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Univer
Joined: 30 Jun 2009 Posts: 282
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Posted: Fri Apr 09, 2010 1:42 pm Post subject: Peleng 17 2.8: Infinity Focus Problem |
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Univer wrote:
Hello All,
I would be very grateful to have the benefit of your thoughts on a lens issue.
Not long ago, on a whim, I bought a used 17/2.8 Peleng fisheye. It doesn't seem to be a terribly common lens, and opinion - what there is of it - seems to be divided on the question whether it's better or worse than its 16/2.8 Zenitar cousin in terms of IQ. But it wasn't too expensive, so I thought I'd take a chance on it.
This is an "A" lens, with the screw-on adapter for M42 and Nikon (and maybe others as well). Mine arrived with the Nikon adapter in place, but I knew where I could get a spare Russian M42 adapter, so that wasn't an issue. I bought the new adapter and installed it - no problem there.
I took the lens out for the first time yesterday evening, on my K20D, and I had awful difficulties focusing it. Not the usual difficulties inherent in using an ultrawide - this was different. It took me a few minutes, and a few shots, to realize that the lens wasn't focusing to infinity, or anywhere near it; at the infinity setting, objects about two feet away (maybe even less) were in focus. On the other side of the scale, the lens does seem to be focusing a bit closer than the focus ring would indicate.
My first thought was that the new M42 adapter was too thick, and was acting as an extension tube. But it fits perfectly, and, compared with the Nikon adapter that originally came with the lens, it seems to have the same thickness. Besides, my understanding is that a Russian "A" adapter is a Russian "A" adapter: that they don't come in varying flavors.
I did examine the rear element, and the tube that holds it is threaded for a screw-over filter (in principle, it's just like the rear element of the Peleng 8/3.5 - although the filters from the 8mm don't fit). But there's no filter in place.
Now, I've read, on several occasions, that the clear filter at the rear of lenses like this one is an essential part of the optical arrangement, and that these lenses should not be used without that filter installed. And I've also encountered the opposite view: that the absence of the clear filter makes no difference whatsoever. But my assumption has always been that the difference - if there is one - would be one of IQ, not one of throwing off infinity focus. I will say this: allowing for the focusing problem, I see nothing wrong, so far, with the IQ of this lens.
Hence my question: do you suppose the absence of a rear filter could account for the lack of infinity focus? Or do you think it's more likely that the lens is simply out of adjustment?
(As a final note, I'll point out that the lens shows no signs of ever having been opened, and that the previous owner claimed that she used the lens with great success for several years.)
Thanks for your help!
Cheers,
Jon |
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DSG
Joined: 04 Mar 2007 Posts: 544 Location: London, UK.
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Posted: Fri Apr 09, 2010 5:28 pm Post subject: Re: Peleng 17 2.8: Infinity Focus Problem |
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DSG wrote:
Univer wrote: |
Hello All,
I would be very grateful to have the benefit of your thoughts on a lens issue.
I did examine the rear element, and the tube that holds it is threaded for a screw-over filter (in principle, it's just like the rear element of the Peleng 8/3.5 - although the filters from the 8mm don't fit). But there's no filter in place.
Now, I've read, on several occasions, that the clear filter at the rear of lenses like this one is an essential part of the optical arrangement, and that these lenses should not be used without that filter installed.
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I have Tamron SP 300mm f2.8 LD IF which came with a 43mm clear filter installed in its drop in filter holder. I too heard the story that it was supposed to installed at all times when not using any other filter but that proved to be nonsence as it actually works better without it.
Not sure about your lens but perhaps the same is true? |
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Univer
Joined: 30 Jun 2009 Posts: 282
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Posted: Fri Apr 09, 2010 6:15 pm Post subject: |
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Univer wrote:
Hi,
My experience is like yours; the images from this lens (the few that were in focus) seem very crisp, so I have trouble believing that the missing clear filter significantly degrades IQ. I probably wouldn't even have thought about its absence if not for the focus problem. (And I'm not sure I understand how the missing filter could create that issue either.)
