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UltravioletPhotography

M43rds user question about sensitivity


dabateman

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I just acquired an Olympus Em1 camera. I also just ran it through some controlled lighting tests.

My questionable used full spectrum Olympus E510 using a tmount kuri 35mm clone with my lights, gave acceptable image with Iso 800, 15sec f5.6.

I have tested my stock Olympus E3 and see between 1 to 2 stops more exposure is needed to match the E510.

Now after testing the Olympus Em1 I see the same. The Em1 is just more than one stop less sensitive than my E510. Iso 800, 30sec, f5.6 is acceptable.

So I wonder have any of the M43rds users on this forum compared their Olympus cameras before and after full spectrum conversion?

Do you see more than 2 stop improvement?

I also at the same time compared my Panasonic Gm5, which I know to be less sensitive to Uv. And again tonight it was 5 stops less sensitive than the Olympus E510.

I ask as I bought this camera to convert to full spectrum, but now that I am more interested in the lower wavelengths, I wonder if I should. I have to test it, but the Em1 was reported as being 10Ev less sensitive to Ir:

 

http://www.wrotniak.net/photo/m43/em1.1-ir.html

 

Thus using the internal Ir filter to help against IR leakage and the ok uv sensitivity, I don't think it make sense to convert it. Unless people saw better than 2ev response after a reputable conversion.

Any thoughts please.

Thank you.

 

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No I bought it from igoriginal and have not taken it apart. He fixed what looks to be a 46 to 52mm step up ring on the lens.

Why do you ask?

 

I know my basement lighting is weak. I was using a grow light and compact fluorescent bulb for this test.

After I tested a new GE 75W halogen bulb and was able to get one stop more UV, than the 23W compact fluorescent bulb. The halogen is part of their new incandescent bulb replacement. So its a halogen bulb inside a glass bulb. I would guess a straight halogen bulb with out the extra glass layer to be better.

I also may pick up a 175W Hg bulb from home depot to test. There only about $15. But will have to build a stand to support it. The halogen fits in a regular desk lamp.

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I ask because a "clone" with no brand name is a mysterious unknown factor.

Also, did you mention the filters you are using? Or no filters?

ZWB1 perhaps? Cheap glass from China, not as efficient as Schott or Hoya...

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Sorry,

Don't want any confusion. I was using my Baader venus 2 for this test. I do have the 2mm zwb1 and 2.2mm bg39, but they require more light and my controlled setup is weak.

Yes I should have specified the full method.

On a tripod I have the cameras set up, single shot to allow for dark frame noise subtraction. I have noise filter set off, as this just smears the image.

Manual focus using manual exposure. Both using live view.

The Em1 is used but seems to have been babied. I don't think any alterations have been done to that camera. I got it with just 603 actuations.

I bought the full spectrum E510 used from Spencer's camera in 2009. I question it as I never got an answer to how or with what it was convert with. May just be cheap glass. For what I paid though, I never complained. Included 14-42mm, 40-150mm and 70-300mm Olympus lenses with the camera, all for $600.

The filter on lens was venus baader 2.

The lights are a fluorescent grow bulb and 23w compact fluorescent bulb. In a lighting test. The grow bulb was one stop better than just the 23w compact fluorescent bulb. A clear tungsten bulb I have was terrible with low uv output. Equally bad were my incandescent 75w black lights. Very little light output and not much into uv. The halogen tested much better though, as I would expect.

I used the 35mm f3.5 kuri clone as from recent lens test, it was the best. It has a tmount but I don't know much more about it.

I will comment on my lens tests in an other thread as I was surprised by some.

 

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Hi David -

 

Let me make sure I have all this correctly:

  • filter: BaaderU on UV-capable lens.
  • light: fluorescent UV grow lights
  • full spec conversion: Oly E510 = f/5.6 for 15" @ ISO-800.
  • stock: Oly EM = + 1 stop
  • stock: Oly E3 = +1-2 stops
  • stock: Panasonic Gm5 = + 5 stops

So the question is - under this lighting, with this lens and filter ((or with any fixed lighting/lens/filter))

 

How many stops difference in UV sensitivity should we see between a full spectrum conversion and a stock camera?

