Possible alternative to barlows/teleconverters (1 Viewer)

[Paul Corfield]

Canon 100-200mm (FD mount) arrived today. Another nice low power telenegative in this lens. Mounting as close to the camera as possible it gives me 1.55X and it is sharp right to the corners. I photographed a brick wall keeping everything as square as possible and the corner detail was still very good, no smearing or stretching of the detail.

Here's a few images. The Chiffchaff is uncropped and then a crop showing detail. Range was around 12m (40 feet).

Speckled Wood butterfly is uncropped from around 10m (30 feet).

Paul.

 

[Musoman]

That is excellent - the stock of decent TN's is building up nicely.

 

[Paul Corfield]

Putting a teleneg behind a normal lens doesn't behave like a normal teleconverter would. It acts more like a barlow and you lose the ability to focus more than about 40cm away. I have my Sunagor 100-200mm teleneg permanently glued into an empty teleconverter housing and yesterday I tried it out behind my Pentax SMC 50mm f1.7 lens.

On the scope the 100-200mm teleneg gives a 1.5X increase in mag. However, placing it behind my 50mm lens gave me a 3X increase in mag taking my 50mm lens to 150mm and it made a useful macro type lens due to the close focusing restriction.

Here's two uncropped photos taken from the exact same range, one without and one with the TN.

Paul.

 

[alphan]

Another discovery to put the TN to more use? Paul, you are full of imagination and excellent at them. I currently do not have any prime lens on hand but got two on the way. Does the near focus increase the magnification or the magnification remain the same? The objective when mounted in front of my 75-300 at 300mm, the magniufication ration goes up to something like 4:1 but the glare was just too much. I find that above 2:1, the glare start to wash out the object.

 

[goldenarrow]

distortion with 80mm TN

As Paul suggested, there is more distortion with the higher Mag telenegatives. The pic was taken with my Tamron 103A TN and you can see the outer 25% all the way around has color aberrations and distortion, especially towards the edge. Nice in the center though, and if in focus, can highlight the "portrait" effect. Also, not bad for a used Celestron Onyx 80mm EDF tripod mounted, f/6.25+TN???, 1/750th sec., 400 ISO. Shake Reduction was turned off.

I will move on, however, to 100mm TN's. I have two now but won't have time for it until the weekend.

 

[goldenarrow]

TN vs. non-TN crops

At least in this case, it seems cropping has a slight edge over using a Canon 100-200 FD telenegative. The first pic is with the TN, the second one without and, even if allowing for some variation in camera shake, the contrast and resolution seems better without the TN.

Some light post processing was done to both pics, the exact same steps for each. TN mounted in a cheap Chinese extension tube, is giving me 1.92x magnification. I must have mine mounted further in than Paul does (1.55x mag). Distance to target is 79 feet according to Google Earth. TN was at 1/20th sec., without 1/90th - perhaps the reason for the better resolution right there. The contrast was better too, so a second reason to believe that the TN is not up to pro quality. Sorry, the EXIF data got stripped-out when converted from .TIF to .JPG.

The difference is slight, however, after a little extra post processing, so it might come in handy if I need the extra reach and don't want to crop for some reason, like very high ISO or dark conditions, or both. Just drawing my own conclusions, your own results might be different.

I do have two other pics that show that I can read the license plate from my car from about 490 feet away. Again, cropping was slightly better in both resolution and contrast than this particular TN. Color rendition was excellent in both.

I might try other tests but have very limited time.

 

[Paul Corfield]

I'd say there's too much camera shake in the first image to be able to draw any conclusions at all.

I have mine mounted as close to camera as possible and it's a nice push fit in the rear of an empty Prinzflex teleconverter tube. I don't think it would go much closer without hitting the mirror.

TN's, barlows and similar things need some degree of baffling to bring them in line with the contrast the scope produces on its own. With all those things being equal then it's mainly down to range, size of the subject etc as to what type of extra mag is necessary. A tiny bird at 100 feet would need the TN where as a large bird at the same range would probably be fine with cropping.

I know for a fact that all my 100-200mm TN's will perform equally as well as my Kenko Pro 300 1.4X teleconverter so in that respect they are a great money saver.

Paul.

 

[goldenarrow]

contrast and other things

I'd say there's too much camera shake in the first image to be able to draw any conclusions at all.

I have mine mounted as close to camera as possible and it's a nice push fit in the rear of an empty Prinzflex teleconverter tube. I don't think it would go much closer without hitting the mirror.

TN's, barlows and similar things need some degree of baffling to bring them in line with the contrast the scope produces on its own. With all those things being equal then it's mainly down to range, size of the subject etc as to what type of extra mag is necessary. A tiny bird at 100 feet would need the TN where as a large bird at the same range would probably be fine with cropping.

I know for a fact that all my 100-200mm TN's will perform equally as well as my Kenko Pro 300 1.4X teleconverter so in that respect they are a great money saver.

Paul.

