Wide angle lens better on Rf or SLR?

kshapero

kshapero

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I have heard that the use of a wide angle lens, say a 20/21 mm, used on a RF shows less lens distortion then on a SLR lens of the same size. True? Are there other differences? Why?:rolleyes:
 
They say so. Something because of retrofocus design.
I skip this, as well as diffraction.
 
Yes, not only 21mm, actually all lenses below something like 60mm on SLR's have to be retrofocus, what complicates the lens design , especially as the focal length decreases. The most notable problems are distortion and curvature of field. The RF has no mirror, so the problem starts being apparent again only below 24mm I believe. True symmetrical wide angle designs are easiest to correct optically. The best examples are probably the Hasselblad Biogon 38/4.5 and the G Contax wide angles. I use both Zeiss ZM lenses and ZF lenses, and for example the 25/28 Biogon is really visibly more rectilinear and sharper across the frame than the Distagon 25/2.8 ZF.
 
it sounds like with a SLR 21mm lens, it is a wide angle lens and with a RF 21mm lens it is more like a wide frame lens.
 
kshapero said:
I have heard that the use of a wide angle lens, say a 20/21 mm, used on a RF shows less lens distortion then on a SLR lens of the same size. True? Are there other differences? Why?:rolleyes:
Click to expand...

True and not true at the same time.. and unfortunately this myth is kept alive because of the abundance of lens reviews by pixel peepers. These contain distortion figures measured to the tenth of a percent; the holy grail being whether wide angle lenses are absolutely ruler straight at the edges. Well, let's face it.. it makes good reading and is good for shooting architecture. But it's not for shooting people!

A rectilinear lens needs a different amount of magnification at the side of the frame than in the middle. This is to counter horizontal lines tapering away towards the horizon at a far distance, like they do for the naked eye. This is perspective basics. Imagine you're standing in front of a wall stretching to infinity left and right. You know the builders built it level, but still, far away, the top of the wall converges with the horizon.. in other words, you see that level wall bend downward away from where you stand. By exagerating the size of the wall at the edges of the frame, the lens designer can make that wall come out straight again in a photo. The wider the lens, the more pronounced this exageration needs to be.

But imagine what happens with people near the edges close by. You get the egg-shaped head look. Not flattering, and not like you see the world in reality. To avoid the egg-shape look, you need barrel distortion!

If a camera system can only have one type of lens, as is the case with an RF, the designer has to make a trade-off between ruler straight for shooting architecture, and barrel distortion for shooting people. What you get is usually halfway between..

But SLRs, with their 'what you see is what you get' principle, offer the designer the option to spread these targets over two or more types of lenses. One being the common wide angle with barrel distortion that's ideal for reportage purposes, the other the ruler straight tilt/shift lenses that are oriented toward architecture anyway.

So, in short, you'll see the average RF wide angle have less distortion than the average SLR wide angle. But they aren't as corrected as perspective control lenses are..
 
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Eh - I've heard this, that wides = RF. And, I'm sure it's true if you're a lens tester. However, I've got a killer (and fairly inexpensive) Sigma Super Wide II 24/2.8 in Pentax K. My SLR is smaller and lighter than most of my RFs (it is, however, noisier...) I still say SLR is a better design for interchangeable lens systems. I can see that wide perspective - or portrait perspective, "full frame" in the VF for composition instead of looking through these little boxes... But for general photography, prime "standard" focal length (45mm preferred), the fixed lens RF is king.

Oh - we were talking about "wides"... Yes - technically "better", due to this or that design consideration, but there are some killer wides for SLRs, I think the SLR design is better in use (minority opinion here, I'm sure) that the RF viewing system which more than compensates for the minor difference in distortion that will show up only as a spec in some lens test...

Oh - did I mention they're probably much cheaper too?
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On a different topic - I can focus wides better on my rf as my eyes are as old as the rest of me...

Having said that, I think my dslrs focus better than I do, so that's not a good reason really.

Mike
 
Because of low magnification, I find the focusing of wide angles to be faster and better on rangefinders.

That being said, I have a 24/2.0 mounted on a Nikon F3 with a Action finder. Using zone focusing at f5.6 makes this rig like a point and shoot and more like a rangefinder (fast) in operation. I can shoot from the chest and the lower height adds foreground (something I do on the subway all the time). I kinda only shoot at two f-stops; mostly at 5.6; and sometimes wide open at 2.0.

