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UltravioletPhotography

Anyone using Sony A7 series for UV


A Stranger In The Wind

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A Stranger In The Wind

I am wondering if anyone has had a Sony A7 series converted as a Full Spectrum camera for shooting UV. I am toying with the idea of converting my A7s to full spectrum once I receive my new A7s MKII.

 

I mainly use my current A7s for video shooting, and would like to do some UV and IR videography. I have no problem shooting IR video on my converted 5D MKIIs as I can easily shoot at 1/60 at 29.97fps but UV is a different issue. Given that on color photos I often shoot upto ISO 10000 on the A7s and with my Canon I usually stop at ISO 3200 I am exploring to the possibility of converting the A7s to full spectrum for UV video.

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I have no personal experience with this series--though I have heard that the A7s II is the best low-light camera out there, with a sensor gain dial that goes up to something like 1,000,000+ (!) On the other hand, these new cameras with pellicle mirrors are different from SLRs in one important way: the mirror is a permanent part of the optical train and cannot be removed, even for a conversion. Some of the other products do not have a pellicle mirror, but have a hot mirror that is integral with the sensor, i.e. it is not removable. What the UV-transmitting properties of these elements are, I cannot say. I myself have long lusted for something that could render starry skies/star trails in UV, which in some ways might be seen as a similar challenge (needs at least 6400 in the visible, and heaven knows what through a Baader.) So I say you have a chance at it, if UV can actually get to the sensor.
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There is certainly no problem with any of the Sony sensors when it comes to recording UV. Most of my converted Nikons have had Sony sensors.

 

As Clark has astutely noted, the pellicle mirror might indeed present a problem. If you can find out what type of glass is used in that mirror, then you might be able to better determine the UV capability of the A7 series.

ERROR CORRECTION: A7 does not have pellicle mirrors. The A77 model (and some others) do.

 

I would like to know myself as I have some interesting old lenses which are UV capable but which have a flange focal distance too short for infinity focus on my D600 (Nikon) and K5 (Pentax). So one of the Sony bodies would be good to have.

 

The folks at Life Pixel have always been helpful with this kind of thing. You could call them and ask if they have done any Full Spec or UV-only conversions of A7 bodies and if so, then how well they thought the conversion worked out.

 

As for video, for some time the Panasonic Lumix G line of cameras were winning all the kudos. Bjørn has made UV videos with his GH3. So we need to get him to weigh in here about how high an ISO setting he needs for that and anything else he has learned about UV video. Sony has always made excellent videocams and so one would think that they probably have been able to put good video in their digicams.

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Firstly, my familiarity with the Sony A7-series is limited to trying a few shots with the camera(s) lent me by a friend. Last time it was the fancy high-ISO capable version I believe. Secondly, I fail to understand the reference to a "pellicle mirror" for these cameras. If you remove the lens, you look directly onto the sensor surface itself.

 

As to UV video, my work has been done with a converted Panasonic GH-2. It works quite well except for the less than stellar high-ISO performance. I have shot the videos with ISO settings from 400 to 3200. The lens mainly was the Coastal Optics 60 mm f/4 APO lens (before it fall apart). The frame rate drops substantially as the UV levels decline of course, but in bright daylight there is no problem as such, apart from the usual focusing issue for EVF cameras in UV.

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Thank you me too Alex. I know that some Sonys do have that pellicle mirror and some dont. But it is difficult to keep track of the numbers on all these lines of cameras. :)
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A Stranger In The Wind
Thanks for all the information. Life Pixel converted my 5D MKIIs several years ago. I will likely get it converted but I will send Lifepixel a message to see if others have converted the A7s. I am sure someone has but more likely IR and not full spectrum.
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The lens mainly was the Coastal Optics 60 mm f/4 APO lens (before it fall apart).

 

I have not seen you mention this trouble before. Will you elaborate?

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The lens fell apart on my recent trip to South Africa. Turned out the internal mechanism had some mechanical design flaws and by using it, the guidance supports for the focusing helicoid eventually wore out and left the lens inoperable. The lens is now on its return to the US for a rebuild.

 

Food for thought that my UV-Nikkors by now have been used for up to 30 years without anything untoward happening to them. The oldest one needed to be re-lubricated and cleaned internally after 15 years of hard use, but that is entirely acceptable in my book.

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Coastal is aimed at "industrial" market, like UKOprics, Melles Griot, Edmund Optics, etc. In my limited experience, price does not reflect quality...
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Indeed. The repair bill for a damage that is entirely due to the poor internal design is $2000 .... :(

 

The pieces that sheared off rattled around inside and scratched two of the elements badly. These elements must be replaced, the lens completely rebuilt, and then tested and adjusted on an optical bench. $$$ out the window for collateral damage due to engineers not up to the task of designing a sturdy lens which can withstand normal field use.

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This certainly changes my perspective. Having until now, apart from controllable hot-spotting, heard only high praise for this lens.
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Optically speaking, yes, it is truly superb. The hot spot issue can easily be controlled by judiciously choosing the optimal funnel-shaped lens hood. But that won't help you much if (or when) the lens actually breaks down under field use and sheared-off pieces start to gnaw themselves into the elements.

 

As I in fact got my lens for free, I gave the repair shop the nod to go ahead. But I will make sure this flaw is exposed to the full extent it deserves.

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What a disaster with the Coastal 60 !! May I ask why you are actually spending that kind of money to repair it?

It is good, but not that good.

 

Call me curious.

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Currently I am 'negotiating' the matter with the CEO of the company. I have told Jenoptik, in no hidden manner, that the problem is collateral damage from their own inadequate mechanical construction of the lens internals and that such a flaw needs to be exposed to the general public. I don't think they are too pleased with the situation and neither am I.
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Well Jenoptik were also not pleased with me when I "discovered" that hot spot. (And you didn't believe me at first!!!!) But at least they eventually acknowledged it online.

Do you have photos of the damage?

We should probably split off this discussion about the Coastal 60 from the question about using Sony for UV video.

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Breaking news on the Coastal 60 repair:

 

After having received a quotation for $2000 for the repair of my damaged 60 APO, I wrote directly to the CEO of Jenoptik and told that this costly repair should be handled in a better manner, as the problem clearly was due to poor construction and not the user. In passing I added that I would make a full report of this issue on my web pages.

 

Just now I got an e-mail from the company stating that they have "reconsidered the repair" and would make it under full warranty, free of charge (the lens is 7 years old, by the way).

 

Never underestimate consumers' power.

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enricosavazzi
I always thought that the CoastalOpt 60mm (or at least my copy) has a far stiffer focus ring than most of my lenses. I wonder if this has anything to do with parts of the focusing mechanism wearing out because the focus grease is too stiff.
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Interesting idea. I just received a message stating my 60 Coastal is repaired and can be picked up tomorrow. I'll discuss the repair details with my Nikon tech then.
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The lens was shipped to the US for repairs. Without an available repair manual the local shop didn't want to take it on. Besides two of the elements had been damaged by the sheared off screws rattling around or being jammed inside so some elements had to be replaced.

 

Got the lens back earlier today. Looked fine, but the aperture was stuck at f/45. Had to have my tech pals at FotoCare here in Oslo to open the lens up and fix the problem. That lens reminds me eerily of British cars of the '60s. Brilliant designs that were shoddily implemented. Anyone using a Mini or similar from that time period will know exactly what I mean.

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