 

Good question, and I personally don't have an answer because I've always used conversions for UV/IR work. But let's see if other members have some input on that. And I will ping Bjørn because I think he might have some observations on this.

 

A point about the lighting: You are using a UV-pass filter which has a peak around 350 nm. Where do these fluorescent lights peak? Is there a mismatch?


 

About your full spectrum conversion - The Spencer's conversion of my D300 years ago was made with a plastic filter. While it is certainly true that some plastic does pass UV (and IR), the conversion was unacceptable for image quality (flare, some strange artifacts, softening) and exposure length. I removed the plastic filter myself and continued to use the D300 quite sucessfully until I moved on to newer cameras. I wrote about the plastic filter at the time on another website. And I will not list Spencer's in our Sticky's list of reputable retail conversion shops even though I do not know what Spencer's is currently using for full spectrum conversion filters.

 

You should always, always be provided with a specification and transmission chart for glass (GLASS!!!) used in any full spectrum conversion. There are no acceptable secrets in any conversion. It is a straightforward process, and the good conversion shops are happy to supply you with complete information. They should do so without your having to ask. Typically the type of conversion filter used is listed on their websites.

 

I'm counting Spectrasil as glass.

 

One can quibble over what "should" be used for a full spectrum conversion, Spectrasil or WG280, anti-reflective coating or not. They all work. But if a conversion shop is not willing to give you complete information, then do not spend a large chunk of money to get an unknown filter.

 

I'll go now and see if I can find Bjørn Birna (nfoto). And please, anyone who might have some data to answer the primary question, please let us know.

 

We might somewhere actually have an answer already posted. But after writing almost 6K posts myself, I've long ago lost track of where everything is on UVP !!!! :lol: :lol: :lol:

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I'm also looking around on Enrico's excellent website. I note that he has written extensively about Olympus cameras which he uses. If I find something there to answer the Stop Increase question, I bring back a specific link. Here is the entry link: http://savazzi.net/p...phy/default.htm

 

 

BTW, Enrico's website is so interesting!! There is so much good stuff there. I could spend hours there (and probably have.....)!

 

I'm also writing Enrico for his input on this very very interesting question.

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wow, after integrating under that halogen curve, I see that it's even worse than natural sunlight......!

 

Halogens are so danged hot, that I never tried one again after the first time. Don't even remember anymore what results I got, or didn't get. Yes, the flower totally fried.

 

j/k about the integration....

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dabateman: Your comment "Thus using the internal Ir filter to help against IR leakage and the ok uv sensitivity" does make sense. I also have a stock M1, and have never considered that the internal UV/IR-block filter, might actually be beneficial to UV photography. Using an Andrea U2 filter, in full sun, I can get a usable response (1.0 sec @ iso 400) on my M1, but I expect that your Baader would be a much longer exposure and higher iso. Funny that you mention the 'kuri' lens...I ordered the same one!

 

Cadmium and Andrea: That's interesting news about Spencers. In the past I've had a Spencers conversion done on an Olympus P2, and it worked fine for infrared and full spectrum shots, but I don't recall having any great success with UV.

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I didn't know about Spencer's using plastic, but back when I was first shopping for a conversion, Spencer's had the best prices it seemed, but they also had a lot of negative reports,

so I decided to go with one of the more reputable conversion companies. I even tried contacting Spencer's at the time, even called them, and I was not satisfied with the results.

I think the two most reputable and experienced camera conversion places are LifePixel and MaxMax. Anyway, mute point perhaps.

 

What I would really like to know, even though it may have nothing to do with your question, is does your lens have a brand name on it?

Maybe it had a brand name that has been removed? AKA an 'X' lens...

That's when someone takes a lens, removes the labeling so no one knows what it is, what it was, and in so doing, hiding information about the item.

All the lenses I have ever seen have the brand and the mm and minimum aperture and a serial number on the front of the lens, or the side...

Does your 'clone' have any info on the the lens?

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Your comment "Thus using the internal Ir filter to help against IR leakage and the ok uv sensitivity" does make sense. I also have a stock M1, and have never considered that the internal UV/IR-block filter, might actually be beneficial to UV photography.

