0.8mm for those (see: http://hannu.mallat.fi/oddities/rayxar/rayxar.html or http://oldlens.com/delftrayxar50f075.html among others found after googling the lens name ).

You could also think of adapting it to your GF1... Considering scheimpflug's reply, it might be easier

[Scheimpflug]

Sean - do you have a photo of the back of the lens?

[orangealpaca]

here is an image of the back of the lens. yes, i was the chump that paid 100eur for a lens with a cracked rear element (though it is on the side and does not seem to affect the image.... so far....)



the diameter of that rear part is stepped - 27mm and 32mm dia - the actual glass that the metal shroud is holding in measures 24.5mm.

when i held it up to a piece of perspex it seems to have a focal plane distance of about 4-5mm when focussed on an object about 3m away.

i held the lens into my gf1 as far as it would go, and with light leakage and shaky hands i took pictures in the shadows (at 1/2000 sec) at about 20-30cms distance it is in focus. very saturated and dreamy as seems to be their thing...



i was initially planning just to mount it extended, but now it is here all big and glassy, would love to find some way to make it more flexible.
http://oldlens.com/delftrayxar50f075.html
this page with the japanese guy using one on a rangefinder at 2m is exciting, but he had his optically modified, and i was thinking of a less hard-core way and more diy way of going about it....
i am wondering about the shutter - ways around reducing the distances in there (besides video, which i am guessing would be shutterless?)....

[Scheimpflug]

Hmm.. Ok.

What are the dimensions of the baffled portion of the GF1? Is it possible that you might be able to grind a bit to "square off" two or even four sides of that rearmost element to allow it to fit inside the baffles and sit closer to the GF1 sensor?

It's a rather extreme approach... but not necessarily any more extreme than building a Frankenstein with the LX1.

[orangealpaca]

right behind that baffle is the shutter - i could only gain 1mm at the max, but more like 0.5 - the shutter zips right under the thin sheet baffles unfortunately.... it will have to be a short - macro lens on the gf1.

hmmmm - have to think about it. i would love to use it for stills, so i guess i should be looking for the camera with the most compact shutter arrangement (which i thought would have been something like the gf1 - maybe that is as good as it gets?) and i really want it to be digi.

thanks for the thoughts Scheimpflug - even having somebody consider it has given me some confidence of finding a solution....

[ylyad]

And what about getting rid of the LX3 case? I mean, you could re-use the sensor and electronics in a homemade case built around and for your lens. I don't forget the complexity, but your project is far from easy anyhow, so avoiding some constraints could help a bit.

You can take a look here http://www.collection-appareils.fr/phpBB3/viewtopic.php?f=37&t=8822&start=0&st=0&sk=t&sd=a this guy built up a SLR virtually from scratch. This doesn't correspond to what you're looking for, but most of your constraints would be similar and this could be inspiring.

Anyway, I wish you sincerely "good luck"!

[orangealpaca]

thankyou ylyad - that is most inspiring! that is about the capabilities of my workshop too, though gear cutting i have not done - screws yes - gears look painfully slow to set up....

i agree - it may be the best way to take the lx3 and dismiss the body - i still need the shutter in there though - that 0.75 aperture is going to get pretty bright pretty fast....

i have been eyeing off an old fuji finepix s602 sitting in the corner neglected - i am thinking that this has an interline sensor (just reading about all this now) and does not use a mechanical shutter. this would be perfect - i could get close to the sensor without worrying about a shutter....

more reading required.... more smarts and knowledge and experience required!!!

[Scheimpflug]

Yes, you're definitely not out of options yet.

Here are a few more:

• LX1: You could skip the shutter and grab stills from video.
  
  
• GF1: If you have a lens for the GF1 that can focus really close, you could make a "depth-of-field adapter". The way those work is you put an intermediate frosted screen behind your big lens, so that the image is focused on that, and then take your camera with a different lens and focus it on the backside of that screen. They're commonly used by amateur filmmakers to get shallow DOF with small-sensor video cameras with "slow" lenses.
  
  
• GF1: You could build a "relay lens", where you stack two lenses front-to-front to create a 1:1 (or close) path for the light... essentially an "optical extension" that doesn't change the focus or size of the projected image. There would certainly be some light loss with all of the extra glass, but the ultra shallow depth of field would still be there. Relay lenses are one technique that people use to handle the invasive fisheyes, so it should work for your situation as well. Here are two examples:
  http://www.naturfotograf.com/D1_fisheye_1,html.htm
  http://www.nearfield.com/~dan/photo/wide/fish/index.htm
  
  
• LX1: You could save the lens for night shots, and use a cover on the lens as the shutter. Basically, you would do this:
  • Put the camera on a tripod
  • cover the lens with something dark
  • start taking a picture with an exposure time that is longer than you need (say 5 seconds)
  • wait one second after pressing the button and then remove the lens cover
  • wait another second or two (the "actual" exposure) and then replace the lens cover
  • wait for the remaining second or two of the camera's exposure and then wait until the camera displays the image
  By doing this, you can ensure that the camera still sees darkness during the times that the shutter would normally be closed (shutter readout, dark frame subtraction, etc)... so the lack of an actual shutter isn't really a problem.

