How important is the tube lens for image quality?

[nielsgeode]

Currently I use a Canon 200mm f/2.8L II for my Mitu's. However, I hear a lot of positive things about the Raynox tube lenses. Stephan Wolfsried, who is a passionate mineral collector and photographer writes in one of his articles:

"October 2014 I tried Raynox macro lenses as tube lens and had good results with both, the DCR-150 and the DCR-250.
In combination with an adjustable aperture the results are really convincing. Stacking is easier and not so time consuming in postprocessing. The total length of the setup is significant shorter than with the Nikkor 180 and 200 mm manual focus lenses as tube lenses. The resolution ist higher than with any setup I ever used before. With the Mitutoyo M Plan 20x NA 0,42 I achieve 1100 LP/mm with a target of Carl Zeiss. This means a resolution of 0,0009 mm. The used lenses are now Mitutoyo 20x, 20xSL, 10x, 5x (each with a Raynox 250 in reverse Position as tube lens and a aperture between objective and Raynox)"

1) What benefit would you have from the aperture ring in the tube lens?
2) What is your experience with normal Canon lenses vs. the Raynox tube lenses in terms of image quality?
3) the numbers 150 and 250 suggest that these are the focal lenghts. Am I correct? If so, wouldn't you expect to see 7,5 and 12,5x magnification with the Mitu10?

[Ichthyophthirius]

3) the numbers 150 and 250 suggest that these are the focal lenghts. Am I correct? If so, wouldn't you expect to see 7,5 and 12,5x magnification with the Mitu10?

Confusingly, nominally they are

DCR-150: 208 mm (+4.8 dpt)
DCR-250: 125 mm (+8 dpt)
http://extreme-macro.co.uk/raynox-adapter-techniques/

Regards, Ichty

[mawyatt]

1) I believe this helps with contrast when used between the objective and tube lens.

2) I used a Nikon 70-200 F2.8 as a "tube" lens on FX body, then tried the Raynox 150 reversed with the Mitutoyo 5,10 and 20X. I had better results with the Raynox. Eventually I went with cheap 52mm dia. screw type extensions from eBay, I was seeing a little vignetting on the FX (D800) body with the 43mm extensions.

3) Answered by Itchy above.

Best,

Mike

[nielsgeode]

1) I believe this helps with contrast when used between the objective and tube lens.

2) I used a Nikon 70-200 F2.8 as a "tube" lens on FX body, then tried the Raynox 150 reversed with the Mitutoyo 5,10 and 20X. I had better results with the Raynox. Eventually I went with cheap 52mm dia. screw type extensions from eBay, I was seeing a little vignetting on the FX (D800) body with the 43mm extensions.

3) Answered by Itchy above.

Best,

Mike

Maybe a dumb question, but how to you attach the Raynox lens to an EF-mount? Can you directly attach it or do you need a certain flang distance (and bellows or extension tubes)?
My current Canon 200 f/2.8 features a ring collar which can be used to rotate the lens in the desired position. How would this be possible with the Raynox?

How much differenc ein image quality between your Nikon 70-200 and the Raynox 250 with the Mitu 20 did you see?

[mawyatt]

Enough to make the relatively incremental small ($100) investment worthwhile IMO. If you are using Mitutoyo objectives, then you've made the $ decision to get the more expensive objectives, so why not use a better tube lens setup?

Rik and others have posted many times here, and the image quality of the Raynox 150 & 250 used as a tube lens is as good if not better than the dedicated tubes lenses from Nikon, Edmund Scientific and Mitutoyo.

Attaching the Raynox is just a matter of getting the right adapters. For the Nikon body you need the F mount adapter, or BR2A reversed lenses adapter which I use, then 52mm screw extensions 28mm in length (5), 49mm to 52mm to reversed Raynox, 52mm to 43mm from reversed Raynox, 55mm to 52mm (used was a 52mm through), 14mm length 52mm screw extension, 52mm to 26mm (0.7) Mitutoyo lens adapter. This places the reversed Raynox 150 at the proper distance from the Nikon camera sensor to focus at infinity. Be sure to flock the inside of the extensions.

Search on this site for the details on lens construction.

Best,

Mike

[ChrisR]

1) What benefit would you have from the aperture ring in the tube lens?

The only point of this afaik, when it's right next to the objective, is to reduce the aperture of the objective, rather than the tube lens.
Where the tube lens is a camera lens, closing its aperture a little can stop minor internal reflections. It has a tiny effect on the 200mm f/4 lens I use.

Otherwise isn't useful, as it soon causes vignetting.

David - if you haven't seen Mike's methods... http://www.photomacrography.net/forum/v ... 480#175480

[JH]

Hi
If your lens outresolves your sensor at 200mm and/or if you use a camera with a 24x36 mm sensor and corner quality is important you might want a longer tube lens than 200mm.

Regards Jörgen