Mirror lens or regular lens

Discussion in '35mm Cameras and Accessories' started by Jeff Kubach, Aug 23, 2008.

  1. Jeff Kubach

    Jeff Kubach Member

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    How does a 500mm mirror lens compare to a regular 500mm lens?

    Jeff
     
  2. ehparis

    ehparis Member

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    The mirror lens creates little donuts for the unfocused background.
     
  3. Pinholemaster

    Pinholemaster Member

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    And the donuts tasted yummy.

    A telephoto 500 mm has an variable aperture, while the 500 mm reflex lens has a fixed aperture.

    The reflex lens is usually lighter in weight, and shorter in length.

    Optically you should test, but I've experienced more sharpness with a telephoto style 500 then a reflex design.
     
  4. Fred Aspen

    Fred Aspen Member

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    Mirrors are typically much less expensive than their bigger aperture brothers in the same focal length and, after having both, the traditional lens beats the mirror hands down. Images made with mirrors are softer, have OOF donuts and contrast is noticeably less than a traditional lens.

    I doubt you will ever see a pro wildlife or sports photographer with a mirror.

    Mirrors are initially fun to play with but I tired of it quickly and it went to live elsewhere.

    -Fred
     
  5. cowanw

    cowanw Member

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    Doughnuts are more of a specular highlight issue. But out of focus lines will look doubled and this is often described as bad bokeh. Although in grass and foliage I find it in character. they are F8 usually so you change the shutter speed or use filters or different iso film. The mirror lens is Much lighter. the mirror lens is less contrasty But jumps into focus. The inside element is a replaceable glass and comes clear, yellow, orange, red and polaroid. I rather like my Sigma 600mm in Contax mount on safari as the decreased contrast softens the harsh shadows of the African sun.
    But I am an amateur.
    it cost 90 dollars and I like it better than my fixed zeiss lens
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Here's what the double line bokeh and donut shaped highlights look like from a Soligor compact 500mm/8.0 macro mirror lens (pay attention to the background)--

    [​IMG]

    Too bad, because this was such a compact little lens to carry around, and the close focus ability was a plus. Contrast was also lower than a refractive lens, but in this image of a great egret in full sun, I could have used even less contrast.

    Here's the smooth bokeh of a Canon FD 600/4.5 refractive lens--

    [​IMG]
     
  7. WRSchmalfuss

    WRSchmalfuss Member

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    Don't waste any money on cheap mirror lenses! They are optical not very good. A used rare (former East German) Carl Zeiss Jena 5,6/1000mm mirror lens in good condition is costing today approx. 3000 Euro's, without camera adapter. Advantage of this lens is, it works fine also on medium format cameras.

    Cheers
     
  8. Jeff Kubach

    Jeff Kubach Member

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    Thanks David, Yes the mirror lens is compact, but looks like the refractive lens takes better images. Thanks everyone for the comments.

    Jeff
     
  9. AgX

    AgX Member

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    I was puzzled by that but I assume you refer to an inserted filter and in the latter to a polarizing filter.


    Concerning Bokeh.
    At times the manufacturers marketed those lenses because of those rings. I personnally got my problems sometimes with those doubled lines.
    Anyway, this is a matter of taste and subject. By using a simple mask cut in shape as you like as additional aperture in front of the lens you can change the of out-of-focus image.
     
  10. cowanw

    cowanw Member

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    Yes the filters are inserted at the back but in addition to being filters they are an actual part of the lens' optical system and you must have one of them in.
     
  11. Tom Hoskinson

    Tom Hoskinson Member

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    No Powdered Sugar on My Doughnuts

    Nice bokeh donuts with my 500mm mirror lens, But no powdered sugar.
     
