Speedboosters and astrophotography

[EDBR]

Hello

 

Just a question for those who actually tried this. How is it performing. The most important question here is how it performs at night (with stars) versus coma, CA and sharpness (corners, presume center will be ok).

Real life examples would be welcome. Didn’t find much found on the web so presume it must not be so good.

Not interested in propositions to use other lenses...just FF-lens + speedbooster on a6000 or other aXXXX.

 

Friendly greetings

 

[Golem]

Speed boosers have noticeable curvature of field.

I doubt you can get the whole frame focused to

infinity unless you stop waaaaay down, which you

prolly won't want to do.

[EDBR]

Thanks Golom for your reply, didn't know this fact.

And certainly don't want to stop down, not even one stop :-)

No experience at all with speedboosters...

[Golem]

Not even ONE stop ? Remember, "first one's free". 

You'd just be "giving back" the extra stop that gives

the Speed Booster its name, not that just one stop

would compensate for field curvature.  

  

The way I raionalize it, for general photography, is

that I get to use my old FF wide angles on APS-C

bodies and get reasonably decent IQ for general

subjects and scenes ... all at a cost of losing only

one stop of useful speed.

  

If the math looks wrong, lemme clarify. Decent IQ

for general subjects starts at 2-stops down. One of

those stops was never there when the lens was on

a FF body without a Speed Booster. The other stop

is the only "real cost". IOW, put an f/2.8 on a Speed

Booster and it's an f/2.0. Stop it down 2-stops and

you're at f/4.0 ... only a ONE-stop penalty vs the fully 

wide open f/2.8 when it was mounted on a FF body.

[nomad]

@EDBR: Are you referring to the original Speedbooster by Metabones or one of the Chinese knockoffs?

 

If it's the original SB, I'd think it depends on your lens, since some of my old Zeiss Contax lenses (I only have the SB for those) are pretty much flat tfield.

[EDBR]

Golem, for landscaping I'm almost always using f8-f11

Nomad: Metabones (no Chinese things), lenses Samyang 14mm, 24mm and 35mm (ordered the Laowa 12mm)

 

The mean reason why I'm so demanding for using the lenses wide open is for the moments I would like to do astrophotography with a A6x00 in stead of my A7r2 or A7s. 

Why a 6x00 :

- Sometimes I like to travel real light, without my A7series and with just 2 or 3 lenses

- To do time-lapse (while I'm using the A7x for photography) without the need to bring more lenses...

But maybe it's cheaper and better to just buy an extra SY 12mm

 

https://edwarddebruyn.myportfolio.com/astrophotography