Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-20-2008, 03:34 PM   #1
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Pentax A 50 f/2.8 + Cosina 1:1 Macro adapter

I think I am closer to 1:1 in putting the Cosina 1:1 Macro adapter onto my Pentax A 50mm f/2.8 1:2 Macro. Here are some test shots done this morning.

Somehow, it is my first time to do closer to 1:1 macro and I find it a bigger challenge to shoot macro without a tripod. A lot of not-so-sharp shots come from the minute movement of my body upon focusing. And once the adapter is mounted, the DOF becomes razor thin making it very difficult to hand hold the shot in 1:1 in minimum focal distance. Overall the adapter gets the job done for me without much loss in bokeh and lighting.


Thanks,
Hin


Last edited by hinman; 06-24-2008 at 05:18 PM.
06-20-2008, 03:37 PM   #2
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
Not a great photo, but here is the perspective shots with the adapter mounted


Without adapter


With adapter mounted



Thanks,
Hin
06-20-2008, 07:35 PM   #3
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
B&W, Narrow DOF question

One shot in b&w conversion due to harsh and contrasty lighting with shadow





In the test shots, I get many narrow DOF shots that is very thin from off focus. I wonder if that is normal in using an adapter or if there are ways to address that with a smaller aperture. C&C welcome especially on the thin and narrow DOF when I use the adapter and shoot closer to minimum focus distance, e.g. a big portion of the flower following shot is out of focus




I shot it in f/5.6 and I wonder if upping the iso and a smaller aperture can minimize the effect.

Thanks,
Hin
06-20-2008, 08:50 PM   #4
Veteran Member
heatherslightbox's Avatar

Join Date: Nov 2007
Location: Gainesville, FL
Photos: Gallery
Posts: 2,594
Hin,
Those are gorgeous shots! They have a surreal quality about them, almost like paintings.

Heather

06-22-2008, 06:23 PM   #5
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
QuoteOriginally posted by hwblanks Quote
Hin,
Those are gorgeous shots! They have a surreal quality about them, almost like paintings.

Heather
Thank you! The adapter works well for me though the dof becomes very thin.

Last edited by hinman; 06-23-2008 at 10:33 AM.
06-24-2008, 04:46 PM   #6
Senior Member
Groundloop's Avatar

Join Date: Aug 2007
Location: Toronto, Canada
Photos: Gallery
Posts: 236
Nice shots Hin. I also have the 'A' 50mm Macro, and coincidentally I got out yesterday after a thunderstorm to do some flower shots, though I stayed in the 1:4 to 1:2 range. I could have put an extension tube on to get closer, but i was too lazy to drag out my tripod.

As to the razor thin DOF, that's just a function of close/macro focusing. Stopping down will increase DOF as usual, but it's unlikely you'll be able to get a full flower in focus. For example, I shot a strawberry at 1:2 and f/22, and the DOF started to trail off by the middle of the berry (maybe 3/4" - 19mm).
06-24-2008, 04:57 PM   #7
Forum Member




Join Date: Feb 2007
Location: Singapore
Posts: 62
Hi Hin, the water droplets on grass and flower (red ones) are really really beautiful! Razor sharp as well.. How did you managed to steady your hands to get such shots?!

I have this lens too and recently during a Singapore Pentax Meet, took these photos with it (Handheld, Lowlight, Drizzling)...











I would love to try the Cosina 1:1 Macro Adapter though, as these are at best 1:2. Where did you get it? Mind to share that info?

Anyways, Highly recommended!
06-24-2008, 05:12 PM   #8
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
QuoteOriginally posted by Groundloop Quote
Nice shots Hin. I also have the 'A' 50mm Macro, and coincidentally I got out yesterday after a thunderstorm to do some flower shots, though I stayed in the 1:4 to 1:2 range. I could have put an extension tube on to get closer, but i was too lazy to drag out my tripod.

As to the razor thin DOF, that's just a function of close/macro focusing. Stopping down will increase DOF as usual, but it's unlikely you'll be able to get a full flower in focus. For example, I shot a strawberry at 1:2 and f/22, and the DOF started to trail off by the middle of the berry (maybe 3/4" - 19mm).
Thanks for the comment. I will try smaller apertures with f/11 to f/22 as you suggested. The DOF is so narrow and a bit of movement will destroy the shot as off focus in a blur. The A 50mm f/2.8 is very sharp and I have used it for non-macro shot on portraits.

06-24-2008, 05:30 PM   #9
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
QuoteOriginally posted by Bernard Yeo Quote
Hi Hin, the water droplets on grass and flower (red ones) are really really beautiful! Razor sharp as well.. How did you managed to steady your hands to get such shots?!

I have this lens too and recently during a Singapore Pentax Meet, took these photos with it (Handheld, Lowlight, Drizzling)...

I would love to try the Cosina 1:1 Macro Adapter though, as these are at best 1:2. Where did you get it? Mind to share that info?

Anyways, Highly recommended!
Very nice shots you have. I think a tripod, bellow and rail are needed for better and serious work with macro.

But for the novice in me, I tried hand-holding. I push myself into hand-holding every time I get an opportunity. With the adapter mounted on A 50mm f/2.8 1:2 Macro, I get out of focus shots more than usual. And in an attempt to try 1:1, I turn the focus ring all the way to minimum focusing distance, and I use trap focus and move my body in and out from the center focal point -- it is prone to errors due to body movements. I have better shot with turning the focus ring instead. So in short I used two techniques:

1. At MFD exactly at 1:2 marking, I move in and out with minute movement and use trap focus to hit the shot

2. At close to MFD, say 1:4 and 1:3 marking, I trap focus in turning the focusing ring while remaining still in arm and body.

And about the adapter, I don't think you can buy it as a separate item, I happen to luck out in getting it as a side-item in a totally unrelated lens purchase. Here are article blog post about the adapter with link to Cosina/Pentax/Promaster 100mm f/3.5 Macro in lab review of the original lens with matched adapter

Last edited by hinman; 06-24-2008 at 05:38 PM.
06-25-2008, 04:11 PM   #10
Forum Member




Join Date: Feb 2007
Location: Singapore
Posts: 62
Thank you for the info! I'll try that out on the field...
06-26-2008, 10:37 AM   #11
Site Supporter
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,425
Original Poster
QuoteOriginally posted by Bernard Yeo Quote
Thank you for the info! I'll try that out on the field...
Bernard, I love your photos with the DA 35 that you replied with Jay's thread on showing why DA 35 Macro 1:1 does not suck.

Yesterday, my Vivitar AT-22 auto extension tubes arrived. And I have the K 100mm f/4.0 1:2 Macro to try it out. I may not know what I am doing, but I use 36+12mm = 48mm extension to add to my 100mm. For the life of me, I can't make a reasonable shot with the extension tubes on 1st try. For one, I lost the trap focus capability and the focal panes is so thin that I can't hand hold a shot without the trap focus. My experience make me to appreciate greatly the photos that Jay, you and others have shown with the DA 35mm limited.

Last edited by hinman; 06-26-2008 at 11:01 AM.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, adapter, corner, cosina, f/2.8, k-mount, macro, pentax, pentax lens, slr lens, tech
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Anybody else use a Cosina 28-210 macro? PentaxPZ Pentax SLR Lens Discussion 4 08-15-2009 03:29 PM
For Sale - Sold: Cosina 100mm F3.5 AF Macro edumad Sold Items 2 03-12-2009 08:20 AM
For Sale - Sold: Phoenix (Cosina) Macro schmally Sold Items 7 05-19-2008 08:34 PM



All times are GMT -7. The time now is 01:15 AM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top