Xpan and the 35/4 Leitz PA-Curtagon-R

[simon larbalestier]

Has anyone used the 35/4 Leitz PA-Curtagon-R with the Xpan and the Leica R-Xpan

adapter? Any images made with this combination would be most interesting to see.

[Rob F.]

Now, that is an interesting idea! 35mm could be a good focal length on the XPAN, especially if no center filter is needed. Question is, even with the extended image circle of a PC lens, will it cover the XPAN format? We are talking an image circle of just over 72mm, corner to corner. Now, how far can the Curtagon be shifted? My PC_Nikkor 35 goes 11mm. I seem to recall that the Leica shift lenses are a bit more limited--maybe 8 or 9mm? Well, in round numbers, let's say we can shift 10mm. So that means that the image circle extends about 10mm beyond the edge of the picture--left & right. So we are looking at about a 56mm image circle--more or less, depending on how close my 10mm guess is. The XPAN negative is 65mm across, so I don't think it's going to cover. But it might be useful for some pictures, if the full width isn't needed. The only point I can think of, is that it will give more image height than the standard 45.

[simon larbalestier]

Thanks for this info Rob. I think from what I've been able to read on the net the movement is 7mm left and right. I've mounted one on my Xpan, just not had the time to test it out before i consider buying the lens.

Do you know what the FOV/ Focal length would be when used in the pano format Rob? I could live with coverage up to 56mm.

[Rob F.]

Calculating for the diagonal, I think a 7mm shift would give you about a 56mm image circle. That's the 43mm diagonal of the 135 format, plus 7mm + 7mm, = 56mm. So the picture diagonal would be 56mm. The rectangle inscribed in that circle would be less wide than 56mm. The batteries died in my scientific calculator, so bear with me. I'm trying to do this on a slide rule. It look like the picture will be about 50mm wide. So, hmm, half of 50 divided by 35m the tangent of the half-angle is .715; 35.6 degrees, times two, is 71 degrees, close enough. So it looks like the lens could cover an angle of view of 71 degrees, horizontally. On the diagonal, 75 degrees.

 

Looks to me that is the same as a 28mm lens covers, on the 135 format. So maybe pick up a 28mm instead? I think it would be easier. Hope I did all that right.

 

BTW, the focal length won't change. 35mm is 35mm!

[simon larbalestier]

Thanks Rob for the info. What confuses me a bit is that the 45mm becomes a 25mm or near to when in pano mode so i was expecting the 35mm to be wider when in the same mode? Lens has sold so i can't test it but i should be able to lay my hands on another in the next few months. I was just trying to research its history a bit but have found very little.

[raymond_tai]

Yes I have used this combination. I don't think I scanned any of it but if I can find the

prints and negs I am more than happy to send them to you. I have since sold the Xpan kit

to concentrate on the Leica M something I regret. I had the Xpan 30mm lens and with the

center filter on it the max aperture effectively becomes something like f/11 which is

useless to me because I shoot handheld. I then saw a huge wall print shot with the

Curtagon on an Xpan and

decided to experiment. I tried a variety of R lenses and the results were very

interesting. None of the lenses fully cover the Xpan frame but two came very close with

just small black corners and they were the Curtagon (no surprise being a shift lens) and

the

current Vario 21-35mm at the 30mm position. I was astonished at the image circle of this

zoom. I was further astonished by the fact that both lenses at max aperture did not have

noticable fall off. I did not blow up the negs so can't comment about corner resolution,

etc. I also tried the current 28 Elmarit and the early version 35mm Summicron both had

smaller image circles of course but their coverage was respectible. I think if you already

have these lenses you should first see if you can live with smaller

coverage because some modest cropping can preserve the pano look.

[don dudenbostel]

Simon:

Hope you're doing well and know you're making great images. I had the new version 28PC Nikkor for years and seem to remember it had more than 7mm shift. If you can get adapters for Nikkors it's a superb lens. I had the roundshot 35 for years and sold it then started looking for the 120/220 version. The Nikkor 28PC is what they recommend for that camera and covers the full wertical dimaension of 120 and I think gives some shift.

[Rob F.]

Don: Yes, my 28mm PC-Nikkor has 11mm of shift.

 

Simon: I think when you asked what focal length it would be in the pano mode, you were asking what the equivalent FL would be in terms of picture width. So disregard my comment that it would still be 35mm. As best as I could figure from the data I had, I came up with 28mm worth of coverage. I was taking the amount of shift available as an indication of the probable image circle. Raymond's observations seem to suggest it might be a bit wider than my estimate, which was meant to be conservative.

[simon larbalestier]

Don, Rob and Raymond thanks for the info and replies.

 

Raymond: the combination sounds very interesting as i'd like to shoot wide open at F4 and gain some speed without having to use a center filter on an Xpan or Fuji 30mm which effectively then becomes a F8 lens. The smaller coverage would be fine so long as the way the lens draws the image is acceptable.

 

Don: i'm doing welll thanks how are things with you?

