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UltravioletPhotography

New-to-me lens: Meyer-Optik Görlitz Telemegor 180mm/5.5


Andy Perrin

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I got a Meyer-Optik Görlitz Telemegor 180mm/5.5 today. I am trying to get lenses in a nice range of focal lengths. Starting to get tired of shooting 35mm or 50mm for everything.

 

Test shot using 2.5mm BG-39 and 2mm UG-11 in sunshine, WB off the pavement, with the NEX-7. Post processing was exposure adjustments, saturation, denoising and sharpening.

 

F/11 2" ISO100

post-94-0-78259900-1484160794.jpg

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The spatial resolution seems quite good. It is harder to judge other things such as bandpass or focus shift from this photo alone. How close to infinity can you get wide-open? Certainly, there are relatively few long optics capable of quality UV imaging.
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Woo! A 180. You've got some reach.

 

Looking forward to seeing more tests with this one.

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Bill De Jager
I look forward to more shots to see what this lens can do. I recently tried to get one on Ebay, fumbled my attempt at sniping, and lost the lens even though I would have had the high bid. Oh well... I have other lenses that need to get some time in the field.
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Nice shots Andy.

You could reduce your exposure time by switching to S8612 1.5mm. It would also increase the depth of your UV bandwidth (depending on the UV transmission depth of your lens).

This assumes your UG11 2mm is in fact UG11 glass for sure (this graph is based on Schott glass data).

post-87-0-68371800-1484204317.jpg

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Steve, believe it or not, I tried 1.5mm S8612 and 2mm UG11 FIRST! It had a major IR leak. Barely looked like a UV photo. I also computed those same curves just now trying to figure out what was going wrong! (My curves include the partial reflections, so may differ slightly from yours.)

post-94-0-17174200-1484207632.jpg

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1E-04 is not an IR leak.

I suggest that one or the other of your UG11 2mm or S8612 1.5mm was not what it was suppose to be, because you would not have an IR leak with such a stack.

 

If you used S8612 2mm it would be below 1E-05.

 

There is never any reason to use BG39 instead of S8612, they have the same suppression per thickness, but BG39 cuts off more UV.

post-87-0-95452600-1484213252.jpg

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Well, the UG11 was the same as the one in the BG39 stack, and it worked fine there. So if there is a problem it is with the S8612. I mounted that myself so perhaps I have a light leak.
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Would make for a good test in a separate thread......

 

I'm loving this IR photo of the moon! I gotta try that.

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Mystery solved. I had a look at the original listing and it is QB21, which I assume must not have an identical spectrum to the S8612 despite the seller listing it as an S8612 alternative. The current relisting has a note on it that reads:

I made a mistake when ordering and ordered 1.5mm instead of 2.0mm. This means that a single filter is useless for blocking all IR light when engaged in UV-photography.[/size]

My test photos were accomplished using 1, then 2 of these filter stacked, in conjunction with a ZWB1/UG11 equivalent 1.5mm filter. What I have found is that in 1.5mm thickness, it allows a very balanced mix of ultraviolet and infrared light expressed in the final image. Please note that this isn't entirely advisable for UV-only photography, but it clearly produces functional results.

I dispute the "functional results" part of it!

 

I bought it last April, and up till now I have been using it to take visible light photos, as an IR-blocker. It was okay/so-so for that. This was the first time I had tried it for UV photography.

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Late to the party ...

 

I have this 180/5.5 lens and just moved it out of its focusing barrel and onto a small Novoflex bellows I had floating around. The lens will happily focus to infinity also on my Nikons and the UV response although not spectacular, isn't bad either. One can do UV landscapes with it for sure. Or the traditional UV flowers for that matter. The working distance will of course be much longer than with the usual 35 or 50 mm optics.

 

This is the ubiquitous Colt's Foot Tussilago farfara, captured with the Tele-Megor on a Nikon D3200 (internal Baader U filter). The rendered image is almost indistinguishable from that delivered by the UV-Nikkor 105/4.5 in terms of UV floral signature, but the sharpness is not unexpectedly a bit less.

 

I1304210250.jpg

 

(the blur within the disc flowers of the upper composite head is an impatient bumblebee)

 

There is significant focus shift in UV, though, so a Live View approach is strongly recommended.

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Would make for a good test in a separate thread......

 

I'm loving this IR photo of the moon! I gotta try that.

 

I think it is good to keep it here in this thread.

I won't go on and on about it, but it is important when talking about formulas to know and say exactly what is being used.

However, it is hard to 'know' what is being used sometimes, because there is a lot of glass being sold that may not be what it is 'branded' as being,

and there are a lot of so called 'equivalents' that are not equivalent.

Andy has further defined the glass, thanks Andy.

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