Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.

---

Focal reducer/Speed booster adapter

for/Pentax PK K bayonet lens to Sony NEX mount 5 6 7 camera FS700 FS100

All metal structure, with excellent opticals (4 elements/2 groups, super multi-coated)
what it does:

•
reduce the focal length (by 0.72x wider)

•
Ex. 50mm lens on NEX with the adpater, eff. focal length is 50mm x 1.5(crop) x 0.72 = 54mm

　
•
effectively increases the maximum aperture of the lens by 1 stop



•
(in other words, under the same aperture, you can use faster shutter speed (by 1 stop).

　 what it does not:
there is no electronic integration, no auto fucusing

(you still need to manually focus your lens and aperture, etc.)

Focal Reducer Speed Booster Adapter Pentax PK K to Sony NEX 3 5 6 7 FS700 FS100 | eBay

[Sliver-Surfer]

Great idea! I must not have a EVF... Can live without it on my K-01 very well...

ok then a optional plug in EVF because on a sunny day it is fantastic to have one

[devorama]

mind posting a side by side? I'm curious how it effects the field of view and the depth of field.

I created a new thread for this because I figured other people might be interested too.

Evaluting the Lens Turbo

[rparmar]

All these shots seem soft as all get out. Disappointing.

[Sliver-Surfer]

All these shots seem soft as all get out. Disappointing.

They are samples of how the turbo looks straight out of the camera. Most of these shots are not sharpened using Post Processing and are done wide open on fast lenses.
IMHO too much PP sharpening usually will ruin the natural look of a picture
Ill take some shots with a sharp lens closed down for you

---

Last edited by Sliver-Surfer; 06-27-2013 at 02:14 PM.

[devorama]

They are samples of how the turbo looks straight out of the camera. Most of these shots are not sharpened using Post Processing and are done wide open on fast lenses.
IMHO too much PP sharpening usually will ruin the natural look of a picture
Ill take some shots with a sharp lens closed down for you

Yeah, I mean you have to look at the relative sharpness I guess. I could stop down the lens for more sharpness, but then I'd have a much deeper DoF. That kinda defeats the purpose for me.

[kenafein]

The price of the adapter is down to 166, from Roxen, on eBay.

[Sliver-Surfer]

Pentax K strong Backlight f1.8 Nice effect I think No Post Proccessing at all Ill get to some stopped down soon..Im just felling portraity today

Attached Images

View Picture EXIF

File Date

 

[rparmar]

They are samples of how the turbo looks straight out of the camera. Most of these shots are not sharpened using Post Processing and are done wide open on fast lenses.
IMHO too much PP sharpening usually will ruin the natural look of a picture
Ill take some shots with a sharp lens closed down for you

PP is not the issue. These shots are poor under any circumstances. Researching further I have found side-by-side tests that confirm that these knock-off adapters are quite bad optically. I guess I'll wait for Metabones to bring out a K adapter. That'll give me more time to save my pennies.

[Sliver-Surfer]

PP is not the issue. These shots are poor under any circumstances. Researching further I have found side-by-side tests that confirm that these knock-off adapters are quite bad optically. I guess I'll wait for Metabones to bring out a K adapter. That'll give me more time to save my pennies.

Oh well to each their own, save your pennies and cross your fingers..

[Sliver-Surfer]

here's my pentax k 1.8/55mm at f5.6 sharpness sample no pp sharpening full size
peep away
Link to Original click

100% crop

[DavidSKAF3]

Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!

[VisualDarkness]

Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!

It's like an inverted teleconverter that makes the focal length shorter and aperture wider. Note that you need a lens that projects a bigger circle natively than you r sensor.

[Sliver-Surfer]

Can someone explain what this adapter actually does and the difference between this one and one that has no glass at all and which one is better or worse? Thank you!

Zhongyi Is my favorite. all the other info is in the first page of this thread.
Also funny you rehashed this thread I discovered yesterday that some of my Pentax lenses cover the sensor on my A7 fairly well which would make for super panoramic shots (pentax-m 3.5/28mm in particular) also m-2.8/40mm m-1.7/50mm m-2.8/28mm

[Mikesul]

Zhongyi Is my favorite. all the other info is in the first page of this thread.
Also funny you rehashed this thread I discovered yesterday that some of my Pentax lenses cover the sensor on my A7 fairly well which would make for super panoramic shots (pentax-m 3.5/28mm in particular) also m-2.8/40mm m-1.7/50mm m-2.8/28mm

Perhaps I misunderstand. Are you saying that the focal reducer is useful on the A7? I thought it only did anything on crop sensors.

[Sliver-Surfer]

Perhaps I misunderstand. Are you saying that the focal reducer is useful on the A7? I thought it only did anything on crop sensors.

I am trying to discover whether it is, and which lenses work best . So far it seems more pancake like the lens is the better so Pentax-M have an advantage, I think. I haven't thrown any m42s on it yet. Here are some advantages I see so far.
1.Panoramic crops( distortion to the left and right)
2.Square crops(no issues..top and bottom nearly perfect)
3 Increase light sensitivity
disadvantages
1.distortion on sides
2.dark vignettes(need to be cropped)
these are on -m 3.5/28mm


The samples images I gave are not the best example because the bright chandleirs cast the dreaded blue circle and bight light reflection