donkom

donkom

Lives in Canada Barrie, Ontario, Canada
Works as a Advertising
Has a website at http://www.donkom.ca/
Joined on Jan 22, 2010

Comments

Total: 30, showing: 1 – 20
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On article Hands-on with new Canon L-series primes (295 comments in total)
In reply to:

donkom: Just a quick correction: in a few places you mention the 135 TS-E as being F/2.8. It's an F/4 lens. :) Thanks for the hands-on with these new lenses, I'm eager to test them out myself.

It all depends on how well such a lens handles extension tubes, if at all. I have very little practice with tilt-shift lenses in this area, but if it could push past 1:1 magification while still generation a complete image on a full-frame sensor, there could be many interesting applications. If not on FF, then a crop sensor could still yield viable results!

Link | Posted on Oct 27, 2017 at 00:26 UTC
On article Hands-on with new Canon L-series primes (295 comments in total)

Just a quick correction: in a few places you mention the 135 TS-E as being F/2.8. It's an F/4 lens. :) Thanks for the hands-on with these new lenses, I'm eager to test them out myself.

Link | Posted on Oct 26, 2017 at 21:44 UTC as 46th comment | 3 replies
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

nandbytes: It can be achieved even cheaper (at least with things that don't move like flower) if you use UV flashlights - https://www.flickr.com/photos/nandbytes/albums/72157680392089404

(of course those flashes are nicer but I haven't got $500, I spent more like $50)

Great results here nandbytes, with only minimal contamination in the visible sprectum from the light source. Of course this doesn't work well for subjects that can move, but it's a fun way to start!

Link | Posted on Oct 16, 2017 at 01:28 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Carabajal: please where is possible to buy the MidOpt BP365 filter??

There are a list of distributors on their website - contact the one closest to you. :)

Link | Posted on Oct 16, 2017 at 01:27 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

ewelch: I work with longwave and shortwave UV light to make photos in the studio of gemstones and diamonds. Our research scientists warn us not to look at the UV light source directly without using protective UV filtering eye protection. Direct exposure can damage one's retinas. Reflected UV light is no problem, just don't look at the source light with nekkid eyes!

You're absolutely right, I wear protective eyewear. :) I did think this was a "given" thing though, like a helmet on a motorcycle. I hear that UV exposure can lead to early cataracts, so be careful!

Link | Posted on Oct 14, 2017 at 01:13 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Coby: Can you clarify the $500 cost? Are you saying 3 * $95 for the flashes and the rest for the filters for the flashes?

$500 is for one flash + the filters required. $1500 for three flashes, roughly. The MidOpt filter is the wildcard - regional suppliers would tell you the price. :)

Link | Posted on Oct 14, 2017 at 01:11 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

jscalev: This is extremely interesting and easily one of the best articles I've seen. A few questions.
1) Does having a UV specific lens like the Nikon UV-105 or Coastal Optics 60/4 or 105/4 allow for shorter exposures for UV fluorescence? Or do they only make a difference for UV reflectance?
2) Are there any sites with instructions on how to modify the Yongnuo 685s?
3) I see a company that sells the Hoya U-340 on EBay. Do the MidOpt D365s need to be ordered direct from MidOpt or is there another online seller?

Thanks for the interest in my work!
1) You do not need anything special in terms of optics for fluorescence, it makes no difference. In fact, some of these images were shot with a Trioplan 100 and only because it was a decent 100mm lens I had lying around my studio and for no other reason.
2) I don't think so, but it's just the few visible screws on the outside of the flash head, and some metal clamps under the rubber circles on the side and the flash head is opened. Remove two pieces of plastic between the xenon flash tube and the outside world. NOTE: read the safety warning in the article.
3) The MidOpt website has a list of suppliers. I use Bock Optronics because they are the closest to me geographically, but check out that list and find your best contact person.

Link | Posted on Oct 13, 2017 at 22:23 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Carabajal: How do you focus, removing filters previously?, manually?

You focus like you would for any image - there are no filters over the lens and the camera is not modified in any way. The light source is filtered to only allow UV light to be emitted, and the camera captures the visible light that fluoresces off of the subject.

Link | Posted on Oct 13, 2017 at 15:53 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

ovatab: did those insects survive?

