Viewfinder magnification?

Hi all, I have a K5 II, though recently dug out my old Olympus OM2 for a day or so - first time in a decade probably. Long story short I found composing pictures so much more instinctual, and basically enjoyable, with a large full-frame size viewfinder. I haven't owned enough SLRs / DSLRs to know if the viewfinder size changes between brands and models, but I'm assuming that the physics of the matter is that crop-frame sensor cameras have smaller viewfinders than full-frame.

So, I've no intention of moving systems, or for forking out for the Pentax full frame whenever that'll come out, but I wanted to know - is there anyway (any add-on gadget) that magnifies the viewfinder image of a crop-sensor DSLR? And, if so, one that'll work on a Pentax ?

Weird question I know, but I thought I'd throw it out there....

Hi,

I have a K5 and my sons K3 viewfinder is definitely an improvement. You can put one of these on all the DSLR's link

I believe your assumption is wrong because the light path to the viewfinder does not involve the sensor at all. It's only when the mirror lifts the light falls on the sensor.


Comparing the two camera viewfinders the OM-2 has a magnification of 0.92 and a field of view of 97%. The K5ll is 0.92 and 100%

Hi Barrie, I'm not sure it's a field of view issue - being 97% or 100%, for example - I mean the actual size of the window by which I look through - or the size of the image that you can see in the viewfinder.

Using a 50mm lens on the OM2, and a 35mm lens on the K5, the image is the same size within the frame, of course, but it fills the viewfinder on the OM2, whereas it appears smaller in the K5 viewfinder.

Ok, so as said, it's a funny question . . but I do feel the difference.

looking at the above diagrams - I'm not great on physics - but I guess it is the internal space by which the light has to travel, which dictates the maximum 'size' to which it can be projected on the viewfinder. So a larger body allows for greater distance for light path to travel, and therefore greater projected size - ?

And Bill, thanks for the link to this magnification attachment, perhaps it'll make the difference I'm thinking about... I'll try and find a shop that has one I can try out!

The light path to the viewfinder does not involve the sensor at all, is indeed correct Barrie. However, a 35mm format camera has a wider field of view than an APS-C (for any identical lens) so needs a larger mirror to "see" the full image.

If the mirror box and viewfinder were no different in size between the APS-C and 35mm formats, Pentax-Ricoh could have dropped a 35mm format sensor in an istD onwards.

Best regards

Thanks camera dextrous - so does that mean my experience, as I try to explain it, makes sense in some way then? Or have I lost the plot?!

Having checked an OM40 against a K5 I can see the difference in size of the mirror and focus screens

But is that increase in image size not "compressed" to fit the same size oblong of the viewfinder window

This is simple optics. The size of the 35mm film gate is 24 x 36mm, and that's the size of the focusing screen. The APS-C format and screen are smaller, so is the image we see.

To see this, just look through a DSLR and then through an SLR and it's very clear.

Viewfinder magnification is of course a factor, so, say on a film camera, a viewfinder with 0.86x magnification will look smaller than one with 1x magnification.

Another factor is viewfinder coverage. It costs more to show 100% of the image recorded as this requires higher accuracy in assembly.

Thanks for the breakdown of factors John.

Though is there anything on the market that I can purchase that'll give me the same viewfinder 'experience' with my K5 II ?

The pentaprism finders of the Pentax DSLRs are so much better than the penta-mirror alternatives that I think it's as good as it gets. I've just got used to it, and although an ME Super finder, for example, is bigger and brighter I don't use those routinely any more.

I wouldn't add anything to the finder, even if something were available, it would probably add bulk as well as expense. And proper quality would be definitely expensive.

Thanks again John, this question was nagging me for a while... I'd be interested to put my hands on a K3 and see if there is much of a difference as Bill suggests.

many thanks,

Forbes

It would be interesting to hear from someone who uses one of those eyecups in Bill's link - 1.2x magnification doesn't seem much but does it significantly improve the view?

Cheers.
Philip

I have the O-ME53 on my K5iis and K5 bodies - personally I find them excellent, but you do have to work your way around the frame a little sometimes.

If you're interested keep an eye out in the classifieds as they do come up at reasonable prices from time to time

What exactly do you mean by this LennyBloke?

Hi fsharp, because it's magnified I don't see the full area of the viewfinder immediately. The edges of the view and the data readouts are that little bit further from my normal field of vision, so I find I'm looking a bit further downwards or sideways to see the information. But that said, the majority of photographs are composed from the centre, so the magnification improves the clarity (for me) but it's not an effort to look around the viewfinder that little bit more.

Don't know whether this makes sense or not :