 

Hold on....let's back up a bit here.....

 

There is nothing at all beneficial to UV photography performed while shooting through an internal filter which blocks UV light. That's like trying to run the Boston Marathon in your LL Bean hiking boots. Extraordinarily painful and tedious with last-place results.

 

Yes, good digital UV photography requires some expense to get started. I can't apologize for that because that's just the nature of the game. We do everything we can to provide information about ways to save money, but skipping the conversion step is definitely not recommended.

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Cadmium: I've also had excellent conversion results with Kolarivision.

 

Andrea: I totally get your point; a conversion is the ONLY way to go for dedicated UV work. The stock M1 does seem to have good UV sensitivity, but not sure if a conversion would be enough to make it a excellent UV performer. Do you have any experience with Olympus m4/3 digitals ?

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Some older cameras' internal filters had relatively little UV blocking (they were initially designed to block IR; and not much UV gets through many newer lenses anyway.) The Canon I used to own had maybe a stop of UV attenuation, if even that.
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I haven't received mine yet, but no brand name indicated. With a little google searching, I'm guessing vintage Soligor ??
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OK, you don't have the lens yet, sorry, didn't know that.

Well, given a full spectrum converted camera, the lens is the main bottleneck of the UV transmission and sensitivity.

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Andrea B.

Do you have any experience with Olympus m4/3 digitals ?

 

No. My current conversions are Nikon (6), Sony (1), Pentax (1) and Panasonic (2). However, of those conversions 4 are "retired", 1 seems to be broken (electrically) and 1 is in process of being sold. That leaves me with 4 active conversions -- which is probably 3 too many. :D But I've always thought it really important to have experience with multiple brands/models so that I can be at least partly conversant with what other members are using and experiencing. I've enjoyed all my conversions. They each have their pluses and minuses.

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Very useful information, and lots to think about. Thanks for the savazzi link, Andrea!
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Here is a link to a thread with some more information about clones (Kuri). :)

http://www.ultraviol...__fromsearch__1

I also have some made by Soligor with the same good transmission as in the top images in my post #5 in that thread.

When buying I was inspired by the information by Enrico Savazzi.

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Andrea B.

Yes, Enrico's website rocks! And we have stored some other good UV links in the Sticky, including some other members' and friend's interesting websites. Sticky :: UV Photography: Cams, Mods, Lights, Links

 

Anytime anyone finds a good link, let me know and I'll add it.

 

I did write both Bjørn and Enrico to ask them the question about stop differences between converted & unconverted cameras. We are a sloooow little website :D , but eventually we will hear from them.

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dabateman

Thank you for all the wonderful replies.

Sorry I was not clear, next time I will pose the question first rather than explain why I am asking it. Andrea has it exactly, I am asking if any user here compared before and after full spectrum conversion with an Olympus camera to determine how much improvement was gained when using a reputable conversion service.

I lurked on this website for the last year after I discovered it, reading all the posts and this has not been mentioned.

Very interesting to learn that Spensor may be using plastic. That may not be bad if PMMA (plexiglass) as it transmits 300nm to 900nm, but maybe not as good for photography as its not optically intended.

Also to clarify for the Olympus/Panasonic test I used a Grow light (long fluorescent bulb) and a 23W single coil compact fluorescent bulb, which I know contains mercury to give lower wavelengths. Later and the next day testing the SD14 I used the 75W halogen. Yes it gets hot.

 

@Andy, thank you for the IR curves. That explains some of the results I got with the SD14 in testing a lens. I was using the Halogen light with the SD14 comparing my M42 Steinheil Munchen EDIXA 50mm F2.8 (which is good at transmitting UV) to a Sigma EX 50mm f2.8 Macro lens. I don't know the exact model of the Sigma (there are many), I got it for $50 as the AF motor is dead and can be used for MF only. But it transmits the same amount of UV as he Munchen. I will create a sperate post with images soon. I did see a good uv pattern with Baader venus 2 filter. What I was surprised by was when I added the ZWB1 2mm with BG39 2.2 mm I got from Igoriginals, I lost the UV pattern. Outside I don't have this issues but your IR curves explain the problem. The Sigma is an IR camera. I don't remember the exposure setting off hand but its at least one stop better with a 720nm filter on then with the B&W 486 filter. Full spectrum is fun with this camera. So the small IR leak that this stack has, will blow out the UV with the Halogen. I will post the comparison soon with the compact fluorescent.

