Xpan fast lens project, part XIVLMM

[didjiman]

Well, looks like Huw Finney are busy with *something* so he never finishes the

XPan fast lens nor the digital M2 mad projects. To recap, here's what *we* (the

royal we) want: fast (F2 but not faster due to Xpan RF baselength) 35 or 50 lens

for normal and not pano view. Why? Because then you can carry your Xpan outfit

plus one extra lens and you'd be good for most everything. I know I can sell at

least one lens to Lutz :-)

 

Here's what we know:

- You can still buy the Nikon-Xpan adapter for Nikon F, for around $300.

- Huw came up with the idea to make a RF CAM to couple his Chinnon SLR lens

 

Leica M lens are probably no good due to their shorter flange distance.

 

So if someone does the same RF cam hack to a Nikon lens, wouldn't that work?

[ilkka]

You can use a wide range of SLR lenses on XPan but without rangefinder focusing. I have a Leica R mount and have occasionally used my 60mm macro Elmarit. Nothing would stop me from putting a 1.4 lens on it. It is of course theoretically possible to rig some sort of cam (to at least some lenses) to allow for rangefinder focusing but for it to work properly it needs to be a very accurate fit. I doubt it would be worth the trouble and expense. And in any case, if you need to focus close, it is best to use an SLR anyway.

[didjiman]

Thanks Ilkka. I know it is hard to do, but Huw did it, so it can be done again!

[lutz]

Richard,<p>

 

The short answer: Unfortunately, there is no satisfactory solution available, yet...<p>

 

Haven't heard from Huw for ages. Ultimately he sent me the Hassy flange that he had got hold on and unsuccessfully tried to marry to a Summicron lens head. I had tested that combo and focus was off. In the meantime I learned about a guy (former Hassy technician, it appears) in the Netherlands who produces SLR lens adapters for the XPan. Here's a (quickly and dirtily googled) link to Wilco Jansen's offerings, maybe this helps:<p>

 

<a href="http://www.fotoapparatuur.nl/Hasselblad/Adapter/Ad39111.html">http://www.fotoapparatuur.nl/Hasselblad/Adapter/Ad39111.html</a><p>

 

According to him, the tolerances for machining an adapter which focuses reliably are in the 0.02mm region(!). He claims to be able to achieve these. (My humble efforts have been unsuccessful so far.) The problem still remaining with his adapters is the unavailability of rangefinder action. And, yes, the M lenses are to be excluded for the reason you mention.<p>

 

My latest thinking goes towards adapting/mounting Contax G 2/45 lenses - fast, sharp, affordable, 45mm frames available in the Xpan finder. All we would need to find is a lens shop to produce a small batch of mounts for a number of aficionados. If we can gather 5-10 people that could work out at, say, $500 (or less) for each lens plus ??? for each mount. There are lens machining shops in Japan, I'm told, which are very capable but reluctant to communicate in any language but Japanese - and mine is non existent.

<p>

If you are "hot" enough to join a similar venture I could try to get hold on somebody in Tokyo who might act as a translator/communicator. Or maybe you have even better contacts over there...?<p>

 

Cheers,

Lutz

[warwick_lawton]

Like many Xpan users and the lack of anything from Hasselblad to solve the missing 'fast lens' problem I've had to come up with other solutions. Fiddling with flashes, missing shots and no shadow details

just got too much and distracted the whole purpose of the Xpan

being a high performance versatile camera. Below are some pointers and comments that may be of use to others:

 

I've managed to get hold of a rare Contax C/Y Lens to XPAN adapter,

and my lens choices are the Carl Zeiss Distagon f2.8/25mm and

the Carl Zeiss Distagon f2.8/35mm with appropriate Voigtlander

view finders that are readily available. Of course, no Panoramic

coverage but this was not the purpose - I am of the view there

is no real substitute to the Xpan lenses in this respect.