If I were a betting man, I'd be wagering that the lens needs an infinity-focus adjustment.
Cheers,
Jon |
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aoleg
Joined: 22 Feb 2008 Posts: 1387 Location: Berlin, DE
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Posted: Fri Apr 09, 2010 8:32 pm Post subject: |
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aoleg wrote:
Univer wrote: |
Hi,
My experience is like yours; the images from this lens (the few that were in focus) seem very crisp, so I have trouble believing that the missing clear filter significantly degrades IQ. I probably wouldn't even have thought about its absence if not for the focus problem. (And I'm not sure I understand how the missing filter could create that issue either.)
If I were a betting man, I'd be wagering that the lens needs an infinity-focus adjustment.
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Jon, you would lose your bet. I have the Peleng-17, and it came with the filter in place. If removed, the lens stops focusing anywhere close to infinity. Put the filter back, and it's all fine. You need the filter. Unfortunately, it's not of a standard size, so I don't know where to get one.
The physics behind using this piece of glass to obtain infinity focusing is easy: each piece of glass, whether placed in front or in the back of the lens, alters its optical properties slightly. With telephoto lenses this does not matter because they have a huge travel to focus all the way from close-focus to infinity; however, in wide-angles, the travel is short, and a filter changes that... _________________ List of lenses |
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fatdeeman
Joined: 13 Jun 2009 Posts: 780 Location: UK
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Posted: Sat Apr 10, 2010 1:37 am Post subject: |
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fatdeeman wrote:
Click here to see on Ebay
Maybe that will help? _________________ - Dave
www.lensporn.net
www.flickr.com/photos/fatdeeman/
DSLR: Canon EOS 60D, Samsung GX-1S (Pentax *ist DS2)
Mirrorless: Panasonic DMC-G1, Sony NEX-5N
Compact: Canon PowerShot G3
Lenses:
Wide: Tokina RMC 28mm F/2.8, Tamron Adaptall 2 28mm F/2.5, Sun Optical 28mm F/2.5, Super paragon 28mm F/2.8, Sigma filtermatic 24mm F/2.8, Fujinon 35mm F/2.8, Sun Optical 35mm F/2.8
Standard: Industar 50-2, Helios 44-2, Helios 44M, Helios 44M-3, Pentax-M 50mm F/1.4, Pentax-M 50mm F/1.7, Pentax-M 50mm F/2, Ricoh 50mm F/1.7, Chinon 50mm F/1.7
Tele: Pentacon 135mm F/2.8, Pentacon 200mm F/3.5, Optomax 200mm f/3.5, Sun Optical 135mm F/3.5, Soligor 350mm F/5.6
Zoom: Tokina 28-70mm f/3.5-4.5 SZ-X270 SD, Sigma Zoom Pi 35-200mm F4-5.6, Sun Optical 28-80mm F/3.5-4.5, Sunagor 80-205mm F/3.8, Tokina RMC 80-200mm F/4, Vivitar 70-150mm F/3.8, Tamron 95-205mm F/6.3, Tamron Adaptall 28-200mm F/3.8-5.6 LD Aspherical, Tokina RMC 70-210mm F/3.5
Mirror: Falcon (Samyang) 800mm F/8, MTO-11CA 1000mm F/10, Tamron Adaptall 2 500mm F/8
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visualopsins
Joined: 05 Mar 2009 Posts: 10960 Location: California
Expire: 2025-04-11
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Posted: Sat Apr 10, 2010 2:28 am Post subject: |
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visualopsins wrote:
Those are different size, for Peleng 8mm. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony ILCE-7RM2, Spotmatics II, F, and ESII, Nikon P4
Lenses:
M42 Asahi Optical Co., Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200, Tele-Takumar 1:5.6/200, 1:6.3/300, Macro-Takumar 1:4/50, Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm, Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element), Super-Multi-Coated Fisheye-TAKUMAR 1:4/17, Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500, Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100, Super-Multi-Coated Bellows-TAKUMAR 1:4/100, SMC TAKUMAR 1:1.4/50, 1:1.8/55
M42 Carl Zeiss Jena Flektogon 2.4/35
Contax Carl Zeiss Vario-Sonnar T* 28-70mm F3.5-4.5
Pentax K-mount SMC PENTAX-A ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (151B), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto (Kiron)
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aoleg
