mike_j
nobbut a beginner
Reged: 23/08/2005
Posts: 1298
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I had a look at a secondhand 500mm M42 lens in the photo shop today. I has a M42 adaptor on my Olympus at the time so we tried it and the result seemed quite good (1000mm equivalent FL but usable, especially with live view to help focussing)
It was an old fashioned three element lens about 600mm long in total but very light. I didn't recognise the make but quite a lot of manufacturers produced such items.
Anyone any experience of these lenses - worth buying perhaps? They seem very cheap and I have no problems with manual focus aperture setting.
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Tacitus
History
Reged: 17/01/2006
Posts: 871
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My experience of such lenses is that with care they can give pretty good images used with a digital camera. Centre sharpness can be pretty good to excellent, and the soft corners seen on film cameras are usually no longer a significant problem. Purple fringing isn't often a problem with the telephotos (compared to wideangles) either. Any deficiencies in contrast are easily remedied in post processing.
The down-side is that focussing may be less accurate without a film camera type of split-image screen, although with AF assisted 'rangefinder' focussing good sharpness may be achieved if the scene's contrast is good enough. With the effective/apparent increase in focal length on digital cameras the use of a very solid tripod becomes essential, but the ability to vary the ISO on such cameras can help to some extent. Initially metering can seem imponderable, but is rarely a real issue after a few trial and error tests are completed.
Overall, such lenses can be quite effective, but there may be hidden snags that can't always be anticipated (such as flare). I use several old manual focus (incl. pre-set apertures) mid-range and telephoto Tamron, Tokina and pre-AI Nikkor lenses - it's only the wideangles that tend to be really unsatisfactory.
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hhmr
Reged: 21/04/2005
Posts: 296
Loc: London
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Mike,
I've got a cheap and cheerful 500mm mirror Centon lens in a T-mount which I used to use sometimes with my Minolta gear where it seemed to fall between too stools, not really long enough or inconveniently long apart from the less than marvellous colour rendition. See my note in the SPI fora, I've just been trying it with my Pentax K10D for some rowing event pictures (see my site, 2007 Pairs Head of the River). It seems a whole lot more useful as a "750mm equivalent" and the camera seems to eliminate some of the things I didn't much care for when using it with film. Mind you rowing events vary a great deal. You can sometimes get close enough to fill the frame with an VIII using a 21mm lens (see my Diploma galleries for an example).
Henry
http://www.pbase.com/hhmrogers/2007_pairs_head_of_the_river
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36824
Loc: Everywhere and nowhere, baby
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The old 500s were generally quite reasonable - worth a try.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4406
Loc: Really Here In Name Only
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Quote:
500mm mirror Centon lens in a T-mount ... the less than marvellous colour rendition.
Surprises me, there are less opportunities for a mirror lens to foul up the colour. Sometimes with these there is a small screw-in filter (30.5mm is common) accessible from the lens mount end - are you sure there isn't anything nasty in there? Might be worth trying removing it anyway, a flat surface reflecting directly back at the sensor doesn't sound like a good idea.
However the worst feature of mirror lenses is surely the doughnut-shaped off-focus highlights. Not nice bokeh at all.
The nice thing about them, compared with the usual "long toms", is that they're relatively easy to hand-hold - though bright light and/or a fast film (or high ISO setting) is required to get a shutter speed of 1/500 sec or faster.
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hhmr
Reged: 21/04/2005
Posts: 296
Loc: London
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Quote:
......Surprises me, there are less opportunities for a mirror lens to foul up the colour. Sometimes with these there is a small screw-in filter (30.5mm is common) accessible from the lens mount end - are you sure there isn't anything nasty in there? Might be worth trying removing it anyway, a flat surface reflecting directly back at the sensor doesn't sound like a good idea.
However the worst feature of mirror lenses is surely the doughnut-shaped off-focus highlights. Not nice bokeh at all........
Because these lenses have a fixed apperture they often come with a UV and 3 neutral density filters to extend the range of possible exposures. I tend to use the UV filter, just to keep muck out of the works, and there's nothing wrong with it. I've found no evidence that it creates flare with a digital sensor, btw. But, after all, a mirror 'lens' can only be as good as the mirrors and the coatings used. This particular lens is, as I said cheap and cheerful. The colours it produces look 'cheap', compared with better quality optics, but they are easy enough to tidy up in the editing software. I tended not to use it much with film, but I find it quite handy with digital because of the narrower angle of view.
Doughnut shaped bokeh certainly is one of the traditional objections but I've not yet found it a nuiscance in practice.
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36824
Loc: Everywhere and nowhere, baby
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Biggest problem I find is the feeble contrast.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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hhmr
Reged: 21/04/2005
Posts: 296
Loc: London
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Quote:
Biggest problem I find is the feeble contrast.
Quite agree. Subjects in flat lighting need the contrast turned up quite a lot. But subjects in bright sun with a big contrast range already don't seem to suffer too much.
My conclusion is that the lens I bought wasn't really very useful before I bought a DSLR but is now that I have done so. A 750mm equivalent focal length lens for around £100 makes the effort of tidying up the images well worth while if the subject matter benefits from a long lens. Probably isn't a good way for 'fine art' type subjects, though I'm thinking of trying some London architecture and converting to B&W.
On a slightly different tack I'm still enjoying playing with a Lensbaby I bought last winter. There is a place for 'strange' images, though I wouldn't want to do that all the time.
Henry
www.pbase.com/hhmrogers/lensbaby_jungle
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4406
Loc: Really Here In Name Only
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Quote:
Because these lenses have a fixed apperture they often come with a UV and 3 neutral density filters to extend the range of possible exposures.
I bought my Tamron SP 500mm f/8 mirror lens second hand, it only had the UV filter. Which was apparently only single coated and was quite dirty - but it cleaned up nicely. Haven't found not having the ND filters a problem as I very rarely use film faster than 200 ASA and lighting which demands shorter exposures than 1/2000 sec at f/8 are "somewhat unusual".
I haven't use it with a DSLR yet, but I've shot a fair number of images with it on film.
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I've found no evidence that it creates flare with a digital sensor, btw.
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Biggest problem I find is the feeble contrast.
The feeble contrast might well be a symptom of reflection from the back of the filter.... I've found my Tamron, when used with a film camera, to be perfectly acceptable in terms of colour rendition, and to have plenty of contrast, in fact rather more than I've come to expect from conventional prime focus lenses of 300mm+ focal length.
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Doughnut shaped bokeh certainly is one of the traditional objections but I've not yet found it a nuiscance in practice.
Does depend on the subject. For landscapes where everything is at "infinity", or at least within the depth of field, there is no problem. If you sometimes use the lens as I do, for taking photos of wild flowers when it is going to be impossible to get close enough to use my usual 90mm macro lens, the bokeh certainly is a major disadvantage.
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hhmr
Reged: 21/04/2005
Posts: 296
Loc: London
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Quote:
........The feeble contrast might well be a symptom of reflection from the back of the filter.... I've found my Tamron, when used with a film camera, to be perfectly acceptable in terms of colour rendition, and to have plenty of contrast, in fact rather more than I've come to expect from conventional prime focus lenses of 300mm+ focal length........
The reason why my own experience so far suggests that's a minor issue is that I have had better results with digital than with film. There may well be some in camera compensation going on of course. When I know my digital SLR better I'll probably have more insight into this.
Meanwhile the lens will get more outings than it's had in the past because it's now more useful. And of course in-camera 'anti-shake' is a bonus with any simple longish lens.
But I wouldn't think my 'cheapo' Centon is going to match your Tamron for image quality.
Henry
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