Some very basic lens test with ? dandelion

[Cadmium]

Jim, Don't thank me. I think I sounded rude, and I should just try to keep my mouth shuts sometimes, and that was one of those times, I believe.

Most of us on here toss around ideas more than photos, it seems, not referring to you here at all, testing all sorts of interesting things, and some of my tests are probably beyond ridiculous,

but all of it expands out knowledge.

[Jim Lloyd]

No offence taken Steve!

[Andrea B.]

Found my EL-Nikkor 80 new version!!!! Thought I had sold it. So I’ll make a test of some kind with old and new models.

[Jim Lloyd]

Continuing my explorations ...

 

Weather has been poor and I have been sidetracked into other aspects of my art projects, but I have just bought two new lenses and as weather was better today have done my first quick experiments:

 

First lens is Photax f=35mm f/3.5 preset s/n 35687 ebay £20 front screw thread = 46mm T mount fitting. Apart from the word "Photax" this lens is indistinguishable visually from the 35mm f/3.5 mm Optomax lens I have - my hunch is that they were probably made by the same company, (the optomax s/n is 36766). The Photax lens is similar to the one shown here by Enrico Savazzi, but not identical as it does not have the letters O and C on the preset ring.

 

As I said before I think my Optomax lens (f 35mm f/3.5 T mount) is probably the best I have for UV, but it has a fault in that the aperature ring does not click into position, but moves very freely. The Photax lens looks optically very clean and mechanically is very good.

 

I noted on Enrico site that the Photax doesnt have quite such good UV reach as some other similar lens.

 

Anyway I don't have equipment to test this properly - but here is the result of my testing using my Colt's foot and Dandelion "test object"

 

 

Photax on the left - Optomax on the right.

 

Same equipment as before namely:

 

D3200 full spectrum converted camera

BG40 2mm + UG1 2mm

f/11

ASA 200

8 seconds

Outdoor sunlight - late afternoon

Processing in Lightroom

WB using calibration file and then setting on grey background slab

Auto tone

Cropped

 

I can't see a difference. So I am pretty pleased with this. I need to do more testing to look at resolution and other quality issues, but I think this is going to be a useful lens.

 

 

The second lens I bought was an Optomax f=35mm f/2.8 Auto (s/n 301109). This has a more modern look. I got it in an ebay auction for £15 (didn't actually expect to win - was the only bidder!). It wasn't clear what the mount was and it turns out to be M42 - so no infinity focus without additional lens on Nikon f mount. I tried with a non-lens adapter and on the plus side this gives a much closer focus than the other lenses tested.

 

Same equipment and setting as above. Here is the comparison

 

 

The f/2.8 M42 version is on the right and the f/3.5 T mount version is on the left

 

Looks pretty good I think, although I still have slight preference for the Photax or Optmax f/3.5 version. When I tried to use this with a lensed adapter I had problems and I wasnt able to move the focus properly. Not sure why seemed like adapter had the wrong depth. As far as I could see on live view it looked like the adapter lens was passing UV (I could see the dark flower centre).

 

I will now do some more extensive testing of the Phtoax lens - It might become my go-to lens for UV landscape . I will try it more in the field next.

 

I would be interested in any comments on this lens - Based on these very simple tests it seems as good as the Optomax f/3.5 which would be at odds with Enrico's tests here, but I guess what I am doing is not sensitive enough to tell how far into the UV I am going?

[Andrea B.]

Sometimes different manufacturers made these older lenses for re-branding. So there could be sample variation based on slightly different coatings or lack of coatings, slightly different glass and so forth. Perhaps your Opto 35/3.5 is just a little different from Enrico's. Then age and wear & tear on the lens plays a bit of a role also. But doing these tests is exactly the thing to do in order to find a good-performing lens for a particular shooting scenario.

 

You've mentioned an important point about M42 lenses. Even though you cannot reach infinity focus on a Nikon body with an M42 lens (unless an adapter-with-lens is used), you can still put it on an adapter or helicoid and use it for close-ups.

 

I love finding the old lenses in a T-mount so's I can Nikon them.

 

---

 

Half the battle in UV photography is the finish - what's done in the converter/editor.

 

---

 

The lack of aperture detents may not be a flaw. It might be a design feature. This is seen in a lot of older lenses. I think I recall seeing that certain new current manual prime lenses are built this way. (but where?)

