72 mm close-up lens for Sigma 28-200?

[dhbebb]

<p>Does anyone have experience of this and in particular know its strength in diopters? I have just bought a 200mm lens for my Kodak Retina Reflex and hope this close-up lens will let me focus closer than the "official" limit of 8 meters. Ideally of course the close-up lens should be 0.125 diopters so that the focusing ranges with/without the close-up lens meet with no gap. All info gratefully received!</p>

[JosvanEekelen]

<p>Diopters are not great for close-up work, forget about the single element ones, have a look for 2-element diopters (Nikon, Canon) instead. Be aware, these come at a cost.</p>

[jim_momary]

<p>Let me take a swing at an answer, but know my knowledge is limited.</p>

<p>BH lists a 72mm Canon 500D (doublet as discussed by Jos). It is +2.0 diopters I believe. What that means is it will cause the lens upon which it is mounted to focus at 0.50 meters (with the lens set to infinity). {1.0 meters ~ +1.0 diopter}</p>

<p>Apparently Canon makes the 250D and 500D still, and in variable sizes such as 52, 58, 72 and 77mm. The 250D is +4.0 diopter.</p>

<p>Nikon made the 3T and 4T in 52mm with +1.5 and +2.9 diopters respectively and the 5T and 6T in 62mm with +1.5 and +2.9 diopters respectively.</p>

<p>Hope that's correct.</p>

<p>Jim M.</p>

[JDMvW]

<p>Close-up lenses work OK, not 'great', but OK.<br>

Unfortunately, when you get to 72mm ones, they get a little costly for the good ones, as do all kinds of screw-in accessories for the front of the lens.</p>

<p>Look at http://www.camera-filters.com/index.php?main_page=index&cPath=502&sort=20a&page=4 and that area for diopters and sets</p>

 

[JDMvW]

<p>BTW, although there is always some small chance of vignetting, a 72mm screw-in thingie will fit <em>any</em> 72mm screw-in filter mount, so it usually doesn't matter what lens or camera is involved.</p>

<p>Nikon, Canon, Contax, and many others had close-up lens RF camera accessories called variously "Auto-Up" - (e.g., http://www.photo.net/classic-cameras-forum/00c3wF ) for just the purpose you're talking about.</p>

[dhbebb]

<p>Thanks for the responses. It is of course true that close-up lenses are optically not the best solution, although achromats (2 elements) work better than single-element types. If I wanted to focus in the range closer than one meter, I would have a wide choice of close-up lenses, but I am trying to find something to use specifically with my Kodak 200mm, for which no extension tubes are available and which has a close-focusing limit of 8.5 meters. For the Retina 135 lens, Kodak supplied two close-up lenses with different weak diopter ratings to help focus closer, but for the 200mm they didn't, which is why I'm considering the Sigma lens, not particularly because it is Sigma but because it is available in a weak diopter strength and in 72mm size. I'll wait and see what strength it is - another option would be to mount the 200 on a Canon EOS body via and adapter I have - I could then use a thin Canon extension tube to focus close.</p>

[AJG]

<p>Spiratone used to sell "Focus Extenders" which were fractional diopters similar to what you are looking for. I never used them, so I have no idea how much of an optical compromise they would be.</p>

[golem_bngolem]

<p>All this talk of 2-element "better" dioptres, etc is<br>

rather unproductive. 8 metres is a terrible near<br>

focus limit and finding aa 0.125 dioptre is just<br>

about impossible. However, it's a pretty"weak"<br>

power as these things go, so don't worry about<br>

using a simple single element, which you will<br>

prolly hafta acquire from an optician, most likely<br>

in optical plastic. Find a cheap filter built with a<br>

threaded retainer ring and have a 0.125 dioptre<br>

cut to fit. <br>

<br>

Frankly, I'd worry less about an exact match to<br>

the "gap" and go for some overlap. It's a two-fer:<br>

1. The overlap is convenient.<br>

2. It will use a slightly weaker dioptre [better<br>

image quality].<br>

<br>

You're gonna hafta avoid shooting wide open.<br>

Thaz unavoidable reality. <br>

</p>

[golem_bngolem]

<p>BTW, as I thinkyou know [from your ability to calculate<br>

that a 0.125dioptre picks up at the 8 meter limit of your<br>

Retina 200mm] the strength of the Sigma is easy to<br>

figger. Mebbe it's already occured to you, but if not,<br>

just focus your 200 to infinity, place the Sigma dioptre<br>

in front, and see where the focus falls. The inverse of<br>

the "infinity focus" is the dioptre power. IOW, if focus<br>

falls at 2 metres, it's a 0.50 dioptre, 4 metres would be<br>

a 0.25 dioptre [2 means 1/2, 4 means 1/4, etc etc].</p>

[golem_bngolem]

<p>I don't know why you would adapt the<br>

Retina 200mm to an EOS or Nikon or<br>

any real SLR. It's a very compromised<br>

clunky lens whose optical design is all<br>

about minimizing the rear element to<br>

use immediately ahead of a leaf shutter. <br>

200mm primes, and excellent 70-210<br>

mid-speed zooms, are a drug on the<br>

market, sellers just wanna kiss them<br>

goodbye. And they focus to reasonable<br>

near limits, too. Why torment yourself ?<br>

</p>

[dhbebb]

<p>Thanks Golem. In fact I have the 200mm focal length covered in 3 other systems, Leitz Telyt, Canon EOS and Nikon AIS, it's just that I want a matching outfit of 1950s/60s lenses for a project. As Retina lenses are so cheap, I already have 28, 35, 50, 85 and 135 lenses, so the 200 would be a good match, I was just curious about ways of overcoming the near focus limit. I have bought a Sigma filter and will try it out.</p>

[dhbebb]

<p>I have received the Sigma close-up lens - it is unmarked but turns out to be a +2 - presumably Sigma thought by being mysterious they would encourage people to buy their lens and not just any +2 lens. This means that my options are to use the 200mm within its intrinsic limits on a Retina or with an extension tube and an adapter on a Canon for close focusing. Thanks once again for responses.</p>

[Mike Gammill]

<p>The Sigma lens (like the dedicated close-up lens for the first Tamron 28-200) might be optimized to work better with the intended lens. I don't know how much difference that actually makes in practical terms. I have the first version of the Tamron 28-200 and do find the dedicated close-up lens a decent enough performer from f8 to f16. However, before I got the close-up accessory I could passable results be using the single element meniscus lens from an old overhead projector. </p>