Lack of quality with fx1 and M2 adapter

[Eric Edwards]

Hey Everyone,

I was hoping that some of you out there with knowledge of the M2 adapter could possibly give me some ideas on how to fix a problem I am having with my FX1 and the M2 adapter.

I’ve been using this adapter since January and I am impressed by the DOP, but I must say that the quality of the image has decreased by about 30-40%. I don’t think that it is my setup of the camera to the adapter as I have gone through it many times and have followed instructions from the redrockmicro forum on how to set it up. I’m not sure if it’s a faulty adapter…or bad ground glass, or maybe if the glass isn’t positioned right.

I know that I have been seeing some videos out there with the same fx1 with a lot higher quality. It definitely preserves their HD quality when shooting. Mine is more of an SD feel, very much downgraded. My subjects are clear…but not defined. There is just a huge lack of clarity when it comes to the image…but it still is clear.

I was wondering if any of you guys had an idea of why it would be like this? It is starting to get a little annoying in a way, and I would like to be able to preserve as much quality as possible.

Any ideas on this would help very much. Thanks Everyone.

[Christopher Witz]

I feel your pain.....

I think it's just a fact that a loss of resolution is normal and unavoidable when you film a "projected" image.

Your adding another arrangement of lenses.... and a ground glass... in front of an already marginal lens for HD ( remarkable as it is ).

I'd say a 30% loss in resolution is optimistic considering the physical barriers implemented for the effect.

I've personally given up on the dof adaptors..... Instead, I try to back up and zoom in on my composition.....

Shallow DOF is like horsepower..... in reality, you don't need it as much as you think. Slow down, save your gas (money), and enjoy the ride (view)

Content is king!

[Ben Winter]

Can you describe what lenses you're shooting with, at what apertures, and with what kind of lighting? And perhaps post a screengrab?

[Chris Barcellos]

Eric:

I have the FX1, and I built my own version of the M2 using the Micro35 plans from Redrock, and their gg disk.

First off, which disk do you have in the M2. I will tell you there appears to be a big difference in my mind between the first disk I got in Fall of 2005, and one I just ordered as back up. The first was thin, and I think "wobbled" more. The difference is thickness, with the latter being at least twice as thick. I just installed the second one and note that I get a better image. However, I also noted a loss ofl light.

Second. One thing we are used to with our HDV camera shooting without adapter is sharpness, and a long depth of field. That translated into a generally sharp image. Of course we want to get away from that with 35mm adapters, and as a result, we are now shooting stuff with most of the scene out of focus, with a 35mm lens wide open, with a miniscule depth of field So if you think you are losing something, you may have to close down the 35mm lens adapter a bit to get a lit more field in focus. When I was doing a lot of 35 mm shooting in the 70's, the chant was always close down the lens, at least a bit, to take advantage of the more superior imaging available at center of lens. Of course, more is in focus, so you have to plan your best shot.

Third. You don't indicate what you are using for an achromat. I assume you are using the 72mm achromat sold in the HDV package. If not, that can be an issue. Being a cheapy, I actually bought the 72mm achromat from Cinevate, and it has worked pretty well. My build of the DIY unit does have the FX1 lens with the achromat set back about 5 inches from the GG on my homemade set up. Set up that way, I am able to get critical focus with the zoom set at 30-50. So I actually get a little zoom capability left in the set up. As I get closer in, I find it is more and more difficult to focus on the image, so I live with that. Be sure you are actually getting critical focus out of the FX1 to the ground glass.

Fourth. I am using Pentax K mounts lenses, and also have some off brands. The choice of lens and focal length is an issue. Some have indicated zoom lens should be avoided. I only pass that on.

Fifth: I know I am not quite set up right because I actually focus out past infinity, losing some close focus, but for the purposes I have used it so far, that hasn't been a big problem. However, I know that can be a problem.

I have wanted to give up the use of the adapter, because it is a pain in the you know what. However, used correctly, it can yield great results. It just takes more planning.

[Bob Hart]

30% to 40% seems a bit disappointing. I get up to 850 lines horizontal res with my best lens, an 85mm f1.8 Nikon at about f4 in good light with 0db gain.

If the FX1 faithfully delivers 1440 lines horizontal res, then your 30% to 40% estimate is fairly close. However, does the FX1 deliver 1440 horizontal lines of res?

Things to search for and to tell us and the Redrock guys.


HARDWARE.


SLR lens on front of your M2. Focal Length? Max available aperture? Brand?

Close-up lens on front of FX1. Is it Redrock's own or another?

If it is another, what is it?

How big is the area off the groundglass you are imaging from?



SETTINGS.


FX1.