[Jim Lloyd]

Thanks Andrea. Maybe the freely moving aperture ring is a feature, but it makes the lens difficult to use in the field as it is so easy to accidentally change the aperture without realising it.

[Andrea B.]

Tape it down? :D

 

There are a lot of "interesting features" in older lenses, aren't there? Every one of them pre-sets aperture differently (and focus too) and some not so easily. I have to practice before taking certain old lenses out for a spin.

[Jim Lloyd]

"Tape it down? :D"

...

 

Well yes - I use blue tak, which does work, but doesn't look good ! - also tends to interfere with the preset ring, which doesn't quite move smoothly enough anyway. I think basically I have found a mechanically better version so I am pleased with that.

 

I do like the preset feature for UV using live view as I can open up for focusing and then quickly stop down to expose. I have some medium format lenses on my Bronica camera which have a nice "depth of field preview" button which does a similar thing (I love that camera!)

[Jim Lloyd]

Looking at sharpness of Photax 35 mm f/3.5 lens using D610 full frame camera asa 100, photographing newspaper at about 1 m.

 

I was really pleased with the results. Centre sharpness was acceptable at f/3.5, very good between f/4 and f/16 and good at f/22. Edge sharpness was poor wide open and at f/4, acceptable at f/5.6, good at f/8 and f/11, very good at f/16 and good at f/22 (this is just my subjective scale - very poor, poor, acceptable, good, very good, excellent).

 

So in summary lens functions well between f/8-f/16

[Andrea B.]

Good stuff, Jim. It's nice to see someone putting their lens finds through some testing to determine the best practical uses for a particular lens. Something we should all try to do for our various nifty finds from Ebay. B)

 

Something you might want to also look for in your lenses is the aperture at which diffraction begins to soften details in Visible light and also in UV light. We have all noted that in reflected UV photography you get an "extra stop" before diffraction begins to seriously kick in. This is due to the shorter wavelengths in UV which are so revealing of surface detail. But I'm realizing that I do not know whether this extra stop occurs in UV landscape work or whether we are seeing it just in close up UV work. I do mostly close-up UV work, and my aperture series tests in close-up work do certainly show that there is an extra stop available before seeing softening detail. I routinely shoot close work at f/11 in UV.

 

So, are you seeing sharpness at f/22 or simply more detail at f/22 in the photo's corners/edges? At f/22 you can be getting more detail than at, say, f/4. But whatever detail you are getting is also softened by diffraction which begins to kick in around f/8 or f/11. We tend to perceive more detail in a photograph as indicative of "sharpness". But, sharpness, or acutance, is about the perception of contrast between physical edges of subjects in a photo and not about more detail.

 

{{I note in passing that the phrase "edge sharpness" is confusing. It can refer to the acutance of a subject's actual physical edges regardless of where the subject is placed in the photograph. Or it can refer to the acutance displayed in the peripheries of a photograph regardless of subject. What is the correct phrase to use? Don't know!! Peripheral sharpness? Corner sharpness?}}

[Jim Lloyd]

Ooh my head is beginning to hurt thinking about this!

 

I think for these relatively cheap lenses then at large apertures lens aberrations probably dominates - certainly at the edges

 

This is a crop at a corner f/4 (in each case I have cropped a 890x890 pixel square from 6000x4000 image and then exported at 500 pixel square)

 

 

And this is the centre crop

 

 

The corner distortion doesn't improve until f/8

 

For landscape I don't really get the depth of field I want until f/11 (9 ft - infinity for 35mm lens focused at 20 ft).

 

I think I need to just go out and photograph some real examples ... Going on holiday to Scotland next week - so might take this lens ...

[Jim Lloyd]

Actually I have used this lens for landscape, but with Hoya R72 (720 nm) filter. (To recap, this is with D3200 full spectrum conversion Photax 35mm f/3.5 lens).

 

I wasn't going to post these as I wasn't that happy with them, but maybe relevant now in the context of this discussion. I set aperture at f/11 and set focus on focus ring so that I was focusing to infinity. 100 asa. exposure 1/30 sec.

 

I thought the focus was soft and wondered if I had done something wrong. It is a possibility that the T mount adapter wasn't quite screwed up tightly enough?

 

Then I got thinking about what you said Andrea about getting an extra stop with UV, presumably then the converse is that you might get one less with IR?