Baffling, yes, very good point. I will have to work on this aspect. Did not do anything to the extension tube housing and would explain a weird "glow" I had gotten on a different picture. But it also brings up a point of how much "fine-tuning" these TN adapters need. We need to start thinking in terms of the quality of workmanship, which I am not that great at. It is also time consuming (at first).

Camera shake is something I need to revisit. The ISO was set too low (only 140), the previous set was some flower pics. I will do the test again at 400 or 800.

Mounting close to the camera body should not be a limiting factor in terms of quality, just magnification and slightly dimmer. I do not see any problem in the pics with the TN in terms of magnification. Actually, I like the slightly higher mag. There is probably a limit to how much a TN can magnify before introducing color problems. The 2X Baader VIP Barlow is known in astronomy circles to start seeing degradation of image at about 2.8x, or so I have read. These cheap TN's can't be much different.

With the two changes listed above, higher ISO and baffling, I should see some good improvement. It might be a week or more since I would like to get some nice baffling paper used in telescope making.

Thanks again for the tips!

:eat:

 

[Paul Corfield]

I suppose at first it takes a few goes to know what you are doing. I got a Sunagor 70-150mm lens today. I had the teleneg out and into a macro tube, all baffled and I was taking photos within maybe 10 minutes of getting the lens. For baffling I tend to use the matt black tubes that I've kept from lenses that I've stripped down in the past.

I'll post some photos later as this new one is a first class teleneg and this seems to be the norm with Sunagor lenses. It's high power, sharp and flat to the corners which up till now has been rare for high power ones as they tend to go soft in the corners.

Paul.

 

[goldenarrow]

I suppose at first it takes a few goes to know what you are doing.

Ah, it also helps to be a talented artist/artisan such as yourself. I tend to be fumble-fingers at everything - you can do certain mechanical things 10x faster than I can. I also really do need a secure connection and cannot handle a temporary or flimsy setup. I tend to destroy/break anything that does not have a more permanent "finished product" connection, just from simple everyday usage. The only reason I keep trying is that I like saving money more than the frustration of not being successful at such things. Will keep trying. Now I need to find flocking paper, which I hear is better than just painting the inside of the extension tube flat black......

Would love to hear how much magnification you are getting from the latest 70mm TN.

:-O

 

[Paul Corfield]

The new Sunagor 70-150mm teleneg is giving me approximately 2.4X magnification when I mount it very close to the camera. I'd say with normal mounting it would be around 2.6X or slightly above and the image is nice and flat.

I did a test comparing it with the Canon 1.55X and also with the scope on its own at a range of approx 115 feet. The target is some television aerial wire which is about 8mm in diameter and the writing is only 3 or 4mm high. The three photos all have the same treatment which was some basic sharpening, no levels have been adjusted. The crops show that the telenegs resolve more detail as their mag increases.

Personally I find that the telenegs will start to out perform the scope at around 10m (32 feet) when the detail is very fine.

Paul.

 

[Paul Corfield]

Another test, this time with a bank note at just 5m range (16 feet).

The detail is very similar but on an equal sized crop it still gets better as the mag increases.

Paul.

 

[Aegea]

Amazing difference in the rendition of the sky between the Sunagor and the Canon. I've noticed some color changes using different TC's, but that is pretty extreme! Did you use auto white balance or a preset?

 

[Musoman]

I'd guess that they were just taken at different times

 

[Paul Corfield]

That's just passing white/grey cloud.

Paul.

 

[goldenarrow]

Now we are getting somewhere!

Baffling, yes, very good point. I will have to work on this aspect.... how much "fine-tuning" these TN adapters need.

The first two test pics are from an actually sunny sunset evening yesterday. Went to the same area and shot without, then with the Canon TN. These are untouched pics, just screenshots of the conversions from RAW files. The contrast is still slightly lower but much improved. Had lined the inside of my adapter with black electrical tape to cover up one of the ring adapters that was quite shiny. The shutter speed is still not the best, not sure how to improve that without getting a much higher ISO camera or much better tripod. I know my tripod head is loose and definitely want to get a new one with a pistol-grip type of function.

Bird is a quick shot with the TN, also without software enhancements. Will have to work on my aim, but things are looking much improved.

|:d|

 

[goldenarrow]

Just to correct a mistake, the Test2 pic with the TN is 1/250th sec.

 

[alphan]

Just received a Canon 75-150 FD. Easy to remove TN and should give 1.9X magnification but because I did not mount it very close to camera, it's giving 2X now.

Attached a few shots of an Stork Bill KF from around 15M, with 80ED and crop, 80ED + 2X and crop and 80ED + 2.3X TN and crop. All photos resized to document size. No other processing done and taken in JPEG mode.

 

[alphan]

Exceeded the maximum 5 photos so the last photo here.

 

[kurakura]

Paul you have pushed the market... I cannot get any 100-xxx lenses below 40GBP sent to Denmark

Was hoping to collect a lens barrel and a teleneg for when I get a scope