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Forum: General Photography 04-04-2020, 12:33 AM  
CS mount varifocal CCTV lens usage in photography.
Posted By tryphon4
Replies: 5
Views: 363
A C-S lens could be used on a Pentax Q, the problem is to find a "C-S lens to Q" ring adapter.
There are plenty of "C lens to Q" adapters but I never found a "C-S lens to Q" one on €bay.


C mount register is 17.526mm, C-S mount register is 12.526mm, Q register is 9.2mm.
Camera Mounts Sorted by Register

You may want to 3D-print a custom adapter, then there is a useful link : C & CS Lens to PENTAX Q mount adapter by nameless911 - Thingiverse
Forum: Photographic Technique 12-17-2019, 11:08 AM  
Macro Another Macro option
Posted By tryphon4
Replies: 15
Views: 966
Well, it does not look so different from what is commonly used by macro fans.

For example, in 2011 I used this setup: Pentacon six lens (80mm F/2.8) on a "PK to Pentacon six" tilt adapter, step-down rings, reversed enlarger lens (Componon 28mm F/4)



You can easily reach 8:1 and more with that kind of setup, what is important is to use very good optics (sharp). In this case the Pentacon was not so good, using the reversed 28mm on long extension rings was preferable :)
Forum: Pentax News and Rumors 12-03-2019, 02:20 PM  
Mitakon 85mm 2.8 1X to 5X Macro Lens $499
Posted By tryphon4
Replies: 48
Views: 3,406
This lens seems to be very interesting!

The announced working distance at 1:1 (230mm) is similar to the Sigma 180mm macro F/3.5's working distance, huge!
The announced working distance at 5:1 is stellar: 95mm. For information, the "famous" Canon MP-E 65's working distance at 5:1 is 41mm only!
In fact it is hard to believe.
Forum: Pentax SLR Lens Discussion 12-01-2019, 07:41 AM  
Pentax macro lens
Posted By tryphon4
Replies: 44
Views: 1,767
The original 60mm F/2.8 2:1 macro lens is made and sold by Venus-Laowa.
However, there are copies of this lens with almost the same shape, they share the same optics and are sold under other brands: Oshiro or Bresser.

According to Laowa, the Oshiro's and Bresser's 60mm are copies, but I have no proof of that. The price is lower for the (potential) copies so I bought a copy (mine has no brand at all but the shape is the same than the Bresser).

Here is the Laowa:


Here is my "copy":


The common characteristics of Laowa, Oshiro and Bresser are:
- No "A" position on the aperture ring: If you set an aperture of F/16, you will compose your photo and focus at F/16, not wide open (and it may be difficult if you have no pilot lamp).
- 14 blades aperture
- same weight, height, diameter: about 500g, 70x95 mm
- same optics (9 elements, 7 groups)
-same minimum focusing distance: 18cm


This is the Venus-Laowa user review section: Venus Optics Laowa 60mm F2.8 2:1 Ultra Macro Lens Reviews - Venus Laowa Lenses - Pentax Lens Review Database

The Kuangren Kx 800 flash is compatible with any Pentax camera. It is fully manual: you separately adjust the power of the two heads.





It contains a led pilot lamp (with variable power), this pilot lamp is hugely useful when you close the aperture at F/8 and beyond.
Forum: Pentax SLR Lens Discussion 12-01-2019, 08:00 AM  
Pentax macro lens
Posted By tryphon4
Replies: 44
Views: 1,767
The working distance is an important characteristic from my moint of view, because insects can be very shy.

You can find below some working distances at 1:1, in centimeters:

(http://hlaville.free.fr/MMP/regle_macro.png)
As it is in French, I have to translate a point: the Vivitar 135mm Close Focus (real 135mm, reaches 1:2 alone) is here used with an extension ring set (650mm added), it is impressive but hard to use because it becomes a bazooka (see below, the last lens).

(http://hlaville.free.fr/images/150macro/_1150019.jpg)
Forum: Pentax SLR Lens Discussion 07-29-2019, 08:48 AM  
Pentax-FA 100mm SMC f/3.5 Macro
Posted By tryphon4
Replies: 8
Views: 1,045
I owned this lens (mine was AF and Cosina branded), it was my first macro lens.