 

Anyway here are some images (sorry this thread is beginning to wander now)

 

(Some of the below have had Red / Blue channel swap)

 

 

 

 

 

[Andrea B.]

Yes, very generally speaking, you get diffraction "earlier" in Infrared. But so much is dependent on distance. I have some photos made of a very long landscape across water from on top of a small mountain. The UV versions have virtually no detail at all due to UV haze and ocean atmosphere so those short wavelengths didn't help at all to defeat diffraction because they are simply getting scattered. The IR versions look like they are full of detail and sharpness because the longer wavelengths could get through the atmosphere and reach the sensor. So there might be some soft edges (on the subjects), but there is lots of detail to counteract that.

 

I'll try to come back and post a link for you to see some of this work.

Later, here's the link.

http://www.ultravioletphotography.com/content/index.php/topic/2166-cadillac-mountain-to-blue-hill-1887-miles-in-uvvisir/

 

Lucky you going to Scotland! I really enjoyed my visit there in 2016.

 

I'd say these IR photos look like they "should" look. Local contrast enhancement is important in IR for bringing out detail, when desired. (Sometimes we play up the softer look, yes?) It was a darkish day there, so certain midtone contrasts are missing also. Lift the curve a bit? Or leave it dark and atmospheric looking? Nice, either way.

[Jim Lloyd]

Thanks Andrea. Great series of landscapes there!

 

I'm back from my Scotland trip and picking up from before (too busy walking to take many pics in Scotland).

 

Following up from what you said about resolution, aperture and wavelength.

 

Here's some more testing;

 

As before:

Camera full spectrum modified Nikon D3200

For UV UG1 2mm +BG40 2mm filters

For Visible BG40 2mm filter only

For IR Hoya R720 filter

ASA 200

1-16 second exposure for UV

Sunlight through window glass

Photax 35 mm f/3.5 preset lens

Processed using LightRoom - WB on gravel in background. Auto tone then some small manual adjustments. For IR increased contrast from auto setting.

 

In each image below aperture varies from 3.5- 22 from left to right / top to bottom (3.5, 4, 5.6, 8, 11, 16, 22)

 

In each case I have cropped 750x750 pixels from 6000x4000

 

My conclusion is that optimum aperture is f/8 for IR, f/11 for visible and f/16 for UV (meaning best resolution visually).

 

It seems to me that this is not too critical, provided the extreme ends of the range are avoided, bearing in mind that these are cropped. For some reason there seems to be a bigger variation with aperture for IR?

 

This is a good site for calculating aperture at which lens is diffraction limited - which is f/8 for 800 nm, f/11 for 550 nm and f/18 for 350 nm - which is remarkably similar to my visual impression of optimum aperture. Presumably this is because this relatively cheap lens suffers from noticeable aberrations when relatively wide open -so a sweet spot is found when it is stopped as far as possible before diffraction becomes an issue.

 

Below: UV, Visible, IR

 

 

 

 

 

 

 

 

[Andrea B.]

Hi there Jim....

 

Good to hear that Scotland was enjoyable. I would love to go there again. Of course, there are so many places I have not seen that I'm always torn about where to go.

 

Lots of Dandelions! They are the coolest little flower for these experiments because unlike so many other flowers there is that dark involucre in IR. So we get something in every waveband with Taraxacum.

 

You are doing such good practical experiments investigating all these aspects of UV/IR shooting. (Everyone should do these experiments at one time or another!) Presumably all these experiments will be incorporated into your final thesis as support for whatever main idea is written about?

 

There is the theory of diffraction and the Airy disk calculators, certainly useful to get one started. But I agree that the practical & best thing to do is what you have done here. That is: for each system consisting of camera + lens + filter, simply run an aperture series. Be sure to run the aperture series at close, middle and far distances in order to see how diffraction and depth of field (or lack thereof) sometimes combine to make photographic life very difficult. :D Then try to figure out how much diffraction can be recovered by proper sharpening in the converter or other editing app.

 

My preference in UV is to stay at f/8 or f/11 for close work because of the problem of having enough UV illumination. For the better sharper color corrected lenses, f/16 is certainly useable, but I seem to stay below that. We should ask Bjørn what he uses as he's had that lens for years and years. (For long distances in UV aperture hardly seems to matter! All that "haze".)

