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Contax G 21mm Samples/Experience?
  
 
genji
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p.3 #1 · p.3 #1 · Contax G 21mm Samples/Experience?


Wow, thanks for the close-ups! They're excellent. Makes me really glad I've ordered a PCX filter for my G28.


Sep 01, 2017 at 10:00 AM
sebboh
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p.3 #2 · p.3 #2 · Contax G 21mm Samples/Experience?


genji wrote:
Wow, thanks for the close-ups! They're excellent. Makes me really glad I've ordered a PCX filter for my G28.


thanks!

btw, if anybody is interested, i should soon be ordering a batch of rings machined for converting the g21 into the rokkor m-mount bodies. if you''re interested in getting rings for your own conversion or in having me do a conversion for you, send me a pm.




Sep 05, 2017 at 06:05 AM
Sam_W
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p.3 #3 · p.3 #3 · Contax G 21mm Samples/Experience?


sebboh wrote:
btw, if anybody is interested, i should soon be ordering a batch of rings machined for converting the g21 into the rokkor m-mount bodies.


Would you happen to be able to compare a G21 conversion into a Rokkor body vs a Hawk's Factory helicoid swap? I'm pondering getting a set of G lenses and going that route, vs having individual donor helicoids, and vs having them custom-rebuilt in Japan.



Sep 05, 2017 at 08:41 AM
sebboh
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p.3 #4 · p.3 #4 · Contax G 21mm Samples/Experience?


Sam_W wrote:
Would you happen to be able to compare a G21 conversion into a Rokkor body vs a Hawk's Factory helicoid swap? I'm pondering getting a set of G lenses and going that route, vs having individual donor helicoids, and vs having them custom-rebuilt in Japan.


there are a number of differences between my conversion, the hawk's factory, and something like the japan exposures conversion. another option to consider might be a custom job by another forum member, JimBuchanan, who does excellent work.

there was a discussion of some of the different conversions here a while back.

my take is that the hawk's and japan exposures conversions have the advantage of lighter weight, rangefinder coupling, and accurate focus scale (my focus scale is only accurate on the g45 since i use the same donor helicoid for all my conversions). The advantages of my conversions are that it's cheaper, more robust construction, heavier duty helicoid, and can focus to macro distances on the wide angle lenses.

here's what my g21 conversion ends up looking like.









Sep 05, 2017 at 04:35 PM
genji
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p.3 #5 · p.3 #5 · Contax G 21mm Samples/Experience?


sebboh wrote:
there are a number of differences between my conversion, the hawk's factory, and something like the japan exposures conversion. another option to consider might be a custom job by another forum member, JimBuchanan, who does excellent work.

there was a discussion of some of the different conversions here a while back.

my take is that the hawk's and japan exposures conversions have the advantage of lighter weight, rangefinder coupling, and accurate focus scale (my focus scale is only accurate on the g45 since i use the same donor helicoid for all my conversions). The advantages of my conversions are that it's cheaper,
...Show more

The fact that I can simply remove the 46-55mm step ring from the G28 setup (that I'll hopefully have before too long) makes the G21 even more attractive. I'm wondering if, in addition to the G21 conversion you've mentioned, you also offer a G28 conversion service?



Sep 06, 2017 at 03:07 AM
sebboh
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p.3 #6 · p.3 #6 · Contax G 21mm Samples/Experience?


genji wrote:
The fact that I can simply remove the 46-55mm step ring from the G28 setup (that I'll hopefully have before too long) makes the G21 even more attractive. I'm wondering if, in addition to the G21 conversion you've mentioned, you also offer a G28 conversion service?


i can certainly do that, in the past i've just given people the rings and instructions for the g28.




Sep 06, 2017 at 03:50 AM
Mathieu18
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p.3 #7 · p.3 #7 · Contax G 21mm Samples/Experience?


I know Derek had already posted some, I'd actually taken these last week but forgotten to process and post. I'm not a flower shooter in general but they do make useful subjects for close up samples.

These were shot on the G28 w/ PCX, and Techart Pro with a 10mm tube. I'd call it pretty good results. ISO was bumped up maybe higher than needed so sharpness could probably improve as well.

genji wrote:
The closer the better, IMO, even with a 28 (that's one reason I like the Distagon C/Y 28/2 so much).






























Sep 07, 2017 at 02:59 PM
cajer
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p.3 #8 · p.3 #8 · Contax G 21mm Samples/Experience?


Does anyone have issues auto-focusing with the techart adapter when stopped down? When I focus stopped down the camera thinks it's in focus and the green squares pop up. But afterwards the pictures seem slightly out of focus. I think this might be due to the very deep depth of field which confuses the focusing system.

Does anyone else have to open up fully on the techart to focus?



Sep 08, 2017 at 01:54 AM
Mathieu18
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p.3 #9 · p.3 #9 · Contax G 21mm Samples/Experience?


