[stevebrot]

So I have taken some pictures with this lens and find it to be very difficult to achieve any kind of sharp focus. It also seems that I must use the filter in the back to ensure that I can come somewhat close to infinity focus.

The back filter is part of the optical path and must be fitted.

That being said, there is a common problem where infinity focus needs to be adjusted. Below are the instructions I posted a few years back to the Zenitar Fisheye group on Flickr:

Before I adjusted infinity focus on my Zen, the lens was sharp from about 6 inches to about 10 feet wide open at the infinity stop. Adjustment involved carefully nudging the rubber focus grip out of its groove, loosening the set screws that secure the outer focus ring to the actual focus ring inside the lens and changing the offset such that the infinity mark actually results in sharp focus at infinity. It helps to use live view or a camera having a split-image focus aid.

As with all manual focus ultra-wide angle lenses, fine focus on the Zenitar can be a challenge even for relatively close objects. Everything in the viewfinder is sooooo teeny. You would think that DOF would make it all work, but that is not the case. Magnified live view is your friend as might be a focus screen with split-image focus aide.


Steve

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Last edited by stevebrot; 04-10-2016 at 10:57 AM.

[W.j.christy]

The back filter is part of the optical path and must be fitted.

That being said, there is a common problem where infinity focus needs to be adjusted. Below are the instructions I posted a few years back to the Zenitar Fisheye group on Flickr:



As with all manual focus ultra-wide angle lenses, fine focus on the Zenitar can be a challenge even for relatively close objects. Everything in the viewfinder is sooooo teeny. You would think that DOF would make it all work, but that is not the case. Magnified live view is your friend as might be a focus screen with split-image focus aide.


Steve

Thanks! I did end up adjusting the infinity focus and that seems to have helped I will also try live view to see where that gets me as well.

[paulh]

Check in with member Dartmoor Dave - he removed the rear filter and is getting nice results from his Zen. I think some modification of the focusing ring will be necessary.

[stevebrot]

Check in with member Dartmoor Dave - he removed the rear filter and is getting nice results from his Zen. I think some modification of the focusing ring will be necessary.

I will do that. I have tried it both ways on my Zen and was unable to attain adequate sharpness anywhere in the frame without a rear filter attached.


Steve

[stevebrot]

I will do that. I have tried it both ways on my Zen and was unable to attain adequate sharpness anywhere in the frame without a rear filter attached.


Steve

Hmmm...no luck (does not accept messages)...perhaps if I try this technique...are you listening @Dartmoor Dave?


Steve

[paulh]

Hmmm...no luck (does not accept messages)...perhaps if I try this technique...are you listening @Dartmoor Dave?


Steve

He usually hangs out in the K10D Club & Takumar Club.

[IgorZ]

Has anyone tried the 8mm Peleng lens? Looks like one crazy lens, but I am not sure if I could use it. I was trying to decide between 16mm zenitar and the 8mm Peleng... By the way, if anyone needs some help reading Russian, let me know.

[ScooterMaxi Jim]

The Peleng isn't considered a terribly sharp or well corrected (CA) lens. The Rokinon is much better overall, and as Steve's image shows the unique projection allows for a very natural look when photographing heads or other near-round objects.

The Zenitar is pretty variable in that some of the lenses were produced with a lower quality coating. I have a good copy that yields colors that seem very much in line with the Pentax rendering - as well as decent flare control. As with most ultra-wides and FE lenses, the edges require f/8 minimum for quality imaging across the frame. However, the center is already quite good by f/4. As with many FE lenses, composing with the thought that the furthest 10% at the edges will be cropped out yields very good results (even if you plan to do modest de-fishing).

[IgorZ]

The Peleng isn't considered a terribly sharp or well corrected (CA) lens. The Rokinon is much better overall, and as Steve's image shows the unique projection allows for a very natural look when photographing heads or other near-round objects.

The Zenitar is pretty variable in that some of the lenses were produced with a lower quality coating. I have a good copy that yields colors that seem very much in line with the Pentax rendering - as well as decent flare control. As with most ultra-wides and FE lenses, the edges require f/8 minimum for quality imaging across the frame. However, the center is already quite good by f/4. As with many FE lenses, composing with the thought that the furthest 10% at the edges will be cropped out yields very good results (even if you plan to do modest de-fishing).

That's very interesting. The 8mm Peleng is supposed to be the sharpest lens from the former USSR, aside from Vega 11u which is a slide projector lens. Maybe lens variation is at play?

[ScooterMaxi Jim]

That's very interesting. The 8mm Peleng is supposed to be the sharpest lens from the former USSR, aside from Vega 11u which is a slide projector lens. Maybe lens variation is at play?

I have only one source - very much trusted - as the reasoning for my comment. Possibly the Peleng has better optical qualities than what Lenstip indicates, and the comments compared to the Samyang/Rokinon are not warranted. Here's the spin at the conclusion of the Samyang review:

It is great news for everyone interested in the purchase of such an instrument and bad news for the dealers of Belarusian Peleng 3.5/8 mm, whose prices have recently reached a level absolutely inappropriate to its optical qualities.

[Dartmoor Dave]

Hmmm...no luck (does not accept messages)...perhaps if I try this technique...are you listening @Dartmoor Dave?

Hi Steve. I'll have to look through my account settings and see about fixing that not accepting personal messages thing. Makes me seem very anti-social.

Anyway: about the Zenitar. Yes, I use mine without the clear rear filter. When I first got it I tested it with and without the filter, and found the overall sharpness and contrast better (to my eyes) without it. Of course I had to adjust the infinity focus, but that's an easy job. I think the rear filter is just a simple dioptre rather than anything really important.

