Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-09-2014, 08:24 AM   #16
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Henry, TN
Photos: Gallery | Albums
Posts: 2,850
QuoteOriginally posted by Jost1 Quote
A helpful tip would be very welcome.
Presuming you have no experience with extension tubes or bellows: You simply may not be close enough to the subject to achieve sharp focus.

Start with a 50mm lens focused at infinity and minimum extension on the bellows in good light. Move the CAMERA toward the subject until you begin to see sharp focus. Gradually focus the lens closer and/or extend the bellows slightly as you gain experience. In any case, don't expect to be able to focus on things beyond arm's length until you have experience with the gear.

A bellows extension of about half the length of the lens focal length is a good starting point. A sand bag or solid table-top tripod will be a necessity.

04-09-2014, 11:46 AM   #17
New Member




Join Date: Jan 2014
Posts: 9
QuoteOriginally posted by pacerr Quote
Presuming you have no experience with extension tubes or bellows: You simply may not be close enough to the subject to achieve sharp focus.
You were most certainly right. Damn! I am not used to going this close to the object :-) The size of the magnification surprises me. The bellow isnīt anything out, but the buds on the cherry tree filled the frame completely on my Pentacon 50 f1.8. Iīm looking forward to when the days are warmer, and my spotmatic is loaded with Velvia 50. By the way…how is it with exposure-compensation? Would that be one stop?
04-09-2014, 01:18 PM   #18
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Henry, TN
Photos: Gallery | Albums
Posts: 2,850
First, the beauty of through the lens (TTL) metering is that it 'sees' the actual exposure -- no math necessary. The metering is correct as you see it -- I thought I'd died an gone to photo heaven when I could first afford a Spotmatic to solve that close-up exposure problem waaay back when.

Second, here's a general rule. 50 mm of extension added to a 50 mm lens equals very close to 1:1 image size -- depending on focus distance. Likewise, 50 mm worth of extension added to a 100 mm lens = 1/2 life-sized on the sensor, etc.

Pleased to hear you're using a Spotty and film . . . but the sad truth is, you'll learn a WHOLE LOT faster shooting digital with instant, no-cost review of your shooting.

Have fun.
04-09-2014, 02:19 PM   #19
New Member




Join Date: Jan 2014
Posts: 9
QuoteOriginally posted by pacerr Quote
First, the beauty of through the lens (TTL) metering is that it 'sees' the actual exposure -- no math necessary. The metering is correct as you see it -- I thought I'd died an gone to photo heaven when I could first afford a Spotmatic to solve that close-up exposure problem waaay back when.

Second, here's a general rule. 50 mm of extension added to a 50 mm lens equals very close to 1:1 image size -- depending on focus distance. Likewise, 50 mm worth of extension added to a 100 mm lens = 1/2 life-sized on the sensor, etc.

Pleased to hear you're using a Spotty and film . . . but the sad truth is, you'll learn a WHOLE LOT faster shooting digital with instant, no-cost review of your shooting.

Have fun.
The problem with through the lens metering is that it needs a battery, which I donīt have in my camera. Since I have an external light meter, I have not given it much effort to get a fresh one. But I will probably find the way to do it little by little. Since I can only use the lens on full aperture, I have only shot on 1/1000 by now, on 200 iso, and are planing on checking out how that roll looks like, before i use it on the velvia. Iīm not worried with the cost of my learning. If it fails, then I just label it LOMO. I am more determined to take you're advice on having fun. Cheers!

04-09-2014, 05:40 PM   #20
Loyal Site Supporter
pacerr's Avatar

Join Date: Jan 2008
Location: Henry, TN
Photos: Gallery | Albums
Posts: 2,850
Yep, and figuring out how to work around the battery issue is part of the fun, too.

The RM-400-R 1.35V Mercury Oxide Battery is no longer available, but the camera lightmeter (a bridge circuit) is not so voltage critical it won't work with a Maxell SR936W 1.5V Silver Oxide Battery. Find a selection of small rubber/neoprene ring gaskets or the plastic ring from an original battery to center the replacement in the battery socket.

Or, there's the Wein Cell 1.35 Volt replacement battery.

Or, you can notch the battery compartment cap to accommodate two thin wires and fabricate an internal "dummy" cell fed by any number of external voltage sources of approximately 1.35-1.5VDC.

One easy way is to duplicate the lens+extension pair and meter with another TTL DSLR to approximate the correct adjustment. In effect you're simply using another camera as a spot meter.

In all cases, it's best to do some meter comparisons to calibrate the readings. The clear north sky around noon provides a repeatable light source for calibration exercises. Completely de-focusing the lens when metering approximates the effect of the diffuser on a hand held meter.

Run a search on spotmatic battery and light meter calibration for lots more ideas - many from the PF archives.
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!
k-mount, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Asahi Pentax SMC-Takumar 50mm f/4 1:2 Macro M42 Mount Lens wallyb Sold Items 3 07-24-2009 06:48 PM
For Sale - Sold: Original ASAHI m42 macro extensions mayoapo Sold Items 2 01-07-2009 08:39 PM
For Sale - Sold: Pentax F35-70 / Kenko 2X macro Converter / M42 bellows (AUS-W/W) ddhytz Sold Items 8 12-03-2008 02:23 PM
T&S Asahi bellows eurostar Pentax Camera and Field Accessories 0 02-01-2007 06:37 AM



All times are GMT -7. The time now is 02:25 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