 

The Munchen I learned about from hear and was lucky to get one for $50 used off ebay. The Sigma has the advantage for shorter minimum focus distance, but UV focus point is closer than normal vision so needs unknown correction. The Munchen is the same focus point in UV an visible, so no correction is needed.

https://kolarivision.com/uv-photography-lens-compatibility/

 

@Cadminum the 46mm to 52mm step up ring seems to be almost glued to the lens. I can not remove it. It is also blocking all possible lens id. All I know is its a T mount made in Japan, has feet markings in orange, meter markings in white and infinity is marked in green "INF". That to me implies a Soligor as I think that is how they are marked. IGoriginals is a member here, so he may chime in if he sees this. His marking indicates 35 mm f3.5 Kyoei Kuribayashi (Clone) no. T17006. I think he has a whole bunch of clones that he cleaned, added the step up ring and is selling. His ZWBI filter is also quite good, without chips, bubbles, distortion and seems to be made of glass. Some straight from China ZWB filters I have seen are made of PMMA with coating.

 

@Andrea "There is nothing at all beneficial to UV photography performed while shooting through an internal filter which blocks UV light. That's like trying to run the Boston Marathon in your LL Bean hiking boots. Extraordinarily painful and tedious with last-place results."

I may actually disagree with you here. It depends on the intent. I learned that the Kodak SLR/n has a S8612 filter cemented on the sensor. The thickness ranges from 0.7 to 1mm. This was confirmed on the Kodak forum by people whom have taken the camera apart and people whom used to work for Kodak. The old Kodak division was excellent and released, unreleased specs and firmware to the die hard Kodak users. So I would not UV convert a Kodak as it has a great filter added for UV work. It just is very hard to use camera and the sensor will fall out one day as it just held in place with epoxy. But my point is if I could get in contact with Olympus, It would be interesting to know what filter is used. After my tests it might be a S8612 or BG39 or BG40. What we do know is that it is very thick, about 4mm :

 

https://petapixel.com/2014/07/08/sensor-stack-thickness-part-iii-summary/

 

So why I may disagree is the intent. Currently I don't own and can not afford a quartz lens. The Kuri clone is my best, which is one stop better than my 50 mm Munchen. So I will not see below 350nm anyway. If I will not get more than 2 stops advantage removing the inplace block filter, then the IR penalty for removing the filter becomes real. Thus it may actually be better to keep an on sensor filter for UV work. This is only because the Olympus cameras seem to allow UV, where as Panasonic clearly blocks UV. I have not figured out how to use the Scott Excel sheet, but when I do it may be interesting to calculate the curves for 4mm thick BG40, BG39 and S8612, to guesstimate the increase in UV by removing this. It might not be 2 EV.

 

Olympus have better UV transmission as reported by people need to add a 2A or even 2E filter with the Panasonic 7-14mm to stop the dreaded Purple blob problem. I now have to test my Panasonic lenses, as since Panasonic knows the camera blocks UV, they may not coat them to block uv. Although I did read on here that the Panasonic 14mm f2.5 lens was very bad for UV work. So this hypothesis may be wrong.

 

Thank you again for all the responses. I hope someone has tested before and after as I would like to know. After I run some calculations and save up some money I may still go for the conversion. I was leaning towards Kolar vision as they are cheaper and I think they use Spectrasil. But I will have to call to find out. If I do go for full spectrum conversion I would like the most trans-missive filter possible.

 

Thank you,

David

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Andrea B.

Very interesting to learn that Spensor may be using plastic.

 

Everyone please remember that my plastic filter experience with the D300 was several years ago in 2009/10. I do not know what Spencer's currently uses in its conversions.

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dabateman
Thank you for dating your experience with Spensor. I actually bought the Used E510 from Spensor in July 2009. So now I am thinking it may be similar.
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