I didn’t shoot much at all last week. I have a few technical ideas, things I would like to try with one or another of the cameras or lighting/staging rigs I’d like to build, but no real will or interest, or even much time to do any of it, and no ideas or inspiration about what to shoot.

So when it came time to set up this week’s posts—News Flash: I set the weekly posts up on the weekend, sometimes weeks in advance, if I have a good thing going)—I didn’t have anything ready. So what to shoot?

I’m still wanting to find a way to digitize negatives, but am currently stuck at how to keep the negatives flat and equidistant from the sensor while also being easy to move from frame to frame, and I don’t yet know what lens to use. I might yet work on that this weekend, but better to go ahead and get posts knocked out so I don’t have that hanging over my head.*

But how to do that and still learn something?

Well, as mentioned, I need to figure out which lens to use. It should be sharp, with a relatively flat focus plane, and bright enough to stand some extension OR easily reversible.

That is very likely the mamiya/sekor 50mm f/2. But it might be the EL-Nikkor CP-2 50mm f/2.8.

And what did I have on the camera at the time? The Petzval. (It’s been awhile since I shot with it, and I haven’t spent enough time with it.)

So, with allergies in full effect, I just started playing around. First, I shot with the Petzval extended by about 42mm. Boring.

Then I extended it all the way to 96. Still boring.

~Boredom is Counterrevolutionary.

But wait… what’s this? The mamiya/sekor 50, just sitting right here. What would it look like if I held it up in front of the extended Petzval?


And an interesting thing happened:

With the mamiya/sekor reversed, we get a tiny depth of field and an extra smooth blur. But with the mamiya/sekor facing the correct way, the macro effect of the extension is nullified, and the field of view changes to something close to what the 50 would produce on its own, rather than what the 85 would make.

Does that make sense?

From the position in the office where I shot this and with the 85 by itself, I can see about 7 strips of blinds. With the 50 by itself, I can see 10. There are 9 strips showing in the picture above…

SubhanAllah. Physics of light is amazing: project 50mm worth of light down an 85mm tube, you get something close to 50mm of light. Now I remember the reversing and stacking of lenses back in the 365 project (see this, this, this, and/or this), and the necessity of stacking the wider angle in front to avoid vignetting, but I think I must have gotten it wrong: it’s not that the 50mm is getting narrowed down to 85mm, the 50mm is somehow filling the 85…

Can someone with some maths/physics/whatever help me out here, if you’ve gotten this far?

Anyway, that was fun, and maybe something to play with some more in the future.

D7000, Lomography x Zenit 85mm f/2.2 Petzval, extended, at f/4, with mamiya/sekor 50mm f/2 handheld out in front (reversed or straight) at f/2, ISO100, AP mode.

*And on these weekly posts hanging over my head: I’m not sure this is doing me any good. The 365 was moderately useful: I learned a few techniques and found some things I enjoyed shooting. The 7/52, likewise, was somewhat useful, though I didn’t shoot as many projects as I hoped. But this year’s (Macro Monday+Black & Wednesday+Phoneography Friday) are feeling a bit like chores, I don’t feel like I’m learning as much, and I wonder what I’m doing and why I bother.

Maybe it’s just the allergies talking, but if I’m not going to do anything with this photography hobby, maybe I should give it up and find something that is cheaper and not so burdened with (potentially) shareable/sellable products to absorb my free time…

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