Q macro

In anticipation of the arrival of my Q to Pentax 110 lens adapter I tried out one of the 110 close up lenses on the Q




I can't wait to use the 18mm, 24mm and 50mm 110 lenses! By my calculations, I know someone will tell me I'm wrong, the 24mm 110 lens (135mm 35mm eqivalent) with its S16 CU lens will focus as closely as 15cm. The magnification on 110 format is 1.41/1 but what will that be on the Q?

Surely it's the same!

i.e. 1mm in real life corresponds to 1.41mm on the sensor.

How that relates to what you can fit into the shot (which obviously will be less on the Q than the 110) I'd have to get me thinkin' head on

EDIT: Wikipedia Sensor Sizes and Film Formats to the rescue!

110 film = 17mm x 13mm
Q sensor = 6.17mm x 4.55mm

So, 110 is about 2.75x wider than the Q (and also a different ratio!)

It'll be fun to see your results!
(I shoved a really cheap macro/wide angle converter on the front of the Q prime lens and the results were stupidly close! Huge fun though )

Matt

Thanks Matt, even without an iris the 110 lenses should be fun and they are a fraction of the size of the Q ones too. I have to take a group photo at an 18th birthday party on Saturday which looks to be a fun outing for the fisheye.

To find the different crop factor for different sensor/film sizes it's easier to use the dimension of the diagonal (if easier is the right word)

The diagonal of the 35mm format is around 43.25mm (I say around as different manufacturers used slightly different sizes for the height, it's normally cited as 24mm X 36mm, but most manufacturers used 25.17 X 36 to make the most use of the film), for 110 film it's 22.05mm and for our System Q it's 7.666mm. Which makes sense of Pentax'es choice of focal length for their 110 lenses

On a 110 camera;-

18mm becomes a 38mm

24mm has the same field of view as a 48mm lens.

and 50mm equals a 100mm lens in 35mm format.

The crop factor for the 110 cameras is 2 times


When we come to the Q we get

18mm becomes a 99mm lens

24mm has the same field of view as a 132mm lens

and 50mm equals a 275mm in 35mm format.

The crop factor for the Q is, as we all know 5.5 times.

What this means for macro on a Q is you be further away from the subject and the even better news is you have a wider depth of field.

I got my adapter last week but unfortunately not had chance to try them properly. Looking forward to seeing your photo's gartmore. I hadn't realised that there were close up lenses I'll have to look out for them

I think you might be wrong there. The depth of field is lens relevant, not sensor relevant. The DOF with a small sensor is deeper because we use shorter focal length on these cameras to get the same field of view we'd have with a larger sensor.

Not true, the only thing that effects DOF is Scale Ratio, sometimes called Magnification Ratio which is how many times your sensor would fit into the frame you are photographing.

If you know the Scale Ratio and Aperture you can read the DOF off a look up table.




How you got to that Scale Ratio and what lens, close up filter, bellows, reversing ring etc. is immaterial. With a 50mm Macro lens from 2 Inches away or with a 500mm lens on a set of bellows from around 10 feet away, if your framing the same shot with the same Aperture, DOF will be exactly the same. Focal length only determines how far you are from the subject to frame the shot.

The smaller the sensor is the lower the Magnification Ratio needs to be than if you were using a larger sensor, the lower the Magnification Ratio the greater the width of the DOF you'll get.

Even the effects of Aperture is Scale Ratio, this time how may times the Aperture would fit into your sensor (Apertures are nearly always smaller than the sensor) the smaller the Aperture the wider the DOF as it reduces the effects of the lens/sensor combination.

DOF is all sensor size related.

Don't get in a tangle over this, but DOF has nothing directly to do with sensor size. The DOF of a lens remains the same regardless of what you put behind it.

At normal distances we observe the not quite accurate but real world situation that we are familiar with.

At closer and closer distances that breaks down and the essential factor is magnification.

However, let's not go there again so soon, would someone like to link to the previous thread on the subject of DOF?

they turn up on eBay regularly, they are:

W21 for the 18mm
S31 and S16 for the 24mm
T86 and T43 for the 50mm
T160 and T80 for the 70mm
T80 for the 20-40mm at 20 and 40mm
S40 for the 20-40 at 40mm
S25 for the 20-40 at 40mm

Pentax Q, plus 200mm F5.6 Takumar, + 13mm extension tube. From 2 metres indoors, F11 2 sec exposure.,very difficult to focus so sharpened although I'm sure it would have been sharp if I could have nailed it.Uncropped. Such fun. Butterflies?

However, on trying the Takumar 200m 5.6 outside on the Q it was very unsatisfactory with massive CA and difficult to focus, focus peaking not seeming obvious if present at all