Possible alternative to barlows/teleconverters (1 Viewer)

alphan · Oct 14, 2010

Paul, your first shot is indeed over exposed but I think there are also elements of OOF. The lost of light seems quite high with the elements as expected but I think the one with macro extension came out the best. Do you stack the front element together with the telenegative or spaced apart?

Fernando, that front element act like a diopter lens or similar to Raynox macro add-on? What magnification did you get?

thornlv, all looks nice but I think your DOI came out more crisp. That 150-500 shot looks like toy camera shot when you put them together with the 80ED.

BTW, can somebody advice on how to do multiple quote with reply?

FernandoBatista · Oct 14, 2010

alphan said:
Fernando, that front element act like a diopter lens or similar to Raynox macro add-on? What magnification did you get?

Yes, I also have the raynox dcr250 and cosina's slightly weaker, about 6.5 or 7 diopters. In the case of the cosina 100-300 front lens, the quality is weaker, since the lens is not so good, but better lenses can make for much better closeups. I tried the front element of my Nikkor 180mm ED AiS and it's great, of course I didn't dismantled that lens for that, I was cleaning the inside and tried it for curiosity.

alphan said:
BTW, can somebody advice on how to do multiple quote with reply?

I usually just copy/paste the quote tags, and place them on the text I want to quote. But if you use the advanced reply box, there's a button on top that does just that, third button counting from the right, at left of the cardinal button.

Paul Corfield · Oct 14, 2010

Here's a photo showing the new mounting method which includes the front objective lens and the telenegative group mounted together in a macro tube. This Miranda lens gives 1.7X magnification using this method and if I take the objective lens out it goes up to around 2.2X. The front element is quite a nice push fit into the macro tube, almost made for each other.

Photo of the Long Tailed Tit taken with the 1.7X and was from around 9m (30feet). Photo is uncropped.

Paul.

Paul Corfield · Oct 14, 2010

Later on today I altered the mounting method that I showed in my last post. I've now mounted the Miranda objective lens inside it's own macro tube just so I can easily split the two. That gives me just the telenegative as a 2.2X converter or when combined with the objective lens it now gives a 1.5X converter.

Also because the objective lens from the Miranda 75-300mm zoom seems to reduce magnification I decided to try it on my Kenko 1.4X. This turns the Kenko into a focal reducer and takes the scope down from 600mm to 480mm F6.

So just one zoom lens which cost £1.00 has provided me with three very useful tools which would normaly cost at least a few hundred pounds.

Paul.

thornlv · Oct 15, 2010

Great LTT pic, I wonder if the focal reduction method reduces minimum focus as well.

Am bidding on some Nikon lenses as quoted on Ken Rockwell's site as being some of the best super sharp lenses, typically low power - 18-55mm etc

Vic

alphan · Oct 15, 2010

[QUOTEI usually just copy/paste the quote tags, and place them on the text I want to quote. But if you use the advanced reply box, there's a button on top that does just that, third button counting from the right, at left of the cardinal button.][/QUOTE]

Thanks for tips. But I do not understand the part "copy/paste the quote tags". Am I doing the right thing with the second part?

(Edited) Oops!!! wrong somewhere....

So just one zoom lens which cost £1.00 has provided me with three very useful tools which would normaly cost at least a few hundred pounds.

Paul, would adding more glasses reduce optical performance? Is there any particular piece of glass from the zoom lens which will increase the FL with minimum elements? Minor distortion should be acceptable for birding.

Am bidding on some Nikon lenses as quoted on Ken Rockwell's site as being some of the best super sharp lenses, typically low power - 18-55mm etc

What the way to go. What about the old Zeiss lenses?

Paul Corfield · Oct 15, 2010

thornlv said:
Great LTT pic, I wonder if the focal reduction method reduces minimum focus as well.

Am bidding on some Nikon lenses as quoted on Ken Rockwell's site as being some of the best super sharp lenses, typically low power - 18-55mm etc

Vic

Small zooms seem to be a different configuration compared to the larger zooms. I don't know if it applies to all of them but the other day I got an old Vivitar 28-70mm and there was nothing in it I could find to use. I made sure it was in a mount that I could use on my Canon via an adapter just in case the lens was no good for stripping down.