Shutter speed? Gain Setting? Manual Iris? Zoom setting?
ND Filter setting if set? CF on or off? Shooting HDV or DV? Capturing HDV or DV? Sharpness setting?


M2.

SLR lens aperture setting? Focussing method? (ie., using separate monitor or LCD, focus assist and peaking or BGOBGTWTWTB?) How much area of the groundglass is being imaged? Is SLR lens correctly backfocused onto the groundglass? - I understand this to be a vexingly fiddly job with the M2 but one that is absolutely necessary for optimum performance, especially with wide and ultrawide SLR lenses.

If you could shoot a test chart and grab a frame, this would be of assistance. The 1956 EIA 4:3 chart is the one most everyone may be commonly familiar with and can be found on the web, downloaded and printed on photogloss paper.

If you can shoot a still-image of the setup and the close-up lens on your FX1, all the better.

A ballpark of what works with the FX1 and Z1P to get up to 850 lines of horizontal res is :-

Nikon 85mm f1.8 autofocus lens set to f4, good lighting.
Groundglass finished with 5 micron aluminium oxide.
24mm wide area off the groundglass.
7+ achromatic dioptre for relay lens, fitted directly to FX1 for closeness to front of zoom lens and to assure concentricity.
Zoom between about 40mm and 54mm.
Camcorder focus reading between 1.4M and 21M with 7+ on front with groundglass texture sharp when positioned anywhere within this zone.With the non-erecting (non-flip) M2 adaptor, the distance from GG to front of 7+ lens will be approximately 5". With a 4+ it will be in the ballpark of about 8".

[Eric Edwards]

Hey guys, thanks for your responses...I really appreciate that, and sorry about not posting more information. More on my setup is:

Using HD Achromat that was shipped with the M2.
I use Nikon Lenses:
Nikon 50mm F1.4, Nikon 35mm F2.0, Nikon 28mm F2.8, Nikon 135mm F2.8

As for camera settings, everyting is basically on manual, manual iris is set to around f2.0/f2.2. Gain is set all the way low (sometimes medium). I usually dont shoot with my lens all the way open, especially if im shooting outside...I tend to shoot in the f2.8 range with my lenses, or anything that gives me an image that is not too bright and obviously not too dark.

I have my sharpness set to around 9-11 on the camera. The zoom set to around 22, and the manual focus is around .3m (as stated should be by redrock).

I capture all my footage with Aspect HD. Also, when shooting, I tend to not shoot with cineframe, its just native 60i (I then transfer to 24p). My setup seems like it should be right as I set it up with the help of people on the redrock forum...however my results are very much lower in quality then results posted.

Unfortuntely im home for spring break and wont be back up to school (where my camera and edited comp is) to post any screen grabs. I can hopefully get some stills up for you from footage and the camera by thursday.

Also, I dont know what version my GG was made, but I did get this just a couple months ago, so im sure its the newest glass that redrock is making.

Also, im not sure where to get that chart to test the clarity of the camera...if there is a place I can download it then take it to blow it up so I can film it to show you guys would help.

If any other questions that would help figure this out, please let me know, but hopefully the above will help a little bit in understand the situation. I can understand if there is quality loss, but the loss on my does seem a little worse then others...maybe im just doing some things wrong, not sure, but it seems to be the case.

Anyhow, thanks again guys for posting and any future information you guys have for me would be great.

Eric Edwards

[James Huenergardt]

Hey Eric,

I'm still in the process of 'tweaking' my M2 and Z1U.

I have your lenses as well and haven't been happy with my results as of yet.

Like you, I've seen some great footage posted by folks even using Cineframe!

I'll post more if I find out something. I'm also going to post over on the RR site.

Jim

[Eric Edwards]

Im sorry your running into the same problem...it seems pretty dissapointing for us fx1 folk who are getting beat bad by dvx folk and other sony users...I just hope that we'll eventually get this dialed in so we start shooting with around equal quality that everyone else is.

I'll keep you posted if any improvements.

[Chris Barcellos]

Okay guys, heres my take, based on what Eric listed as his settings. Take it as you will.

I think you need to back the camera away from the adapter with some kind of extenstion tube. If you are mounting right to the adapter, as I initally tried with my set up, I could not get a decent focus on the ground glass. Backing it off about 4 to five inches let me zoom between 30 and 50, and focus around 1.8 to 2. I have room to focus either side.

Of course this is with the Cinevate 72mm achromat, and not Redrocks, and their spec are likely different. But my experience is that when you get that close to the ground glass, the focus is a big problem.

Take a look at this post, and the 35mmadapter clip. Are you already getting better than this, or worse (remember this is compressed footage):

http://www.dvinfo.net/conf/showthrea...302#post645302

[Bob Hart]

That short focus distance seems very very close to the limit.

When you get back to your camera, could you try this test.