This only applies to APS-C digital, because that's the only way I've used the Zenitar. Of course, if you're going to use it with B&W film you'll want to keep the rear filter in place, so you can use the supplied colour filters when needed.

I didn't keep any of the test shots I did with the filter fitted, but here's a couple of random shots without it. The corner sharpness is good enough for my own amateurish needs, but then I'm no pixel peeper.




(This one is de-fished using PT Lens)

[stevebrot]

Hi Steve. I'll have to look through my account settings and see about fixing that not accepting personal messages thing. Makes me seem very anti-social.

Anyway: about the Zenitar. Yes, I use mine without the clear rear filter. When I first got it I tested it with and without the filter, and found the overall sharpness and contrast better (to my eyes) without it. Of course I had to adjust the infinity focus, but that's an easy job. I think the rear filter is just a simple dioptre rather than anything really important.

This only applies to APS-C digital, because that's the only way I've used the Zenitar. Of course, if you're going to use it with B&W film you'll want to keep the rear filter in place, so you can use the supplied colour filters when needed.

I didn't keep any of the test shots I did with the filter fitted, but here's a couple of random shots without it. The corner sharpness is good enough for my own amateurish needs, but then I'm no pixel peeper.




(This one is de-fished using PT Lens)

Thanks for filling in the blanks and also for sharing your excellent work with the Zenitar.


Steve

[bobbotron]

This thread is a bit old, but I can vouch for the zenitar 16mm on the K3. Nice combo, I keep the lens at f8 to f16, great results.

[goatsNdonkey]

stevebrot, I love that posting. I might just have to print it out!

It is interesting how you pointed out how unfishy 16mm shots on the cropped sensor can be (even without a lot of de-fishing post-processing), but by the same token, tilting the lens up or down could have bent that horizon line from a little to a lot, if the effect had been desired.

Also, as I'm sure you realize but some might not have considered, the maximum angle of view for any fisheye that produces a rectangular image, with the frame format being used, is not across the frame, but from corner to diagonally opposite corner. Putting important subject matter in diagonally opposite corners draws attention to that breadth of view. However, if there is nothing special in the corners, it might not be noticed.

Following from that other poster's statement, if anybody feels like they've definitely have been "wasting their time" shooting a Zenitar 16mm on their Pentax DSLR, before tossing it in the ash can, PM me for my address. I'd be happy to give it a new home.

To be more serious, there is more to shooting with a fisheye than "fisheye effect". While many may buy one as a novelty lens, I use mine (both the Zenitar and Rokinon) as special purpose wide-angle lenses with specific optical characteristics that work well with many subjects.

The bending of lines is not barrel distortion. It is a design characteristic. "Fisheye" is the common name applied to a family of lens designs that use some form of circular projection. Most camera lenses use rectilinear projection (straight and parallel lines appear geometrically true). Those straight lines come with a price when applied to wide and ultra-wide angle lenses. The price is something called "volume anamorphosis" where objects assume unnatural, odd, or distorted shapes. While present through most of the field, this effect is most obvious towards the periphery.

Translation? A rectilinear projection is not consistently true for all aspects of geometry.

A good parallel might be the Mercator projection used for maps where places such as Greenland appear to be disproportionately huge. By using a circular projection, this distortion is largely avoided, though at the cost of non-straight lines in some orientations. What does this mean to the photographer? Consider a small set of talking points:

• The human vision is not rectilinear
• The field of human vision is not flat
• IMAX lenses are not rectilinear
• Much of what is termed "fisheye effect" is simply perspective resulting from the wide FOV. That is why a cropped fisheye image appear less "fishy".
• Straight/parallel lines are very rare in nature. Archeologists leverage this fact when doing aerial or satellite image surveys in search of ancient ruins/cities.
• As long as the horizon appears straight and level, landscape photos taken with a fisheye lens appear quite natural to most viewers
• Fisheye line bending depends heavily on the line's orientation to the lens axis
• In cases where the horizon and other lines appear bent, the scene may still appear quite natural to most viewers, if perhaps a bit disorienting
• For subjects where critical portions "wrap" the viewer, a circular (fisheye) projection will provide a more realistic representation to the viewer

It is that last feature that drives most of my fisheye shooting. Despite the obvious novelty aspect of shooting with the Rokinon 8mm on APS-C, I seldom use the lens in that way. I have used both it and the Zenitar for general landscape photography and for events (wedding receptions are an obvious) and other settings where tightness is a characteristic of the scene. While I have several excellent means to "de-fish" in PP, I seldom do so.

Back to whether a fisheye designed for FF is useful, on APS-C, I would give it a qualified yes. I can and have shot "fishy" with the Zenitar on my crop format cameras. I can and have shot "straight" with both the Zenitar and the Rokinon on APS-C. I have also shot "straight" with the Zenitar on FF 35mm film.

Zenitar 16mm on K10D...most viewers never notice the curve...If the lens axis is level to the earth, the horizon will always be straight, but I was not concentrating on the lens axis...




This Zenitar shot on K10D is very fishy, though you would be hard-put to notice if you had not done the shot.




Rokinon 8mm at my daughter's wedding reception...no alien heads in this scene...



When I show people that last one, they are always surprised when I mention it was shot with a "novelty fisheye" lens.

Steve

[stevebrot]

stevebrot, I love that posting. I might just have to print it out!

Wow! Did I write that? Thanks for the strokes!


Steve