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Rectilux Core DNA - non-rotating single-focus attachment for anamorphic lenses


Zak Forsman
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Thanks again for the response, much appreciated!

With regards to the SLR Magic Rangefinder, when people talk about using it a couple of stops from wide open to obtain acceptable sharpness, would it be possible to achieve the same level of sharpness with a slower lens?  An 85mm 2.8 for example?  

Or is there something about having a lens designed to be a 1.4 and then stopping down that improves the sharpness better?  

As mentioned earlier, I don't think I would have an issue with shooting with a slower lens but if stopping down (with a faster prime) was to cause "hexagonal" bokeh, then that is more of an issue :(

 

May be better to regard the taking lens as not generally needing to go below f4 on any of these variable diopter setups. Having a lens that has plenty of blades and constant circular aperture is a bonus - as it will not 'cut-in' or effect oval bokeh when stopped down. 

The fact of the matter is that all of these variable diopter designs are single element design. Optical physics dictates that there will be a predictable degree of degradation to the image at wide apertures unless using considerably more expensive achromatic glass in it's design. As for Rectilux looking sharper or 'cleaner' - this could be down to a more refined index of glass being used to minimize on distortion at larger apertures, but that is just a guess.

Starting at a f4 + stop on a taking lens on any single element diopter will start to clean up blooming and softness considerably, whilst the diopter 'effect' will still be contributing plenty to give a shallow depth of field. (Think of it as a kind of depth of field booster)

The majority of the worlds best ever made anamorphic lenses that shaped the look of widescreen cinema would have considered f4-f5.6 as fast - and dropping any lower would have been rare. Think it is easy to forget that once you have the ability to focus these old duel focus lenses, people might actually want to be able to follow action with the focus - rather than constantly be fighting a ridiculous shallow depth of field.  

In a nutshell, when using any add-on variable diopter setup with anamorphic, regard your taking lens aperture stops as 1.5 - 2 times faster than they actually are. This way the stopping down of the taking lens helps the single element optics to cope, whilst still delivering plenty of defocus/bokeh for most 'dreamy' looks. 

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Thanks for the reply Hans Punk, great information!  

Could I expect roughly the same results (sharpness wise) from a slower 2.8 prime, as compared to say a 85mm 1.4 that is then closed down to 2.8?

As you have mentioned, I still think that you can get desired shallow D.O.F results shooting anamorphic with these variable diopters, so a prime of 2.8 (or even f4 if they exist) is not a problem..

I do dislike the hexagonal bokeh that you can get by possibly stopping down a lens that maybe does not have very circular aperture blades..

As Zak has pointed out previously, the SLR Magic seem a great choice due to their very rounded aperture blades but unfortunately, they only cover aps-c at best..

Any suggestions for full frame?  

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Generally speaking, closing down on a faster lens yields better sharpness than opening up wide on a slower lens. 

There are a few vintage lenses out there with circular aperture - if budget is an issue, there are a few out there to find (and mostly full frame friendly). Do a search for 'preset lens' - lots of old (mostly M42 mount) German lenses out there with more blades than Freddy Krueger.

The more aperture blades, the better circular shape when closing down.

Meyer-Optik Gorlitz Orestor 2.8 / 135mm 16 BLADE is very nice 135mm example, that really shines on full frame.

Russian vintage lenses - jupiter-9 (85mm f2), Helios 40 (85mm f1.5) as well as the 13-blade version of the Helios 44 (58mm f2).

All of these have very good circular apertures and there are many more types out there, some sharper than others...but if in doubt - try something German or Russian with plenty of aperture blades. If you are on full frame and shooting anamorphic, don't dismiss 135mm as a taking lens length - it is a wonderful look when shooting outdoors (but can make your lens rig look like a bazooka)

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I do dislike the hexagonal bokeh that you can get by possibly stopping down a lens that maybe does not have very circular aperture blades..

Also do some searches for lenses with good bokeh - people really obsess about this quality of a lens.

When people talk about a lens having great bokeh, they aren't only talking about when shooting wide open - a lens with good bokeh should display this at all apertures.

Hans has missed out the king of aperture blades the Tair 11a 135mm 2.8 (20 blades) & it really shines with anamorphics.

The Helios 40-2 85mm 1.5 - when stopped down past 2.8 generates a star like bokeh, which is actually quite nice/odd, but not round.

