PE 105 macro lens vs bellows extention

<p>Presently I have the 105mm macro lens and have been toying with the idea of a Bronica bellows<br>

for my ETRS camera. Other than convenience,( or lack there of ) what are the possible benefits of a<br>

bellows? <br>

Regards,Peter</p>

 

<p>Choices of various lenses on the bellows, different magnification ratios - on the plus side. Typically heavier and more unwieldy than a macro lens on a body.</p>

<p>From what I have been able to find out there were two different auto bellows for the ETR series cameras. I have the first version. I also have the 14 and 28 tubes. Bronica recommended against stacking extension tubes. I suppose someone could use one tube between the body and the bellows and then another one between the back of the lens and the front of the bellows but I have not tried this yet. It does not seem practical or possible to mount a reversed lens on the bellows but I might find a suitable lens to reverse mount to the front of the 100/4 macro.</p>

There is no lens that is suitable for reverse mounting to the front of a macro lens. You get better results using just more extension.

<p>There is one significant trade off between the macro lens and an extension tube / bellows - DOF. The further you bring the lens away from the film plane, the lower the DOF. It can get extreme fast. Depending on what you want this would be a curse or a blessing.</p>

That's not a thing that is linked to what you use to get close, Peter. DoF depends on magnification and f-stop only.<br>So whether more extension in the lens' focus mount, tubes, bellows, reversed lens, supplemental lenses, a reversed lens attached to the prime lens, or even more magnification (a crop) of the negative: DoF at any given image scale and f-stop will be exactly the same.<br>But though the way you achieve that image scale is no consideration as far as DoF is concerned, it indeed is (in a big way) when image quality is concerned. A good macro lens used with extension (tubes, bellows) only will give the best image quality.

<p>DOF is calculated by the focal length, aperture and film image size. What you are changing with bellows is the focal length.</p>

No, Peter, you're not changing focal length.<br>Focal lengths do not change when you move a lens away from the film. Only the conjugate distances, i.e. magnifaction.<br><br>And also no to focal length being a separate factor in DoF. It is already accounted for in magnification (which is the combination of focal length and image distance, or subject distance). So as long as magnification and f-stop are the same, DoF will be the same, no matter what focal length.

<p>At 1:1 (or whatever magnification), you'd get the same DOF whether you were using a macro lens that focused to 1:1 or a non-macro lens with extension tubes, would you not?</p>

<p>The short answer is that a lens with a fixed focal length, whether extended by its own helicoid, a bellows or extension tubes will have the same depth of field at a given magnification. The long answer is that some zoom lenses and fixed focal length lenses employ floating elements in their designs. This can cause the focal langth to change as the lens is focused (with it own helicoid) to its closest focusing distance. </p>

<p> I guess I should make my inquiry more specific. I have for my ETRS, 40mm,50mm and 150mm lens (and of course the PE105mm macro ). As with the original question, I'm ignoring convenience . What possible changes (improvements ? ) might I realize using any of these lens on a Bronica bellows over just the 105mm macro lens ? I've enjoyed the discussions, but don't feel any more up on the pros or cons of the bellows vs macro lens.<br>

Thanks again,Peter</p>

Important to understand is that there is no (!) "vs". Macro lenses and bellows each do a different thing, which you will both need in close up photography.<br>A macro lens is a lens that is made to perform well at short subject distances, compared to non-macro lenses.<br>To achieve short subject distances (and an in focus image) you need longer image distances, you need to be able to move the lens away from the film (no matter whether you are using a macro lens or not). A bellows is a way to provide a variable way of increasing image distance, providing (much) more extension than tubes and lenses' focusing mounts.<br><br>So no "vs": a macro lens ensures best image quality at close range. The bellows provides a way to get into that close range.<br>Many macro lenses have a bit more extension built into their focussing mounts, allowing to come a bit closer than non-macro lenses would. But that is not the thing that turns a lens into a macro lens.<br><br>The bellows will provide more extension, so you get closer, achieve higher magnification. That's it.<br>That works the same with any of those lenses, but since scale is a thing depending on an increase of extension relative to the extension, you'll get closer, with higher magnification, using shorter lenses. The retrofocus 40 and 50 mm lenses however aren't suited for close up work, do not deliver the best quality. So you'd do well only using the 105 mm and 150 mm lenses, with the 105 mm macro expected to deliver the very best results.<br>The 105 mm may be (but i don't think it is) one of those lenses that use floating elements to maintain image quality throughout the focussing range. If so, you will have to set it to its close focus limit even when using it on tubes or bellows, or else image quality will not be as good as it could be.