It reaches 1:2 alone, and 1:1 using the provided diopter. The diopter quality is good: it is an achromatic one.
The image quality is not in par with the quality delivered by a true macro lens (Pentax 100mm/2.8, Tamron 90mm/2.8, Sigma 105mm/2.8 etc.) but it is a bargain if you can cope with the noisy AF, the cheap-looking plastics and the long focus throw.
On top of that, the working distance is quite interesting: about 13cm.

More info here: Cosina ( Vivitar etc) 100mm F3.5 MC Makro Lens Reviews - Cosina Lenses - Pentax Lens Review Database
Forum: Flashes, Lighting, and Studio 05-28-2019, 01:15 PM  
Looking for twin macro light bracket
Posted By tryphon4
Replies: 10
Views: 761
I bought a Kuangren K-X 800 macro flash (single hot-shoe mounted power units with two flexible arms), it is full manual but extremely versatile. Now this is the only flash setup I use in proxi & macro. The continuous LED light improves manual focusing, then the two-heads flash is adjustable by 1EV step for each head.

Forum: Pentax Medium Format 04-26-2019, 05:44 AM  
FA 4/300 with M8 tripod mount - bizarre
Posted By tryphon4
Replies: 12
Views: 1,315
Your M8 thread looks like an helicoil. This kind of insert is easy to put in but very difficult to remove.
Forum: Lens Clubs 03-05-2019, 01:43 PM  
*Macro* lens club
Posted By tryphon4
Replies: 3,864
Views: 511,935
Irix 150mm F/2.8 macro:


exif


exif
Forum: Pentax SLR Lens Discussion 02-16-2019, 07:34 AM  
Any K mount lens that's more macro than macro (ie, micro)
Posted By tryphon4
Replies: 38
Views: 2,239
Micro is by definition between 10:1 and 100:1.
You will need very specialized stuff (e.g. microscope lens, micro slider, bellows, tube lens, etc.) and focus stacking will be your nightmare.

If you plan to shoot between 1:1 and 2:1, some good lenses are available: Laowa-Venus 60mm F/2.8 2:1 macro, Oshiro-Bresser 60mm F/2.8 2:1 macro.
If you plan to shoot between 2:1 and 10:1, you can try a short enlarger lens (e.g. Componon 28mm F/4) or a 5X or 10x microscope lens (if you can afford a MPlan APO ELWD episcopic one, it will be an excellent choice) but you will need some extra stuff (160mm or 200mm tube lens, specialized lighting).

I own lots of stuff but practically I mainly shoot handheld, between 1:4 and 2:1, most of time using a 90mm macro (sometimes with a DCR-250 close-up or with a 1.4x teleconverter), my new Irix 150mm macro or my Oshiro-Bresser 60mm macro, depending on the working distance I need.
Forum: Pentax SLR Lens Discussion 01-18-2019, 12:09 PM  
Macro Lenses Suggestions
Posted By tryphon4
Replies: 73
Views: 3,857
This thread seems to speak about "minimum focus", but don't you think it would be a better idea to speak about "working distance"?

The working distance (WD) is the distance between the subject and the front of the lens.

WD is function of real focal length and magnification.

Here are some examples at 1:1:
Oshiro/Bresser 60mm 2:1 macro: 55mm
Tamron SP Di 90mm macro model 272E: 95mm
Panagor PMC 90mm macro: 127mm
Irix 150mm macro: 172mm

I have more examples at 1:1, 1:2 and 1:4 (other lenses with close-up or extension rings) if needed, you can read this page.
Forum: Pentax SLR Lens Discussion 12-29-2018, 04:00 AM  
Macro Rings or Tubes?
Posted By tryphon4
Replies: 15
Views: 1,148
There are lots of things to say regarding close-up lenses (e.g. the Lensbaby macro filter kit) and extension rings.


Extension rings, tubes, bellows and helicoid tubes basically share the same principle: separate the lens from the film plane (or sensor) by a longer than normal distance.
You can find below, from left to right, an helicoid tube (M42 to PK mount), a three-rings kit (KA mount, rather rare) and a tilt helicoid tube (M39 mount):




Of course I also own some close-up lenses from 1.5 to 8 diopters.
Generally speaking, close-up lenses are preferentially used with long focal lenses (more than 100mm) and rings/tubes/helicoids are preferentially used with short focal lenses (less than 100mm). It is just because the effect of a ring decreases proportionately when the focal length increases.