 

Rob: yes the equivalent FL was the question i was asking as i was thinking of what external viewfinder i could adapt to given me an visual indication of picture width for rough composition.

[Rob F.]

The 28mm PC might be another option. Even if it didn't cover the whole negative, there would still be a very wide angle of view.

[Alex_Es]

For the uninitiated, who makes this converter exactly and where do you get it?

[raymond_tai]

Alex, I got mine through a local dealer and he said they are machined in China. There are

hardly any demand for it so apparently this guy makes several a month. The cost was about

$250 to $300 and there were no back focus or misalignment issues.

[ilkka]

I have the XPan adapter and a PA Curtagon lens. I bought the adapter in China from a company called Kang Tai (www.kt163.com or something like that, not sure if it still works). It cost me a bit more than USD100 at the time, some three years ago.

 

The PA lens shifts 7mm and has image circle of about 59mm so it does not cover the full XPan format. It covers almost to the long edge with all corners being dark. When focused to its nearest setting and at smallest aperture, it almost covers the whole image area with just a bit dark in the corners. I have also tried the XPan with 60mm macro Elmarit and 180mm Elmar. I just got a Hasselblad to Leica R adapter and will try the 80mm Planar and 150mm Sonnar on the XPan as well. I think these lenses would have mechanical vignetting caused by the acute angle from lens throat to the edges of the film plane, even though the image circle itself is sufficient.

 

The 28mm PC lens has a bit larger image circle, is better quality and a stop faster. But it is also much more expensive.

 

I can look up some slides and do some scanning when I have the time. But probably not over the next week or so.

[simon larbalestier]

Ilkka thanks for your input here and i look forward to seeing some scans when you have some time.

[Alex_Es]

Thanks, Ray.

[lutz]

Hmm, Simon... The 45/4 Fujinon being of excellent quality, corner to corner, I don't see the use of a 35/4 neg/slide which would need to be cropped in order to give the same pano ratio to about the equivalent of a, say, 40/4. Less neg space, no RF coupling, unwieldy set up... what gives?

[ilkka]

45 is not very wide from top to bottom. Sometimes you need more coverage up/down but do not need the full 65 mm width. 35 is almost as wide as the very expensive 30 in this respect and 2 1/2 stops faster when the centre filter is accounted for. For similar money, the 2.8/28 would be even wider and 3 1/2 stops faster while almost covering the whole image area. Sure, if you need 65mm wide image, or that aspect ratio, you should use the original lenses. Another reason for me is to have a travel backup body for Leica R system. XPan and its two lenses and a Leica R with two or three lenses makes up a compact package that covers most situations, uses the same film and in a pinch the Leica lenses can be fitted to the XPan body. 35 framing can be quite easily estimated using the whole viewfinder image.

[simon larbalestier]

Hey Lutz :-) how's things? i think Ilkka explains my interest in this lens very well. Speed was one aspect, the way the lens draws the image another. I may end up getting the original 30mm but with a usable aperture of F8 once the centre filter is fitted, it makes it a tad slow especially when i'm use to my 1.4's on my M's!

[ilkka]

Here are now couple of images to show the coverage. The first image was made with a Leica R mount 4/35 Schneider PA Curtagon lens adapted to Hasselblad XPan using a Chinese made adapter. F stop was 22. The image was scanned on Minolta Multi Pro using the glass holder and 6x8 mask into which I have added a 26x67 mm mask. I scanned with 2400 dpi resolution which produced a 41.5Mb TIFF file. The scanned area was set at 25x65mm. The film strip was not exactly parallel and thus you can see a bit more black in the top right than in top left. Enclosed image has been downsampled to 750 pixels wide JPEG while retaining the whole image area and proportions. If the black corners/edges are cropped, the image width would be about 52mm. The image circle is a bit larger than that but rectangular cropping would reduce it to these dimensions.<div></div>

[ilkka]

When a lens is focused closer, its image circle increases. To try how well the PA Curtagon lens would cover the XPan image area when focused at its closest setting, I made the enclosed experimental image. As you can see, almost the full 65mm width is covered. The Curtagon lens focuses unusually close, to 30cm from film plane. Focusing with this combination is difficult because it is not rangefinder coupled. In practice, 'focus bracketing' would need to be done, several exposures with slight adjustments in focusing. Smallest f stop would help as well. This was made handheld using F/8 and it is not critically sharp, but it does show the coverage. Again it is a 25x65mm area scanned at 2400 dpi and downsampled to 700 pixels wide.<div></div>

[simon larbalestier]

Thanks for posting these images Ilkka it's interesting to see what coverage this lens can reach.

[Rob F.]

"The image circle is a bit larger than that but rectangular cropping would reduce it to these dimensions." [Referring to the PA Curtagon coverage on the XPAN.]

 

This is interesting, since when the transparency is mounted in a 54mm wide slide mount for projection, almost all the vignetting would be gone--just a bit left in the corners. Something to consider doing!