How to: Camera Alignment and Focus for Film Digitisation with pixl-latr – With or without a Tripod or Stand

The lens is a key part of any setup for “scanning” film with a digital camera, but to get the best out of a lens, it has to be properly aligned and focused. (By “alignment” I mean ensuring that the film and sensor are parallel to each other). In this article, the second in my pixl-latr series, I’ll describe my alignment and focusing procedure for two different setups.

The first setup I’ll describe is a vertical setup with tripod, but the same principles apply if you use a copy stand. The second is a horizontal setup with no tripod – it’s a bit more fiddly, but may come in handy if you don’t have access to a tripod or copy stand. In both cases, I’m using pixl-latr as a film holder, but much of what I say here is applicable to film-digitisation with a camera more generally, regardless of what film-holder you use.

In this post, and in my pixl-latr series in general, I’m using pixl-latr on a budget, keeping additional accessories to a minimum. My goal is to try and get the most out of pixl-latr – and to help readers do the same – without spending a lot of extra cash. In fact, since I fortunately already owned a digital camera, macro lens, and tripod, I didn’t have to buy anything else at all (as you’ll see, even the tripod is arguably optional).

For the (extremely accurate) alignment method which I describe in this post, you only need a small, flat mirror (I had a shaving-mirror whose silvering had degraded, so I unscrewed and removed the frame).

Vertical setup with a tripod

My preferred setup is with pixl-latr laid flat on a horizontal surface, and a tripod-mounted camera pointing downwards. You can see a picture of my setup below (or see the first post of this series for more details).

The method which I describe here also applies if you use a copy-stand. If you don’t have a tripod or a copy-stand, jump to the next section (“Horizontal setup with no tripod”).

Basic setup, using a tablet as backlight

My tripod (Manfrotto Befree) has a reversible column, which means the camera can be mounted underneath so that the legs are out of the way. The height of the column is adjustable: another useful feature. And finally, a ball-head (or even better, a geared head, which my tripod doesn’t have) is convenient for alignment. If you’re planning to buy a tripod which you’ll use for film digitising, I’d recommend looking for these features.

My sequence of actions, which I’ll describe in more detail below, is as follows: Frame > Focus > Align > Frame again > Focus again. At this point, I’m good to go (luckily you only need to do this once per session).

Framing and focusing

The goal at this stage is for the negative to be in focus, and to almost fill the digital-camera frame (I use “negative” throughout this post, but all this applies to transparencies too).

First, I position the camera so that the lens is above and roughly perpendicular to the pixl-latr. Alignment comes later, so there’s no need to be super precise at this stage. It doesn’t even matter if the pixl-latr is not perfectly horizontal; it just needs to be stable. What ultimately matters is that the pixl-latr and the digital camera sensor should be parallel to each other, which we ensure at the subsequent alignment stage.

I then adjust the distance between the camera and pixl-latr so that the backlit negative almost fills the frame of the digital camera (I leave a little room around to edges to avoid inadvertent cropping; the loss in resolution is negligible). This can be done either by raising or lowering the tripod (generally easier), or by raising or lowering the pixl-latr itself, for example by placing books under it.

Next, I focus the lens (I use autofocus; again, there’s no need to be super precise at this stage). Focusing can cause the image of the negative to grow or shrink. Accordingly, I might raise or lower the camera again and refocus (two or three iterations are usually enough).

Alignment

I use a small, flat mirror for accurate alignment (i.e. ensuring the digital sensor is parallel to the film plane). With practice, this step takes only about 1–2 minutes, but you can treat it as optional; it depends on what your priorities are. If you’re digitising a large number of negatives and don’t care about optimal corner-to-corner sharpness, you can just align it by eye, or by any other method of your choice. Or you can try the mirror method once, see how much of a difference it makes (if any) and decide accordingly.

However, if you want to ensure the sharpest possible results – or if you’re testing or comparing lenses as I plan to do in my next post – accurate alignment is necessary; otherwise, it’s hard to tell if an apparent difference in image quality is due to the lens or due to inconsistent alignment.

For alignment, I simply place the mirror on the pixl-latr. The idea is to adjust the tripod head so that the reflection of the lens is centered in the camera’s LCD. This method is simple but extremely accurate. As I mentioned, it doesn’t even matter if the pixl-latr is not horizontal; the alignment process will ensure that the pixl-latr and the digital camera sensor are parallel to each other, which is all that matters.

The video below shows the alignment process as seen through the camera itself.

Hopefully, the video is pretty much self-explanatory, but there are a couple of tips I’d like to add.

First, it helps if the lens is well lit. So for the alignment stage, I place a table-lamp next to the setup, with its light shining down into the mirror, reflecting off it and illuminating the lens (a phone flashlight shining up into the lens also works).

Alignment stage, with mirror and a table-lamp

Second, I use the AF area (the white rectangle in the centre of the video) as a reference. You can either try to centre it with respect to the filter ring (as shown in the horizontal setup below) or, for added accuracy, with respect to the diaphragm (which is what I did in the video above). In the latter case – which admittedly might be overkill – it helps to stop down the diaphragm using the depth-of-field preview function (though not all cameras have this).