As far as I can tell, none of the insects were affected by the shoot. The only exception would be the aphids, as I plucked the leaf they were feeding on - they'd need to find a new home. Shortly after discovering the aphid infestation in our gardens I purchased 4500 ladybugs to deal with it as a form of pest control... so I don't think they had a happy ending in the long term.

Link | Posted on Oct 13, 2017 at 15:50 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Thomas KP Lee: Great photos. One question, since you were using flash to generate UV light, how did you do focusing? I suppose most are done in MF, but how? Are you able to use live view for focus?

Thanks Thomas. Keep in mind that the camera is not collecting the UV light for these images, but rather visible light that has fluoresced off the subject. This means there is no focusing shift like you would experience in directly recording UV or IR light.

The studio is very dimly lit for most of these images, so dim that an image would appear completely black if recorded without the UV flashes. There is often enough light for me to focus manually, but for the occasions where I'm on a tripod I simply focus first, turn off the lights, and fire.

Link | Posted on Oct 13, 2017 at 15:49 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

entoman: An interesting article Don, with helpful advice about flash modification and filters. I've never tried UV insect photography, but it interests me as an entomologist, because many insects depend (to varying degrees), on detecting and "reading" patterns on flowers (and on potential mates), that are only visible in the UV part of the spectrum.

It would be interesting to find out if it's possible to modify a DSLR or mirrorless camera to record ambient UV in daylight, without using artificial sources such as flash.

AstroStan, you're right in the traditional sense of colour, but just like you can get false colour infrared images at 720nm, you can play with false colour ultraviolet work by remapping the deviations put into play by the colour filter array. In infrared for example, the coloured filters become equally transparent to light beyond 820nm (which is why 850nm IR is monochrome). A similar bit of wiggle room exists on the UV side of things.

Dan Llewellyn of "MaxMax" can modify a camera sensor to completely remove the Bayer pattern filters for pure monochrome work, and the UV reflectance sensitivity goes up about 6X - I have a 5D mark II modified by him and it works great, but is only for black & white work.

eBay seller "igoriginal" sells a variant of the Kyoei Kuribayashi lens that is pretty good for UV macro work, even though it doesn't have quartz elements. For $100, it's far more affordable than the >$8000 quartz lenses!

... but this article was more about fluorescence. :)

Link | Posted on Oct 12, 2017 at 23:29 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Lan: One thing I would recommend when experimenting is wearing glasses (or safety glasses) that block UV. The human eye doesn't benefit from large doses of UV.

I was surprised to find that one of my pairs of glasses block UV, but others appear to pass it with relatively little attenuation. If in doubt, test them out - UV source on one side, fluorescent material on the other - If the fluorescent material lights up, put some safety glasses on as well!

You're absolutely right Lan, and I didn't mention it in the article. One would assume it's common knowledge like not shining a laser pointer in your eye or wearing a helmet when driving a motorcycle. Since all eyewear use UV protection as a selling point, I would hope most people realize that protecting their vision is a good idea. :)

UV light can cause early cataracts to form, and UV-protective glasses cost $5. Worth the investment - but always test them to be sure they work!

Link | Posted on Oct 12, 2017 at 21:11 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

KevinG: Great article as others have said. I do have one question though, is the 500.00 figure the total cost for the flash mods exclusive of the original cost of each flash?

The Yongnuo 685s I use are around $95 each on eBay, so the total build cost includes the flash itself. Thanks for enjoying the article!

Link | Posted on Oct 12, 2017 at 18:16 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

entoman: An interesting article Don, with helpful advice about flash modification and filters. I've never tried UV insect photography, but it interests me as an entomologist, because many insects depend (to varying degrees), on detecting and "reading" patterns on flowers (and on potential mates), that are only visible in the UV part of the spectrum.

It would be interesting to find out if it's possible to modify a DSLR or mirrorless camera to record ambient UV in daylight, without using artificial sources such as flash.

