New kit - Monochrome converted Eos 5DSR (from MaxMax)

[JMC]

Well I now have a serious learning curve ahead of me. Given my interest in the technical side of skin imaging, and especially the UV imaging I decided to jump in with both feet. I've bought a MaxMax Monochrome conversion for my spare Eos 5DSR. So this will go alongside my un-modified 5DSR so I can do a proper comparison of the two as and when the need arises. Paired with my Asahi Ultra Achromatic 85mm lens this monochrome conversion should be excellent for my work on imaging sunscreens (given the enhanced UV sensitivity from removing the Bayer filter, and where I don't need any colour). Just unpacked so no sample images yet. and I'm going to have to get used to not seeing what I'm photographing again when it comes to opaque filters.

[JMC]

Doh, in my excitement I forgot to add this is a full spectrum conversion too. Far to excited for my own good :)

[Andy Perrin]

WOW! I can't wait to see what you do with it!

[JMC]

WOW! I can't wait to see what you do with it!

Yeah, no pressure, huh. According to MaxMax it's the 4th conversion they've done on a 5dsr, and the 1st that's now in Europe. As well as my skin research I want to try it for landscape work as well. Lots of possibilities :)

[Hornblende]

Looking forward to see your pictures :)

[Cadmium]

So what filter you putting on that fancy rig? :-)

[JMC]

So what filter you putting on that fancy rig? :-)

Oh, decisions, decisions. At the moment, Baader U for the UV imaging, B+W UV/IR cut for visible work, and I have a few different deep reds and IR ones for IR work. To be honest this will be a learning tool for me - I want to see what's possible with something like this. Now I just need to find the time to use it :)

[JMC]

Blimey, I do not know how you flower photographers have the patience. I managed to get outside and get a photo of one of the flowers in the garden with the new camera (sorry no idea what the flower is other than it being a white one in normal visible light) in the 3 seconds of continuous sunlight that constitutes the great British summertime.

 

Setup as follows;

Monochrome multispectral EOS 5DSR

Asahi Ultra achromatic 85mm, at f8

Baader U filter

Bright sunshine, UK summer, in between clouds, approximately 11:30AM

ISO 6400, 1/40th second (the only way to stop it moving given the continual wind - again how to you flower photographers have the patience ;) )

No processing, saved as jpeg in the camera.

 

Two images, one the full frame shot (which has obviously had the resolution dropped for uploading here), and the second a crop of the original before dropping the resolution.

 

 

So, how does ISO 6400, 1/40th second and f8 in bright sunshine, with a Baader U compare to a standard full spectrum conversion? I was told by MaxMax that the monochrome conversion should produce a 2-3 stop improvement in the UV region, but I don't have a full spectrum camera to do a direct comparison with.

[nfoto]

The flower is a member of the Daisy family (Asteraceae). Provide some overview pictures in vislble light and we might come up with a better delineated answer.

 

As to the exposure: normal sunlight, Baader U (Venus 2.gen), UV-Nikkor at f/11, 1 sec, ISO 100 to 200 with my Nikon D3200 or D600. So we are talking about 2-3 stops difference here.

[JMC]

Thanks Bjorn. Sure, here's a normal colour photo, taken with my standard 6D.

[nfoto]

Apparently I was mistaken. This is not a member of Asteraceae at all. Probably something in the Rose family instead.

[Andrea B.]

The flower appears to be some species of Wood Anemone.

 

*****

Jonathan, how's that learning curve coming along with the Mono-UV 5Ds?

[JMC]

The flower appears to be some species of Wood Anemone.

 

*****

Jonathan, how's that learning curve coming along with the Mono-UV 5Ds?

Steep, Andrea, very steep. We've had awful weather here for the last week, so that combined with work has limited opportunities for getting out with it. The sun did break through today though, so I was out doing a quick comparison with my UV modified 7D, trying to see whether I could measure how much more sensitive it is to UV, using sun light being bounced from a PTFE plate. While I need to fully analyse the images the monochrome 5Dsr looks to be about 2 stops more sensitive, however there is a caveat here. I assessed the 7D (which has a sensor filter from ACS) Vs the 5Dsr with an external Baader U (as I do not have an external ACS filter). With both I used a Rayfact 105mm lens, but not a true direct comparison given the different filters, sensors etc, but more of a real life usage comparison. I also want to repeat it, given I'm using sun light. I may consider making a UV light box to make it more controlled. Too many things to do :)

[Andy Perrin]

I am also wondering how much (more?) UVB you could potentially image with that camera, if you had a quartz lens.

[JMC]

Over the sensor is a Schott WG280, which according to MaxMax lets in light below where the sensor is sensitive. The Asahi lens will let in light well below that. I do have a 308nm bandpass filter coming for me to try out (http://www.invisiblevision.com/products/accessories/), so let's see what happens.

[Andy Perrin]

That 308nm bandpass is only >OD4 blocking, which, considering how little UVB and how much UVA+Vis+IR in sunshine there usually is, might give you significant leakage if you don't control for it. If you try to do UVB imaging, probably an artificial source would be best? I remember Mark (of this site) was a little disappointed in his OD4 filter. The issue is that you will probably have to expose for a long time which "pushes" the filter a bit.

[JMC]

That 308nm bandpass is only >OD4 blocking, which, considering how little UVB and how much UVA+Vis+IR in sunshine there usually is, might give you significant leakage if you don't control for it. If you try to do UVB imaging, probably an artificial source would be best? I remember Mark (of this site) was a little disappointed in his OD4 filter. The issue is that you will probably have to expose for a long time which "pushes" the filter a bit.

Hmm, interesting, thank you, I hadn't thought of that. It's coming on a 'loan' anyway so will get some pictures in sunlight as i) it will hopefully be available at some point this summer and ii) I'm not sure I want to go shining artificial UVB sources on skin. At least I can compare with the Baader U and see if there is a visual difference, but I'll have to keep in mind the potential for contamination in the image from other wavelengths.

[Andy Perrin]

Yes, shining artificial UVB on skin is a horrible idea! You could try it with some inanimate objects (with decent shielding, I would hope!).

 

I recently learned that shining UVB on the scalp is a treatment for psoriasis, though, which is interesting. I guess they figure the cancer risk is less of an issue than treating the psoriasis.