Welcome to our community

Be a part of something great, join today!

Register Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Lomo 2.5:1 anamorphic stretching and focus issue.

L

Lee M

Well-known member
Joined
Oct 2, 2016
Messages
159
Reaction score
0
Points
16
I am doing some filming with a Lomo 2.5:1 anamorphic lens. The Red Epic only displays / records in 2:1 anamorphic. Should I just record in full frame and stretch it the width out to 250% and leave the height at 100% in Premiere, or possibly shoot at 2:1 and add the 40% difference in premiere?

Also does anyone have experience with the Lomo lenses? The image below is pretty much the most I can get in focus at T2.5, is this normal for these lenses or should I send it in for repair? I specifically using the LOMO Anamorphic OKC1-35-1 35mm f/2 (T=2.5) PL lens. You can also see the original 2:1 scaling of the image, changing to 125% width in premiere gets rid of those sides.

test.jpg
 
The image looks pretty bad/soft in the center. It could be better. But it is too small to tell for sure, The "MGM" is blurry isn't it?
 
Jacek Zakowicz said:
The image looks pretty bad/soft in the center. It could be better. But it is too small to tell for sure, The "MGM" is blurry isn't it?
Click to expand...


Yes everything is blurry but I am sure it's because of the focus issue and not because of the aspect ratio. Not sure if this is normal for the Lomo anamorphics
 
not normal, we service these quite a bit...
 
Jacek Zakowicz said:
not normal, we service these quite a bit...
Click to expand...

I just noticed that when I move the anamorphic attachment further away from the main lens on the rail, that I can get things in much better focus. I am assuming this is because when I am turning the anamorphic focus, it turns the main lens focus ring as well (when they are attached together), are these meant to be separated a tad? Also I am finding the minimal focal length to be 3 or 4 meters away, is that also normal with these lenses? I'd love to send it in for service, what kind of price range am I looking at?
 
The other thing you might want to know is this:

This is not a 2.5:1 “squeeze” lens.

It has a 2x squeeze ratio.

The 2.5 on the barrel is in f number , as in f2.5 (maybe a T2.8?)

So...

Squeeze factor also called Anamorphic Coefficient is different than aspect ratio.

If you are hoping to deliver a 2.40:1 aspect, I would recommend this sensor setting :

#K 6:5 2x Ana

That will desqueeze In Camera how it should be and deliver you a 2.40:1 deliverable

If you prefer a 2.66:1 deliverable

#K 4:3 2x Ana

You can hold down the resolution menu button to bring up advanced settings .

Hope that helps !

As for the service - Jacek does service a lot of these .


Last little thing : the reason you are seeing vignetting on the left and right is that the lens image circle doesn’t cover the whole sensor left to right. Choosing a 6:5 or 4:3 sensor setting will alleviate this. Blowing it up too big in premier will just overscale your image (wasting computer resources/time and not giving you accurate framing while filming) - sincerely hope that helps.

Best Regards,

Dan
 
Hi Dan, the lens description said it is an F2 T2.5, the main lens shows a 2.5 as the lowest stop. However the anamorphic adapter says 1:2.5, f/2 (T=2.5). I have attached a picture of the lens markings and a video showing the anamorphic adapter separated from the lens and turning both focuses.

I see the 6:5 setting but that is in 4K. If I film in 6K with 1.25 anamorphic, it seems to get rid of the sides vignetting and gives me a larger picture to view on the monitor. I am assuming that I stretch the video in post without losing any quality. Also if I shoot in 6k and stretch/scale down to 4k it shouldn't lose quality I am assuming.

IMG-9597.jpg


Video=
[video]https://streamable.com/9n3a9[/video]
 
1:2.5 is the T stop marking for the lens with the anamorphic group installed.

Ilya Volkov - you around to help ?

Maybe try 5K 4:3 2x Ana in the camera.

If you want to sell this lens setup later on let me know, I collect vintage anamorphic.
 
Lee M said:
Hi Dan, the lens description said it is an F2 T2.5, the main lens shows a 2.5 as the lowest stop. However the anamorphic adapter says 1:2.5, f/2 (T=2.5). I have attached a picture of the lens markings and a video showing the anamorphic adapter separated from the lens and turning both focuses.

I see the 6:5 setting but that is in 4K. If I film in 6K with 1.25 anamorphic, it seems to get rid of the sides vignetting and gives me a larger picture to view on the monitor. I am assuming that I stretch the video in post without losing any quality. Also if I shoot in 6k and stretch/scale down to 4k it shouldn't lose quality I am assuming.

IMG-9597.jpg


Video=
[video]https://streamable.com/9n3a9[/video]
Click to expand...

This is a dual focus NAS lens. It is pretty involved to set up correctly. We convert these to single focus BAS style where you don't need support for it. It makes these easier to use, rentable, and it increases the value of he lens quite a bit. These are very popular right now for the artifacts they image onto the sensor.
 
Thank you for the quote Jacek, I am still deciding if making the unit one with a single focus and rings would be ideal.

The pro's are that it would make it a lot easier to focus and pull focus wirelessly as well as make it rentable, it would also give the opportunity to clean up any dust etc on the glass. Right now the focus ring is so stiff that I would not be able to practically adjust focus during the shot so it would have to be setup in advance.

The main con I am thinking is that I can use the Square Anamorphic lens portion with similar sized lenses with different focal lengths. If this is the case, technically I can buy a cheap lomo 50mm, 75mm or even a standard cinema lens with a similar diameter and make them anamorphic (or at least get the vintage anamorphic glare) just by lining up the anamorphic lens infront of it on a rail. Sure, there may be some vingnette but if I am shooting 6k and final cutting at 4k or 1080p then I can always crop it out.

Any feedback would be appreciated
 
As good as it sounds unfortunately there is no way any other combination than the designated one will produce a half decent image. The square fronts are designed in a way that matches the position of the spherical rear section of the lens to the specific position of the front anamorphic section throughout the focusing range. That is the only combination that can render sharp image in the square front anamorphic type design. Anything else will either be very soft or no image at all. I hope that helps
 
Listen to Jacek,
if you get it properly serviced / modified into single focus then that lens I's a gem and really worth a lot. As you have it now you might get picture out of it but it's simply not production worthy, to much to fiddle with before you have a good image.
 
I've seen some of the anamorphic NAS stuff on auction sites and wondered if the front glass would work with other lenses too. I know matching lenses with universal anamorphic adapters like the SLR Magic 2X and Panasonic LA7200 can be tricky but it would make sense if the LOMO element can't work with just anything due to its design. All I can say is do tests, see if it works or not, and if not, oh well, you most likely have to have it serviced anyway with your focus issues so the single focus conversion would be the cherry on top.
 
The nas fronts are designed specifically for the back setion and will not work well with anything else. You may want to look for the round front section. That is more suitable for frankenrigs....
 
You must log in or register to reply here.
Back
Top