Chromatic Aberration Issue??

Elmy

Elmy

Well-known member
Not sure if thats the term to use but basically when i use my 35mm adapter and my Nikon 1.4 50m (or any other lens) The center is in focus but the outside is fuzzy and out of focus. Sometimes its not too bad. but others its quite noticeable. I wanted to know if its because I'm using a DIY 35mm (redrock specs), and its my adapter, or is it some other issue? I thought maybe it was just lighting situations but I've done a lot of different tests and it still shows up. I just want to make sure that its my adapter issues before I go and buy a new adapter.
 
Thats not chromatic abberation, CA is when you get colour fringing (usualy pink or blue) on contrast boundrarys.

What you are describing is edge to edge sharpness and it is usually caused by the achromat lens. Have you tried changing the distance between the achromat and the GG, or the achromat and the camcorder lens? If not, try a different ahcromat if you have one.


Pete.
 
Ya sorry for wrong term....I thought it was possibly the achromat. Unfortunately I bought this DIY, so I don't have spare parts or anything. There is a spacer between the Achromat and the adapter, but nothing between it and the camera
 
welcome to DIY. Edge to edge issues are very difficult to solve even for the major manufacturers of these units. If you have an old Redrock achromat that's half the problem. What camera are you using?
 
This you will have to figure it out yourself - as its a DIY I have no idea what would work well with it or with the HMC. Its somewhat tricky as these are not interchangeable standard elements but rather designed for specific units. I have no idea how you would proceed but a good starting point would be to know what kind of achromat you started with and to know whether it is properly adjusted to your screen. That's one reason I would never suggest anyone invest in a DIY adapter unless you are willing to continue the DIY work yourself. Good luck.

Maybe another DIY builder can help you. I'd contact redrock if its based on their parts and design.
 
thanks for the help anyways :D. I think for now It's not a horrible aspect, causes some small issues but overall its been manageable, I'll probably just upgrade to a more pro adapter when more money comes in rather then invest more in the DIY
 
Hi Elmy,

You don't know what the strength of the achromat is do you, 5x, 8x, etc. Marumi of Japan make some pretty good DHG achromats in varing sizes and strengths. Do you know the thread size of the achromat.
 
Hi Elmy,

Send us an email and we can sort you out with an achromat lens for about £20 plus shipping. This would just be the glass, no aluminium ring.
 
all I know about my achromat is that its a Cinevate 72mm, and on one end it has a 52mm spacer threaded to it so i can attach it to the adapter.

Wayne this might come off stupid but whatever, how would I attach just the glass? wouldn't I need something similar to what I already have so i can attach it to the adapter?

Heres a picture of the achromat and the spacer im talking about, and then one of the adapter, not sure if its relevant but thought why not atleast show what I'm talking about (shot on iphone was too lazy to take out gh1 and take these lol)

photoes.jpg


photo1ta.jpg
 
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Elmy

When I was still at the development stage of my DIY spinning adapter I too reached the point of fine tuning. I had soft edges and CA. I was using, whats probably the first gen, 72mm Cinevate achromat.

I got Wayne's achromat, tho mine had the metal casing, and it solved my edge to edge sharpness issues and reduced CA to minimal.

The DIY adapter i made then became a potent tool in my arsenal allowing me to do high paying and high profile projects.

This one is a sample work using wayne's achromat.

[size=+2]Bohol Island Tourism Video[/size]

This adapter used only a DIY groundglass from a plastic CD case. :-)

If you want to push your DIY adapter to what it can do, Wayne's achromat is a VERY important component in the chain after your GG.

hope this helps you out.
 
I have no doubt Wayne's Achromat will be great, just don't know what I personally can do with just the glass =/
 
I'd test empty 72mm filter rings or try pvc piping. you can use hot glue around the edges. theres enough room to play around with the glass/lens housing since you need to position it at 69 mm away from the GG surface anyway.

Let me add, on after thought, since Waynes's diopter is less than 72mm diameter you can test smaller filter rings.
 
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