 

Now, it may seem strange to go only for a f2.8 but here was the reasoning:

 

1) Lack of range finder coupling; the adapter is ONLY a very well

built spacer with appropriate mount interfaces. With no

range finder coupling, manual focusing with the lens distance range

is quite hit-and-miss with anything faster. The DOF at short

distances (< 2m) with f1.4 and/or f2 becomes very

critical even with a 28mm. Going upto 50mm starts to

become a real challange and so these focal lenses were ruled

out all together.

 

2) Cost, performance and intended purpose compromise. Finding

and paying for a Carl Zeiss Distagon f1.4/35mm or f2/28mm in

C/Y mounts starts to get costly for that 'extra stop' and

availability is an issue since the Canon EOS DSLR guys are

snapping them up like there is no tomorrow.

 

I am primarily interested in low-light interior shots of

concerts and typicaly the darkest areas of interest in the

scenes fall on EV 1.5 - 2.0, with highlights going way beyond

to around 11.0 - 15 EV. This gives essentially two options:

a Delta 400 ISO pushed to the point of blowing

highlights even with a water bath, or a Delta 3200 pulled

down with around N-1 developed in Perceptol and water bath will

give very acceptable results for B&W printing on about a Grade 1.

 

An unsharp mask can then help squeeze the negative

contrast down to make a final print on about a Grade 3 with the

added bonus of increasing apparent sharpness.

 

This can be done with f2.8 at 1/30 sec which gives enough

DOF and shutter speed to give an overal sharpness the

Distagon is capable to deliver while operating hand held.

 

This set-up is proving quite good and could appeal to others

and other low-light applications. It has taken several months

to come-up with a final solution and test each step. The precision

of the adapter has been tested using the focus ranges of 30cm

to 5m with rulers/measures and has proved to pin sharp on the film

plane. Each lens has been modified to have 1/2 f-stop aparture

increments for finer control and balancing between aparture and

shutter speed.

 

To solve the range finder coupling, an initial quick and dirty

solution was to invest in an old external range finder but this

was rejected since the Xpan's hotshoe is already occupied with

the view finder.

 

Looking at the lenses closely, and I think contradictory to what

Huw Finney said about SLR lenses, the Distagons rear element

does move exactly like the Xpan lenses. Ie: closer to infinity

closer to the film plane. This then gives a potential for the

much sought after range finder coupling! Since the spacer width is 10mm or so, plenty of room is availble to install linkage cams

between the lens and Xpan range findr couping wheel. My preliminary estimates are this is very feasable, and more so it looks like

the Xpan range finder mechanism could support the Distagons long

lens travel adaquatly. Another point of this set-up suggests that

ANY C/Y Carl Zeiss Distagon lens can be used without the need to change focus cams etc. since the rear element to mount distance

looks precisely the same between the two lenses. I will

investigate this futher but for the moment it looks promising.

 

Perhaps a long message, but the main point is that this is

very feasible to do with the Chinese company that makes these

adapters. Some measurements, trial and error and basic engineering

would probably find the right solution. The choice of lenses in

the C/Y is excellent and there is good glass available at reasonable

prices. As a foot-note, a M42 to C/Y adapter also means a whole

bunch more of lenses are available; for a bit of fun I've dug

out my old Zenitar F2.8/16mm fish-eye and it works

perfect! Note also the new Carl Zeiss Distagon ZM f2/25mm in

M42 gives a great potential too....

 

On a final note, I would say that Hasselblad have already missed

the boat and it's best left to an enterpising small company

to make the right adapter for the right lenses that are common

and affordable on the (used) market. It's a shame, but Hasselblad

could have put this camera firmly in No. 1 position if it made a fast

lens from the outset.