Third, if you have a ball-head tripod as I do, there’s often a tiny amount of “drift” after you tighten the screw. With a bit of practice, you’ll know how much it drifts and in what direction, and learn to allow for it (that’s what’s happening in the video from 0:17 onwards). With a geared head, this is less of an issue.

Reframing and refocusing

If you moved the camera during alignment, once you remove the mirror, you’ll find that the film is no longer centered. At this point, move your pixl-latr to centre the film; don’t move the camera. Since you’re moving the pixl-latr on the same plane, no further alignment should be necessary. But if you want to be sure, you can do a quick second check with the mirror.

The last stage is critical focus. For film-digitising, I tether the camera to my laptop with a USB cable and the Canon EOS Utility software (most other manufacturers have similar free software). In my previous post I talked about various benefits of tethering, but the main benefit for present purposes is being able to check focus on the larger laptop screen. The tether tool also lets me focus at 10x magnification for greater accuracy.

If you’re shooting untethered, I recommend using the LCD to focus. Most cameras let you magnify the LCD image for accurate focus, which is not something you can generally do on an optical viewfinder.

There are three main ways to focus (though not all cameras/lenses allow for all three): (a) autofocus, (b) manual focus with the lens ring and (c) manual focus with the tethering software. Theoretically, (c) is the most precise (at least on my camera, the software lets me to change focus in tiny increments, smaller than I can manage with the lens ring). But in practice, I find that autofocus is almost always dead-on – and faster. In the rare cases when it’s off, I can see this in the magnified onscreen image and rectify it.

Sample photo

Finally, if you’re bored of looking at setup photos, here’s a 35mm negative (Fuji Acros 100, the same one you saw in the video) digitised using the procedure just described.

As you can see, the results are quite good (if I may say so myself). But pixl-latr can also be used without a tripod or copy-stand, and with a bit of care, the results can be just as good.

Horizontal setup with no tripod

So what if you don’t have a tripod or copy-stand? In that case, I think a horizontal setup is better, simply because it’s easier to keep a camera in a horizontal position, as opposed to pointing downwards.

You need a horizontal surface like a table, and an adjoining vertical surface (the table can be pushed up against a wall – or in my case, a cupboard). I use rubber-bands to hold the backlight (in my case, a tablet) and the pixl-latr together. I use cardboard pieces to mask off any unwanted light from the tablet, and prop the setup against the wall (my tablet prop is a Bluetooth speaker).

You can see a picture of my setup below; I added labels for easy identification.

Horizontal setup

What I’ve shown above is just my own setup, i.e. what works for me. With a flexible system like pixl-latr, you can adapt how you use it based on your own needs and equipment. For instance, you can also use the detachable legs to stand it in front of the light source. I will come back to using pixl-latr on its legs more in a future article too.

Framing

First, I move the camera closer to or further away from the pixl-latr as needed. With each move I refocus, since focusing can cause the image of the negative to grow or shrink. The goal is for the backlit negative to almost fill the frame of the digital camera (I leave a little room around to edges to avoid inadvertent cropping; the loss in resolution is negligible).

I find that I need to slightly raise my camera relative to the pixl-latr in order to centre a 35mm negative in the frame. I do this by placing LP records under the camera, which you can see in my photo above: being thin and flat, they allow for fine height adjustments (newspaper also works).

Alignment

I use a small mirror for accurate alignment. The principle is the same as with a vertical tripod setup, so please first see the “Alignment” section above, which also has a short demo video.

The main difference is that in a horizontal setup, I insert the mirror in front of the pixl-latr, held to it by the rubber bands as shown below.

Horizontal alignment with a mirror

As before, the idea is to adjust the camera-orientation so that the reflection of the lens is centered in the LCD. The photo above was taken after alignment: you can see that the AF area is centered within the lens. My phone is propped up against the speaker; its flashlight is illuminating the lens to help me see it better.

Alignment is a little more fiddly with this setup as you don’t have the advantage of a tripod head. The mirror will check alignment along two axes:

As with the tripod method, I try to centre the AF area with respect to the reflection of the lens. If it’s off to one side, I make Adjustment 1, simply by twisting the camera to the left or right. If it’s above or below, I make Adjustment 2, achieved by placing cardboard shims under the lens barrel as shown below (I generally need to raise the lens, not lower it, since the camera tilts forward under its weight).

Finally, remove the mirror, focus on the negative and check that it is centered. On how to achieve critical focus, please see the “Reframing and refocusing” section above; the same principles apply with or without a tripod.

Sample photo

Once again, if you’re bored of looking at setup photos, here’s a 35mm negative (Kodak T-Max 100, the same one you see in the photo above) digitised with a horizontal setup.

Summary

To sum up, I described how to accurately align and focus a camera for digitising film. I described two setups – one with a tripod (the same principles also apply to copy-stands), and one without. With proper care, the second setup is as accurate as the first; it’s just a bit more fiddly.

For alignment, I used a small, flat mirror placed on the pixl-latr. This method is extremely accurate, and with practice, it takes only about 1–2 minutes. But if you think it’s overkill, feel free to align by eye, or by any other method of your choice. If you’re happy with your workflow and results, that’s all that matters! For more film photography, scanning and darkroom content, you can also follow me on my Instagram. Thanks for reading!