Some very basic lens test with ? dandelion

[Jim Lloyd]

Might as well finish the set!

 

IR (Hoya R720 filter)

and visible UG40 2 mm only

(all settings as before)

 

 

[Andrea B.]

Jim, your renditions of the Anemone are quite good. Please do consider posting your Anemone in our botanical section as a formal entry.

 

You can just cut & paste some "boilerplate" from another botanical entry and edit it to fit your Anemone and accompanying details. I review all botanical entries and make any minor edits necessary. I"m happy to help first-time posters in the botanical section with any details.

 

If you decide you would enjoy doing this, then you can use the reference above from the Collins guide for your reference. I'll provide the missing details for that if you do decide to post your Anemone.

---

 

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?

 

The conversion of an image and the accompanying editing steps - such as white balance - do not always result in the exact same image colors seen in other images of the same subject. This is especially true when dealing with UV false colors. You generally see the same basic color palette across bayer-filtered false color images, but the more nuanced tints and shades may differ because color (in any image) depends on camera + lens + filter + illumination.

 

Added: Color and false color also depends on the particular demosaicing algorithm used to convert the raw file. Converter demosaicing may differ from camera demosaicing if the camera manufacturer provided software is not used. Then any contrast or saturation edits which are made can shift hues. Finally the color space in which you display your photo affects the color in certain ways.

 

The procedure for attaining the best final false color results involves creation of a color profile specific to the converted camera + lens + filter + lighting combination. When converting an image, this color profile is applied. Also when shooting, a UV-stable white balance standard is used to take a UV white balance reading for later application in the converter along with the color profile. All this requires a certain investment of time and money to achieve.

 

However, you can produce a good replication of "standardized" UV false color by rather informal methods. Simple "click around" on your image with a white balance dropper or make a rectangular sample with those WB tools which use that method. Click or sample until you find an area which produces yellow/blue/grey/black/white in the image. Any purple/pink/magenta tints should be gone.

[Jim Lloyd]

Thanks Andrea - I will have a go at submitting this formally later or tomorrow

 

I have another version: The Photax lens - 35mm f/3.5 preset (seems identical to the Optomax I have as well) has a mount that enables M42 fitting, but this can be unscrewed and there is an underlying T-Mount - however, I have found that if you leave this fitting on, you essentially have a short extension tube which enable the lens to be used for macro work. Which is great as my only criticism before was inability at close focusing (minimum about 80 cm) [Edit - by the way ... I like this lens so much I have just bought another one on ebay for £25 - this one looks in very nice condition, looks the same as the one used here, except it is Optomax branded rather than Photax - all the other Photax ones I see on ebay at the moment are a different design to this one]

 

Here is the wood anemone with this lens as described with extension - so no digital image cropping needed. I used teflon tape on another image in the same set up and copied the white balance, although it wasn't much different to what I had before.

 

f/16 - asa 100 15 sec expsoure - filters and camera as above

 

[Andrea B.]

You must have been wind free to get a 15 sec exposure outdoors !!

 

I added a bit to an earlier post about why the colors can vary slightly across platforms.

[Jim Lloyd]

This was indoors illuminated through glass

 

We looked at transmission through car windows a while ago

 

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2133.2004.06098.x

 

For clear glass we found 63% UVA transmission

 

And my recent quick tests suggest that with my set up indoor and outdoor images are very similar

 

There is also an ethical issue about picking plants, but I have limited myself to those which are very widespread

 

Wind free days are extremely rare around here !

[Cadmium]

Ooo, Jim, that one just above is a really nice UV photo!

[Jim Lloyd]

Thanks Steve

[Jim Lloyd]

Got my old version of the EL Nikkor 80 mm f/5.6 lens today (with the silver barrel - I think its the newer of the two silver barreled ones). I am getting a bit jaded with so much testing - so just some quick ones with this compared to the new plasticy version. The newer version was a mistake by me, so I am not thinking of keeping it anyway and a lot has been said already about this. However, I thought maybe readers would be interested. I found that the old version had good resolution from the widest aperture (f/5.6) to f/11 for visible (distance about 1m) optimum about f/8. f/16 and beyond there was noticeable diffraction blur. For UV f/11 was probably optimum for sharpness.

 

Direct comparison was a little tricky as I was doing this outside with light a little changeable, but I think the image comparison below is a fair reflection. The older version does appear to give definite improvements over the newer one. It is certainly not worse and it feels a lot better and does not suffer light leaks like the newer one.

 

I know this is old news - but thought I would share anyway

 

D3200 full spectrum conversion, UG1 2 mm + BG40 2 mm, Sunlight outside, ASA 400 2 seconds, f/11

WB and processing in Lightroom with reference to same pebble in background, auto tone setting, cropped

 

Old on left, new on right

 

[ulf]

I'm glad that you like this new (old) lens.

Your findings about sharpness and diffraction fit the theories reasonable well for the pixel size of your sensor.

 

When I use this type of lens, I often set it to f/22, to gain some DOF especially for my close-up images.

[Andy Perrin]

My camera is about the same as Jim's (APS-C, 24MP) but I often use F/16 in UV? I do have trouble at F/16 in visible light. It's possible that the choice of filter matters somewhat - if you attenuate the longer wavelengths a bit more, that might buy additional sharpness.