Using NON DIGITAL lens on DIGITAL SLR
PhotoCamel: Your friendly photo community, with free discussion forums, digital photography reviews, photo sharing, galleries, downloads, blogs, photography contests, and prizes.
 

Go Back   PhotoCamel - Your Friendly Photography Forum > PhotoCamel Lounge > Photography Talk

Reply
 
LinkBack Thread Tools Display Modes
Old 07-04-2006   #1
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Using NON DIGITAL lens on DIGITAL SLR

Hello Camels!

To save some money I use two types of adapters on my SIGMA SD10. One is for M42 lens type the other one is for NIKKOR lens type. The link is purely mechanical and does not extend to electronic controls (AF motor, aperture control). This reduces obviously the functionality of the camera - lens combo. It does give me the opportunity to use glass that otherwise would collect dust only

When doing a rather comprehensive test with some prime lenses from Nikon, I noted a discoloration in the centre of the picture, when stopping down. I suppose that is due to reflection of the aperture blades or whatever. Fact is that the lens was not designed for reflecting CMOS sensors, rather than film.

This is what I get. Anyone note something like this before...


__________________
Members don't see ads in threads. Register for your free account today and become a member of PhotoCamel to open up the site's many benefits and features.
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #2
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

Oops. Forgot the picture
Attached Images
File Type: jpg Outdoor (Near, Tripod) Nikkor 1.2 55 F16.0.jpg (92.1 KB, 116 views)
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #3
Llama
 
Posts: 670
CamelKarma: 23
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

Not so sure about whether a lens is designed for CMOS or not. Maybe some coatings help it. Most of the FF lens are/were designed with film in mind and they seem to work rather well on most digitals crops.
__________________
Richard
Canon 5D
metalstorm is offline   Reply With Quote
Old 07-04-2006   #4
Camel Breath
 
jfrancho's Avatar
 
Location: Rochester, NY
Posts: 11,666
CamelKarma: 4939
Editing OK?: No
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

You say "stopping down," - how far down? It could be diffraction, which, for Canon sensors, usually manifests as softness, starting at f/11. I have no idea what the limit is for Sigma. There are quite a few vintage lens enthusiasts I know that use some very old glass on digital SLR cameras with excellent results. Do some experimenting with different apertures, and let know what the results are.
__________________
┐ <░)))))><
jfrancho is offline   Reply With Quote
Old 07-04-2006   #5
Dromedary
 
Location: Minnesota
Posts: 1,272
CamelKarma: 6452
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

Sean,

For what it's worth, I've been shooting straight digital for several years and don't own a "digital" lens, I've never seen anything like that.

Now, I don't don't want to start a verbal war with the Nikon gang, but, if this is only happpening with the Nikon lenses, that would explain (posssibly) why Nikon went so heavy into the "digital" lens series, not just for the ratiio difference? Just wondering.

And yes, my gear is all Canon. *I hope someone has the correct answer! it's an interesting one, that I'm sure will have a lot of opinions!

Bill
bill8131 is offline   Reply With Quote
Old 07-04-2006   #6
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

The picture shown is stopped down to 16 (as shown in the filename).

On my 1.2/55 the 'purple spot' effect becomes visible at f=5.6 and get's more obvious from there onwards. On the 3.5/28 I can see more or less the same thing (with less intensity) starting at f=11.

However those two, are the only ones having this effect so far.

What SIGMA claims on their website, is that they have specific coating on the lens (near side camera) to prevent harmful reflections from the imager. I don't know, whether the aperture blades are a factor here.

Cheerio. Sean.
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #7
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

Ok. Let me show me the test results.

I would like to add that I LUV NIKON lenses. The 1.2/55 is crisply sharp at f=2.8! The spot issue was seen also on other sets (one indoor and another outdoor at infinity). Only when stopping down, I get this...
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #8
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

And more aperture settings...
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #9
Former Camel
 
Posts: 839
CamelKarma: 363
Editing OK?: Ask First
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

As I'm stopping down (see filename), you can see the centre of the picture gradually turn colder until the purple spot comes out.

I should add that the Nikkor 1.2/55 is really old (probably my age, haha)

Cheers.
sean_buerger is offline   Reply With Quote
Old 07-04-2006   #10
Camel Breath
 
jfrancho's Avatar
 
Location: Rochester, NY
Posts: 11,666
CamelKarma: 4939
Editing OK?: No
Constructive Critique?: Yes
Default Re: Using NON DIGITAL lens on DIGITAL SLR

My very rudimentary understanding of this, is that at higher aperture settings (small aperture, "stopped down") the light is too unidirectional to properly illuminate each photosite on the sensor, and therefore results in softness and discoloration. How the so called "coatings" work to mitigate that, I have no idea. I, like Bill above, use Canon, and exactly none of my lenses are "digital," or designated EF-S. In fact, I'm pretty sure my 35 f/2 is closer to 20 years old than 10, which automatically predates the digitalera for consumers.


__________________
Members don't see ads in threads. Register for your free account today and become a member of PhotoCamel to open up the site's many benefits and features.
__________________
┐ <░)))))><
jfrancho is offline   Reply With Quote
Reply

« PhotoCamel - Your Friendly Photography Forum > PhotoCamel Lounge > Photography Talk »


Share this topic:

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
Add Lens To My Rebel Or (GASP!) Go Digital? surfinwahine Canon 13 08-13-2006 04:55 AM
The Digital Lens Explained? Mr. Pickles Photography Talk 0 11-18-2005 12:40 PM
Digital cameras and the lens dilemma Petes Photography Talk 14 11-05-2005 01:46 PM