 

****

 

Jim, I'm hoping that sometime during your PhD work you will be able to rent a UV-Nikkor (modern Rayfact version) 105/4.5 or a Coastal Optics 60/4 to create some work with.

[nfoto]

The optimum aperture would depend on a lot of variables beside the spectral band in question. Many of these have already been mentioned. For example, focus distance, illumination quality, and scene contrast are all instrumental in determining the final outcome in addition to the lens or camera.

 

In general, for a single-shot capture, one can stop down more in UV than in IR, as already pointed out by Andrea. A lens with plenty of residual aberrations might need f/16 to deliver peak results in UV, and really long lenses might require f/22 or smaller. However, for a better corrected lens such as the Coastal 60/ or UV-Nikkor/Rayfact 105/4.5, higher resolution will be provided by not going that far down the aperture scale. In fact, for CO 60, the best performance (in UV) is already at f/5.6, thus for focus stacking I see no need for smaller than f/5.6 (-f/8) at most with such specialised optics.

 

IR tends to be substantially softer in its rendition than UV and thus not stopping all the way down might be prudent. However, even in such cases I have used wide-angle lenses stopped down to f/16-f/22. It all depends on the conditions encountered and what one really wants to get out of the photo opportunity.

[Jim Lloyd]

Thanks Bjorn and Andrea

 

Yes a lot of variables to consider! It helps me to isolate them and do experiments which can then help in "real world" situation. Don't think I can use this sort of thing in PhD - I think it's a bit like a pianist practicing their scales, or a painter practicing mixing paint - getting familiar with the tools ...

 

Here are some outdoor shots - maybe closer to the sort of things I am aiming towards. What is the small flower (white in visible - blue in my UV images - grows very abundantly in shaded woodland flowering now Northern England)?

 

Setup as described above - f/16

 

 

 

 

[Andy Perrin]

I love the 2nd and last photos in particular.

[Andrea B.]

probably a wood anemone or hepatica of some kind. I'll go find my book.

[Jim Lloyd]

Thanks Andy

 

Yes Andrea , I think it is wood anemone - I looked at Wikipedia and it looks right. Interesting that it spreads very slowly by roots rather than seeds and is therefore an indicator of ancient woodland. The small wood very close to where I live is covered with these at the moment - it is wedged between farmland and a housing estate and I guess is a tiny remnant of natural habitat.

[Andrea B.]

Found it. Indeed, a Wood Anemone, Anemone nemorosa.

 

Reference:

Wild Flowers of Britain and Northern Europe, 5th Edition, 1996

by FItter, Fitter & Blamey

A Collins Pocket Guide.

 

I got this guide in Scotland. It is excellent. Mine has a prettier cover than shown here. "-)

 

***********

 

The tree roots in #1 are so dramatic!

[nfoto]

Of course it is the wood anemone Anemone nemorosa. Widely distributed in western and northern Europe.

 

In the UK, it often grows together with its yellow-flowered cousin, A. ranunculoides. Both are pretty in their own way and remain distinct in UV too. They occasionally form a hybrid that is intermediate in visible *and* UV.

(I'll post that later -- must dash to finalise the sales of my former estate in Oslo)

 

 

(A. ranunculoides left, A. nemorosa right. Do note the presence of conical cells on the honey leaves of the A. nemorosa)

[Jim Lloyd]

Brilliant Bjorn!

 

Here is my attempt at similar with plant in captivity

 

D3200 full spectrum conversion

UG1 2 mm + BG40 2 mm

Nikon E 50 mm, f/11

Sunlight through window

WB and processing in Lightroom on black back drape, cropped

ASA 200 8 seconds

 

[Jim Lloyd]

I think I've been bitten by a bug ... (metaphorically!)

 

Here with Nikkor EL 80 mm (New version) f/5.6 - at f/11 asa 100 - otherwise as above. Second image is unfiltered [edit - the original version I posted had greenish tint to petals - replaced with version white balance on petals to make them white}

 

In this case using a couple of adapter rings to give extension I was able to get a much larger image, so that the result is essentially un-cropped.

 

 

[Jim Lloyd]

I think this question (or similar) has probably been asked before many times ... but why do I see hints of yellow in the stamen in my images, but not in Bjorn's? (and if the stamen are the sticky out parts what are the very central parts called)