I figure on my M6 I'd need an aux viewfinder for framing; so, for me, it became a coin toss between SLR and rangefinder for ultrawide, but a 35 cron on the M6 works like a match made in heaven.

Calzone
 
How about a Bessa L or T with external exposure readings and a 21mm lens? That would give a similar effect, Calzone.
 
I am using a zeiss 21 lmm on my leica m6 and a canon 17-40 on a 5d and I can say yes the rf lens shows much less distortion compared to the canon lens at the same length as well as better resolution at the edges of the frame.
 
kshapero said:
How about a Bessa L or T with external exposure readings and a 21mm lens? That would give a similar effect, Calzone.
Click to expand...

Please explain more, because I am not familure with the above gear. External exposure readings sounds like an alluring feature. Are 21mm framelines available without an external viewfinder?

The F3 with the addition of the DA-2 action finder and the 24/2.0 for me was a creative use of my girlfriend's F3 HP that was kinda loaned to me indefinately. Although I never use it, auto aperature priority mode is available. Effectively, this rig can be a total point and shoot. The action finder transforms this SLR, in that, it reminds me of a rangefinder viewfinder.

I was considering getting a 21 or 24 for my Leica M, but this ended up being a very practical solution. Not too much bigger than my Leica, still light weight, but not as compact or lite weight as a Leica M.

Calzone
 
pvdhaar said:
But imagine what happens with people near the edges close by. You get the egg-shaped head look. Not flattering, and not like you see the world in reality. To avoid the egg-shape look, you need barrel distortion!
Click to expand...

Peter,

Thanks for this explanation.

I now have a better understanding of why the wide-angle lens on my fixed-lens 6x9 rangefinder does not do well with people shots (group shots) but does well with architectural and scenic shots.
 
Still, an advantage of SLR's over RF cameras is the ability to see exactly what will be on film. Using an external finder can be deceptive at times.Looking through the VF of an SLR, it is easy to get straight horizons ... etc. with wide angle lenses.
 
Calzone is right, RFs because you are working the a rangefinder that is just as accurate on a 21 as it is on a 105, focuses wide better. The wider you go on SLRs the less accurate your focus is because the focusing area is much smaller in the view finder. DOF stuff helps. SLRs get the thumbs up on telephotos. Leica used to teach this in the Leica School of Photography (or what ever it was called) years ago.

B2 (;->
 
I extensively used 17mm~21mm lenses both on RF and SLR cameras, and even though the Leica School may have taught otherwise, I found in my own photography that I had better focusing accuracy with SLR cameras.

I use RF wide angle lenses more often though!
 
I sort of agree with Raid. With an SLR you can see exactly what you're going to get and by tilting the camera a bit up or down you can exaggerate distortion or reduce distortion. At least it seems that way to me.

With the 28/2.0 Ultron on my Bessa R I just take it on faith that I'm going to get slightly more on the negative than I could see through the camera's viewfinder. On the other hand, with the same focal length lens - a Super Takumar 28/3.5 - on my Pentax Spotmatic, there's no uncertainty about what I'm going to get on the negative.

If there's a difference in distortion between the two lenses, it's very slight, and in favor of the Ultron. But again, I'm more interested in content than whether lines converge or sharpness falls off at the edges. I think if it's a powerful enough image no one's going to notice the other stuff.
 
Calzone said:
Please explain more, because I am not familure with the above gear. External exposure readings sounds like an alluring feature. Are 21mm framelines available without an external viewfinder?

The F3 with the addition of the DA-2 action finder and the 24/2.0 for me was a creative use of my girlfriend's F3 HP that was kinda loaned to me indefinately. Although I never use it, auto aperature priority mode is available. Effectively, this rig can be a total point and shoot. The action finder transforms this SLR, in that, it reminds me of a rangefinder viewfinder.

I was considering getting a 21 or 24 for my Leica M, but this ended up being a very practical solution. Not too much bigger than my Leica, still light weight, but not as compact or lite weight as a Leica M.

Calzone
Click to expand...
see site at Cameraquest www.cameraquest.com/inventor.htm
 
Though I think I got somewhat better images with the 15mm Heliar, I sold it and now shoot at that focal length with my Pentax 15/3.5. Same goes for long lenses--I don't enjoy using anything that requires an accessory finder. So I generally use RF for 28-100, and SLR for everything else. (I have normals for my SLR, too, but more often than not I reach for my RF gear when I want to shoot at those lengths.)
 
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