I have always wondered about flash with a long exposure. Seems like the only advantage is that you can fill in your exposure with ambient light once the flash is off and the shutter still open. If you are shooting in a dark room, I don't see a lot of point in it. Big disadvantage in that you have li...

Most things that I have read have blamed purple fringing on overloading the microlenses at the front of the detector with light (CA at these lenses). sometimes blaming it on UV. there seems to be a lot of confusion about this effect online as it is commonly mixed around with just plain magenta/green...

Doing numerical testing has taught me a lot over the last couple years. I just wanted to say that your macro-range ematest results are very interesting and I am not aware of any other sites where this is done - congratulations. Very clear and informative. A post on what adaptations you needed to do...

Second test: Images shot back to back (no change except for those listed). First pic, like the samples in the test. Second pic, adding diffusion to the lighting. The fringe lessens considerably with the diffusion, suggesting to me that it represents purple fringing. Since this is supposed to be a de...

Here is an image of a measurement slide angled at about 20 deg. "0" is closer and "10" is farther. Shot at f/5.6. There is certainly a bit of Long CA at the focus plane with a bit of magenta fringing, but not a massive amount.

Interesting observation. I guess that there are two choices for the fringe on that image: 1: longitudinal CA: since the focus plain is higher on the relief of the coin, the fields are significantly behind the plane of focus. That opens the door for longCA. When you measure the CA with a target at th...

I haven't added any tests in a few weeks. haven't had a lot of time lately. Hopefully I will get a new one up sometime soon.

Doing numerical testing has taught me a lot over the last couple years.

I have gotten good results with older Componons. They have the advantage of an near round aperture (11+ blades). They are also very good optically.

Stack the PSD's. You're using Helicon then? Zerene doesn't accept PSD's (unless there's some capability I don't know about -- always a possibility!). --Rik Yes, I am using Helicon. Bought it a long time ago, before I knew Zerene existed. Helicon does just fine for the things I stack (coins, not par...

I shoot all RAW. I batch process the RAW images through Adobe Bridge. Batch the output from Bridge into PSD's (or TIFF if you want). Stack the PSD's. Takes very little time. Photoshop isn't used until after the stacking for resizing and such.

Even if they are slightly different, my BD objecive fits OK on my mitutoyo to c-mount adapter. That's good enough for me.

I have more problems with M39 threads being slightly different.

The Nikon BR-6 ring allows aperture control on G-series lenses when reversed. The ring opens the aperture. If you also attach a nikon AR-3 shutter release to the BR-6 you can control the aperture reasonably well. If you use the lock on the AR-3, you can stop the aperture down to wherever you want.

I feel like the spacing of the objective and the tube lens is important as Rik is alluding to. The off-axis rays coming in off-center will produce coma in the image (among other aberrations). If the tube lens is closer to the objective that will be minimized - likely a better situation for using a s...

As with all add-on macro lenses, the lens can be no better than the lens that it is working with. I have a DCR-250 and have found that it is quite good (about +6D) and in the same league as the Canon 250D, Nikon 6T. I find good add-on macro lenses to be interesting because they increase the magnific...

As long as the lens can adequately cover ther larger detector, the larger detector will slightly outperform the smaller detector in theoretical resolution even at the same megapixel rating with the same field of view. this advantage will be mainly at low magnification and will disappear as the magni...