WA/Fisheye lens question -- slightly OT

[ampguy]

I have an opportunity to get a used Japan made 18mm lens with m42 screw mount very reasonably (< $40) . I can't tell if it works or not though, other than I can see through it, and the aperture opens and closes (3.5 - 22 I think).

I've always wanted a 16-21 lens, even with all the distortion and all, for the novel effect. Am aware of the adapters that go in front of a regular lens, but am not sure if these are as good as a real WA native lens?

I'm planning on first using it with an SLR I have which has K mount. I ordered a K mount to m42 adapter from B&H which should allow the lens to mate. I notice on the B&H page, they don't mention if their adapter supports infinite focus like some of those on *bay? but hard to imagine they're any different.

So the RF question is, what kind of adapters and viewfinders for say a FSU m39 body are going to be needed to try to glom this lens onto a RF? Is it worth it??

 

[ampguy]

Thansk G'Man

Thansk G'Man

After the obligitory face close ups of friends and family, I think I want to weld it into infinite focus.

Will infinite focus be an issue with m39 to m42 adapters? or only with K mount to m42 adapters?

There are adapters out there to mate it to the FSU cameras. It will be scale focus only.

 

[Dougg]

Will infinite focus be an issue with m39 to m42 adapters? or only with K mount to m42 adapters?

Infinity focus shouldn't be a problem either way. But with a rangefinder camera you will have to guess on the framing because the viewfinder won't show you what the lens sees. Could be fun anyway 🙂

Your original message is a little ambiguous on this point, but there is a difference between a fisheye wide-angle and a rectilinear wide-angle lens. I've sometimes seen people refer to any extreme wide angle as a fisheye, and similarly some refer to any telephoto lens as a zoom. A fisheye has extreme and deliberate barrel distortion, avoided in a rectilinear, and a zoom lens must be able to change its focal length. 🙂

You asked about an add-on wide angle adaptor that would go on the front of another lens; such kits are commonly available for point'n'shoot type cameras, with both wide and long add-ons in the kit. With these they TRY to make them rectilinear but in any such combination there have to be compromizes, and the quality of the results is not nearly as good as a single purpose-designed "prime" lens. I vaguely recall seeing an ad for a fisheye add-on lens accessory too... With these of course the design is probably easier because they need not even try to reduce barrel distortion; indeed just the opposite!

But I'm not aware of any fisheye lens or adaptor intended for use on a non-TTL viewing camera like an RF cam, and no accessory fisheye viewfinder to slide into the accessory shoe. If you adapt an SLR-intended fisheye lens to an RF, then you're on your own for viewing.

On the other hand, there are numerous choices of rectilinear wide angle lenses for RF cameras, such as the 12mm and 15mm Voigtlanders in Leica thread mount, and lots of 21mm choices. Matched viewfinders are available, and even come along with the Voigtlander lenses wider than 28mm.

You might find it interesting to poke around the CameraQuest web site; just click their link in the stack of RFF sponsor ads on the left in most RFF windows, as there's lots of information there.

 

[ampguy]

Thanks for the clarification

Thanks for the clarification

Thanks Dougg,

Your definitions make some sense I guess, especially the zoom part.

I did not realize that lenses in the ~15mm - ~ 18mm range existed for 35mm film cameras that were rectangular and linear. All photos I've seen from these lenses have the "fisheye" effect when uncropped.

My extreme wide angle lens, a Sigma Widerama, 18mm, f3.2 - 22, definitely has the "fisheye" effect regardless of what Sigma's design intentions were or whether they put the name "fisheye" on the lens or not.

Could you link me to some f=15mm 35mm film, uncropped rectangular and linear photos? I've never seen any. I actually get measurable and visible distortion on my f=35mm German designed lens. Thanks!

