XL2 Mini35

[Joshua Provost]

I was checking out your band's web site. I think it's a funny coincidence. I am in a few bands and run an independent record label. I got started in the video world making music videos, and it's expanded from there.

It sounds right. The distance to the GG is supposed to be 44.5mm, right? Why the +4 macro before the GG?

I noticed that SRB sells 55mm spacer rings for around $5 (or maybe its 5 pounds?), so you don't have to take apart existing filters.

So what is the latest evolution in ground glass versus focus screens? Did you have to cut the glass in picture 26 to get it fit in the ring?

[Steev Dinkins]

We're just finishing up our first music video with the XL2 and pretty blown away with the results. It'll be finished by end of year. I'd love to get some feedback on it when we're done.

Regarding the +4 Macro, I guess I got the idea from James Webb's design. I thought it was to possibly correct distortion, but found that it just reduces the amount of spacers needed between the 35mm lens and ground glass. I don't think it's adding any distortion, but I could do a better job at ascertaining that.

I didn't have to cut the glass to fit. The 2" diameter glass from Thorlabs fit good enough, with just a little slop, inside a 55mm ring.

I'd much rather have a cut Beattie focus screen though. When I get $150 to blow, I may try it. Otherwise, I'm wondering if Dan Diaconu's moving ground glass mechanism will prove to be the superior path. I'm waiting to see what system he's devising and how much it'll cost.

Btw, here's a short video shot in about an hour of playing around with the adapter:

http://www.holyzoo.com/111/xl2/35mm/...DanceEdit2.mov

[James Hurd]

Joshua, you wouldn't happen to be a programmer too eh? I've got the whole protools setup etc...

My adapter is a spinner. It uses 'etched-looking' vinyl as the gg.

Have you seen this: http://www.satinsnowglass.com/. Thorlabs has some ggs too.

[Joshua Provost]

I'd love to check out the video when its done. I'm trying to find a forum to talk about music video production, and DVi seems as good a place as any.

About the +4 macro. From what I see of the James design, it was a Vivitar +1 and +2, but they were empty, just spacers.

What's the part number on the Thorlabs glass? and on the SRB M42 adapter? Can we get this down to a part list?

I want to try this on the cheap. I'm thinking about picking up some of these $10 +10 macro lenses, to test the concept. If I can get it to work on my camera, I'll upgrade.

The rotating glass has an obvious quality advantage, but it's way more complex than I care to deal with. What you're working on is much more elegant to me, and the quality looks very good. It has it's own look that is quite charming.

[Steev Dinkins]

James, I tried a glass-inside-55mm-ring direct from SatinSnow. They were very responsive and sent the item right away. I regret to say that the Thorlabs 1500 is far finer, and further, was very inferior to a focus screen. I'm sure it would be great as a viewfinder piece, but what I received, no way it would work for what we're doing.

James, can you post more on how you constructed your spinning adapter?

[Steev Dinkins]

Joshua, regarding James design. Look at #7. It's a Vivitar CU +4, not empty.

The SRB adapter was a special concoction they threw together. If you contact them now and address Ian Broomhead, he should remember me and what he sent me.

The part number for the 2" diameter Thorlabs glass is:

DG20-1500 - Price - $14

http://www.thorlabs.com/ProductDetai...oduct_ID=36117

[Joshua Provost]

Ah, I see the +4 now. My mistake.

[Joshua Provost]

SK Grimes will make the female M42 to male 55mm part for $60. Discounts for quantities.

I can put together the same thing using four off the shelf (though not necessarily easy to find) parts for $35 including S&H, but it won't be as strong or elegant.

The M42 lenses look pretty cool. You can get a lot of vintage lenses on eBay as cheap as $5.

Maybe someone can explain why a plain focusing screen is better than the Thorlabs 1500 ground glass? From what I read in the Intenscreen web site they are made of acrylic. Is this really better?

