Can you use the Marumi +3 or +5 achromat on the Voigtländer 15/4.5 without vignetting? And if you can, what is maximum magnification like? According to my calculator of choice, it should be close to 1:6 for the +5 diopter and rather lame 1:9 for the +3. Are the results any good?
Longer version: after years of thinking I'd never need anything wider than 24mm I recently realized that I do. Up until now, I used my adapted Samyang 8/3.5 with ok results. But I also very much care about close-focus capabilities. Even though I modified it to focus as close as 2mm from the front element, maximum magnification is like 1:20...it's a fisheye lens after all. The native 1:12 of the Voigtländer aren't much better. I know this screams Laowa 15/2. But with a 900€ lens I expect full data transmission. Besides, the thought of building a 3 lens Voigtländer kit has infected my mind.
I've been lurking these forums for quite some time but originally settled for dpreview. For whatever reason Voigtländer is much bigger on here, so this should be the better place to ask.
A +5 diopter will give you, with the lens set to infinity, a 20cm MFD. That won't be much closer than the raw lens, though the performance might be better than with the raw lens set to MFD.
Achromats on wide angles don't help much with magnification - though they are great on tele. Their main use on wides is to improve the close focus quality (but not necessarily increase the amount) of wides without floating elements.
To get closer on an ultra wide, a very thin extension tube might work better. Though the IQ is unlikely to to great on a model without floating elements like that CV.
I also strongly suspect that you'll get strong hard vignetting with a +5 achromat on that lens but I don't have one so I can't be sure. It's just that these lenses are sensitive to thick filters, and a +5 achromat ranges from very thick to extremely thick!
Yeah, would just skip that idea. You'd need a pretty big thread size diameter to avoid vignette completely and then you gotta get the CV modified for the petals too. Laowa 15 is indeed the best choice for you. The founder is a macro enthusiast and it shows.
I know...I know. But since the lens is so short, 20cm of working distance aren't that bad. Initially, I was planning to use an extension ring, but there aren't any thinner than 10mm. I've tested it in a store and it's unuseable. Working distance is less than 5mm, resolution is poor and distortion massive. I'd need a ring not thicker than 5mm.
Unfortunately, I can't test that setup myself, since I only have the +3 in 77mm.
But doesn't the achromat lens change the light path so that the angle of incidence changes?
ftllens wrote:
Yeah, would just skip that idea. You'd need a pretty big thread size diameter to avoid vignette completely and then you gotta get the CV modified for the petals too. Laowa 15 is indeed the best choice for you. The founder is a macro enthusiast and it shows.
Right, but the Laowa the OP mentions is the Laowa 2/15 which has tolerably close focus, but the quality drops off at close distance.
The Laowa 4/15 macro, on the other hand, is very good at close distances, but has some issues that make it less desirable as an all purpose 15 (strong distortion and poor flare performance at longer distances among them)
Egg Salad wrote:
I know...I know. But since the lens is so short, 20cm of working distance aren't that bad. Initially, I was planning to use an extension ring, but there aren't any thinner than 10mm. I've tested it in a store and it's unuseable. Working distance is less than 5mm, resolution is poor and distortion massive. I'd need a ring not thicker than 5mm.
Unfortunately, I can't test that setup myself, since I only have the +3 in 77mm.
But doesn't the achromat lens change the light path so that the angle of incidence changes?...Show more →
Have you attached the +3 to check vignetting.
I’ve considered disassembling and shortening an extension tube.
Or, as another poster suggests, get the kens in M mount with a helicoid adapter...
My wife uses a CV 15 together with a Canon 250D. But on a A6000. So I don't know about on FF, but still maybe of interest to you. CV15 + Canon 250D by Daniel B. Blok, on Flickr
johnsigs wrote:
How about the 15mm f4.5 iii in m mount ,with the m-e close focus adapter ?
I have thought about that but if I went that route, I could just go for the Laowa instead because not getting EXIF transmission is the main reason that makes me hesitant to get it. It might be part of an OCD, but not having all the data is big issue for me.
I’ve considered disassembling and shortening an extension tube.
Or, as another poster suggests, get the kens in M mount with a helicoid adapter...
Well...How? The only way to try would be to cut the petals (I have it in 77mm). The lens not being mine an me being in the store, this was not an option. If this turns out to work with the 77mm version of the achromat and the results being good, I'd probably de-petal mine. It's a lot of effort but this way, I'd get what I want. Data transmission, Voigtländer rendering + sun stars and accepteable magnification. But I'm running in circles. Without knowing that it works, I won't get it. Without having it, I can't try.
I also thought about taking my cheap 16mm extension tube apart, but I doubt I'd get the contacts to work again. EDIT: just took it apart. Top and bottom plate amount to 5mm of thickness. But now there is no way to use the locking pin (minor problem), the screws that used to keep both plates in position or to attach the contact pins. At least not without machining something.
However, the resulting (but fixed) magnification would be perfect at 1:3.
Holy moly! I don't see any (additional) vignetting! This looks very reassuring. Let me virtually hug you!
One last request: Can you measure or show its maximum magnification with a ruler? It should be around 1:6. Real-life number are always slightly lower than what the calculator spits out for some reason.
Egg Salad wrote:
Holy moly! I don't see any (additional) vignetting! This looks very reassuring. Let me virtually hug you!
Can you measure or show its maximum magnification with a ruler? It should be around 1:6. Real-life number are always slightly lower than what the calculator spits out for some reason.
Reassuring for you! But you might want to check the relative mount thicknesses of the Canon 250d and the Marumis before you cut off your hood....
Good point. I will look into that.
But these samples were made with an unmodified lens and a 58mm achromat. If it doesn't noticeable vignette with this one, it surely won't with the 77mm version.