Don't discount modern lenses, since manufacturing a lens with good [round] bokeh is really one of the goals of lens companies that count for something (or give a shit about creating a great lens).

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You can also go to the other extreme with bokeh.
I've always wanted the "silver" version of the Helios 85/1.4 for it's swirley bokeh.
Then there is the AEJ version of the fabulous C/Y 35/1.4, it's aperture blades make triangle shape bokeh.
I didn't like it, so, I have the MMJ version.
Don't forget the famous Trioplan 100/2.8, it gives a "soap bubble" bokeh look.
I shot some Magic Lantern RAW video recently with my ol' 5DMkII after a morning rain and the sun peaking out between the clouds.
I need to process this and post it somehow, it is very interesting.
I have many old lenses with character, I like them better than neutral lenses.

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Zak, which SLR Magic lenses are you using for scope, and how do you like them? I've been using Zeiss C/Y with my Kowa 16-H, and while good, the look is a tad stale/cold for my tastes (at least when it comes to anamorphic). Also, I get the hexagonal and ninja star bokeh when stopping down which doesn't help matters. I've been eyeing the Sam/Rok Cine DS lenses as possible alternatives, but perhaps I should be eyeing up the SLR Magic offerings too?

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i have a GH4, Kowa B&H and Rectilux. For the taking lens, I like using the SLR Magic 25mm, 35mm and their new 50mm (which might not be officially released yet). rounded aperture blades help keep bokeh soft. but I also find these three look great at T/2.8 or T/2 and you can go down to a T/1.4 but I start to see a touch of purple fringing at that point.

I have my eye on the Dog Schidt Optiks FF58/38/88 line for taking lenses with a lot more character. Should look something like this. Notice the swirled bokeh form the Helios 44-2.

 

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Do you think the DSO tele/wa converter fronts will work with the Kowa? They look pretty large.

for a 2.40;1 delivery (ie, cropped sides of a 16:9 sensr)...

ff38 and ff88 attachments will support taking lenses as wide as 50mm on full frame 16:9  so will do 35mm lenses on aps-c and 25mm lenses on gh4, or maybe as wide as 21mm lenses on gh4 4k mode.

from this, I'd imagine with a kowa between the taking lens and the ff38 or ff88 you'll be needing a 100mm on full frame, a 70-80mm on aps-c and a 50mm on gh4 (45mm on gh4 crop mode).

 

multiply your focal length by 0.66x for the FF38 and 1.55x for the FF88.

 

FF38 has a clear aperture on the rear element of 36mm meaning transmission and aperture should be ok for 2x anamorphic f2.8 on full frame, f2 on aps=c and f1.4 on gh4,  The whole optical pathway becomes ridiculously long however.  

 

There may be a possibility of a run of FF38's 'scaled up' to 50-60mm rear elements and an associated wider fov, but would be extremely expensive - but very similar to the custom lens Kubrick had made for his zeiss 50/0.7.  As it happens, the FF38 was influenced by the WA design kubrick had!

 

 

 

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  • 6 months later...
On 3/6/2016 at 6:51 PM, Phillip23 said:

Can someone tell me what the advantage would be of the full Rectilux 3FF over this core DNA?

One advantage on the Rangefinder would be focus marks, but I'd choose non rotation of glass to be more important.

I can tell you the pros and cons between the Core DNA and SRL Magic Rangefinder. I don't own the 3FF

The  Rangefinder and Rectilux each have there strengths.

Rangefinder :

Pros - Is built better then Rectilux. Feels more solid and does not make any noise when rotating. Rotating gear is much smoother. 

You could get it with distance marks. 82mm is easily to mange then 86mm via diopters. 77mm is very nice when connecting to anamorphic verses 75mm but I was lucky it fit my Redstan Baby Hypergonar jacket perfect! Half the price of Core DNA.

Rectilux Core DNA :

Image quality is better, sharper and does not tint the image on the warm side. The Core DNA is tac sharp at 1.2 and the Rangefinder needs 2.8 or higher. I'm not a big fan of Rangefinder blue flare blobs. The Core has a non rotating front, which is important to me for a circular polarizer and ND filters being I love shooting nature. For me it was well worth the extra cash. 

A short video I shot with it.

https://www.youtube.com/watch?v=5zS1pw5p7yc&list=PLIEXyH1Xyq4ToDcZ0ZVCl6bVk060hc_O-&index=3

Here is a list of extras I have compiled to take the Core DNA to the next level.

