Thursday I took my 6x17 Shen Hao out to Langdale to the same place I was at in my previous post. I wanted to shoot a roll of panoramas with the 90mm f/8 Nikkor to get a feel for the difference in angle of view compared to the 38mm XL with 35mm film like I shot before.
It was as I expected. The panoramas felt a little "cramped" comparatively. the long edge of the shot on 6x17 is about 168mm, compared to 112mm on 6x12. That's a 1.5x longer negative. The vertical height of the 120 negative is 56mm, compared to about 35mm for the entire height of the 135 negative, with sprocket holes - close to the same ratio. Therefore, to "match" the look of the 38mm XL, I need a roughly 57mm lens. The 58mm XL, though, is only rated to 166mm for the image circle, while it needs 176mm approximately to cover the 6x17 format (diagonal).
All this jargon means is that I can't get the same field of view with the 6x17 as I can with the 35mm stuffed into the 6x12 back. Which makes sense - the 58mm XL is rated to 110° while the 38mm XL is rated to 120° (the 47mm XL is rated to 120° but still has the same 166mm coverage, just a wider view).
This is really interesting to me, personally. The connection between focal length, image circle, and field of view (in degrees) is quite fascinating.
That said, I think the 38mm XL image circle isn't fully used for the 35mm panoramas. Cropping the (very slight) vignetting from the 58mm XL on 6x17 actually does probably equal it, or close enough. But the issue there is I can't use the center filter for the 58mm XL without cutting even more image off! So the exposures are uneven. It seems to me that the 38mm XL is the ultimate panorama lens for wide-angle junkies like me.
Of course the 6x17 is a bit easier to work with, not having to finagle the 35mm cartridges into the holder, and certainly has a lot more film real estate, making more detailed and smooth images. But I can actually print the 35x112mm strips in the darkroom from the 6x12, unlike 6x17 since my enlarger can't take that size negative! What a conundrum.
I've written way too much. Here are two 6x17 images from the same location as the last post - check out the similarities if you are interested. Taken with the 90mm f/8 along with a polarizer and ND8 filter so I could get 15-minute exposures, on T-Max 100 rated @64 and developed in Rodinal 1:100 semi-stand for 45 minutes: