4" F/7 ED refractor

[tico]

Hello,

Perhaps a banal question, but can someone tell me if the 4" F/7 ED refractor could be a good generalist telescope, a bit of planetary, lunar, double and single DSO, Messier type?
Does it usually take a long time to cool down?
How do you see it to put it on top of an AZ mount?
Thank you
titic.

Edited November 15, 2023 by Cornelius Varley
background colour to text removed

[dweller25]

Yes, a 4” is a good choice for all the objects you list.

Sharp and quick to cool, lightweight too and very easy to use.

It will sit happily on the Skywatcher AZ4 mount.

The Starfield 4” F/7 sold by Firstlight Optics is a good choice.

Here is my 4” on an equatorial mount.

Edited November 14, 2023 by dweller25

[Stu]

To me there is nothing better for all those. The main limitation is obviously aperture for deep sky, but for everything else; convenience, quick cool down, lunar, planetary, doubles, widefield deep sky, white light solar in particular with a wedge, a 4” doublet apo is hard to beat.

I had some time, although not a lot this evening, and have mine out getting some wonderful views of Jupiter. The seeing is not brilliant, but not disastrous either and a 4” cuts through it very nicely.

The Starfield scopes are highly regarded and very well priced.

 

[RobertI]

What they said. ☝️ Four inches doesn’t seem much, but the 4” refractor just seems to hit the spot in so many ways. I have six scopes, but use the 4” refractor ninety percent of the time. 

[Mr Spock]

A 4" is the scope I use the most often, though I prefer an EQ mount to AZ. It takes my 12" to beat them on planetary and I prefer the views to my 8".

Here's the two I've used. Each at a different price point but I can recommend both and neither will disappoint. 

 

[John]

Another thumbs up for the quality 4 inch refractor from me. I seem to have collected a couple of them over the years and both get well used. 

[mikeDnight]

2 hours ago, tico said:

Hello,

Perhaps a banal question, but can someone tell me if the 4" F/7 ED refractor could be a good generalist telescope, a bit of planetary, lunar, double and single DSO, Messier type?
Does it usually take a long time to cool down?
How do you see it to put it on top of an AZ mount?
Thank you
titic.

Quick to cool down. During the warmer months a 4" will work perfectly straight from the house, but on those cold winter nights you might need to wait for 15 mins for a doublet to become thermally stable. A triplet may take a little longer. It's not a problem if you spend the first few minutes observing with a low power eyepiece  just to pass the time. Personally  I'm an equatorial fan and a 4" F7 is easy to man-handle on a Vixen GP or SW EQ5, but its a great size scope for an AZ4 or similar altazimuth mount too.

Edited November 13, 2023 by mikeDnight

[Sunshine]

You can never go wrong with a good 4" refractor, they are the equivalent of a woodsman's pocket knife or a mechanics adjustable wrench. They don't have the light gathering punch for the faint objects but you'll find yourself reaching for it often, we love our 4" refractors. @Stu made mention of the Starfield refractors, I have looked through both the 102 and the 115 models and I can say they were impressive at their price points.

 

Edited November 14, 2023 by Sunshine

[Nicola Fletcher]

I can also recommend them. I have two 4” refractors and they are fantastic all rounders and very quick to cool. They are great on planets, the moon and brighter DSOs. You can also get lots of larger objects into one field of view with a low power eyepiece (the double cluster and the Andromeda galaxy are two of my favourites). If you can get to a dark sky, you’ll be amazed what you can see through it!

I have two alt-az mounts: the Skywatcher AZ-EQ5 when I want GoTo (photo below) but mostly a manual alt-az for simplicity (I use a Giro Ercole mini on a carbon fibre tripod). I also have an equatorial mount which works very well but I prefer the alt-az personally.

Hope this helps!

Edited November 14, 2023 by Nicola Fletcher

[Stu]

10 minutes ago, Nicola Fletcher said:

I can also recommend them. I have two 4” refractors and they are fantastic all rounders and very quick to cool. They are great on planets, the moon and brighter DSOs. You can also get lots of larger objects into one field of view with a low power eyepiece (the double cluster and the Andromeda galaxy are two of my favourites). If you can get to a dark sky, you’ll be amazed what you can see through it!

I have two alt-az mounts: the Skywatcher AZ-EQ5 when I want GoTo (photo below) but mostly a manual alt-az for simplicity (I use a Giro Ercole mini on a carbon fibre tripod). I also have an equatorial mount which works very well but I prefer the alt-az personally.

Hope this helps!

Very nice scopes Nicola. Out of interest, why have two such similar setups, do you find each better for certain things?

[Nicola Fletcher]

1 minute ago, Stu said:

Very nice scopes Nicola. Out of interest, why have two such similar setups, do you find each better for certain things?

The honest answer is because I was given the Tak as a gift and I am too sentimental to sell the Starwave 😊

But it’s also because I rate the Starwave so highly. I like its big focuser and I can put a RDF and another finder on it at the same time. It’s very sturdy and the sliding dew shield is great (something I don’t think is shared on the Tak - I hate the sliding dew shield on the DZ and I wish they’d just put a fixed one on like their other smaller refractors). I like going to public outreach events and sometimes it’s nice to have two setups going if there are not a lot of scopes available. I do prefer the views through the Tak but I don’t think there is a huge difference between them. Not sure if that’s enough of a justification but I’ll cling to it anyway!

