| Author |
 Replies: 75 / Views: 10,219 |
|
|
|
Pillar of the Community
 2087 Posts |
OK that explains why the results seemed sharper. I had tried coupling lenses a while back I discovered very quickly that its not that easy to find good coupling combinations. The Oly 135 and this SK is very good. I just tried the Oly 80mm bellows lens with the SK and although the color performance is much better than the Oly 80mm with the Oly close up lens ( gives 2X magnification), on full frame there is very strong vignetting. The SK with the oly 80mm will work on APSc.
|
|
Pillar of the Community
2087 Posts |
I am quite impressed with the SK and Oly (135mm) coupling. Even though its only three times its producing results better than my previous experience of coupling lenses. To recover some of the losses from diffraction this is an image reduced to half size.  Edited by austrokiwi
08/21/2016 11:34 am
|
|
Pillar of the Community
Canada
2784 Posts |
austrokiwi like that one. that is very well done. I wonder if there is a diopter lens. that would do even close to this setup. have you ever tested diopter lens. to see there effect. what they produce in coin photography images. just wondering, nice work austrokiwi
|
|
Pillar of the Community
 United States
4038 Posts |
Looks good AK. The 2x-3x range is very tough to get good results because of the effective aperture tradeoff. Maybe the best way to go is with lens stacking. Might be good to compare some of the best lenses at 2-3x (the Canon 35MP; Nikon 95PN) vs a stacked arrangement like this.
Contact me for photographic equipment or visit my home page at: http://macrocoins.com |
|
Pillar of the Community
2087 Posts |
Quote:
I wonder if there is a diopter lens I have used a Raynox in the past, but I had the 505( may have the number wrong) it was useless on FF. I have the close up lens designed to go with the Oly 80mm that takes the lens out to 2X but the CA is bad. Quote:
Might be good to compare some of the best lenses at 2-3x Its a good idea, I have sold off my least performing lenses so I am probably not the person to do it. What I think would be useful is a thread( like the El Cheapo thread) that lists effective lens combinations for this kind of lens coupling. I know the mamiya 645 80mm macro with the Mamiya 645 35mm wide angle is a bad combination, as is the The SK 40/2.8 and the PN 105mm |
|
Pillar of the Community
2087 Posts |
While writing the previous post I suddenly realized I actually had a 210mm tube lens I could use right away. Its only suitable for Sony A mount users and E mount users who have one of the two available adapters. So for this test I converted my camera to a DSLr using Sony's LAEA 4 adapter( adds in a translucent mirror) the lens I used as a tube lens is the Minolta AF 70-210 F4 lens. Better known to most Minolta/Sony users as the "beer-can". I usually avoid zoom lenses for macro work because of the lens creep when mounted in a vertical rig. The beer-can focus's internally and I have never experienced zoom creep I didn't have high expectations of this combination. The Beer-can is loved by Minolta fans due to its unique color rendition ( canon and Nikon users tend to dislike it). So I was surprised to find the performance was much better than I anticipated. CA is less than in other trials. Only issue is some vignetting. Any Sony Alpha camera users should note that the following picture tells use that on APSc this coupling is very successful, for Full frame ( A99 and FE mount users) it still works but it isn't ideal. This trial has me wondering about the SK 210 coupling. the SK210 has a 72mm filter size ( the Beer-can has a 55 mm filter) although I expect Filter size is not the issue rather the optical design. The beer can is a fixed F4 lens. Working distance will read as restrictive(20mm) but due to the small diameter of the beer can combined with the shape of the reversed SK40/2.8 ( the SK 45/4 would work the same way) lighting is very easy to set up. Although Auto focus nailed the focus every time I tried, the following shot was taken using manual focus: I know a significant number of A mount users have the beer-can so this is a combination worth knowing about   Edited by austrokiwi
08/21/2016 12:35 pm
|
|
Pillar of the Community
2087 Posts |
I took a test stack. at 5.14X ( sk 40 coupled with Minolta Beer-can. I first tried at APsc, and the image area covered was so small I reverted back to FF capture. The vignetting in this case isn't too distracting. I forgot to use the blower so there are a couple of annoying hairs in the shot. I reduced it to a quarter of its original size. You can see one area where I hadn't set the start of the stack deep enough.  Edited by austrokiwi
08/21/2016 3:12 pm
|
|
Pillar of the Community
2087 Posts |
I have taken the first part of rmpsrmps's suggestion with coupling the 40/2.8 with my SK 210/5.6 large format enlarger lens. First off its a very workable combination. It still needs to be mounted on a bellows so as to set the SK210 to infinity focus. Here are some test shots( I didn't bother setting white balance) First the full resolution target picture, note the width of the area imaged is 7 mm( width of the sensor is 36mm):  The above shot was severely reduced for posting with the result there was some image degradation( despite using Bicubit sharper) so the following is a full size 100 % crop:  Single shot( non-stacked) of a penny( also substantially reduced in size):  May be next month I will get the 2X convertor. Edited by austrokiwi
08/31/2016 10:00 am
|
|
Pillar of the Community
United States
4038 Posts |
Looks good. My first reaction was "that's less than 5x" since I'm used to seeing the date and MM of a Cent fill the screen, but then I remembered you're shooting FF. The lower left corner looks sharp so coverage is good.
|
|
Pillar of the Community
2087 Posts |
Quote:
My first reaction was "that's less than 5x" That's the crop factor, from memory canon APSc has a 1.6 crop factor. If I have done the maths correctly; 5X on a canon APSc sensor will give the same field of view as 8X on a FF frame sensor..... So the 5.14X I was using has the same field of view as 3.2X on a canon APSc sensor. |
|
Pillar of the Community
2087 Posts |
Decent stacking attempt at 5X magnification. I was quite impressed with using the SK210 Enlarger lens as a tube lens. So to day I performed a full stack ( 43 images) of a New Zealand medal. I was very pleased with the result. Although I can get the 5X with just a bellows the SK 210 as a Tube lens produces a much sharper image. I am really determined to find a suitable 2X teleconvertor now to try it at 10X. Here is the image from today. It was reduced by half to counteract some of the unavoidable diffraction artifacts.  Bottom left corner evidences that I didn't set the start of the stack deep enough. Edited by austrokiwi
09/06/2016 10:45 am
|
|
Pillar of the Community
Canada
2784 Posts |
austrokiwi when you use the sk 210 as a tube lens. how do you have every thing mounted. a image would be nice to see the setup. that is a very good photo I like it. I have just received my Z focus block. I will try some of this soon.
|
|
Pillar of the Community
2087 Posts |
Here is what it looks like set up. The 40/2.8 is reversed and mounted onto the 210/5.6 via a 43mm-52mm stepping ring attached to a 52mm-72mm coupling ring. The SK 210 is mounted on a bellows which is adjusted so that the SK 210/5.6 is at infinity focus. The silver ring is the adapter for mounting the 210/5.6 to my bellows {I don't have a fancy way of setting infinity focus I simply point the lens and bellows at an object across the road from our house ( about 100 meters away) and adjust the bellows until that object is in focus.} |
|
Pillar of the Community
2087 Posts |
This morning I looked at the 5X stack again and was not happy I checked the settings and realized I had set the step increment too high. I will repeat the stack later I expect to see a significant improvement in IQ
|
|
Pillar of the Community
2087 Posts |
yes I had set the stacking step increment too large. here is a better stack: SK 40/2.8 coupled to SK 210/5.6  |
| |
Replies: 75 / Views: 10,219 |
First Page
Previous Page
Posted 08/21/2016 07:30 am