[lutz]

Thanks for your update, Warwick. It's comforting to read that I haven't been the only one to spend (waste?) so much time on the issue... ;-)<p>

As for the RF-coupling issue: <p><i>

Looking at the lenses closely, and I think contradictory to what Huw Finney said about SLR lenses, the Distagons rear element does move exactly like the Xpan lenses. Ie: closer to infinity closer to the film plane. This then gives a potential for the much sought after range finder coupling! Since the spacer width is 10mm or so, plenty of room is availble to install linkage cams between the lens and Xpan range findr couping wheel. My preliminary estimates are this is very feasable, and more so it looks like the Xpan range finder mechanism could support the Distagons long lens travel adaquatly.</i><p>

Hmm, the crucial question is: Is the Zeiss rear lens mount rotating or not while moving into the body when focusing? If it's not, then chances are high that it is not advancing into the camera body in the right progression required by the RF lever. If it IS rotating and if there is enough space to fit a cam (like a circular ramp) between lens mount and RF lever, then there is potential for a solution...<p>Enjoy your Hassy and lets see some results. :-) Cheers

[dan_fromm2]

Pardon my ignorance, but what's the point of using a lens that covers 43 mm, if that, on an Xpan? I say "if that" because image quality in the corners of lenses made for 35 mm cameras, especially fast lenses, usually isn't that good.

 

I can see the point of using a lens that covers 80 mm, i.e., nominal 6x6, but where's the gain from using a lens made for a 35 mm camera?

[warwick_lawton]

Lutz, I've 'wasted' energy on this for sure! The drive is basically eliminating the need of a parallel 35mm camera system which is of

course a lot more cost and energy waster! The range finder coupling is something that could waste even more time!

 

Primarily, the 35mm is the one to have RF coupling due to a more critical DOF; I would be happy with some sort of 'precision' between 0.7m to 3m. Over 3m can be done with the distance range rather successfully.

 

To answer your very valid (and researched!) question about the rear

element rotation, NO it does not rotate. You are totally correct that the 'chances' of lens travel and the XPan RF wheel are synchronised are slim. This is to be verified 'how slim'. My visual observations seem that it is very close though; the travel of the XPan RF wheel

is rather amazing since it can support the closest distance of the

30mm (which from memory is 0.7 meter) to almost infinity and at

the same time provide parallex correction for the 45mm and 90mm lenses. The Distagon travels much more, and the 0.7m to 0.3m travel in itself is a significant proportion (60%?) of the total. This is part of the reason why I believe the 10mm spacer width is usefull to accomodate a mechanism to make the lens and RF wheel synchronise together.

 

I will try it out with some mock-up bits and pieces. I have a

3 dollar plastic vernier scale as a main tool.....precision engineering is not in my realms since I don't have access

to micro-meters, lathes, lasers and god knows what etc. Trial and error using stiff plastic pieces that are easy to cut and then going on to metal if the tests are successfull is my line of thought. Another line of thought is to look closer into how the Distagon is

made and find out what revolves and what doesn't and why....I am

reluctant to modify the total construction of these lenses though for the obvious reason ;-)

 

I'll make a post if it progresses, but like I mentioned the company in China who makes them could probably sort this out and get a production run of 500 and sell the adapters at 250 dollars or so.

 

So far, these adapters are always branded for attempts to substitute

the Xpan lenses with expensive Perspective Control lenses that don't

do the job in covering the full panoramic frame! I think this is

the totally wrong approach - the fast lens in normal mode is

surely the selling point to anyone who wants to maximise this camera's

usage.

 

Dan, the reasons for this are covered in several posts - this is

not for panoramic coverage. If you have used the Xpan 30mm lens which only goes down to f5.6 the amount of potential shots you loose is significant. Making the concession of having a normal 35mm photo in a low light situation with the same camera versus no photo at all is the key. The two stops gain from f5.6 to f2.8 also means that the 100 ISO film can also stay in the camera a little longer in the late afternoon sun rather than reaching for the 400 ISO. That two stop increase means increasing the enlargement potential too. Fully agree that the corner quality does suffer when (any) lens that is used wide open - this was the main reason for getting the CZ Distagons rather than the Yashica's ML or DSB series and setting the f2.8 limit.

