UKC

Advice, please.

I want to get my old SLR lenses back into use and am thinking about buying a second hand DSLR and compatible converter.

I understand that
1.) I will only be able to work manually
2.) there will be a cropping effect, i.e. turning my 50 mm standard lens into a 80mm short telephoto ( unless I go full frame or 4/3)

What I can't work out is: - will the 50 mm lens converted to an 80 mm lens have the same foreshortening effect as a genuine 80 mm lens?

Any other pitfall advice would be welcome.

In reply to Tom Valentine:

It all depends what make your old SLR is: you'll have to give more details.

In reply to Tom Valentine:

You shouldn't need a converter , so old EOS lenses fir new EOS DSLRs etc.

In reply to David Barlow:
My lenses are C/Y.
E bay has got converters for Canon, Nikon, even Samsung NX in this fit.
Most of my lenses are Yashica, Tokina or Sigma but my prime lens is a Contax 50mm 1.7 and this is the one I am most keen to revive.

In reply to Tom Valentine:

Foreshortening is purely an effect of distance from the subject. If you stand in the same place, and use a 50mm lens on a full frame camera and a cropped camera, then the picture from the cropped camera will look just like a crop of the full frame picture.

So, since your 50mm lens now behaves like an 80mm, you will alter your position accordingly - so yes, foreshortening will be the same.

In reply to Nutkey:

So, if I put my 210 lens on it will show an image area equivalent to a 336 mm lens but without any of the foreshortening that a genuine 300mm lens will produce?

In reply to Tom Valentine:

I'll try again.

It's the distance between camera and subject that determines foreshortening. The lens has zero foreshortening effect, it's just that different lens cause you to take pictures from different distances.

If you take a portrait with a 20mm lens, the subject will have a big nose. If you now, without moving, replace the 20mm with an 85mm portrait lens, take several shots and stitch them together, then the subject will still have a big nose.

In reply to Nutkey:

With respect, although you are absolutely correct, I think that your example there could be a little confusing because an 85mm lens is unlikely to have the close focusing required to take a portrait from the distance that makes the nose look big.

A nice example is illustrated in Langford's "Basic Photography".
He shoots a kind of landscapey scene twice from the same position, with a wide angle and then a telephoto. There is a small signpost near a pond. The telephoto shot is shown at 100%, the wide angle photo is shown at 100%, and also an enlarged crop of the wide angle shot is shown, enlarged to "match" the "field of view" of the telephoto shot. Obviously it is grainier, but the PERSPECTIVE (or foreshortening) is the same - as you have already stated i.e. it is not a function of focal length. What IS different in both shots is the depth of field but that's another subject altogether.

It does get confusing, I know! When I first had a crop sensor dSLR with a 24-70mm lens, I assumed the wide end would work like a 38mm lens and wondered why some of my portraits (well, concert shots) looked unflattering. There are indeed some confusing (and often incorrect!) "explanations" of the relationship between sensor size and focal length and "crop factor" out there. Field of view would be a more accurate description than "equivalent focal length", I guess...

But what you have written is totally correct. I was just trying to clarify it and flesh it out a bit. Hope I have not made it more confusing for anyone

In reply to Nutkey:

Thanks for your patience.

In reply to Tom Valentine:



A pitfall of manual focusing on a dSLR is that some of them have smaller darker viewfinders than old 35mm SLRs. I gave up, in despair, with my Nikon D70 with 24mm and 50mm manual primes, I never seemed to get anything in clear focus. Not a fault of the lenses or of the camera "innards", but simply the viewfinder. And it took me a while to figure this one out. YMMV. Some people find it a doddle. I guess it is dSLR-specific.

In reply to Blue Straggler:


Fair point!



I thought that the only difference in DoF in those two cases would be due to the f-stop difference?

In reply to Tom Valentine:

You're welcome. Another way of looking at it, is that if you have a 50mm lens on a full-frame SLR, and the same lens on a crop-frame, it should be clear that if put the cameras in the same place, there is a zero difference in the photos - except that the crop-frame photo is cropped.

By and large (with the exception of tilt-shift and lens baby, for example) camera lenses are trying to have no effect on perspective at all.

In reply to Nutkey:




Aaaah you may very well be right. I did not have Langford to hand when I wrote all that.

In reply to Nutkey:

Thanks . Your 50 mm example makes perfect sense.
It's just that I have spent my entire life believing that telephoto lenses foreshortened/compressed an image (like watching cricket looking down the wicket on telly) and it's hard to get rid of the notion.
Since your explanation I have found several useful pictorial examples online (not that I didn't believe you in the first place, of course... )