HV20/30 + Letus Mini = Vignette?

[Sean Michael]

Letus Mini owners, I have one more question....

When setting backfocus, is it NECESSARY to use manual focus? Or can it be set using autofocus?

The reason is that I picked up a dirt cheap HV20 today. But there was one catch: the manual focus wheel is not working.

[thequads]

you can focus using the buttons on the lcd screen, so you should be okay.

[silosr]

And yes, you can use autofocus also. In fact, that's what they say on the instructions. Dirt cheap? Lucky!!!!!

[Sean Michael]

And yes, you can use autofocus also. In fact, that's what they say on the instructions. Dirt cheap? Lucky!!!!!

Thanks guys, that is good news.

Got the last HV20 at my local Circuit City today... for $294! It is going on the Letus Mini I ordered Friday.

[booggerg]

I have to agree with twoniel, it does depend on the setup you have. I have recently added a condenser to my diy adapter as I'm using Alex's ggs and I have zero vignette.

This is my hv20 zoomed all the way out:


some footage: http://vimeo.com/1013650

WOW!

So I guess you can shoot at f2 or so and still fill the entire view? WHat is the condenser that you added? Is it sort of like an acromat?

[Dennis Wood]

That frame grab is showing a high level of chromatic aberration...what are you using for an achromat?

Silosr, you should definitely use manual focus only when using an adapter! Autofocus will hunt at some point during a shot, ruining your shot. Autofocus is OK to initially focus on the GG, but you should definitely turn it off...same goes for OIS.

Cheers,
Dennis.

[Gymnut808]

That frame grab is showing a high level of chromatic aberration...what are you using for an achromat?

Silosr, you should definitely use manual focus only when using an adapter! Autofocus will hunt at some point during a shot, ruining your shot. Autofocus is OK to initially focus on the GG, but you should definitely turn it off...same goes for OIS.

Cheers,
Dennis.

Hi Dennis,

I'm a newbie in terms of the terminology, but how were you able to deduce that the above frame grab has a high level of CA, even though it was all the way zoomed out?

[thequads]

examine the high contrast edges, like along the tree leaves/trunk and sky or gray roof and white trim, even against the black matte box and image.. You see that blueish halo effect? That's it.. it's probably more noticeable on the full sized image.

[Gymnut808]

examine the high contrast edges, like along the tree leaves/trunk and sky or gray roof and white trim, even against the black matte box and image.. You see that blueish halo effect? That's it.. it's probably more noticeable on the full sized image.

Ah I see, although wouldn't that be less pronounced once zoomed in enough into the ground glass? Or would that bluish cast still be prominent?

[silosr]

That frame grab is showing a high level of chromatic aberration...what are you using for an achromat?

Silosr, you should definitely use manual focus only when using an adapter! Autofocus will hunt at some point during a shot, ruining your shot. Autofocus is OK to initially focus on the GG, but you should definitely turn it off...same goes for OIS.

Cheers,
Dennis.

Hi Dennis,

just to clarify, I'm not talking about setting auto focus ON while shooting. His manual focus ring does not work so I'm just reassuring him that at setup, he can choose auto focus, but then as you say it should be turned off once focused. So setup steps for me are:

1) Mount adapter to the HV20
2) zoom in all the way
3) Use auto focus OR manual to focus on the ground glass
4) Once set, turn OFF auto focus
5) Attach lens
6) zoom all the way out
7) zoom in until no vignette or whatever looks good for you

After that, it's actually an advantage that his focus ring on the HV20 does not work so it doesn't accidentally move around.

Thanks for clarifying though.

Cheers,
Ronnie