[lutz]

Warwick, as I wrote in my earlier post, critical flange to film tolerances are in the 0.02mm ballpark - I suppose the very same applies for RF cam issues. So, that rules out anything but the high precision tools you mention not to have at your disposal. Been there, done that - handmade stuff just doesn't cut it, unfortunately :-(<p>

My last approach was to find a person with the right tools and craftsmanship to rework the mount of a 2/45 Planar, available for comparably small change (150-200 USD) and of excellent optical quality for the Contax G. Unfortunately, I haven't found the person yet to be interested enough in coming up with the necessary focussing mount for that lens head. It would be just perfect... I'm sure the cost of a prototype development would very soon be recooped. I'd be willing to spend 500 USD for a conversion, pronto. And I guess many other afficionados would, too.

[warwick_lawton]

Lutz, this weekend I made an attempt to understand better what is involved to RF couple the Distagons to the Xpan. A few things 1) The 35mm and 25mm Distagons are NOT at all the same in lens travel; and more so in mechanical dimensions and build quality (Japan vs. West Germany?). 2) On the 0.7m to infinity distant range, the Xpan lens travels about 4mm. The Distagons travel about 1.5mm / 2mm. In other words, a significant mis-match requiring a rather precise compensating cam mechanism to be built 3)An extension tube about 9mm would be needed to bridge the gap between the lens rear flange mechanism to the RF wheel of the Xpan. It would also need to be tapered going from about 30mm to 38mm outside diameter.

 

Finally, I would be prepared to modify the Distagons lens rear flange to add a 9mm extension tube; this is totally possible

having pulled them to pieces and realising the flanges are nothing

more than dust/light covers. This extension tube could then be used to afix a cam that would be adjustable via a few screws - course tuning would be with a needle file. I was thinking on the lines of Huw's Chinon SLR modification but having the freedom to re-try and adjust based on error. BTW: 3M Scotch tape makes an excellent ground glass on the Xpan and with a 7x loupe you can get damn close enough for focus trial and error without shooting off loads of film.

 

When I had the Distagons in bits on the table, it did occur to me

that the ideal would be exactly has you mention. Forget adapters, but rather remove the propriety mount of the lens and replace with

an extension tube + RF couple mechanism + Xpan mount in one go.

 

The 2/45 Planar would be an excellent choice; however the G

mount has a smaller flange to mount distance than the Xpan (http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html); this would probably require major surgery.

 

Let's hope others are interested; I too would

be prepared to pay around 700 USD for the complete package. Ideally,

three lens varities 25mm, 35mm, and 45mm all f2 and range finder coupled. I would also appreciate if this could be done without

external viewfinders, but rather explore attachements to the existing

finder. Also, maximum filter size 58mm. Is this asking for too much....? ;-)

[lutz]

Err..., yes. ;-) <p>

<i>The 2/45 Planar would be an excellent choice; however the G mount has a smaller flange to mount distance than the Xpan (http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html); this would probably require major surgery.</i><p>

As I said, it's not an "add-an-adapter" thing - rather, the lens head would have to be extracted and mounted into an appropriate focusing barrel. But that should be doable, similar jobs have been done for all kinds of glass to fit Leica M mounts.<p>

Good luck with your own surgery attempts. I myself wouldn't spend another hour on anything like it, rather invest in an expert's labor. But that's me. Have fun and report. :-)

[warwick_lawton]

Lutz, if I get what you are saying: get a 45mm second hand Xpan lens and commit the ultimate sin - rip out the element groupings and stuff in faster element groupings instead from another lens, say from Voigtlander with it's smaller diameter? Sorry to put this in crude engineering terms, but isn't that what it's about....the upside is that all your Xpan lens would cosmetically match but at a fair price!

[lutz]

Hmm, that could be an alternative. The RF action would be perfect, at least in relation to the barrel scale - but I'm not optician enough to tell if a different lens group would require the same amount of focusing travel within the barrel as the original Fujinon. If not, a mechanism would be needed that interacts between the two given focusing requirements - the one dictated by the alternative elements and the one dictated by the barrel - AND fits within the tiny amount of space between the two... So apart from this approach being costly in terms of raw materials, it also appears to be trickier than starting a barrel design from scratch.