Letus HVX Achromat + DIY

Tunnelmen

Tunnelmen

Active member
Has anyone tried a combination of the HVX Optimized Achromat from Letus along with a diy adapter? I've been thinking of trying it out, but I don't really know the pros and cons of it. Its my understanding that the optimized adapter improves the edge to edge sharpness for the hvx....is that right?
 
The concept of an optimized achromat is somewhat of a myth I'm afraid. Getting the camera into a different zoom range (where edge softness is less prevalent) is all that is being done. If you're doing a DIY adapter, our non-flip achromat works great on the HVX. Keep the camera at f4 or so (where the stock lens is happier) and you'll get great results.

Bob Gundu shot this clip nearly four years ago now using our non-flip achromat, Brevis35 (a very old one) and his HVX200.

Cheers,
Dennis.
 
I'm afraid that I have to respectfully disagree with Dennis here. I'm not sure what he means by an optimized achromat being a myth. It might be possible that all it does is put you in a different zoom range but that needn't mean it doesn't improve things.

I know i have tested a number of adapters - principally the Letus and then the SGBlade both before and after they "improved" their achromats for the Ex-1. I don't know what those improvements were (they may have only been strength which would fit in with Denis' argument) however I can tell you for sure that on the EX-1 the achromat changes made huge improvements for both Letus and Blade. I can't say how much of a difference they made on the HVX.

My recollection was that when Letus improved their achromat for the EX-1 they also billed that as an improved achromat for the HVX and that the optimized EX-1 and HVX achromats are the same. Not certain though.

I can say that in my experience you can get pretty decent results with either the Blade or the Letus achromats at wide open apertures ( f1.9). F4 is always going to sharper but I can rarely afford the stop and shoot wide open often with no issues. All my testing incidently was done with resolution charts so I feel pretty confident about decent corner sharpness especially with the Blade.

However its important to note that as far as I know both Letus and Blade achromats were designed to work with their flips units and that may make the distance to the screen different. Perhaps other optics are involved in the flips as well. My recollection is that when the manufacturers of these units added flips their resolution got better as well, but I'm a bit out of my technical expertise here.

BTW although I disagree with Dennis' statement above I have no idea how any of those achromats might work with your DIY and perhaps Dennis' suggestion would be a great choice.

Lenny Levy
 
Lenny, once the achromat is designed correctly, then the only way to address edge softness is to change the amount of zoom being used by the camera. As a rule, less zoom = better edge to edge. In the case of the adapters you referenced, a stronger achromat is possible due to short optical paths. More glass = more chromatic issues which are observed with those adapters. That's why our EX1 "fix" uses internal corrective optics and leaves the achromat alone.
 
Dennis, we've talked about some of these issues before and I'm sure you know more about the optics than I do. Whether or not the so called correction is just a stronger achromat that changed the zoom amount, I can say that the achromat changes worked very well and allow for shooting at wide open apertures on the Ex-1 with sharp corners. The Blade is particularly sharp.

I have no idea how that would carry over to a DIY though.
 
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