Take the FX1 outdoors with the M2 mounted up but the groundglass stationary, and point it at something plain and uniformly the same bright light colour across the entire frame. Set the SLR lens aperture to something like f11 or f16.

This is to make the groundglass texture visible as a sort of grubby sandpaper appearance because you want something to test relay focus against.

Adjust the videocamera ND so you can set as wide an aperture on the videocamera itself as you can without burnout. This will reduce the videocamera's own depth of field so that a more accurate assessment of relay focus can be made.

Once you have set up so that the plain light frame is seen, select autofocus on the FX1. It should go to sharpness on the groundglass.

If you are unable to get a sharp focus on the groundglass texture, then it may be that the RR achromat may not be a good match for your arrangement. I recall somebody else having a similar issue awhile back with an M2 plus FX1.

I think then it was difficult for the videocamera and achromat to be brought close enough to the groundglass to get a sharp image. The solution might be to try a lower power achromat and set the videocamera back from the groundglass a little furthur.

I am really only guessing here and probably badly at that.

Another little experiment you can try is to mount the RR achromat to the FX1 then set the camera up on a tripod or tabletop. Draw a movie frame 24mm x 18mm on a stiff white paper or cardboard and set it up in front of the camera lens about 100mm away.

Play around with zoom, focus and add or subtract distance between front of lens and the cardboard until you get a frame and sharp focus.

Once you have got this, take a measurement between front of lens and the cardboard. Then measure the distance from front of achromat lens to groundglass in the M2.

If the distance in the M2 is shorter than you can mount the videocamera to, you might have to get a lower power achromat so you can recover a useable focus range.

Another loser for resolution is if you take too small an image area off the groundglass. The scale size of the "grain" becomes larger proportional to the frame size. Although the moving groundglass effectively de-resolves the groundglass texture, the image will be softer the smaller the groundglass area used.

[Eric Edwards]

Thanks guys for these tips...I will go ahead and give them a try as soon as I possibly can. I'll be working on this all weekend and next week to try and fix this.

As for Chris, the clips that you showed, especially outside, do seem better then the footage that I have...what lens did you use for the footage outside?

[Chris Barcellos]

Eirc:

Sorry, only the girls shot with 35mm adapter, as indicated in post. Used Pentax 1.4 50 mm. Probably around 2.8.

Other shot with regular FX-1 setup, or maybe Sony 1.7 tele adapter....

[Gints Klimanis]

Originally Posted by Eric Edwards

Using HD Achromat that was shipped with the M2.
I use Nikon Lenses:
Nikon 50mm F1.4, Nikon 35mm F2.0, Nikon 28mm F2.8, Nikon 135mm F2.8

As for camera settings, everyting is basically on manual, manual iris is set to around f2.0/f2.2. Gain is set all the way low (sometimes medium). I usually dont shoot with my lens all the way open, especially if im shooting outside...I tend to shoot in the f2.8 range with my lenses, or anything that gives me an image that is not too bright and obviously not too dark.

Eric Edwards

I also have the M2/FX1 but I haven't really gotten around to using it. Shame ...

Not all of the Nikon lenses in your list will be that sharp at f/2.2 and wider.
The 50mm f/1.4 is the best Nikon lens in terms of sharpness close to wide open. I owned the 35mm f/2 briefly - giving it up because it was really soft until f/2.8 . I do a lot of sports/action photography with my Nikon lenses and D2H. You have to pay a LOT for sharpness at wide apertures in primes.

Top Tier:
Nikon 28mm f/1.4, 50mm f/1.4, 85mm f/1.4, 105mm DC f/2, 200mm f/2
(I actually own all of these)

2nd Tier
Sigma 30mm f/1.4
Nikon 50mm f/1.8, 85mm f/1.8, 135mm f/2

[Bob Hart]

Eric.

Chris's solution matches pretty well with my own for the FX1/Z1P so I can endorse it.

My own non flip adaptor and flip adaptor use slightly smaller groundglass area than the P+S Technik Mini35-400 which yields a better image than my own.

On YouTube is an early test I did with it. There's only about five seconds of mute footage.

http://www.youtube.com/watch?v=eEIBGlsuXZs

A reported test by a DOP on the set of "24" last year put the M2 in front of the Mini35 except for it not having the optical image erection or "flip" facility.

I have posted at brightcove.com, this clip from the flip version of my adaptor, which is probably the best of the tests. http://www.brightcove.com/title.jsp?title=572028460 The M2 at its best should be better.

[Chris Barcellos]

Bob:

Nice to see that footage from that flick you shadowed. I recalled you talking about, but did not realize you had posted it somewhere. Nice job on that material....The cameraman in front of you on those shots looked like he was bouncing around more than you were.