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Speedboosting an Aero Ektar 178mm f/2.5
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PostPosted: Wed Jun 19, 2019 6:51 pm    Post subject: Speedboosting an Aero Ektar 178mm f/2.5 Reply with quote

Hi,

I'm brand new here but made an account to ask some folks who might be familiar with this lens and the possibility of speedboosting the original 5x5 image circle of the Aero Ektar 178mm f/2.5 down to medium format (6x7?)

Thanks for your time!

-Calvin

@calvinsstory on instagram


PostPosted: Thu Jun 20, 2019 5:10 pm    Post subject: Reply with quote

No way the speed-boosted LF lens could cover 6X7.
The format of the speed-boosted image is given by the Speed-Booster regardless of the initial format covered by the lens. An APSC Speed-Booster will only cover APSC, regardless of the format covered by the lens. I've tried my Metabones Speed Booster with LF lenses and the resulted image was always APSC. There is an older post somewhere on this forum with the resulted Ground-Glass image of a LF lens with my Metabones Speed Booster. If I remember well it was a ~3cm. diameter circle on the GG.
There are some newer Speed Boosters that cover FF with MF&LF lenses, but that's the maximum you can get.


PostPosted: Tue Jun 25, 2019 6:17 am    Post subject: Reply with quote

I do a lot of speedboosting since years, often with homebuild speedboosters. So I speedboosted projection lenses on a Canon EOS 5D DSLR for example, longe before Kipon made the medium format to fullframe speedbooster only for mirrorless.
But my speedboosters are not perfect, I even try sometimes to optimize them for interessting bokeh. But one of my comparisons showed at first impression (!) that one of my DIY speedboosters ist not too far away from the Kipon.

From my point of view it could be possible to speedboost for a 6x7cm camera, but the long mirror box does not help. And the ideal speedboosting factor 0.5 and resulting f/1.25 are making things not easier.
For my speedboosting adventures I bought likely 200 lenses to act as speedbooster. About 40 of them are the most used in the experimental kit. Don´t even start with simple achromats or triplets for your idea.
And not everything one calulates as result is correct.

http://www.4photos.de/camera-diy/Homemade-Lenses.html


PostPosted: Tue Jun 25, 2019 12:40 pm    Post subject: Reply with quote

Good points ZoneV
I don't have an Aero Ektar but a Biotessar 16.5cm/2.8
It covers 4x5
I would like to get its qualities on digital but that is a lost cause.

The only option is to do as you did, by making your own optics.

As for mounting, a 4x5 press camera may be best anyway, with a 120 roll back. You have a focal plane shutter already and a built in focusing system. The only thing lacking is convenience.


PostPosted: Wed Jun 26, 2019 7:50 am    Post subject: Reply with quote

dan_ wrote:
No way the speed-boosted LF lens could cover 6X7.
The format of the speed-boosted image is given by the Speed-Booster regardless of the initial format covered by the lens. An APSC Speed-Booster will only cover APSC, regardless of the format covered by the lens. I've tried my Metabones Speed Booster with LF lenses and the resulted image was always APSC. There is an older post somewhere on this forum with the resulted Ground-Glass image of a LF lens with my Metabones Speed Booster. If I remember well it was a ~3cm. diameter circle on the GG.
There are some newer Speed Boosters that cover FF with MF&LF lenses, but that's the maximum you can get.

The Kipon Baveyes focal reducers allow mounting various MF lenses on Fuji GFX cameras (43.8mm x 32.9mm sensor). It won't cover a full 6x7 negative, but it delivers very nice images on digital medium format: https://www.josephdagostinophotography.com/blog/2018/1/10/fujifilm-gfx-and-pentax-105mm-24

Cheers!

Abbazz


PostPosted: Thu Jun 27, 2019 5:57 pm    Post subject: Reply with quote

I'd be happy to construct my own optics. I've heard about Binoculars being used? Any insight on this?

Thanks for your attention!


PostPosted: Thu Jun 27, 2019 6:44 pm    Post subject: Reply with quote

keep us apprised of your progress. It sounds very interesting.