How To Find Three Useful Prime Lenses Buried In a Crazy 10x Zoom Lens

For March in my One Month, One Camera project I’ve chosen the Panasonic Lumix DMC-TZ2, a camera designed for travel (TZ = Travel Zoom).

This means it’s pretty small and pocketable, but also that the zoom goes from a fairly wide 28mm up to 10x that, 280mm.

For my needs, about 80% of this optical zoom range will be redundant. 

With virtually all digital zoom compacts I’ve used, I tend to use them at their widest focal length and never touch the zoom rocker.


With the TZ2 though, I discovered in my initial explorations of its menu, that it has a rather untypical Zoom Resume function. 

Zoom Resume simply remembers the position the zoom is at when you turn the camera off, and returns to it when you power up again.

So if I wanted to use the TZ2 as a 35mm lens camera for a couple of weeks, I can set it to 35mm, then the Zoom Resume will return to that focal length every time I turn it on.

This is a great start, but unfortunately the TZ2 doesn’t tell you what focal length you’re at, either the actual figure (between 4.6 and 46mm), or the 35mm equivalent (28-280mm).

All you get is a next to useless 1x, 2x etc, each of which covers multiple steps on the zoom so is so imprecise that you wonder what possible value Panasonic thought this would provide the user.

So for the Zoom Resume to be of any practical use, I needed to do some detective work. 


What this Lumix does show, despite being fully Auto Exposure (AE), is the aperture and shutter speed the camera will use.

Helpfully, for many reasons, the camera tends to use the widest aperture wherever possible, and the maximum aperture gets smaller as you go up through the zoom range.

In other words, from the aperture displayed, you can tell which focal length you’re at.

What I needed to do before this was of much use is take a picture at every step of the zoom, then note the actual focal length at each aperture, using the EXIF data.

From this, using the sensor’s crop factor, I could then translate to the 35mm equivalent we’re all used to.


Because I don’t use zooms at long focal lengths I didn’t bother tracking the full range, and indeed I didn’t really need to go beyond 50mm.

You can see in the table above I’ve highlighted the three focal lengths most useful to me – 28mm, 35mm and 50mm.

So I know that when the maximum aperture is f/3.3, the focal length is 28mm, f/3.7 means 35mm and f/4.2 means 50mm.

If I want to use the TZ2 as a 28mm lensed camera, I just zoom wide open and leave it there.

If I want 35mm (probably still my favoured focal length for all compacts), I zoom in either four steps, or until I see f/3.7.

For 50mm I go another six zoom steps, or until I see the second f/4.2 (the first is 48mm anyway, so close to 50 it doesn’t really matter if I use this instead).

To use the camera at just one familiar focal length for a whole photowalks – or multiple photowalks – I just enable the Zoom Resume feature so it stays at 28, 35 or 50mm, then forget about the zoom and treat it as a prime lensed camera. 


I’m sure most are reading this thinking it’s far too complicated and analytical.

Of course the original target customer of the Lumix TZ2 – someone wanting a pocketable and well made digital compact that will zoom wide and long enough to cover every possible situation on their holidays – is unlikely to care what focal length they’re at, as long as they get their photos.

But I’m not the original target customer of the TZ2!

I don’t like using zooms by standing still and zooming in and out, and as I said before, I rarely even use the zoom on these kind of cameras and use them at their widest.

I do like to know what focal length I’m using though, and sometimes 28mm is too wide (or rather there’s too much distortion up close), so 35 or 50mm is what I prefer.

Plus I do acknowledge and admire the fact that Panasonic included the Zoom Resume, perhaps a feature that most users complete ignore, but is an excellent addition for the more geeky and inquisitive photographer like myself.

It’s allowed me to discover and easily use at least three very useful focal lengths within a faintly ridiculous (to me) 10x zoom lens.

All photos in this post were taken at 35mm.

How about you, how do you use a zoom lens?

Do you just shoot it at its widest? Do you zoom as much as you need so the composition fits the screen or viewfinder as you wish? Or do you prefer having a form of step zoom and/or feedback on screen or on the lens barrel so you know what focal length you’re using?

Please let us know in the comments below (and don’t forget to tick the “Notify me of new comments via email” box to follow the conversation).

Thanks for looking.

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7 thoughts on “How To Find Three Useful Prime Lenses Buried In a Crazy 10x Zoom Lens”

  1. Boy, is this a timely post for me Dan! I have a Panasonic DMZ-LZ8 I picked up in a thrift shop last year for a few dollars. It works well, but I am a zoom-hater, so I used it once and put it away until my young co-worker expressed an interest in photography and asked me to recommend a camera. Knowing the she has very limited funds (she is a student) I offered her the camera. We figured everything out more or less, but I was stumped about how to figure out where 50mm f.l. was. I will forward this post to her, I think your camera is similar. Thanks again!

    1. Jon, I had the LZ1 and really liked that, the LZ8 must be a later version.

      If it has that great Zoom Resume function it makes it easier, especially if you always like to shoot at one focal length that isn’t the widest zoom.

      Even if not you can figure out focal lengths as I did above – the EXIF data shows the actual focal length in any photograph. You only have to do this once, then you have the figures.

      Or if you just want one focal length, say 50mm, a quicker way would be to get another camera that is 50mm, then zoom the LZ8 until the field of view in the screen is the same as with the 50mm camera, then note the max aperture (ensure you’re in low light so it’s forcing it to use the max aperture at that zoom).

      Then just zoom until you’re at that max aperture in future when you want that focal length.

      With a bit of experimentation and thought, these fairly basic consumer zooms can be great fun and can work for your specific needs.

      1. Thanks for the tips Dan, I didn’t think of that. This camera was boxed and like new, I think it will be perfect for Ali.

  2. By George that would be a BRILLIANT addition to a fixed-zoom camera: preset zoom lengths! Maybe only film users would appreciate it, but others could learn. I’ll have to add that concept to my “ideal digital” design. Thank you!

    1. It’s invaluable yes. A few Rioch cameras have it, the GX100 and GX200 (I think, I don’t have one), and some of the more consumer end zooms like the CX and R series. I had a CX1 which had it and was great –

      Note with the GX100 you can also save the focal length the zoom is at under one of the custom settings on the mode dial. I assume this is the same for other Ricohs with step zoom and custom settings.

      So for a while I had my GX100 set up with custom setting 1 as Aperture Priority, black and white with the 24mm focal length, and custom setting 2 as exactly the same but 35mm.

      Yes I could just zoom between the two but I just liked having essentially two prime lensed cameras in one, a 24mm and a 35mm, depending on whether the mode dial was on MY1 or MY2.

      Fantastically designed cameras, from the R and CX series up to GX and GR…

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