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Old Dec 4, 2003, 9:29 AM   #1
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Default Minolta A1 vs Nikon 5700 II: Lens Converters

Hi All,

This is my second post regarding the operation issues of 5700 vs. A1. Again, I will only concentrate on "operational" issues and will not touch upon image quality of the cameras and lenses. My previous posts can be found here:
The third one has been somewhat controversial. However, all theories that I have heard cannot explain the problem well I reported. From conversations I had with some real experts in this area, the problem is not so simple. So, if you are not interested in knowing some AF issues in a very odd situation, you might want to skip part 3 above.

The 5700 and A1 both have very high quality lenses. Using any lower quality converters reduces overall image quality. As a result, I only look at some of the best quality converter lenses. Both Nikon and Olympus offer the best converters, while Minolta have none. Nikon's 5700 uses a very strange thread size 50mm that nobody even bothers to supply step rings. Fortunately, Nextphoto at www.nextphoto.net has a popular adapter Coolfix 5700 that can fix this problem. This adapter has two threads, the inner one is 50mm for Nikon's converters, while the outer one has a commonly used 62mm size.

Since Coolfix is mounted on the body of the 5700, it is very sturdy and offers a protection of the camera lens. The Minolta A1 SLR type lens has a commonly used 49mm thread. Unfortunately, mounting a heavy converter lens on this 49mm thread may break the lens barrel if the combo is handled improperly. Well, I am not sure if the lens barrel WILL break or not; it looks very scary with a large and heavy converters mounted. Thus, when using such a combo, hold the converter lens rather than the camera body or camera lens. See the image below for examples.

(1) Fisheye:
Both Nikon and Olympus have fisheye lenses. If my recollection is correct, Olympus has one and Nikon has two (one for the 9xx, 4500 and 5000 series and the other for the 5400 and 5700). The Nikon fisheye lens FC-E8 has a 28mm thread and is not suitable for 5700 and A1. Thus, we only use FC-E9, the one for 5400 and 5700. To mount FC-E9 on the 5700, a special adapter UR-E12 is needed. Since the A1 has a 49mm thread and the FC-E9 has a 46mm rear thread, a 49-46mm step-down ring is needed to use FC-E9. This is shown in the image below. The FC-E9 projects an image circle smaller than A1's image frame. However, one can zoom the lens in to about 35mm (i.e., the design focal length of the 5700) to have an image circle that touches the top and bottom edges. Note that this zooming DOES NOT change the angle of view which is greater than 180 degree. It only brings the image "closer." One can zoom the lens further to have a full-frame fisheye image. If you don't mind the distortion a fisheye lens produces, a full-frame fisheye image can be considered as a result obtained by an ultra-wide angle lens!

(2) Wide Angle:
Nikon has WC-E80 and the Olympus has WCON-08B. Both are 0.8X wide angle converters. The Nikon WC-E80 can be used on the 5700 with Nikon's UR-E8 adapter or Coolfix 5700 adapter. Due to its odd thread size, the WC-E80 cannot be used with Minolta A1. Fortunately, since the Olympus WCON-08B has a 62mm thread, it can be used with the 5700 using Coolfix 5700 adapter and the A1 with a 49-62mm step-up ring. Note that if you wish to use the WCON-08B, you'd better buy a thin step-up ring. A thicker one may cause vignetting. Since most wide angle adapters are designed for 35mm focal length, the most popular focal length among consumer level digicams, it is very likely that vignetting may occur when they are used with the A1 at the 28mm focal length. This is especially true if you use a thick step-up ring or more than one step-up rings. The focal length of the combo (i.e., WCON-08B and A1) is 22.4mm. The following image shows a WCON-08B on a A1.

(3) Telephoto:
There are more options here. Again, Nikon's high quality TC-E15ED 1.5X can only be used on the 5700. There are three more excellent tele converters, Olympus TCON-14B 1.4X, Olympus TCON-17 1.7X and Sony VCL HGD1758 1.7X. All of these three tele converters can be used on both 5700 and A1. For the 5700, the best solution is again Nextphoto's Coolfix 5700. Since TCON-14B has a 62mm thread, the 5700 plus Coolfix 5700 does not need any extra ring. However, the 5700 plus Coolfix combo will need a 62-55mm step-down ring and a 62-58mm step-down ring to use Olympus TCON-17 and Sony HGD 1758, respectively. On the other hand, the A1 will need 49-62, 49-58 and 49-55 step-up rings to use TCON-14B, Sony HGD1758 and Olympus TCON-17, respectively. The TCON-14B and Sony HGD1758 are large and heavy. The TCON-17 is lighter but longer, and may cause a slight and visible corner light fall-off. The TCON-14B, TCON-17 and Sony HGC1758 have rear glass diameters 47mm, 38mm and 42mm, and the A1 has a front glass diameter 40mm. As a result, the maximum image circle projected onto the A1 lens by TCON-17 is smaller than the front lens element of the A1. Since the camera does not use the maximum image circle projected by a converter, the TCON-17 would only cause a slight and visible light fall-off.

The following images show TCON-14B, TCON-17 and Sony HGD1758 on a Minolta A1. From these images, one can see that these high quality tele converters are *BIG* and *HEAVY* compared with A1's size and weight.

Any converter mounted on a camera will cause some light loss. Fortunately, all of the above mentioned converters do not cause significant light loss. I would say that light loss is un-noticeable. Since the A1 can only use one wide angle converter WCON-08B, I will not get into the quality issue. As for tele converters, IMO, the
best is TCON-14B, although its power is 1.45X according to its documentation. The TCON-17 has a slight edge over the Sony HGD1758; but the former has corner light fall-off.

Nikon does have a very nice wide angle converter for Coolpix 5000, the WC-E68 0.68X. This converter can bring the Coolpix 5000 to 19mm ultra wide, the only combo of all digicams that can go as wide as 19mm. Note that this WC-E68 is a wide angle converter rather than a semi-fisheye. This converter has a rear 46mm thread. Unfortunately, it will cause serious and unusable vignetting (with the use of a 49-46 step-down ring).

The following table is a summary.
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