Good luck.

[orangealpaca]

thankyou - the relay lens option sounds do-able. i will look into it!

there is one other option i have been thinking of late at night. i have an old fuji s602 zoom that is old and never used. from what i can find, it seems that it uses and interline sensor that requires no mechanical shutter (uses the sensor itself as a shutter) - that way i could chop it up and get as close to the sensor as i can mechanically arrange. i had no idea about this - was just reading here about shutter systems -
http://www.steves-digicams.com/knowledge-center/why-digital-cameras-have-mechanical-shutters.html
and have read through a service manual i downloaded for the fuji - no mention of a shutter anywhere. it goes to 1/10,000 sec also, which makes me believe that it is an electronic shutter within the behavior of the sensor.



does anyone know about this??? interline sensors seem not to need a shutter....

i am learning lots in this process!

[orangealpaca]

i emailed a guy who had been pulling these cameras apart - the fuji s602 zooms - and he replied that -
"It uses an "electronic" shutter for image capture, but can use the mechanical
iris focus shutter to kill all light when off etc."
his page is here - http://www.digsys.com.au/S602Z/S602Z.html

So I am going ahead with my hack soon.... Taking out the fuji lens and seeing how close i can get that rayxar to the sensor....

[Pancolart]

I removed top glass from AGFA DC-833m. My XR-Heligons were sharp as hell and had infinity started around 4cm from camera. It seemed ideal but i wanted more and started removing zoom-ing mechnism. Then camera died.
Now i am in search for the similar camera that would have some override when zoom removed. Or person who would modificate compact-digital.

I can confirm - nothing dreamy about these X-ray lenses when properly used.

[pat donnelly]

This lens is a real challenge!

Could taking the top, front, lens off of an old 50mm lens, say a Domiplan!, enable the lens to be attached temporarily to the remaining lens?

A GRAFT?

The crop factor for a compact would suggest that it is a dead end for this lens?

No idea if it will work....

Good luck!

[Pancolart]

For Heligons crop factor on compacts would only be 1.5x and that is still very usable.

On photo you can see mechanical shutter that is just around 3mm thick so it could be squeezed beneath the lens.

Enjoy view on my AGFA prepared for the "big eye". Sadly on error now.

[orangealpaca]

Pancolart - great stuff!!! This is exactly where I am headed (got stuck doing "real" work temporarily, unfortunately...)
The Fuji has an electronic shutter so mehopes that I will be able to get within 3-4mm of it. the image circle from the back of the rayxar seems to be only about 21mm, so I am thinking that this is a good match (with the Fuji sensor) - it will crop but at the least I will end up with a short tele sort of crop, since the lens is only 50mm focal length as it is.
As soon as I get the Fuji apart i will post pics and show what it is like - just as Frankenstein as the Agfa, no doubt! I am a bit worried about all the sensors talking back to the chip, so I may have to keep the original zoom attached and moving until I can work out how to report back that everything is going according to original plans (zoom, lens, etc....)
Thanks heaps - gives me hope!!!

[Pancolart]

I'm keeping my fingers crossed!

[Pancolart]

Received my Rayxar today. What a beauty! How about removable (screw) back elements? Did anyone try to replace them with let's say 1.4/55mm normal lens back?

[orangealpaca]

that back glass element goes deep into the lens - anything you put in its place would require extensive modifications to either that glass, or the rear of the lens barrel itself - tricky, but maybe worth a try (though you would definitely bugger the lens in the process - seems like a one-way journey with no going back....)
this is a diagram of the lens - that back element is very deep - you would need to set something right in if you want to catch all the light that makes these things special, i am thinking. but i really don't know too much about all this - just gassing off.....



good luck and tell me how it goes!!!

[Pancolart]

You're right. Will come to that as last resort. I thing few mm flange will be easier to achieve. And i rather demolish many compact digitals then hurt one Old Delft . What about Sony Nex - did you try it yet?

[orangealpaca]

sony nex? i have not tried it. i am only going with what i have lying around - the fuji is next up for the operating table - i just wish that my work would slow down so i could get back to playing with this.... as soon as i do - pictures will be up - good or bad!
good luck pancolart!