Close-up lens as a Condenser

[U_Jeen]

Hello.
I have to apgrade my DIY spinning adapter with a condenser. So I have a question. Can I use a Close-up macro lens +1 or +2 as a condenser?

[stevenbruce]

Hello.
I have to apgrade my DIY spinning adapter with a condenser. So I have a question. Can I use a Close-up macro lens +1 or +2 as a condenser?

That would not be strong enough, most people use a condenser lens around +9.

Close up lenses are not great for condensers, I use a DCX lens which only cost $3 and the results are pretty good.

Read the section on condensers in my adapter tutorial, i link to the one i use there.

http://stevenbrace.co.uk/35mm/

[U_Jeen]

Thanks a lot. But it's a trouble to buy a 4$ lens in the USA, because the shipping to Russia will cost a lot. Will the lens from simple magnifying glass (loupe) suite?

[Ted Ramasola]

as a DIY adapter maker and user, I have been that route.

First try is magnifying lens. -WONT WORK
2nd try close up lens. -WONT WORK
3rd try Achromat from india. - full of CA and soft edges.

What works.
CINEVATE, REDROCK and SGPRO achromats.

If your in europe, get in touch with wayne kinney at sgpro, hes in UK.

[U_Jeen]

I'm not in Europe, I'm at the Far EAST of Russia. It is near China and Japan.
The Cinecity was the nearest achromat supplier to me. Indian achromat is not the best, but it suites me at the moment. It does not reduce vinetting (and as far as I understand it should not).
It's my first adapter and I want to reduce vinetting first of all. I tried to put the achromat instead of condencer and approximately the result suited me, but I could not focus with the camera on the GG. So I need something as a condenser and I can't find anything suitable. So, the only thing I can try at the moment is close-up lens or magnifying glass.
Tomorrow I'll do the test with the Resolution Chart and post some Images.

[Ted Ramasola]

You must realize that the function of the achromat is different as a condenser lens.

a condenser lens controls the falloff of image luminance to your gg or cam lens, depending on where you position your condenser in the chain, thus enabling you
to control the amount of vignette in your image.

The close up filter you speak of can allow you to focus on objects near to the camera lens just like the achromat. BUT, the similarity ends where the achromat is designed to remove chromatic aberrations on your image.

Some designers INCORPORATE a condenser WITH an achromat and not a condenser only design.

I would however recommend not to add several elements in the optical chain to minimize further image diffusion.

Your inability to focus on your gg is also partly due to these factors.

Your achromat distance from the gg and your achromat power.

This distance is determined by the power of your achromat.

What id the distance of your achromat to gg?

A friend of mine in australia provided me this comparative chart;

3+------approx 10 inches
4+------approx 8 in
7+------approx 5 in
10+----approx 3 in

in my set up i have 2. 3/4 inch distance from gg to achromat lens.

I have no vignetting (40mm to 200mm) even without a condenser.

Check the extreme sides of your image and corners. shoot a chart or black text on white back ground.
You will notice either softness on edges of your frame or a green/purple fringe aka CA on the indian achromat. Its much worse using a close up filter.

I think on my tests the indian achromat has a distance of more than 3 inch from achromat thus indicating it is lower power than as advertised as 10+.



Ted

[U_Jeen]

I realise the difference between Close-up and achromat. Before I started my DIY project, I've read aloust every topic about 35mm adapters on this forum, on hv20.com and some russian forums. At the beginning I refused to use a close-up and ordered an Indian Achromat. To say the truth I can't see terrible CA with it. The distance GG->Achromat is 62mm. That is 2.48 in. If i get further or closer, the image suffers optical distortion. I've put achromat instead of the condensor just to find if some macro lens can help. And it helps. But it is very hard to find a lens supplier in Russian. And ordering from the USA is expensive. Let me post some tests to continue our conversation.

[U_Jeen]

Here is the first pic from the resolution chart.
http://www.dvxuser.com/V6/picture.php?albumid=159&pictureid=1035
Few moments I want to mention:
-yes, there are lines from the GG, because it's a laser matted GG for adapter adjustment only;
-yes, the optical axis is displaced a little, because camera mount is not ready at the moment;
The image is flipped. So I have a question.
Why only the half of the image suffers CA?
Left side
http://www.dvxuser.com/V6/picture.php?albumid=159&pictureid=1036
Right side
http://www.dvxuser.com/V6/picture.php?albumid=159&pictureid=1037
Centre
http://www.dvxuser.com/V6/picture.php?albumid=159&pictureid=1038
Could it be because of the displaced optical axis?

And I forgot to mention my SLR lens. It's old Micro-Nikkor 55mm 1/2.8
http://kamera-boerse.com/os/catalog/images/n55m_1.JPG

[U_Jeen]

Indian achromat is about +9

[Ted Ramasola]

ok, the CA on the other side is there, but its not bovious. one reason is the type of rez chart your using has a dominant gray back which hides this. I have used this in my early development stages too. I recommend you use the charts commonly used for HD tests in this forum.
The chart you use was designed for SD 4:3 ratio as well, also, due to its gray circular matting, you cant detect very well the vignette on the image.

please PM me your email so i will send you a PDF file of the rez chart so you can print it and use it for your tests. The chart i'll send you is better suited for testing edge to edge performance of your setup.

Ted

[U_Jeen]

I shot an outdoor video today and found the reason of my troubles. It's GG first of all, because the image suffers not vinetting but hotspot. It can be seen perfectly while shooting the sky.
http://www.dvxuser.com/V6/picture.php?albumid=159&pictureid=1041
Thanks to teddybear for help. Later I'll shoot the test with new Resolution chart.

[bwwd]

Do you have properly diffused ground glass ? If its too transparent then this could be the reason of hotspot.What happens if you stop down lens all the way ,is it dark and center is dark too or do you have bright point in the center ? If you have this point then your ground glass needs to be more diffused.
Also take out your ground glass and adjust distance between camera and condenser , this is not easy to explain... if you take off ground glass when you are on zoom then you should not see any black circle in your image,there should be only image from lens with more Field of view thanks to condenser ,if you see black circle then you must adjust distance between camera ,condenser and lens until it disappear.You can adjust it without ground glass.

[U_Jeen]

But I still don't have a condenser. I started this thread to find out what kind of lens I can use as a condenser. I'm going to solve the problem with the GG diffusion, then if the image suffers problems I'll continue adapter ajustment using a condenser.

[bwwd]

Well condenser is needed to enlarge field of view ,ihave 70mm condenser and 80 something focal lenght.So picture is quite big on it and i can zoom in.
I have also smaller condenser and it doesnt give as much field of view as bigger one.I dont know whats the main reason of this.Adapter without condenser is not really adapter.Unles its with focusing screen from camera,they have built in condenser and achromat.
Good ground glass is most important thing in adapter.

[U_Jeen]

I've posted my first test video.
http://www.vimeo.com/4738480