Infinity focus shouldn't be a problem either way. But with a rangefinder camera you will have to guess on the framing because the viewfinder won't show you what the lens sees. Could be fun anyway 🙂

Your original message is a little ambiguous on this point, but there is a difference between a fisheye wide-angle and a rectilinear wide-angle lens. I've sometimes seen people refer to any extreme wide angle as a fisheye, and similarly some refer to any telephoto lens as a zoom. A fisheye has extreme and deliberate barrel distortion, avoided in a rectilinear, and a zoom lens must be able to change its focal length. 🙂

You asked about an add-on wide angle adaptor that would go on the front of another lens; such kits are commonly available for point'n'shoot type cameras, with both wide and long add-ons in the kit. With these they TRY to make them rectilinear but in any such combination there have to be compromizes, and the quality of the results is not nearly as good as a single purpose-designed "prime" lens. I vaguely recall seeing an ad for a fisheye add-on lens accessory too... With these of course the design is probably easier because they need not even try to reduce barrel distortion; indeed just the opposite!

But I'm not aware of any fisheye lens or adaptor intended for use on a non-TTL viewing camera like an RF cam, and no accessory fisheye viewfinder to slide into the accessory shoe. If you adapt an SLR-intended fisheye lens to an RF, then you're on your own for viewing.

On the other hand, there are numerous choices of rectilinear wide angle lenses for RF cameras, such as the 12mm and 15mm Voigtlanders in Leica thread mount, and lots of 21mm choices. Matched viewfinders are available, and even come along with the Voigtlander lenses wider than 28mm.

You might find it interesting to poke around the CameraQuest web site; just click their link in the stack of RFF sponsor ads on the left in most RFF windows, as there's lots of information there.

 

[Kim Coxon]

Hi,
I will try and post some shots at the weekend from my Pentax 15mm lens which is just about the best corrected SLR version around.

Kim

 

[Dougg]

Could you link me to some f=15mm 35mm film, uncropped rectangular and linear photos?

Sure; here's a link to one of mine in the RFF gallery: http://www.rangefinderforum.com/pho...e=12&ppuser=77&sortby=f&sorttime=9999&way=asc

Search the RFF Gallery for "15mm" and you'll see a bunch from other members too. Let me see if I have a couple more examples... You can certainly expect to see perspective distortion in wide lenses, but that's simply a function of being close to some subjects and being far from others... relative distances, not optics. Another kind of perspective distortion is when the film plane is not parallel to a flat surface, like when you point the camera up to include the top of a building... and that accentuates the vertical lines tipping inward.

Barrel distortion would cause those vertical lines to appear to bulge out at the middle and curve in at top and bottom like a wooden barrel. This does tend to happen with some wider lenses (especially zooms at the wide end), if only slightly. And that is an optical fault of the lens, unless you WANT it, as with a fisheye lens. 🙂

 

[ampguy]

Hi Dougg

Hi Dougg

Those are outstanding pictures, especially amazing to me if they are uncropped.

What I mean by fisheye effect is say the effect in your ROMA pic. It's a great pic, but it clearly has to me, "fisheye effect", and to you, "perspective distortion".

To illustrate this further, put your camera with 15mm lens on a tripod, and take an exposure of a perfectly straight brick wall (or straight wall, ceiling of 4" x 6" boards, etc.).

Print this and scan it, uncropped, and this effect of the bending of the edge lines, that in real life we know are straight, is what I am calling the "fisheye effect", which I think you are calling "perspection distortion."

An extreme case of "perspective distortion" would be something like this:

http://scotthaefner.com/present/KAPiFrance05/images/fisheye-example.png

which I'll bet your setup might be capable of doing if you tried??

Sure; here's a link to one of mine in the RFF gallery: http://www.rangefinderforum.com/pho...e=12&ppuser=77&sortby=f&sorttime=9999&way=asc

Search the RFF Gallery for "15mm" and you'll see a bunch from other members too. Let me see if I have a couple more examples... You can certainly expect to see perspective distortion in wide lenses, but that's simply a function of being close to some subjects and being far from others... relative distances, not optics. Another kind of perspective distortion is when the film plane is not parallel to a flat surface, like when you point the camera up to include the top of a building... and that accentuates the vertical lines tipping inward.

Barrel distortion would cause those vertical lines to appear to bulge out at the middle and curve in at top and bottom like a wooden barrel. This does tend to happen with some wider lenses (especially zooms at the wide end), if only slightly. And that is an optical fault of the lens, unless you WANT it, as with a fisheye lens. 🙂

 

[SRMC]

I have a Russian Zenitar in M42 mount that I've used on a Zorki 4 with an adapter. It is unwieldy, zone focus only, and leaves much of the framing to guess. I created a viewfinder out of a foot from a flash adapter and a door peephole viewer. It is workable, but it is MUCH MUCH MUCH better on an SLR. After all of the trouble, I don't think it was worth it.

