What’s Your Preference?

wulf · #1 (**permalink**) 03-06-2011, 08:23 PM

How about this:

That's my computer screen. I'm getting about 1px per mm on my sensor; I'm not sure how big a pixel is but that has got to put me beyond a 1:1 ratio!

I took it using my Vivitar 90mm (that gets me about 1:2 on its own). I held my 18-55mm lens reversed in front of it, set on 18mm. There is an aperture release lever on the 18-55mm which opens things up, letting more light in (although I still had to boost the brightness a bit in post processing).

I'm planning to do more with this - I want to see if I can use the camera gear I've invested in as a kind of microscope. Anyone else played with this kind of superzoom!

Wulf

daft_biker · #2 (**permalink**) 03-06-2011, 11:21 PM

Quote:

Originally Posted by wulf

Anyone else played with this kind of superzoom!

Aye.....

Great minds....

wulf · #3 (**permalink**) 03-07-2011, 08:01 AM

What was your combination of lenses? Any idea how zoomed in that really is?

Wulf

daft_biker · #4 (**permalink**) 03-07-2011, 09:49 AM

Quote:

Originally Posted by wulf

What was your combination of lenses? Any idea how zoomed in that really is?

Wulf

I think it was around 3:1 with the MP-E 65mm on a tripod and focus rail. It was quite hard to focus on the screen as the filter on the front blurs the LEDs.

Have you tried your setup on a bird feather? I find they make great test subjects for macro as there's loads of interesting details to see even at higher magnifications.

I recently tried photographing photosites on a camera sensor. It didn't work!

STEVE DIAS · #5 (**permalink**) 03-09-2011, 05:45 PM

I can't figure out how to post in this forum so I'll post the pic. in macro sec. I used a 70-300mm lense zoomed to 300mm with 67mm of extention tubes plus Raynox DCR250 at a focal distance of about 1.5 ft

wulf · #6 (**permalink**) 03-09-2011, 07:01 PM

I've fixed the picture for you - check our FAQ, which has an illustrated guide to posting from Flickr.

What is yours a picture of? Another LCD screen or is a CRT monitor or TV?

Wulf

STEVE DIAS · #7 (**permalink**) 03-09-2011, 07:19 PM

It's my CRT computer screen. Thanks for fixing the post. I've never had that problem before. I'll try to post something somewhere else. Maybe there's something not right with this pic., because the EXIF info is wrong also. but you got it to post.

wulf · #8 (**permalink**) 03-09-2011, 09:20 PM

Quote:

Originally Posted by STEVE DIAS

It's my CRT computer screen...

When you get that close, the difference between CRT and LCD is very obvious. I'm looking forward to explore more and seeing what other small details I can turn up.

Wulf

wulf · #9 (**permalink**) 03-15-2011, 11:59 AM

I have spent a bit more time experimenting with how close I can get using my camera set up. With this shot, I used my Nikon D40 attached to my Vivitar 90mm lens (including extension section, which takes it to a 1:1 ratio), my Raynox DCR-250 and a reversed 18-55mm at 18mm (aperture held open). I have brightened the image with Picnik so you can see the markings (about 8mm across the ruler). My sensor is about 24mm wide so that works out at about a 3:1 ratio. The gold standard is 1:1 (1mm in real life equals 1mm on the sensor) so I have surpassed that.

A 1mm wide section is 320px wide, so 1px must be is about 3μm across. Therefore, given better lighting, I should be able to see plant cells and pick out details of the larger ones as, according to my online searches, plant cells vary between 10-100μm wide.

Magnification depends on the size of screen the image is viewed on. On my monitor at 100% image size, 1mm on the ruler takes up 12cm (120mm) so magnification is x120. That is not as much as some of the relatively cheap USB microscopes boast but I suspect the image quality is much higher.

I don't know how that compares to the example I posted at the start of this thread - the advantage of using a ruler as a subject is that you can then immediately translate your results into meaningful figures.

Wulf