Best Diopter For Sony 90mm Macro Lens?

[Kristian Laine 2]

Hi guys,

Sorry if this has already been discussed here but couldnt really find a thread that talks about this directly.
 

So I'm just wondering whats the best diopter “wet lens” for the Sony 90mm macro lens or full frame cameras in that focal range in general? I know that Nauticam SMC-1 is apparently the best quality but its also very expensive. 
 

I was given the Dyron +7 (Bluewater +7) for test use at the moment because I was originally thinking of getting the Kraken KRL-08S but I was told this is their best seller so thought why not just test it out. But I find that the Dyron +7 seems ok but just wondering if I should still get the Kraken KRL-08S because I have seen some amazing photos with that and every review seems to indicate this is better for full frame cameras than the Dyron one but not sure and hard to know without testing both?
 

Anyone with experience on this? Thank you

[ChrisRoss 150]

I think you are talking apples and oranges a little bit here, the SMC-1 is quite a powerful diopter giving 2.2x magnification on the Sony 90mm.  In the same magnification class is the INON UCL-67 which is a +15 lens and it will give 2.7x magnification .  A little less powerful is the INON UCL-90, a + 11 diopter power giving 2.2x as well.  The Kraken lens you are talking about is a +6 diopter and the Bluewater +7 which will give you around 1.4-1.5x magnification so not directly comparable with the SMC and the INON lenses.

As you get more magnification you get less working distance for example the SMC-1 has 45mm working distance at max magnification while INON claim 55mm with a 100mm lens.

The lens to choose starts with chosen subject, it's easy to leap to the conclusion that a stronger lens is better , but the minimum working distance and high magnification makes them more difficult to use, not to mention minimal depth of field.  You can back off a little with a strong lens but the working range is quite limited.  The SMC-1 for example will only focus between 45 and 93mm from the subject.  Quite often a lower power lens is more useful.

Unfortunately finding sample pics is difficult, most reviews might post a 1000 pixel image, not that useful for comparisons.

 

[Kristian Laine 2]

Thanks ChrisRoss

 

yeah youre right i should have been more specific. It is like comparing apples to oranges cause they are all different strength. 
 

i guess my question was more of a whats a good diopter for sony 90mm macro in the +5 or +6 or +7 ish range or even +8 etc. so i guess in the mid range because its kind of confusing when lot of diopters are reviewed or recommended mostly for compact cameras like the dyron +7 is highly recommended for compact cameras whereas the kraken krl-08s is mostly recommended for mirrorless but i guess i wanted to know if the dyron still works just as well for full frame as the kraken one does etc. because the dyron is cheaper than the kraken so not sure if i should just get the kraken for peace of mind so if anyone has tried both would be awesome to know. Ps. Im new to macro so just a bit unsure whats the best choice. Cheers

[Barmaglot 251]

What is your purpose for a diopter on the Sony 90mm lens? At a risk of stating the obvious, this is a macro lens - i.e. it is capable of generating a 1:1 image of a subject on your camera's sensor; this means that when you're using it on a full-frame camera (A1, A7, A9), you can frame a 36x24mm subject at closest focus, which is achieved 28cm from the camera sensor, or roughly 13cm from the lens front element. If you want to fill the frame with a smaller subject, you need to get closer than 13cm, which the lens cannot do natively - and this is what diopters do. However, since the lens already focuses fairly close, a weak diopter is going to have little to no effect - a +7 lens will let you focus within 14cm (1m divided by 7), which is already within the lenses capability, so it will do nothing but limit your maximum focus distance.

Personally, I use a Weefine WFL05S +13 diopter (same thing as Kraken KRL-05S). This gives me approximately 2.3x magnification - on my crop-sensor A6300, I can frame a ~23mm wide subject with the bare lens, and ~10mm wide subject with the diopter attached. To be honest, I don't use it very often - it isn't common to come across something that tiny to begin with (ricegrain-sized nudis, squat shrimp, etc), and even when such a subject is found, focusing and lighting is quite difficult - the subject is maybe 2-3cm in front of the lens front element, and both they and the camera have to be absolutely still to achieve focus, at least with my aging camera body and meager skills. The vast majority of macro shots, unless you're in some location that has an unusual proportion of tiny marine life, can be achieved without add-on lenses.

I have posted some full-resolution samples here:

Note again that those are on a crop-sensor A6300; if you're shooting a full-frame camera, the images will be proportionally bigger.