  12. thuggins

    thuggins Member

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    A reflex lens is MUCH smaller and lighter that a refractive lens of the same length. My Tamron 500mm reflex is not much bigger than my 35-70mm, f3.6 Zuiko and about the same weight. It can be hand held with 400ASA film. This makes it a very practical user lens, and the ultimate value of a lens is whether you have it with you when you need it. The Tamron also focuses to less than 6ft, a remarkable close focus for a lens this long. A reflex lens is much cheaper than the equivalent length refractive. As for image quality, the Tamron 500mm is very highly regarded and performs well in objective testing.

    I really get a kick out of those people who throw around the word "bokeh" and act as if it something real. They make sweeping claims about one blurry thing being intrinsically better than another blurry thing! Many people prefer the textured "bokeh" produced by a mirror lens.
     
  13. cowanw

    cowanw Member

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    Don't astronomers use mirror lenses with great sharpness.
     
  14. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Mirror lenses, to the extent that they don't use lenses (and in practice they often do use lenses to make them more compact among other things), are inherently apochromatic, so they can be very sharp. Astronomers don't usually have to worry about things in the background, and everything is pretty far away, so I doubt they have to think at all about the out of focus area, because they don't have one.

    If you photograph birds in trees or any kind of wildlife standing in tall grass or reeds, I would say that indeed, double lines make a cluttered background more cluttered, so for such purposes, which are common uses for long lenses, bokeh is a real practical issue.

    There's also the fact that these lenses are usually f:8, while the big telephotos used for wildlife, sports, and such are typically in the f:2.8-5.6 range. A 500mm refractive lens of this type would usually be around f:4, and it would usually be used wide open or close to it, so a lot of the image might be out of focus, and you want that part of the image to look good.

    In some situations, those little donuts look good and can be used creatively, but they don't come up that often, which is why the wildlife shooters spend the money on the big lenses and go to the trouble of schlepping them around.

    Of course before there was any of this, there was this delightful camera--

    http://cgi.ebay.com/RARE-1908-Natur...39:1|66:2|65:13|240:1308&_trksid=p3286.c0.m14
     
  15. Ole

    Ole Moderator Staff Member Moderator

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    As an aside, they may well be f:8, but due to the bit in the middle they are usually t:10 to t:12.
     
  16. AgX

    AgX Member

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    Ole, that `bit in the middle┬┤ is less than half of the front lens area. How could that lead to f 1:12 ?
     
  17. Tom Hoskinson

    Tom Hoskinson Member

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    I have a A Multi-Coated Russian Rubinar 500mm f5.6 Maksutov casegrain mirror lens that I use on my Contax 35mm SLRs.

    I agree with OLE, the Transmission Number (it is not an f number) is pretty large (thus a slow lens). That said, I am pleased with the optical performance of my LZOS Rubinar lens - its resolution and color characteristics are quite good.
     
  18. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I think the transmissive loss with these lenses is also due to the quality of the mirrors used and the optics involved. I used a Nikon 500mm reflex lens once in the early 1980s, and it was very sharp and pretty bright, but it was also physically fairly large for a mirror lens. I wasn't shooting wildlife at the time, but in retrospect, the images I remember from that lens were shots with simple, uncluttered backgrounds. More compact lenses (like the Soligor I owned) in general are optically like shorter lenses with built-in tele-extenders, and those usually add some transmissive loss. I had a 1000mm/11 Meade lens for a while as well. It could get one close to the subject, but it was kind of low contrast.

    Another factor with these lenses is that I think the compact size deludes users into thinking they can use the same small tripod with them that they use with their other lenses. Maybe it's not necessary to have quite as large a tripod as one would want with a long lens that weighs 10 lbs., but the angular rotation caused by camera shake is the same with a mirror lens as it is with the big glass, so a larger tripod and head are still in order.
     
  19. Jim Jones

    Jim Jones Subscriber

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    The image quality of my 500 f/8 Nikkor mirror lens did not compare well with some off-brand 400mm f/5.6 to f/8 lenses. Despite its close focusing and compactness, the advantages of conventional lenses were overwhelming.