Macro strength? Stack macros?

[Carl Jakobsson]

Hi!

I wonder how many dioptres that generally is needed for most cameras to be able to zoom in enough on the groundglass. I've used a cheap magnifying glass so far that is 4 diopters, and I believe it's not enough. I have a dedal on one 3 diopter and one 4 diopter macro. Would stacking those two give satisfying results?

[Tim Johnson]

i believe 9-10 is the normal amount for your average minidv to focus on a gg screen.

[Carl Jakobsson]

Ok!

One more question, would the diameter of the macrolens make any difference - eg if I buy a 49mm macro does it give the same enlargement if I put it in front of a 37mm camcorder? Or is a 37mm macro to prefer, and in that case why?

To put it another way, should the macro have the same diameter as the camcorder it will be used with?

[Francois Poitras]

Carl, what camcorder are you using, and what is the distance between you cam and the GG? Some camcorders are able to zoom in and focus on the GG without a macro, provided the distance is right. The Panasonic GS400, and I suspect other models from the GS series, is an example.

[Carl Jakobsson]

Francois; Funny because one of the camcorders I use the most is one of the first 3CCD NV-GS (can't remember the number). It has problems zooming in and focusing even with a +5 magnifying glass.

I'll probably mostly use NV-GS camcorders, but I also have access to some really big Sony DVCAMs. Therefore I thought that maybe it's safer to buy a macro with a big diameter, so I can use it with different camcorders.

As I understand it's not good to have a too strong macrolens either, so therefore I think that maybe it's a good idea to have stacked macrolenses, so I can remove or add macros depending on the camcorder I use.

[Carl Jakobsson]

I should clarify that the adapter I'm building is supposed to be versatile to fit different cameras with different sized lenses, from small 37 mini-dvs to larger ~50 mm DCCAM-camcorders. That's really the reason why I'm considering buying larger 49 mm stackable threaded macros designed for SLRs rather than buying one macro for each camcorder.

[Francois Poitras]

Maybe you have an older model or your usable image frame is smaller. With the GS400, I can zoom in (about 3X) and focus on a 36mmx24mm frame between about 4-5cm from the camcorder.

I guess if you have other cams, it is indeed safer to use a macro or an achromat. Then, for better results, I suggest you use a good quality achromatic lens. Simple macros, especially stacked, tend to give bad CA and blur towards the edges.

[Carl Jakobsson]

Ok, I was considering Hoya macros, they can't be too bad. This http://www.waynesthisandthat.com/closeuplenses.html had some interested reading about stacking macros.

[Francois Poitras]

Good article. What he says about sharpness and distortion in the "what I learned from these experiments" section is interesting, and has been confirmed by many who tried macros.

It depends what you are after in terms of results. The Hoya macros are probably OK, but I think you would get even better results with a Century Optics (58mm, I think) or a Cinevate (72mm) achromatic lens. More expensive, obviously, but better.

[Bob Hart]

Affirming Francois comments.

For simply testing for framing and focus ability, a stack of Hoyas 1+, 2+ 4+ for 7+ , will give you a frame as tight as 24mm x 18mm at about 120mm from front of lens to GG for a PD150 or FX1.

Approx 70% + zoom-in is required depending on how large you want the frame on the GG to be.

The image colour however looks very muddy. Once you have the required power of the lens established by testing, then go for the acromatic of the same power.

I'm using the Century Optics +7 achromatic dioptre with 58mm filter thread mount. It works into the FX1 via a simple step-up ring 58mm to 72mm.

The 58mm mount face and the 72mm mount face should be on the same plane. It is helpful to drill two small holes in the adaptor ring to help remove it from the camcorder body if the dioptre comes out without bringing the ring with it.

I had to make my own. If you need to do this, the thread pitch for 58mm and 72mm is 0.7mm. Take care to dress the threads afterwards so there is no wearing action because the threads on the Sony cameras are plastic and will not take much abuse.

[Dennis Wood]

Up to +3 or so, my testing shows that single element macros are OK. Go beyond that, and CA/resolution loss becomes very obvious. I've seen a few adapters with two +10 Asians stacked which is a huge image degradation factor. There are too many factors to just figure out a single achromat for all cameras as each adapter (and it's internal optics) are different. Basically build it, then test with cheap macros. Once you know what's required, you can start shopping for achromats.

[Carl Jakobsson]

Thanks for all the replies! I took your advice and bought a cheap ($6 incl shipping!) "ITOREX 49 mm MACRO +10 JAPAN". It will be fun (or maybe not) to see what it does to the image.