Good 300mm lenses for use with Nikon CFI 10X?

[martincito]

I'm driving myself nuts chasing around eBay searching for the perfect 300mm lens to use with my Nikon CFI 10X objective. I already use a Canon 100mm 2.8L macro lens and a Nikkor 200mm f4 and would like to try a step up. My preference would be the lightest, shortest, cheapest option that still gives excellent results with the Nikon objective.
I'd appreciate any suggestions or comments, please.
Best wishes,
Martin

[Ichthyophthirius]

Hi Martin,

Have you read about the reverted Raynox DCR as tube lenses (i.e. the 208mm version)? The price is unbeatable. http://www.photomacrography.net/forum/v ... hp?t=23898
http://www.photomacrography.net/forum/v ... hp?t=18145

[enricosavazzi]

I'm driving myself nuts chasing around eBay searching for the perfect 300mm lens to use with my Nikon CFI 10X objective. I already use a Canon 100mm 2.8L macro lens and a Nikkor 200mm f4 and would like to try a step up. My preference would be the lightest, shortest, cheapest option that still gives excellent results with the Nikon objective.
I'd appreciate any suggestions or comments, please.
Best wishes,
Martin

A 300 mm tube lens can be used, but don't forget that the NA of the objective remains the same. In other words, you are going to get a higher magnification but not a correspondingly higher real detail. With a modern DSLR, you may be getting close to the point where the added magnification is empty magnification.

I have a Mitutoyo FS-60 scope with a 200-400 mm zoom tube lens, and at the 400 mm end the image gets quite dark, and detail is noticeably less good than at 200 mm. 300 mm is practically as far as I use it. It might be a better idea to get a 15x (if available) or 20x objective with a higher NA, and shoot stacks with a higher number of pictures.

[martincito]

Thanks for your replies!

Raynox DCR as tube lenses

I think the DCR-150 gives about same magnification as my Nikon 200mm f4 lens, which I'm happy with (at the moment).

300 mm tube lens can be used, but don't forget that the NA of the objective remains the same

The Nikon objective has a NA of 0.25. With that NA would there be ANY advantage of using a 300mm tube lens? They are usually cheaper on eBay than good quality objectives.

[Greenfields]

The Nikon objective has a NA of 0.25. With that NA would there be ANY advantage of using a 300mm tube lens? They are usually cheaper on eBay than good quality objectives.

Probably not, to be honest.

You could use a 1.4x teleconverter with your 200mm lens. That would produce 14x magnification on the sensor which is close to 15x magnification of a 300mm tube lens, but a dimmer image = longer exposures.

The teleconverter magnifies the central area of the field of the 10x objective. If you use a full frame sensor you will see some extra detail in the centre of the image if that it really what you are looking for because the centre of the 10x will out-resolve a FF sensor.

Another way of saying what Enrico Savazzi has said is that because the 10x out-resolves a full-frame sensor the image it produces in the centre of its frame looks very sharp.

With a 300mm tube lens the balance between the resolving power of the sensor and the objective changes and you are more limited by the objective, so the bit of extra resolution will look disappointingly soft because the extra fine detail close to the limit of the resolution of the lens is being captured at a "just noticeable" low contrast. Increasing the contrast in post increases noise.

If you are using a smaller than full-frame sensor you probably have a higher photosite density so are already closer to the limit of resolution of the objective.

Basck to the Raynox: I once used a Nikkor 200mm f/4 Ai-S as a tube lens for both Nikon and Mitutoyo objectives and was pleased with the results. However, in my experience the Raynox is even better, especially close to the edges of the field on a full frame sensor. So if you do use a full-frame camera it is worth trying the Raynox.

Henry

[martincito]

Thanks for this. I'm using an APS-C T3i for stacking, so I think the message is think about a new objective rather than a 300mm lens.

[rjlittlefield]

Thanks for this. I'm using an APS-C T3i for stacking, so I think the message is think about a new objective rather than a 300mm lens.

Yes, on that camera the sensor already out-resolves the objective even at 10X, where it has effective f/20. If you push it to 15X and f/30, the improvement in captured detail will be minimal.

--Rik