Extension tube or close up filter?

Discussion in 'Medium Format' started by mikeivnitsky, Jul 7, 2008.

  1. Hi,All!

    I have the 150/4PS but want smaller focusing distance(tight head shots).

    My options are:
    18mm extension tube for about 110$
    close up filters for about third to half that.

    Buying another lens is not an option.

    What do you say?
     
  2. It depends on the quality of the results you want to achieve. I've personally had better results from using tubes than diopters, but I've never tried the more expensive diopters either... With tubes you lose a stop or more depending on their length (18mm should not be that bad), and with a diopter you don't. With tubes you have no optics between the lens and the recording medium, while you do with a diopter. If you choose the diopter route, pick one that is from a reputable vendor rather than the no-name variety that pollute the market so much these days.

    - Randy
     
  3. Extension rings to retain optimum imaging qualities of any given lens, especially for critical copy work requiring field flatness an best possible qualities out to the edges. For example, the Zeiss S-Planar (Macro Planar) 120 and 135 objectives give their scientific best at f11 at any extension within the recommended range. But at the cost of resolution can work nicely for an intimate portrait at full aperture and a Proxar.

    The Hasselblad Close-up diopter ("filter") is the above mentioned Zeiss Proxar, in three different strengths. But any good quality item will do the trick. Proxars turn up on eBay often enough. Most big photographic suppliers will also have Schneider B+W filters, and will at least be able to order in the right one for you if they don't have it in stock.

    (I don't recall what a 150/4PS is. It helps to mention the camera name to save responders going off on the wrong track.)

    Anyway, hope that helps. Cheers, Kevin.
     
  4. how close would I be able to focus with a 18mm tube and a 150 lens(minimal focus 1.5m)?
     
  5. the camera is a bronica SQAi
     
  6. 150 mm lens, 18 mm tube, lens alone focussing to 1.5 m:<br>1.6 m to 0.96 m focusing distance<br>= 1:8.4 to 1:4 image scale<br>= 48 cm to 24 cm field of view.
     
  7. Do you know the focal length or diopter strength of the closeup filters? Given the diopter strength you can work out the focal length: focal length = 1000 / diopter

    The focal length tells you how far the filter focuses in front of the lens (focused at infinity). Most closeup filters have a focal length around 500mm or less, which will be too close for your purposes. A closeup filter with a diopter less than 1 (focal length more than 1m) may be useable for portraits.

    The 18mm tube will give a useful focus range for close portrait shots as shown by Q.G. de Bakker above and is probably the best option. If you don't need to get so close, a shorter tube would allow you to focus a bit further out but reduce the close focus less, which overall may be more flexible for general shooting.
     
  8. If you don't need to get so close, a shorter tube would allow you to focus a bit further out but reduce the close focus less, which overall may be more flexible for general shooting."

    Generally, yes.
    But as you can see, the range without, and that with this particular tube just overlap. So using a shorter tube does not do much more, except restrict how close you can get. The 18 mm tube seems/appears to be the ideal tube to have with this lens.
     
  9. The 18 mm tube seems/appears to be the ideal tube to have with this lens.
    I agree, with the tube the focus range starts where the lens leaves off, with a bit of overlap for convenience. Overall this option gives the greatest focus range with no gaps.
    However, it's only the best option if most portraits are photographed in the 1.6 - 0.95m range (5 - 3 feet). That is quite a short, limited range and you'd need to swap the tube on and off again when crossing the 1.5/1.6m boundary. A 12mm tube would give a focus range of 2.2m - 1.06m (6 - 3.5 feet) and magnifications from 1:12.5 - 1:4.8, which may be more useful for general portraits.
     
  10. I doubt bronica made a 12mm tube,I am aware of 18 and 36
     
  11. Some information at:
    http://www.buonaluce.com/ClosedFocus.pdf
     
  12. david_henderson

    david_henderson www.photography001.com

    I don't believe Bronica made a shorter tube for the SQ system either. They did make one for the ETRS.
     
  13. Your best bet would be to purchase a 0.5 dioptre close up lens ( I use a Heliopan ) which is what I use on my PS 150mm lens. This will give you a perfect range of focus for portraiture, with no loss of light as is the case with extension tubes.

    The 0.5 dioptre is very weak, and has no easily discernable adverse affect on the optical quality of the prime lens.
     
  14. I have never seen a 0.5 diopter close up lens being sold,can you find a link for me please?
     
  15. Michael, I've done a few searches, but it would appear that 0.5 diopter lenses are no longer available. I've checked both the Heliopan and B+W catalogues, but neither manufacturer has them listed. I purchased mine about ten years ago, and even then it was quite a difficult item to get hold of.

    You could try a 1 diopter lens, but I'm not sure if this wouldn't be a bit too powerful and not allow you the focussing range you need for a portrait. I'll try this combination on my camera when I get home tonight and let you know how I get on.
     
  16. Pentax T226 Size:67mm Diopters:+0.44 2 Element (Achromatic) SMC Close-up Lens
    available at B&H
     
  17. Pentax T226 is only 20-30$ cheaper then the extension tube is it more or less effective?
     
  18. Pentax T226 is only 20-30$ cheaper then the extension tube is it more or less effective?
    The focal length of the T226 is 2260mm, or 2.26m, so if you screw it to the front of your lens, adding the length of the lens etc, the total focus distance with the lens set to "infinity" will be about 2.4m, of 8 feet. If my calculations are correct, the lens will focus to 1m (3 feet) with the filter, giving a magnification of 1:4.8. The filter gets you that little bit closer without being extreme. Given the focus range and magnifications I'd say this is an excellent choice for tight portraits. Pentax "T" filters have two elements so are highly corrected, I'm sure you will get very good results.
     
  19. I ordered the Pentax T226 today.
     

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