I find AF-C to be better than AF-S, but not 100%, I'd have to look at it more. Also, on the G28 with PCX filter, the Techart I currently have won't quite reach infinity.

Is anyone from Techart active on here? I thought I remembered someone commenting a while back. It seems to just be a software issue, be nice if they'd give us a software update for PCX lenses!

cajer wrote:
Does anyone have issues auto-focusing with the techart adapter when stopped down? When I focus stopped down the camera thinks it's in focus and the green squares pop up. But afterwards the pictures seem slightly out of focus. I think this might be due to the very deep depth of field which confuses the focusing system.

Does anyone else have to open up fully on the techart to focus?




Sep 08, 2017 at 02:30 AM
cajer
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p.3 #10 · p.3 #10 · Contax G 21mm Samples/Experience?


This is a very dumb question. What size lens cap do you use after you have install the PCX filter and the retaining ring?


Sep 08, 2017 at 05:30 PM
 

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Samuli Vahonen
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p.3 #11 · p.3 #11 · Contax G 21mm Samples/Experience?


cajer wrote:
This is a very dumb question. What size lens cap do you use after you have install the PCX filter and the retaining ring?

No dump questions exist... General answer: lens cap is the size of thread you have the retention ring installed into assuming you don't have extra step-up rings etc.

G21: I'm using 55mm filter frame installed directly to lens, and 55mm retention ring (pain in the ass to find one having inner diameter small enough) -> if I would use the lens without polarizer (=almost never) I would use 55mm filter. Typically I use G21 with B+W 82mm filter (= 55mm -> 82mm step-up -> 82mm polarizer -> 82mm lens cap) and if there is water in picture then there is high likelyhood of having 82mm ND-filter on top of the polarizer.

G28: It depends, in my 1500mm reversed PCX filter setup I have 46mm->55mm step-up + empty 55mm filter. But I mostly use this lens on Kolari v2 thin filter camera with 2500mm PCX, and that has 46mm->58mm step-up, 58mm->52mm step-down, so in rare case I would use just the lens (=actually this has never been the case this far) I would use 52mm lens cap. In real life I either step-up to 67mm or 82mm for polarizer (+ND) and use 67mm or 82mm lens cap. Sometimes the 2500mm filter has been used on Zeiss Biogon T* 2.8/25 ZM, which will vignette on any 52mm configuration, and the 2500mm is housed on 46mm->55mm step-up -> 55mm filter setup and then it's naturally 55mm.

Samuli



Sep 08, 2017 at 05:44 PM
genji
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p.3 #12 · p.3 #12 · Contax G 21mm Samples/Experience?


cajer wrote:
Does anyone have issues auto-focusing with the techart adapter when stopped down? When I focus stopped down the camera thinks it's in focus and the green squares pop up. But afterwards the pictures seem slightly out of focus. I think this might be due to the very deep depth of field which confuses the focusing system.

Does anyone else have to open up fully on the techart to focus?


The fact that the green autofocus area lights up does not indicate that the camera has found focus. Correct focus is indicated by the appearance of the green dot in the lower left: steady if the image is in focus (AF-S), steady and surrounded by double brackets (AF-C). If only the double brackets appear, autofocus is in progress (AF-C) and if the green dot flashes autofocus has failed.

In my experience, obtaining accurate autofocus with the Techart TA-GA3 depends on a number of factors (that I am aware of):
* the ambient light (the brighter, the better)
* the aperture (wide open is best)
* the position of the focusing area rectangle (centered is best)
* the autofocus mode (AF-C is better than AF-S).

So the TA-GA3 will struggle to accurately autofocus when stopped down in low light with the focusing area off-center. I would also note that the Techart PRO (for M-mount lenses) suffers from these limitations to a lesser extent than the TA-GA3.



Sep 10, 2017 at 05:32 AM
genji
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p.3 #13 · p.3 #13 · Contax G 21mm Samples/Experience?


Mathieu18 wrote:
I find AF-C to be better than AF-S, but not 100%, I'd have to look at it more. Also, on the G28 with PCX filter, the Techart I currently have won't quite reach infinity.

Is anyone from Techart active on here? I thought I remembered someone commenting a while back. It seems to just be a software issue, be nice if they'd give us a software update for PCX lenses!


I've found AF-C to be better than AF-S too. And that on my G28 with the PCX filter, the TA-GA3 doesn't reach infinity. This doesn't worry me so much because I tend to photograph relatively close subjects. But I also like to photograph in the late afternoon and early evening and have been so disappointed with autofocusing the G28 in lower light that I've decided to use the ULATA manual focus adapter with that lens and the TA-GA3 with the G45 and G90 lenses.



Sep 10, 2017 at 05:39 AM
Mathieu18
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p.3 #14 · p.3 #14 · Contax G 21mm Samples/Experience?


FWIW, I messaged the guy that popped up when the new Fotodiox TAP was announced, he claimed to be representing Techart, hasn't responded.