Adding the extra element as I did for the LTT lets you focus down to just a few meters. For further away I can get away with no extension tubes in the scope at all.

Paul.

Paul Corfield · Oct 15, 2010

alphan said:
Paul, would adding more glasses reduce optical performance? Is there any particular piece of glass from the zoom lens which will increase the FL with minimum elements? Minor distortion should be acceptable for birding.
What the way to go. What about the old Zeiss lenses?

The front objective lens from the zooms tend to only be two elements and the telenegative group would only be two or three elements. 5 elements in total is very acceptable. A Kenko Pro 1.4X is 5 elements in two groups for example.

The piece of glass from the zoom that increases focal length is the telenegative group, typically giving around 2.3X. The other nice thing about the telenegative is that they are so thin allowing you to make a powerful teleconverter only about 1.5cm thick.

Zeiss lenses are expensive, but feel free to buy some and save me some money

Paul.

thornlv · Oct 15, 2010

So Paul, In your opinion what has been the best configuration you have tried so far.

FernandoBatista · Oct 15, 2010

Paul Corfield said:
Also because the objective lens from the Miranda 75-300mm zoom seems to reduce magnification I decided to try it on my Kenko 1.4X. This turns the Kenko into a focal reducer and takes the scope down from 600mm to 480mm F6.

That's something really useful too. Shooting in a blind most of the times, I sometimes wish I could backup when bigger birds then expected appear. This is a very nice solution for that. Good find.

FernandoBatista · Oct 15, 2010

alphan said:
Thanks for tips. But I do not understand the part "copy/paste the quote tags". Am I doing the right thing with the second part?

(Edited) Oops!!! wrong somewhere....

You put the “]” in the wrong place

You wrote “[quoteI usually just….” And it should be “

username said:
I usually just….”

The copy/paste thing is something I’m used to do, but probably not the simplest way.
The simplest way to do multiple quotes I think it’s copying the text you want to quote into your reply, and use the quote button as you did now. But you should also use the name of the person you’re quoting too.
For example, when you use the quote button it will only add the

around the selected text, you can then put

username said:

to make it simpler to know who you’re quoting.

Click to expand...

Click to expand...

Paul Corfield · Oct 15, 2010

thornlv said:
So Paul, In your opinion what has been the best configuration you have tried so far.

The Vivitar, Sigma and Miranda telenegatives all gave about the same magnification/sharpness but there were slight differences in depth of field and maybe edge softness although I found edge softness to be very acceptable, no worse that barlows/teleconverters for example.

For now I'm sticking with the Miranda, only because the front element on the lens I purchased was intact. The Sigma one I got cheap because the lens was damaged. The Vivitar front element is a strange arrangement and once removed from the lens the elements have some play and move maybe half a mm in and out.

As far as what was best, I've not really been able to separate all three apart from the Vivitar had slightly less depth of field than the other two.

I shall buy some more as I see them and keep trying stuff out.

Paul.

alphan · Oct 16, 2010

FernandoBatista said:
That's something really useful too. Shooting in a blind most of the times, I sometimes wish I could backup when bigger birds then expected appear. This is a very nice solution for that. Good find.

I haven't had problem of too big a bird to shoot when near, but did encountered a few times when they are too near to focus. Last sunday found a few Pygmy White Eye some 3m away which would have beautifully almost fill up the frame but alas, cannot get in focus. Should find something to reduce minimum without additional extension tube or beyond what the extension tube can do. BTW, thanks for the quote tips.

Paul, Zeiss lens will only be cheap if certain part are damaged. Just keep an eye for them to pop up especially Contax mount. Would any elements from a prime tele lens act like TCs?

Paul Corfield · Oct 16, 2010

alphan said:
Paul, Zeiss lens will only be cheap if certain part are damaged. Just keep an eye for them to pop up especially Contax mount. Would any elements from a prime tele lens act like TCs?

I suppose it depends what you want stretch to. I'm only looking to pay around £5 for a lens and I've got around 30 on my watch list at the minute. A faulty Zeiss will go for maybe £20 or £30, maybe more if it's a rarer one. There's an example here, already got 4 bids and the it's cheapest Zeiss zoom on there at the moment. I suppose if you are careful in the dismantling then it can be put back together and resold if.

