Rodenstock TV-Heligon 50mm f/0.75 on Nikon - part 1

[dalex_257]

Hi All,

This is a followup on my original thread to get this ultrafast lens converted to Nikon mount. Here are some details and photos of this conversion.

I did the conversion part yesterday took me about 5 mins plus leaving it overnight to dry out. I bought the cheap aluminium extension tubes set on eBay for Nikon F-mount. The extension tubes came in with 2 Nikon F connectors one to attach to the camera and one to the lens with 3 extension rings. All of them attach to each other using 58mm threads same as the filters. After some measurement, it appeared that only those 2 mounts need to be used - they provide just enough height for the rear lens element to be leveled with new lens mount. Since it was important to me to make the rear lens element to stick as far as possible without damaging the mirror (this is to allow as large as possible focussing distance since this lens has register of 7mm and hence won't focus at infinity) I then decided to use only those two mounts without all the extension rings.

The mount that attaches to the rear of the lens was then glued to the lens back with industrial strength epoxy glue (special version of it for metal bonding) with it's extension thread facing back/up (i.e. just like it should be used with normal lens when used for it's intended purpouse). Photo here (the "other end" F-mount adapter is lying next to it):

The other connector or any other extension ring or adapter (or even another lens) can then be screwed in using the 58mm thread. I simply have the second F-mount from that extension ring set screwed in directly on top of this. So it looks like this:

This is how it looks on my D200 attached:

A very first sample photo of the tiny 5mm metall ball made up with this lens:

Contrary to my previous experience to take photos hand holding this lens - this is way much better and easier to focus now. The focus plane seems to lie somewhere around 10-20 cm in front of the lens which makes it easier to use than reversed-lens macro.

I have also tried it with extension rings added like so:

And it produces those magnification (photos are of the daffodil central part).

1. Taken without any extension rings

2. Taken with 20mm ring

3. Taken with all 3 rings

More examples, in the followup message.

 

[dalex_257]

Crocus "sunrise"

Morning dew

Daffodil veil

Daffodil

Rosmary flower

Cherry blossom

 

[puddleduck]

I really like the dreamy quality from this, especially from your first "Crocus sunrise" shot.

I also like a few of them here when you were just holding it unmounted.

http://www.talkphotography.co.uk/forums/showpost.php?p=1361720&postcount=24

Looks a nice thing to play with

 

[Blapto]

You really are tempting me to do this myself now!

Have you considered making some circular aperture blades for it? I know you have it because it's f/0.75 but I'm just curious.

Have you tested it with a lightmeter to find the effective aperture seeing as you're essentially using it with a degree of extension?

 

[dalex_257]

You really are tempting me to do this myself now!

That's the idea

Have you considered making some circular aperture blades for it? I know you have it because it's f/0.75 but I'm just curious.

Short answer is no. Longer answer is that it would be even more difficult to add this then to make this lens manually focused. The diaphragm blades ideally should go inside the lens where the nodal poing is and looking at this hefty chunk of nearly solid metal without any visible entry points (no screws nothing), I'm just not brave enough to disassemble it.

The other stage I'm considering is to have it manually focussed but it is slightly problematic - it has really short back protrusion and ideally needs a focusing helicoid from old flat pancake lens. And those are not always cheap.

If I see one, I'll look into doing this but for now, it is enough for me to use.

Have you tested it with a lightmeter to find the effective aperture seeing as you're essentially using it with a degree of extension?

No but I did intrinsic tests with built-in camera meter and it looks like effective aperture for the shallowest mount I can do with my adapters is somewhere around f/1.8 (either side). But viewfinder is really bright - much brighter than with my Nikkor f/1.4.

Bjorn Roslett reports that for his mount it is somewhat around f/2.0.

 

[dalex_257]

I really like the dreamy quality from this, especially from your first "Crocus sunrise" shot.

Thanks for comments. This is precisely why I wanted to have this lens. Unfortunately the "Crocus sunrise" suffers slightly from the jpeg compression artefacts - looks like rainbow banding around it on this small photo. This seems to be due to Zenfolio compression for the smaller image sizes that it generates on upload and it seems I can't control that. The original has all the transitions very smooth.

 

[dalex_257]

Another flower photo made with this lens which makes a nice abstract - "Sunrise":

 

[dalex_257]

Have you considered making some circular aperture blades for it? I know you have it because it's f/0.75 but I'm just curious.

Having digged tons of lens construction information on a web and analysing the nodal point and iris placement at the other lenses, I came to the conclusion that it is actually possible and dead easy to add iris to this lens. It appears that the nodal point lies just at the surface of the rear element (probably is the reason why iris was not there in the first place).

I have tried today to make some shots with a home made quick and dirty iris - attached the soft plumbing washer at the back lens element with a tape (tape attaches to the lens metal so the rear element kept clean). Take a few shots and voila - DOF is much increased. It still give the smoothness of the tones in OOF areas. The focusing was difficult though as the viewfinder went quite dark (still visible). I used tripod and took a few photos which I'll post this evening to illustrate this increased DOF:

I will need to think about making this permanent somehow so will try to experiment with broken lens irises (have posted requirements in my wanted thread for this).

Also an update - got myself 50mm E-Series Nikon pancake lens - will try to modify the lens to attach to this so it will be zoomable. It will still be usable only for macros (since the back distance cannot be increased) but at least I will be able to make focus adjustments without moving the camera.

Stay tuned for progress...

 

[Messiah Khan]

Nice to see you got it mounted. It's a shame that the focal distance is so short though. I would love to use a lens like this for something like portraits, but the focal distance would prevent this. Shots are looking good though.

 

[dalex_257]

Nice to see you got it mounted. It's a shame that the focal distance is so short though. I would love to use a lens like this for something like portraits, but the focal distance would prevent this. Shots are looking good though.

For portraits you need a bit longer and not that fast - Rodenstock XR-Heligon 90mm F1.1. This have longer back focus distance and will allow taking portraits. But that lens is a beast and imho more difficult to adapt...

Edit: the easier and more adaptable lens would be XR-Heligon 75mm f/1.1 - examples of it including portraits are here