The principle of a close-up is to decrease the focal length of the batch (lens+close-up). The focal length decreases while the distance between sensor and lens remains constant, so the enlargement increases.

I choose a close-up with a long lens (e.g. my 135mm F2.8 1:2) when I want to keep a long working distance.
I choose an helicoid ring or one or more extension rings with a short lens (e.g. my 60mm F2.8 2:1) when a short working distance does not bother me.

Here you get 3.9:1:


Here you can see a tilt helicoid setup:



Extension rings, tubes, bellows and helicoid tubes do not contain any glass, they are full of air so they cannot reduce the image quality, whereas a close-up can visibly decrease the photo quality, specially if it is not achromatic.
Single lens close-up should never be bought, instead you shall choose a two-elements or a three-elements achromatic or apochromatic close-up.
Forum: General Photography 12-30-2018, 07:14 AM  
What is your "Lens of the Year 2018"
Posted By tryphon4
Replies: 32
Views: 2,161
Well, I have two "lenses of the year 2018", both of them are not Pentax, sorry!
I love these lenses, they are not perfect but I find that color rendition, bokeh and sharpness are amazing.

EXIF data is available in the full sized photos (just click the photo)


1. Oshiro/Bresser (true copy or rebranded Venus/Laowa ?) 60mm F/2.8 2:1 macro










2. Vivitar 135mm F/2.8 close focusing








Old gallery: https://www.flickr.com/photos/tryphon4/
Current gallery: https://www.flickr.com/photos/160313322@N07/
Forum: Pentax SLR Lens Discussion 05-25-2018, 11:58 PM  
Rokinon 20mm users
Posted By tryphon4
Replies: 16
Views: 1,263
I own the Pentax A 20mm F2,8, it is a superb lens.
The only drawback is the barrel distorsion, but it is not excessive, in fact I never correct it.
Sadly, it is no more manufactured.
I bought mine used. The FA 20mm F2,8 share the same optical formula.

Previously, I owned a Soligor 20mm F2.8, less sharp than the Pentax but cheaper too and able to deliver very interesting bokeh.
Forum: Pentax SLR Lens Discussion 05-17-2018, 11:45 AM  
Lens Radiation Revisited. This time with the State of Arizona involved !
Posted By tryphon4
Replies: 71
Views: 4,189
170 micro rems?
I think that the whole World (even the USA) now use Sievert (Sv) instead of Rem.
1 Rem=0.01 Sv so 170 µRem=0.0017 mSv

If your lens really emits 0.0017 mSv/h, you will get 6mSv in only 147 days* (or you will get 14.9 mSv/year), it is a lot.
For example:
In nuclear power plants (in France) the maximum dose, for "B category people", is 6mSv/year.
The natural background radiation, global average, is about 2.4mSv/year.

* if you put your lens into your pocket and carry it all the time even when you sleep.

So my advice is: when you do not use your lens, keep it into a lead closed box.
Forum: Pentax SLR Lens Discussion 03-10-2018, 10:16 AM  
I want this lens
Posted By tryphon4
Replies: 17
Views: 2,286
False. Depth of field is proportional to magnification (and also to aperture value and confusion circle diameter).
So at i.e. 1:1 and F/8, a 25mm, a 100mm or even a 200mm will provide the same depth of field (but not the same bokeh, the latter one will be the smoothest).
This kind of mistake is very common, I don't know why. :confused:

Well, there are many ways to get 5:1 magnification (macro lens and bellows/extension tube/helicoid tube, macro lens and close-up, microscope lens and so on) but this lens has an advantage: it goes from 2.5:1 to 5:1. Using a bellows or helicoid tube, it is possible to do the same (but not versatile) but if you use close-up or extension tube I wish you good luck...
Forum: Pentax K-1 04-02-2018, 12:14 AM  
Cosmetic Question-77mm 1.8 Limited on the K1
Posted By tryphon4
Replies: 35
Views: 3,586
Here is my K-1 with FA77/1.8 (and Refconverter A viewfinder):




Forum: Pentax SLR Lens Discussion 03-16-2018, 02:23 PM  
Anyone got any experience with the no-name 60mm 2:1 manual focus off ebay?
Posted By tryphon4
Replies: 11
Views: 2,387
I own this no-name lens.