As far as I know prime lenses don't need the telenegative group that we find in zooms. Any prime I've ever taken apart hasn't had anything useful to put on the scope.

I've been looking at a few exploded diagrams of lenses and there tends to be 3 or 4 elements in the telenegative group.

Paul.

alphan · Oct 18, 2010

Paul Corfield said:
I suppose it depends what you want stretch to. I'm only looking to pay around £5 for a lens and I've got around 30 on my watch list at the minute. A faulty Zeiss will go for maybe £20 or £30, maybe more if it's a rarer one. There's an example here, already got 4 bids and the it's cheapest Zeiss zoom on there at the moment. I suppose if you are careful in the dismantling then it can be put back together and resold if.

As far as I know prime lenses don't need the telenegative group that we find in zooms. Any prime I've ever taken apart hasn't had anything useful to put on the scope.

I've been looking at a few exploded diagrams of lenses and there tends to be 3 or 4 elements in the telenegative group.

Paul.

Thanks Paul for enlightening me. So what would be the better affordable zoom that we can possibly use? When I mean affordable, means faulty lens condition since we would not be using those parts which normally gets damaged.

Paul Corfield · Oct 18, 2010

Fernando, thanks for the tip about using the front element as a macro lens. Here's a photo taken with my Pentax 50mm f1.7 and the Miranda zoom front element placed on the front of the Pentax. Spider is a false widow or steatoda nobilis

Alphan - I'd just try any lenses you can get hold of, you never know what they will turn up. I won a Praktica 80-200mm today on ebay so that will be my next one to dismantle. I've got a few on my watch list ending tomorrow as well.

Paul.

alphan · Oct 19, 2010

Paul, what's your original magnification and magnification after adding the front element? It may perform differently with different lens. My Raynox 250 gives 2:1 magnification on the 18-70 kit lens but only 1:3 with my upgraded 16-105.

Without any zoom arriving yet, I can only wait. I do have a few older minolta lenses waiting for disposal but they cost too much. Will continue to look out for more affordable lenses to grab and try.

Will all who tried, post their (your) findings here so that others will know what to watch out for and what to expect so that we can progress faster with our project.

Paul Corfield · Oct 19, 2010

alphan said:
Paul, what's your original magnification and magnification after adding the front element? It may perform differently with different lens. My Raynox 250 gives 2:1 magnification on the 18-70 kit lens but only 1:3 with my upgraded 16-105.

With the front element lens added to the front of my Pentax 50mm it allows me to get within 3 or 4 inches of the subject. Without the lens I can only get to within about 16 inches so the big gain is allowing me to get very close. In that respect there is a big gain in magnification.

On this lens I can't compare what the before and after is because the maximum distance using the front element is less than the minimum distance when not using the element. I can't take a photo from a distance where the two methods cross over.

On my 18-55mm Canon kit lens I can do a comparison and I get a 40% increase in size from the same range. See photos, both taken from same range of approx 20cm.

Paul.

Paul Corfield · Oct 19, 2010

This seller always seems to have a lot of faulty lenses for sale that start at low prices.

http://shop.ebay.co.uk/gggcam/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p4340

Paul.

alphan · Oct 20, 2010

Paul Corfield said:
With the front element lens added to the front of my Pentax 50mm it allows me to get within 3 or 4 inches of the subject. Without the lens I can only get to within about 16 inches so the big gain is allowing me to get very close. In that respect there is a big gain in magnification.

On this lens I can't compare what the before and after is because the maximum distance using the front element is less than the minimum distance when not using the element. I can't take a photo from a distance where the two methods cross over.

On my 18-55mm Canon kit lens I can do a comparison and I get a 40% increase in size from the same range. See photos, both taken from same range of approx 20cm.

Paul.

Then this front element have similar characteristic as the Raynox 250 which cost me quite a bit. When mine arrive, I will salvage both front and telenegative, sell of my Raynox which should easily recover my cost for the TC adventure LOL.

Looking into that seller's auctions. Would be interested in a few items.

Possible alternative to barlows/teleconverters (1 Viewer)

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