Joined: 22 Feb 2008 Posts: 1387 Location: Berlin, DE
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Posted: Sat Apr 10, 2010 2:42 am Post subject: |
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aoleg wrote:
Different size. Unfortunately, there are no marking on my filter, only the "H-1" designation, which means "neutral, 1:1 light transmission". It's different of filters used in Zenitar-16 and Mir-20M (interestingly, rear filters for Mir20M aren't flat - but Mir-20 can be used with or without them). _________________ List of lenses |
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unclemack
Joined: 21 Jun 2009 Posts: 51 Location: UK frozen north
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Posted: Sat Apr 10, 2010 11:46 am Post subject: |
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unclemack wrote:
First I would ask the seller to check the bottom of her camera bags for the filter. I've been lucky nearly as many times as I've been unlucky.
If Aoleg would be prepared to measure the thickness of the glass of his filter you should be able to find something which will at least do the job until you can find the correct filters, even if you have to attach it with Blu-tak.
If the infinity adjustment is easily accessible (no idea - I've never even heard of your lens - sorry!) then adjustment should give satisfactory results but of course then you'll find a set of filters the next day!
Not sure anyone actually NEEDS his own weight in lenses anyway... |
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Univer
Joined: 30 Jun 2009 Posts: 282
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Posted: Sat Apr 10, 2010 3:15 pm Post subject: |
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Univer wrote:
Hi,
Thanks, everyone, for the replies. I'm actually glad to know that the missing filter is in fact the culprit - although I don't know how realistic it is to think I'll be able to find a replacement. (I will definitely contact the seller, however.)
Blue-tac occurred to me as well; at a minimum, I could temporarily secure the clear Peleng 8mm filter, just to see if there's any improvement.
I also thought I might contact some of the "usual suspects" who deal in Russian lenses, just to see whether someone might be able to locate a spare filter. The fact that the lens seems to be rather uncommon makes me less than optimistic about this option, but I reckon it's worth a try. Would anyone happen to have a specific suggestion for a dealer who might be a likely candidate? (Please feel free to PM if you prefer.)
Thanks again!
Cheers,
Jon |
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lahnet
Joined: 10 Apr 2007 Posts: 1164 Location: Denmark
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Posted: Sat Apr 10, 2010 3:50 pm Post subject: |
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lahnet wrote:
I have the lens, and can confirm that it is impossible to use without the rear filter.
I been thinking about selling mine, can I ask how much you payed? _________________ Henrik
Lahnet-Foto
My FLICKR
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aoleg
Joined: 22 Feb 2008 Posts: 1387 Location: Berlin, DE
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Posted: Sat Apr 10, 2010 7:58 pm Post subject: |
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aoleg wrote:
lahnet wrote: |
I have the lens, and can confirm that it is impossible to use without the rear filter.
I been thinking about selling mine, can I ask how much you payed? |
These lenses are rare birds, so there's no 'set' price for them. I paid, if I recall correctly, 49 GPB for mine, delivered from Malta. However, I was one of very few bidders who were even interested in this lens. So it really depends if the lens gets noticed and recognized by the buyers - or not.
I would say, it's optically about on par with the Zenitar. It's much bigger and heavier though. My copy exhibits black corners (so it covers maybe 98% of the full 35mm frame), and its images has to be cropped one way or another. So I guess its 'user' value would be a bit less than the Zenitar, but its 'collector' value can be much higher (or lower) due to its rarity.
_________________ List of lenses |
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