I don't know whether it is a Venus copy or a rebranded Venus lens, all I know is:
- Bresser 60mm looks exactly like Venus 60mm.
- Oshiro 60mm looks more or less like Venus 60mm (there are minor differences).
- Laowa pretends that Bresserr, Oshiro and no-name are counterfeits lenses.
- The optic formula, minimum distance, aperture blades number are identical, even the distances on the lens are the same...

The aperture is not automatic on this lens (whatever the brand), i.e at F/10 it is very hard to focus because there is not much light.

There is a thread about this lens here (sorry, in French and on another forum): Venus/Laowa 60mm F/2.8 2:1 macro

To resume:

On a K-1 you won't be able to shoot at infinity because of vignetting:

F/2.8-------------------------------------------------------------------------------------F/22


F/2.8 portrait (taken using a K-3), not so bad (resized to 1280*1024):


100% crop of the previous


Round aperture:


I performed a comparison (F/8, about 2:1) between APO Rodagon 50mm F/2.8, 60mm F/2.8 macro, Componon 28mm F/4, the results show that the 28mm looks like the best, the 60mm is 2nd, the 50mm is 3rd but they all are in the same league.

Here you can see the real Venus and the no-name, there are slight differences:



The working distance between 1:1 and 2:1 is constant but tiny:


Using a dedicated macro flash (Kuangren Macro Twin Flash KX-800) is generally a good idea:





To resume my feeling: I often use this versatile lens, it is not for beginners but when you get accustomed to it, it enables interesting macro shots.
Forum: Pentax SLR Lens Discussion 03-04-2018, 07:44 AM  
Super wide/Fisheye advice for the K1
Posted By tryphon4
Replies: 15
Views: 1,722
What are your requirements, what is you budget?

If you can cope with a K mount lens, the Zenitar 16mm fisheye F2.8 is full frame compliant and 137°*88° field of view.



Forum: Pentax SLR Lens Discussion 03-04-2018, 07:58 AM  
Super wide/Fisheye advice for the K1
Posted By tryphon4
Replies: 15
Views: 1,722
AFAIK, you can find the Samyang 12mm fisheye in K or KA mount.

Here you can see the "A" pin: https://www.pentaxforums.com/userreviews/data/114/large/samyang_12mm-f2_8_fi...ide-pentax.jpg
Forum: Photographic Technique 08-29-2017, 03:14 AM  
Macro Extension with 1:2 macro lenses
Posted By tryphon4
Replies: 20
Views: 2,542
Well there is a point not to ignore: some lenses, when used at macro distances, are not at their official focal length, it is a common trick.
For example, a 70mm macro could be a 50mm at macro distances. Then the working distance will be about 50mm, like with a 50mm.

BTW, when you add some extension rings (or bellows) to a lens, the working distance will, at 1:1 and beyond, reach the real focal lenght (i.e: my 50mm, at 2:1, 3:1 and so on, will have a working distance of 50mm.)
Forum: Pentax K-1 07-14-2016, 02:29 AM  
K-1 marketing in France
Posted By tryphon4
Replies: 7
Views: 1,233
That's right.
I bought my K-1 there, i highly recommend this store.
Forum: Pentax K-1 05-11-2016, 01:46 PM  
Review from French site
Posted By tryphon4
Replies: 5
Views: 1,464
The guys at Focus Numérique are not objective, i demonstrated this comparing the K-1 Af coverage vs the D810 (or D750) and the 5Ds R coverage: they are almost the same.
So why don't they write "AF coverage restricted 24x36" in the D810, D750 and 5Ds R test?
Because they like Nikon and Canon and dislike Pentax.



Forum: Pentax K-1 05-01-2016, 06:31 AM  
Post your K-1 pictures!
Posted By tryphon4
Replies: 29,182
Views: 2,573,160
Forum: Photographic Technique 04-25-2016, 04:17 AM  
Macro Reversing with 50 and 135
Posted By tryphon4
Replies: 12
Views: 1,627
A reversed lens acts like a close-up lens.
Its power is given by this formula: P=1000/F
So reversing a 135mm is equivalent of using a (1000/135)=7.4 diopter close-up and reversing a 50mm is equivalent of using a (1000/50)=20 diopter close-up.

You can either screw the reversed lens in front of a normal lens or directly mount the reversed lens on the SLR.
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