What about this Nikon screen for $25?

http://www.bhphotovideo.com/bnh/cont...u=37515&is=REG

[Dario Corno]

Why not use a simple macro extension tube insthead of an expensive M42 screw mount ?? I found a tube for my 35mm photographic Pentax lenses, it has a perfect mount and a female filter screw (59mm) on it.
It is built up of four segment and every segment has a normal filter screw to be conncted to the following,so you can use as many "parts" as you want changing the macro extension (and in our situation changing the distance to the GG).
It's WAY CHEAPER and it works fine IMHO.

Finally my mount (I'm just missing to build the wax gg) looks like :

Mount 1 :

35mm Pentax Lens -> MacroTubePentaxMount -> 59to49StepUpRing -> GG -> Macro -> 24mm Relay Lens -> NikonXL1Adapter

Mount 2 :

35mm Pentax Lens -> MacroTubePentaxMount -> 59to49StepUpRing -> GG -> Macro -> 72to49StepDownRing -> Standard XL1 Lens

[Steev Dinkins]

Joshua, I've seen a focus screen be both brighter and finer than any ground glass.

Regarding the Nikon screen through BHPhoto, my question is what size is it?

Right now, I have my eye on this one:

http://www.bhphotovideo.com/bnh/cont...ku=4402&is=REG

It's a little over 2" by 2"

[Steev Dinkins]

Dario, how's your Mount 1 version with Relay lens on Nikon mount coming along? What Macro Lens are you using? Is there less lens distortion? If you figure out how to make a good wax focus plane, please do tell. :)

[Joshua Provost]

Dario, can you post a link to these macro extension tubes? Maybe I missed them.

[Sebastian Scherrer]

Hi folks - especially Steev -

I find those adapters pretty impressing. It's been a while since I studied the art of the home-made mini35 - the M42 lenses are definitive the way to go!

Steev, how much will I have to set aside (in terms of money) for a XL-2 adapter? How much did you spend, all in all?

Best regards,


Sebastian

[Steev Dinkins]

Sebastian, I've spent a total of $700 to develop my current version. Some of the parts weren't needed, but were part of the experimental process.

Here's a breakdown of needed parts and costs as I see it:

35mm Lens - $35
Thorlabs Ground Glass - $38
Optical Parts from Adorama - $250
M42 to 55mm Adapter from SRB - $70
Spanner Wrench & Cleaning Supplies - $90

So that's about $500 minimum. I've found that spanner wrenches are expensive, trial and error with an array of random parts was critical, trial and error adds up in $$, and cost savings comes in unexpected places. I called 15 local companies and had 2 call me back to give me free samples of 3 micron Aluminum Oxide abrasive powder.

Which leads me to my final comment. I received my 2nd ground glass from Thorlabs after the first one arrived with imperfections that I smoothed out with the 3 Micron AO. The 2nd ground glass is not good enough to use as is either. I'd have to do a quick grind on it with the Aluminum Oxide and a 55mm UV glass blank like I did for the first one. So I can't say this is fail safe.

I would still say that a Beattie Focus Screen would work right out of the box. Only question is how to trim it to fit in a 55mm ring. That would be another $150 from BHphoto.

Not exactly a cheap endeavor overall.

After doing more successfull work with deep depth of field with the Manual lens on the XL2 recording 24p with tasty post production, and now having a flawed but artistic way of doing shallow depth of field with this home brew adapter, I think I can call the mission generally satisfied (Lens distortion, grain, and all).

[Dario Corno]

<<<-- Originally posted by Joshua Provost : Dario, can you post a link to these macro extension tubes? Maybe I missed them. -->>>


This is exactly what I bought (I have lot of good 35mm Pentax K lenses).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=15240&item=3861555054&rd=1

If you look closer at the pictures you'll notice there are 3 or 4 rings, they have a screw mount between them.

The last front ring has a standard pentax bayonet mount (but there are models for every make) and the last ring on the back has a standard "male" mount (the same present on the lens).

My one is 52mm in diameter and the first one with the lens mount perfectly fits a 49 to 52mm step up ring.

I'll post some pictures ASAP.