Here is a link t to the Zenitar - Zorki combo.


SRMC

 

[ClaremontPhoto]

The depth of field with these wide lenses is so immense that focusing is largely a non-issue. For example, the Voigtlander 25mm has only three click-stopped focusing postions: 1m, 1.5m and 3m. Imagine what their wider 21mm, 15mm and 12mm are capable of.

Voigtlander also make clip on viewfinders which are 'free' with a lens but seem a bit expensive on their own. GBP85 for just the 15mm viewfinder sounds expensive when it's only GBP234 for the lens including the viewfinder.

 

[ampguy]

Great info.

Great info.

Thanks, your setup looks very good, but I agree that at least for me, the effort in trying to get a semi-accurate vf for this lens isn't worth it.

I still don't understand why a fisheye lens, or lens with extreme whatever kind of distortion you want to call it, would have a different field of angle than a "rectilinear" corrected wide angle of the same focal length, for general framing purposes?

I have a Russian Zenitar in M42 mount that I've used on a Zorki 4 with an adapter. It is unwieldy, zone focus only, and leaves much of the framing to guess. I created a viewfinder out of a foot from a flash adapter and a door peephole viewer. It is workable, but it is MUCH MUCH MUCH better on an SLR. After all of the trouble, I don't think it was worth it.

Here is a link t to the Zenitar - Zorki combo.


SRMC

 

[ampguy]

Hi Jon

Hi Jon

I'm sure your correct. FWIW, the Sigma 18mm has a lot of rotatin for focus, and the lens moves in and out a good cm or so, maybe it's for fine focusing close-up, or it could be broken, I haven't tried it yet.

That 15mm viewfinder price is outrageous.

The depth of field with these wide lenses is so immense that focusing is largely a non-issue. For example, the Voigtlander 25mm has only three click-stopped focusing postions: 1m, 1.5m and 3m. Imagine what their wider 21mm, 15mm and 12mm are capable of.

Voigtlander also make clip on viewfinders which are 'free' with a lens but seem a bit expensive on their own. GBP85 for just the 15mm viewfinder sounds expensive when it's only GBP234 for the lens including the viewfinder.

 

[XAos]

Fisheye auxilliary viewfinders are available in Lowes, next to deadbolts and doorlocks.

I've been thinking about picking up a Zenitar for my PZ-20. I really want one for the RB but I can't afford a grand for a goofy lens used only occasionally.

 

[Pherdinand]

The depth of field with these wide lenses is so immense that focusing is largely a non-issue. For example, the Voigtlander 25mm has only three click-stopped focusing postions: 1m, 1.5m and 3m.

The real fun in ultrawides (for me) is in the fact that you can play with the perspective by being able to focus very close and still include lotsa background. In that case, DOF can be rather thin. I have a 17mm (slr lens) that i can focus to just 10 cm in front of the lens; wide open (f/3.5) this gives a rather blurred distant background.
Here's an example, cropped on the top.

 

[dmr]

One of my favorite lenses is the Sigma 18mm rectilinear ultrawide. I don't really care for the fish-eye distortion, but this type of lens gives you a lot to work with.

Not RF, sorry ...

 

[ampguy]

got first roll back from 18mm wa

got first roll back from 18mm wa

this was on an slr. Mine is like yours I think, it has close focus, and needs a lot of attention focusing. I also have to focus wide open, then manually stop down. I'm not going to bother fitting this to a RF, this particular Sigma 18mm needs a lot of attention to focus right unless it's at infinity, it seems.

Out of that first roll, I did get a couple of outstanding photos, both indoors, and out.

The real fun in ultrawides (for me) is in the fact that you can play with the perspective by being able to focus very close and still include lotsa background. In that case, DOF can be rather thin. I have a 17mm (slr lens) that i can focus to just 10 cm in front of the lens; wide open (f/3.5) this gives a rather blurred distant background.
Here's an example, cropped on the top.