At any rate, the fact that the G28 will no longer AF is purely firmware driven. Without a lens mounted it's clear there is no hard stop on the AF motor. And if you manually wind the lens in, then mount it, you can MF and achieve infinity. As soon as AF kicks in, it racks focus and will no longer retract far enough to reach infinity.

My request was I believe would be a simple firmware update, open up the infinity parameter a bit further to allow the adapter to retract the lens barrel further, which would give us infinity. If anyone knows how to better reach those guys, pass it along!

genji wrote:
I've found AF-C to be better than AF-S too. And that on my G28 with the PCX filter, the TA-GA3 doesn't reach infinity. This doesn't worry me so much because I tend to photograph relatively close subjects. But I also like to photograph in the late afternoon and early evening and have been so disappointed with autofocusing the G28 in lower light that I've decided to use the ULATA manual focus adapter with that lens and the TA-GA3 with the G45 and G90 lenses.




Sep 22, 2017 at 03:15 AM
hanay78
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p.3 #15 · p.3 #15 · Contax G 21mm Samples/Experience?


Dear Samuli,

you mentioned you provided the link with the retention ring, or filter, you bought. I did not find it. Can you post it here? thanks you in advance

regards



Oct 02, 2017 at 07:26 PM
Samuli Vahonen
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p.3 #16 · p.3 #16 · Contax G 21mm Samples/Experience?


hanay78 wrote:
Dear Samuli,

you mentioned you provided the link with the retention ring, or filter, you bought. I did not find it. Can you post it here? thanks you in advance

regards

Hi hanay78,

Problem with eBay filters (well applies to Amazon as well) is that they vary from batch to batch.

My "painful" experiences: Front filter thread and [[url=http://www.fredmiranda.com/forum/topic/1453834/73#13987294]http://www.fredmiranda.com/forum/topic/1453834/73#13987294]http://www.fredmiranda.com/forum/topic/1453834/70#13971566 p71 #10] and [http://www.fredmiranda.com/forum/topic/1453834/73#13987294[/url] p74 #18]. PS. I do not have any magic way to find these, just browsed through the thread.

Generally I would recommend to order from may suppliers (=from different batches) and you may find some, which will have small enough inner diameter. From cost point of view it does not matter as filters cost next to nothing and you can order without shipping fee from eBay (thou not very environment friendly and you may waste $20-30). I have gigantic pile of 55mm and 52mm filter frames in my desk, as >95% of what I ordered did have not suitable retention rings.

Samuli



Oct 02, 2017 at 08:49 PM
sebboh
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p.3 #17 · p.3 #17 · Contax G 21mm Samples/Experience?


finally did an infinity comparison of the contax g 21/2.8 with and without the reversed optosigma 1.5m filter on an a9:





full sized
it looks pretty good.




Oct 02, 2017 at 09:55 PM
Mathieu18
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p.3 #18 · p.3 #18 · Contax G 21mm Samples/Experience?


Thanks for that, looks pretty good. Haven't pulled the trigger yet but it's on my short list. Need to sell some M4/3 stuff I'd been playing with.

Think we can get enough people using a TA-GA3 to get Techart to increase focus travel a bit so these wides with filter will AF to infinity? More so for the 28, but still.

sebboh wrote:
finally did an infinity comparison of the contax g 21/2.8 with and without the reversed optosigma 1.5m filter on an a9:
http://c1.staticflickr.com/5/4455/37203654340_9b10d844fe_o.jpg
full sized
it looks pretty good.





Oct 03, 2017 at 01:12 AM
sebboh
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p.3 #19 · p.3 #19 · Contax G 21mm Samples/Experience?


Mathieu18 wrote:
Thanks for that, looks pretty good. Haven't pulled the trigger yet but it's on my short list. Need to sell some M4/3 stuff I'd been playing with.

Think we can get enough people using a TA-GA3 to get Techart to increase focus travel a bit so these wides with filter will AF to infinity? More so for the 28, but still.



beats me, how many people actually use the TA-GA3? does it actually focus fast enough to use on the newer sonys (i only tried it briefly on an a7)?

y'all should just convert to m-mount.




Oct 03, 2017 at 03:41 AM
Mathieu18
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p.3 #20 · p.3 #20 · Contax G 21mm Samples/Experience?


Valid question, I'm sure it's not enough for them to care.

Speed wise, it's pretty good, similar to the TAP, maybe a hair faster than the Sony FE 50mm in AF-S. Good enough for most situations. I'd be a lot more happy if I could use my 28mm beyond about 8' with it though.

I would but Hawks is way to expensive and I hate the look of old Minolta lenses, only Canon FD was worse. If you can find a way to transplant into Super Takumars, count me in.

sebboh wrote:
beats me, how many people actually use the TA-GA3? does it actually focus fast enough to use on the newer sonys (i only tried it briefly on an a7)?

y'all should just convert to m-mount.






Oct 03, 2017 at 01:54 PM
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