<blockquote>

<p>At 1:1 (or whatever magnification), you'd get the same DOF whether you were using a macro lens that focused to 1:1 or a non-macro lens with extension tubes, would you not?</p>

</blockquote>

<p>+1, DOF is a product from magnification and aperture; CoCs are a matter of definition.</p>

Reread my post, and it does need some more... <br><i>"since scale is a thing depending on an increase of extension relative to the extension, you'll get closer, with higher magnification, using shorter lenses. "</i> should read "since scale is a thing depending on an increase of extension relative to the extension <b>at infinity focus</b>, you'll get closer, with higher magnification, using shorter lenses."<br>Some more about this: at infinity focus the distance from 'lens' (the rear principal plane) to film is equal to the focal length, so shorter for short focal length lenses, longer for... you get the picture. Adding X amount of extension to that distance has more effect if X is larger relative to the focal length, so you need less extension with short focal length lenses, more with long focal length lenses to achieve the same magnification.<br><br>The main thing to remember still is that a macro lens is a lens corrected to give (or maintain) best performance in the close up range, and you need extension (provided by things such as a bellows extension unit) to get into the close up range.<br><br>And yes indeed, "DoF at any given image scale and f-stop will be exactly the same" no matter what lens is used.

<p>Well this keeps the brain cells active. So if I read your remarks correctly the only suggested lens with a bellows attachment would be my 105mm macro and the 150mm lens. To make my ignorance of the subject clearer, how much more magnification would the 105mm lens on the bellows (Bronica) realize? Life size (is this referred to as 1:1) or larger ? With the 105 on the bellows this could require a fairly rigid tripod,no ?<br>

Thanks for all the input,Peter</p>

Magnification is easy to calculate. It is the amount of added extension divided by the focal length.<br>The bellows provides a variable amount of extension, and i do not know what the minimum and maximum extension are. But for life size (1x, or indeed 1:1. "1:X" stands for the size of the subject on film - "1" - compared to the size of the subject in real life - "X") you will need to add an amount of extension equal to the focal length.<br>So a bit of arithmetic, assuming life size using the 105 mm on the bellows, the same amount of extension will produce a magnification of 105/40 = 2.6x (or 2.6:1) using the 40 mm lens, a magnification of 105/50 = 2.1x using the 50 mm lens and a magnification of 105/150 = 0.7x using the 150 mm lens.<br>Note that i didn't add the amount of extension provided by the lens' focusing mount, i.e. left the lens set to the infinity mark. If the macro lens employs floating elements to maintain best image quality at close range, you must set the lens to its close focus limit whenever you are using it with tubes or bellows. And then the amount of extension doing that adds should also be added in the calculations.<br><br>Believe it or not, but using a good tripod always helps improve image quality enormously. Even with short lenses and fast speeds. And in the close up range, it is nearly impossible to get usable results without.

<p>Thank you all very much and a special thanks ( to Q.G. de Bakker ) for clarifying my concerns with a concrete example! Time to consider some bidding. Regards,Peter</p>

<p><em>Believe it or not, but using a good tripod always helps improve image quality enormously.</em><br>

But not if you don't use mirror lock up and a cable release.</p>

 

<p> Well, I took the plunge and have a bellows on order. And why would one use a camera on a tripod and not use a cable release? ( or am I a bit naive ?) Anyway I'm awaiting it's arrival and I have every intention of posting some comparison pics, hold on! Peter</p>

<p> So I got my first experimental roll of film back. I'm going to have to redo the trial again as I screwed up. But I can make a few remarks, earlier it was mentioned that the shorter focal length lens would not be appropriate, I'm going with that, the objects were hard to focus and had to be very close to the lens. Maybe taking pictures of stamps or slides? The 150 and even the 250 lens I have worked well enough as did the 105 macro lens. However I think the bellows makes sense if one doesn't already have the 105 macro lens ( it's certainly less expensive than the lens). It is fun to play with and is quite the sight with the 250 lens on the bellows. Pictures with the next post.<br>

Peter</p>

<p>I have the 105mm/4.5 PE, and have observed that when focusing, the front cell moves much farther forward than the rear.</p>