UV reflectance photography is a ton of fun as well entoman, though you only ever get muted colours.... but you're after the patterns! There are a few things to consider here:

- Get a camera modified for full-spectrum photography
- Get a lens that allows for greater UV transmission. Most lenses made of standard glass will not transmit UV light effectively. There are (very expensive) lenses constructed with quartz elements but less expensive alternatives exist. I have a lens modified for this and it works pretty well - send me an e-mail and I'll give you a link to where I bought it.
- You'll need to filter out all visible AND infrared light from the camera. The best filters I've used for this are the XNite 330C and the XNite BP1 together.

At high ISOs or more relaxed shutter speeds, it's possible to shoot UV reflectance imagery in bright sunlight. :)

Link | Posted on Oct 12, 2017 at 18:15 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

c h u n k: The ladybug image - the ladybug has a fungle infection. When I 1st saw this (though on visible light) in one of my own shots, I spent a while looking to see what it was and thought it was a worm like parasite, but found that its a fungus. The funny thing is that the research paper I read describes it as a ladybug "std" as they commonly become infected by eachother when mating. Looks like the fungus flouresces green too.

Yes, this was surprising to me at first as well! It's a parasitic fungus, Hesperomyces virescens to the best of my ability to identify. So far some spiders, aphids, and that weird fungus are the three things I've found that fluoresce green. I'm sure there's more!

Link | Posted on Oct 12, 2017 at 17:54 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

tjwaggoner: Great article, and interesting photos. To be clear; any photography done in this way must be done in a completely dark environment. Correct? I mean you can’t walk around your yard or the park and experiment with this.

There are certainly stray photons of light around when I make these images, sometimes even even for Live View to return a meaningful image at it's extremes. The trick here is to turn off your UV lights and take a test shot at your required exposure settings. If you see a completely black image, then the amount of ambient light is of no consequence to your image. David summed this up nicely as well.

Link | Posted on Oct 12, 2017 at 17:51 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

Greg VdB: Really nice article and (funky) pictures, Don, thanks for sharing!

Have you by any chance tried photographing minerals with your setup? That's where I know this kind of photography from.

I have some minerals here in my studio that respond to long-wave UV light, the best specimen I have is hackmanite. Technically it's not fluorescent but rather teneberescent, but the visual response is similar. Many minerals fluoresce with short-wave UV, and I've been trying to obtain a decent light source for this - my most recent purchase arrived broken.

While I have the minerals, I don't think they would be as interesting as the organic subjects. The real magic would be mixing the two together, and I have some ideas that will be fun to explore. :)

Thanks for enjoying the article!

Link | Posted on Oct 12, 2017 at 17:48 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

MacM545: I tried this with an LED that's supposed to be 365nm and it's actually visible light.

There are many $10-$20 UV flashlights on eBay and Amazon that bleed a lot of visible light, mostly blue. As they are intended to detect dog pee on carpets or scorpions in your garage, they still function for those intended purposes. As willmore points out, it's simple to tape a filter to the front of those flashlights, so long as whatever filters you are using block 100% of the visibly-emitted light from the LEDs.

Link | Posted on Oct 12, 2017 at 17:43 UTC
On article The magic of ultraviolet nature and macro photography (72 comments in total)
In reply to:

willmore: "If anything in the frame fluoresces, visible light bounces back to the camera."

Sorry if this sounds pedantic, but saying 'bounces back" when it's different light coming back is confusing. Fluorescence works by having a high energy photon (UV in this case) striking a molecule which absorbs the energy from it. Some time later--from tiny fractions of a second to hours--it will emit a photon of a lower energy. In the case of the photos here, it'll be a visible light photon and probably given off very quickly after the UV photon is captured.

Kodak used to have a bunch of great publications on this topic (and IR as well) 'back in the day'. Does anyone know if there are scanned versions of those old docs? They would make great suppliments to this article. Fine article, too. I enjoy this kind of unusual photography.

Haha, I love pedantry like this. :) Even a rubber ball bouncing against a wall isn't an "immediate" thing on small timescales, and it bounces back with less energy than it hit the wall with. I am ill-equipped to find a better phrase than "bounces back" for the general readership to understand without getting needlessly complex for an article such as this. Glad you enjoyed the article!

Link | Posted on Oct 12, 2017 at 17:39 UTC

You know there is no R in Photomatix, right? :)

Link | Posted on Jun 12, 2017 at 19:32 UTC as 10th comment | 1 reply
Total: 30, showing: 1 – 20
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