I would highly recommend getting these extras to make the Core DNA ready for use.

 1. M3/M4 Stainless Steel Nylon Head Grub Screw Plastic Brake Buffer Bolt Screws Hex

This is so you don’t scratch up the coating of your anamorphic lens or housing.

http://www.ebay.com/itm/281858121964?_trksid=p2057872.m2749.l2649&var=580836260280&ssPageName=STRK%3AMEBIDX%3AIT

 2. 86mm UV filter to protect the front of the Core DNA glass.

 3. Metal back cap for whatever size you end up using for your coupler if bigger then 75mm. 

 4. A custom coupler made from this lens hood fits perfectly. “FOTGA Screw Mount 67mm Standard Metal Lens Hood for Canon Nikon Pentax Sony Olympus” 

http://www.amazon.com/FOTGA-Screw-Standard-Pentax-Olympus/dp/B009GFY858

Then a step down ring or step up ring for whatever the size of your front anamorphic thread is. I’m doing 77mm because this is what most of my front clamps are. I’m making a custom 75mm to 77mm coupler for Kowa 1.5x and Kowa 1.75x.

 5. 86mm Fixed Spacer Ring

http://srb-photographic.co.uk/86mm-fixed-spacer-ring-5713-p.asp

You want a uv filter to protect the glass but having it on you can’t completely go to infinity. Lucky, even with the uv filter on and not being able to turn the Core DNA to infinity, I’m sharp for over 100 feet. This spacer is for clearing the full range of the focus and using filters.

 6. You want to get some 86mm or higher diopters. You need them if you want to get sharp and close.

 

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  • 2 weeks later...
On 3/11/2016 at 10:32 PM, roccoforte said:

I love the sharpness of my Rectilux 3FF, but I dislike the feel of the focussing; very raw and metallic. Does anyone have a suggestion on how to make it smoother / tighter?

I had the same problem with a bit of metallic vibration and it just felt a bit loose so I re-greased mine. It's stiffened up nicely now but be careful not to put too much, the more you put the harder it will be to turn plus it could 'leak' all over the glass. 

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1 hour ago, liamlumiere said:

I had the same problem with a bit of metallic vibration and it just felt a bit loose so I re-greased mine. It's stiffened up nicely now but be careful not to put too much, the more you put the harder it will be to turn plus it could 'leak' all over the glass. 

John Barlow has the following advise: 

"Yes some customers experience issues with the grease and some with noise. I have traced the issue to when the package is in the low pressure cargo hold of the aircraft. This causes some grease to be sucked away from the helical during flight. The noise or movement is because some part of the helical is without grease. Rectilux was designed for easy self-maintenance as shown on page 37 of the manual. Sometimes it is best to use a brush to spread the grease uniformly. Rectilux will be smoother after a bedding in period and will be a lot quieter - the more you use it the better it will become. Mobil grease can be obtained here:
https://www.silmid.com/products/mob2800400-mobil-grease-28-390gm-cartridge-m "

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  • 1 month later...
On 9/1/2015 at 11:20 PM, Zak Forsman said:

i have a GH4, Kowa B&H and Rectilux. For the taking lens, I like using the SLR Magic 25mm, 35mm and their new 50mm (which might not be officially released yet). rounded aperture blades help keep bokeh soft. but I also find these three look great at T/2.8 or T/2 and you can go down to a T/1.4 but I start to see a touch of purple fringing at that point.

I have my eye on the Dog Schidt Optiks FF58/38/88 line for taking lenses with a lot more character. Should look something like this. Notice the swirled bokeh form the Helios 44-2.

 

Some great footage there, Zak.  I also like the Helios 44-2 taking lens, but haven't had much chance to play with it.  I did a lens test with the Helios and the Bolex 16/32 last year and like it.  Here's the test:
Bolex 16/32, Helios 44-2 Anamorphic Test in Snow

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  • 3 months later...

Great work! Really love it!  Was also going to ask whether you were using an external monitor that had anamorphic "desqueeze" but have just seen that the Blackmagic URSA 4.6K offers this...  I assume that this is what you are using?

Maybe I need to front up to the cost of the Core DNA for use with my Kowa B/H.  I also have a Isco anamorphic attachment, is this similar to the Schneider in "look" that you know of?

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