[LarryHallas 44]

The problem I have had with super-macro lenses is the autofocus performance. Some of them I could not get to focus at all, and had to use manual focus. I have had the best autofocus with the Nauticam SMC-1. It took quite some time to get used to, but it is a great piece of glass!

[Barmaglot 251]

My setup doesn't allow for manual focusing (SeaFrogs A6xxx housing; 80mm port diameter - the lens just barely fits through but there is no room left for a focus gear) but autofocus works with a Weefine WFL05S. It's slow, usually takes several attempts to lock, and requires a focus light and bracing the camera on something, as any movement will prevent focus lock, but it works.

[ChrisRoss 150]

4 hours ago, Barmaglot said:

What is your purpose for a diopter on the Sony 90mm lens? At a risk of stating the obvious, this is a macro lens - i.e. it is capable of generating a 1:1 image of a subject on your camera's sensor; this means that when you're using it on a full-frame camera (A1, A7, A9), you can frame a 36x24mm subject at closest focus, which is achieved 28cm from the camera sensor, or roughly 13cm from the lens front element. If you want to fill the frame with a smaller subject, you need to get closer than 13cm, which the lens cannot do natively - and this is what diopters do. However, since the lens already focuses fairly close, a weak diopter is going to have little to no effect - a +7 lens will let you focus within 14cm (1m divided by 7), which is already within the lenses capability, so it will do nothing but limit your maximum focus distance.

 

I'm not sure that is exactly how it works;  when you add two lens together the result is a "new" lens with a different focal length by the formula 1/f1 + 1/f2 = 1/fnew so if you take a 90mm lens and add to it a 165mm lens (+6 diopter) you get a 58mm lens which will focus a little closer - you just don't get the full value you might get on a lens that doesn't focus so close.   

If you look at the wetpixel live where Alex talks about using a +3 diopter on a 105mm macro 1000/3 = 333mm while the 105mm macro focuses at 159mm at minimum.  there was some argument whether it was a +3 or +5 (200mm focus), a calculator shows a +5 will give 1.3x magnification at min focus and if that is all the magnification you need that's fine.

[Barmaglot 251]

Perhaps - I don't own any diopters other than my +13 one, so I haven't had a chance to test it. Regardless, I don't see much point in paying a couple hundred dollars to go from 1x to 1.3x magnification - modern cameras have enough resolution that a slight crop will be just fine. If you're investing the money and effort (carrying the diopter during the dive, attaching it to the lens when needed, detaching when not needed; if it's on a flip adapter then it sits in your field of view when not in use, etc) then it better be for shots that you cannot take otherwise - ricegrain-sized nudis, tiny shrimp, and so on.

[TimG 62]

Barmaglot makes some really good points. 

A true macro lens will generally get you 1:1 and, as he explains, with a modern camera, cropping is barely an issue unless you want very big printed outputs - or are selling them for commercial (rather than editorial) use.

Supermacro sounds amazing. I found the reality similar to Barmaglot's experience. A huge amount of faff with the diopter which screws/clips/twists/bayonets/whatever in front of the lens but is always in the way went not in use; then incredibly hard to find the subject; minimal (MINIMAL!) DOF; and any kind of water movement (surge, swell etc) makes it almost impossible.

I decided it was not something I wanted to have with me on every (hardly any!) dives. As Barmaglot writes, fine if you are determined on a  dive to macro photo a specific micro-subject but, otherwise, for me just not worth the candle. And I love macro photography. 

[ChrisRoss 150]

17 hours ago, Barmaglot said:

Perhaps - I don't own any diopters other than my +13 one, so I haven't had a chance to test it. Regardless, I don't see much point in paying a couple hundred dollars to go from 1x to 1.3x magnification - modern cameras have enough resolution that a slight crop will be just fine. If you're investing the money and effort (carrying the diopter during the dive, attaching it to the lens when needed, detaching when not needed; if it's on a flip adapter then it sits in your field of view when not in use, etc) then it better be for shots that you cannot take otherwise - ricegrain-sized nudis, tiny shrimp, and so on.

That's one way to do it, though I know Alex Mustard was a huge fan of using the lower power diopter - you can  after all go to 1.3x and then crop into that.  That is a +5 diopter, the +6 + 7 gets you 1.4 - 1.5x  and again you can crop into that.  The lower power is less demanding on limited focal range and would be easier to use than the full 2x - Alex view was a serious macro-hog would have both.