Nikon 28/2.0 AIS: Informal Look at Its UV-Capability

[Andrea B.]

The Nikon 28/2.0 AIS can record some UV. Seems best in the upper range - probably 370-400 nm? We have found over the years that many older lenses have some UV capability in that range. I tried the 28/2.0 with three different UV-pass filters on a test scene of water, boats and docks where visible focus was at infinity. The 28/2.0 needed focus pulled back from infinity when using the UV-pass filters.

 

It was a rather overcast day, so while there was reasonably good UV, exposure times were a bit longer than typical. To avoid misinterpretations based on exposure time, I'll therefore present the results in terms of relative stops. (I will try to come back later with a total EV.)

 

Gear: Nikon D610 Conversion + Nikon 28/2.0 AIS

Exposure: All were f/8 @ ISO-100 with various exposure times.

 

Three UV-Pass filters were used:

• StraightEdge Gen-1
  This filter does not leak any violet and peaks around 380 nm IIRC. (must look up to confirm!)
  

• LaLaU 363fwhm50
  This filter was chosen to represent the "normal" UV photography filter.
  
• U-340 x 4.0 + S8612 x 2.0 Stack
  This combo was just for fun. A kind of stress test of UV capability, perhaps? If a lens can record through 6 mm of glass in this "below normal" range, then we would probably want to consider the lens as UV-capable. YMMV, of course. :)
  

.

Nikon 28/2.0 AIS

Visible Photo: ..................base

StraightEdge Gen-1: .......+8.66 stops

LaLaU 363fwhm50: ........+10.00 stops

UG-340/S8612 Stack: ....+14.66 stops

(And this thick stack needed more exposure time. Would have had to go to bulb. Was lazy and didn't.)

 

I'm accustomed to the StraightEdge1 as being about 0.5 - 1.0 stop faster than the usual 360 nm filter. So the fact that the Nikon 28/2.0 is getting slower faster* than a UV-dedicated lens (see next) is obvious to me here.

 

 

I decided to see how the UV-Nikkor 105/4.5 would perform with the same three filters. Remember this is an informal test just to get a feel for things. So no discussion of the dreaded Equivalence is necessary here. Let's just say that I'm not dim-witted and do know that when the scene is reframed, exposures may change. :D

 

UV-Nikkor 105/4.5

Visible Photo: ..................base

StraightEdge Gen-1: .......+7.00 stops

LaLaU 363fwhm50: ........+7.66 stops

UG-340/S8612 Stack: ....+8.66 stops

 

 

Here is a very boring sample photo to show you what I was photographing. I used a Monochrome setting to enable better judgement of exposure time by pushing brightness histogram to the same place on the right for each shot.

 

Visible

 

 

Ultraviolet with LaLaU

Everything is moving in this scene except those big stone walkway supports. So there is some water smoothing. And the boats and docks may not appear as sharp as in the Visible photo. This of course is not the fault of the lens. But having said that, I do note that the UV-Nikkor is sharper than the 28/2.0 at f/8. For all test photos I focused on the dock support which is 2nd from left of the 4 nearest supports.

 

 

 

*Did you make it through that expression "getting slower faster"? How about saying it this way: "the 28/2.0's resistance to UV increases more rapidly as UV gets shorter than would that of a dedicated UV-lens".

[Andy Perrin]

Interesting test, and a lovely scene. We do need more wide angles, as people were saying elsewhere around here. I know I personally would not get any lens that doesn't allow good false colors in UV, since I just have no interesting in shooting monochrome images. I know some around here like those, though, so maybe this is good for them?

[Andrea B.]

This scene probably does not have much false colour. I'll go translate the file and see what it has. BRB.

[Andy Perrin]

Andrea, would you like some FALSE false color? I can edit the image (with your permission)!

[Andrea B.]

No, not much false colour at all.

This is with the LaLaU on the 28/4.0. There is some false blue from some of the boats characteristic of how white paint sometimes looks. There is the usual green in the trees when seen at infinity focus. But to get the false blue and false green I had to boost the saturation to max.

 

On days with strong sunlight & no clouds, the sky can often show a pale false yellow. But over water that may change? And I did not have strong sunlight.

 

f/8 @ ISO-100

This was photographed a bit before the (same) scenes in the first post.

[Andrea B.]

Andy, sure, go ahead and play with the images. B)

[Andy Perrin]

I've always found the sky has yellow in it if it isn't overcast, even over water. Like, I took this one at Onset, Mass. (shared here previously), which has had the saturation pushed up. There are also some dichroic artifacts at the corners:

 

Here you go! FALSE false color. 100% fake.

[Timber]

seems like it's not as good as the AI-S 24mm f2.8. I have tried the AI-S 35mm f2.0 and that was quite meh too... :'( I love 35mm for portraits... I had high hopes for that lens :)

[Andrea B.]

And how nicely it brought out those large dust bunnies which I had *not* noticed! :D :D :D

Time to find the sensor brushes.

 

A very pretty rendition, Andy.

 

I probably would have picked up a bit more false colour in full sunshine?

[dabateman]

I wonder why the 28mm seem poor in UV. My Tamron Adaptall 24mm f2.5 is actually good in UV, whereas the same series Tamron Adaptall 28mm f2.5 is horrible.

Most likely it due to element number or something. But its interesting that a 24mm may be good but a 28mm is really poor.

[Andrea B.]

oh who knows? :D It's likely because of coatings and number of elements and how they are constructed within the lens. I'm sure there are reasonably good 28mms out there somewhere. I forgot what I have, but I'll go look for any 28s.

 

Added: Nope, don't have any myself. But there is a 28mm Enna München on my list to look for which is supposed to be good.

 

Edit: Changed my accidental 24 to 28.

[Mark Jones]

2.0 aperture makes is pretty expensive. I just bought a 28mm Enna München off ebay for around $80

[Andrea B.]

Not a lot of UV false colour out over Somes Sound even when lots of sunlight.

Maybe try different filter?

 

D610-bb + UV-Nikkor 105/4.5

 

Visible: f/8 for 1/2000" @ ISO-800 with Baader UV/IR-Cut

What is interesting is that the camera/lens/filter is "seeing" a lot more humidity than I'm seeing with the naked eye. Perhaps application of a dehaze brush would help?

 

UV: f/8 for 1/25" @ ISO-800 with BaaderU UV-Pass

Seeing haze and less detail in the distance is normal for UV.

[Andy Perrin]

That one looks normal to me. I pushed the saturation in the one I took above.

[Andrea B.]

I've noticed that in distant landscapes, false green or false dark green-with-slight-yellow often occurs after white balance. But in all my close work, I have hardly ever seen false green after white balance. And in the few close work instances where false green *might* be happening, it is very dark and leaning to the cyan side.

 

It is so very easy to move the color wheel with just a slight bump in the white balance, that we probably should not put too much faith in false color generalizations like I just made. :D

 

And that reminds me to check out one of the old dark greens in a certain photo by looking at it in Raw Digger which I didn't have at the time I made the photo. I'll go dig it out. Maybe it is worth a write up. It is a flower which Birna and I photographed on the Scotland trip.

[dabateman]

Andrea,

Try using your 293nm filter. Clouds will appear that you can't see. Thats what I remember when trying my 280bp10, photographing the sun.