[Stu]

7 hours ago, Nicola Fletcher said:

The honest answer is because I was given the Tak as a gift and I am too sentimental to sell the Starwave 😊

But it’s also because I rate the Starwave so highly. I like its big focuser and I can put a RDF and another finder on it at the same time. It’s very sturdy and the sliding dew shield is great (something I don’t think is shared on the Tak - I hate the sliding dew shield on the DZ and I wish they’d just put a fixed one on like their other smaller refractors). I like going to public outreach events and sometimes it’s nice to have two setups going if there are not a lot of scopes available. I do prefer the views through the Tak but I don’t think there is a huge difference between them. Not sure if that’s enough of a justification but I’ll cling to it anyway!

That all makes total sense. The focusers on these types of scopes are so much better than the standard Tak offering in my opinion, that’s why I have FTs on mine! Even then there is no easy way of attaching a finder so I have to put a shoe on one of the tube rings. Not rotatable either 🤪 how hard is it 🤣

Thinking about it, I have three four inch scopes and somehow manage to justify that to myself, however illogical 🤪

Meet Geoffrey, Phil and Florence….

FC-100DC f7.4 - fab all rounder, very portable

Televue Genesis f5 - beautiful flat wide field up to 5 degrees

Vixen FL102S f8.8 - just because. Lovely for higher power planetary and double with the longer focal length

The FC is the one which gets most use and travels around with me. I don’t want the Genesis to get a knock as the collimation is perfect currently, and the Vixen is SO much bigger than the Tak that it needs a bigger mount.

 

[Mr Spock]

2 minutes ago, Stu said:

The focusers on these types of scopes are so much better than the standard Tak offering in my opinion, that’s why I have FTs on mine!

Yep, I felt a huge step down when I moved from the Starfield to the Tak. So disappointing. Even the inexpensive Astro Essentials dual speed I have fitted to the 120 is a step up from the Tak focuser! The Tak has only come back from FLO yesterday after having the focuser tweaked.

However, expensive as it is, I do have an FT on order (up to 4 months delivery) so I can enjoy my scope to the fullest.

[Nicola Fletcher]

7 minutes ago, Stu said:

Thinking about it, I have three four inch scopes and somehow manage to justify that to myself, however illogical 🤪

It’s interesting to see how different 4” scopes can be and the different mounting requirements. Something to consider for definite when choosing one!

I agree there are a lot of reasons the Starwave/Starfield etc is so popular. I really like mine and would hate to part with it. The 4” Taks are also excellent and all are fairly lightweight which is an important consideration.

But if I had that Genesis or the Vixen, I don’t think I’d part with them either! Beautiful scopes 👍🏻

[Saganite]

My 4" is the only scope in my possession that I would never part with and If I could keep  only one of my telescopes , this would be it, does everything....🙂

 

Edited November 14, 2023 by Saganite

[JeremyS]

I love 4” refractors. I have two: Tak FS 102 (getting on for 25 years) and an FC 100DZ.

Having said that, the TSA 120 is a step up, yet not that much bulkier that the FS 102.

 

[davidc135]

Two refurbished 4'' scopes, a B&L 4000 and a 1985 Tak FC100. 

I was comparing the Airy discs from an artificial star in the garden and noticed serious astigmatism in the FC100. Luckily, rotating one lens relative to the other resolved the problem. Hopefully I'll soon get the opportunity to try out the Tak on the heavens.

Edit. In answer to how to attach a scope to an Alt Az mount, the Skytee accepts either a dovetail or two sizes of machine screw. Here 2 M8 x 1.25mm socket head screws secure the Tak OTA cradle

David

Edited November 14, 2023 by davidc135

[Stu]

2 hours ago, Mr Spock said:

However, expensive as it is, I do have an FT on order (up to 4 months delivery) so I can enjoy my scope to the fullest.

Well worth it, the fine focus makes such a difference for high powered observing.

Which one have you ordered, FTF2025BCR? I use the A20-304 adaptor on mine.

[Stu]

1 hour ago, davidc135 said:

Two refurbished 4'' scopes, a B&L 4000 and a 1985 Tak FC100. 

I was comparing the Airy discs from an artificial star in the garden and noticed serious astigmatism in the FC100. Luckily, rotating one lens relative to the other resolved the problem. Hopefully I'll soon get the opportunity to try out the Tak on the heavens.

Edit. In answer to how to attach a scope to an Alt Az mount, the Skytee accepts either a dovetail or two sizes of machine screw. Here 2 M8 x 1.25mm socket head screws secure the Tak OTA cradle

David

Very nice to see these older scopes still in use and being maintained 👍

[Stu]

2 hours ago, Nicola Fletcher said:

The 4” Taks are also excellent and all are fairly lightweight which is an important consideration.

Agreed. As much as performance, the compact lightweight nature of the DC is one of its main strengths for me. I’m sure the Starfield/Wave scopes run them pretty close optically.

[Stu]

2 hours ago, Nicola Fletcher said:

But if I had that Genesis or the Vixen, I don’t think I’d part with them either! Beautiful scopes 👍🏻

I rarely use them, but can’t see myself selling them as they are such lovely examples. I’ll make a point of getting some use out of them if we get some decent clear nights 🤞

[bosun21]

Another thumbs up 👍 for a 4" refractor. I am very happy with my Starfield 102 and it's my most used scope by far. I have looked at possibly buying a Tak but I doubt my aging eyes would really see much of a difference between them. Never say never though. I really have to fight myself some nights to give one of my other scopes an airing.

[Mr Spock]

27 minutes ago, Stu said:

Well worth it, the fine focus makes such a difference for high powered observing.

Which one have you ordered, FTF2025BCR? I use the A20-304 adaptor on mine.

Ordered an FTF2025BCR focuser with an A20-304 Adapter! Looking forward to it. I didn't get on well with the MEF3, which I will be selling shortly.

[IB20]

The 102ED f7 is a wonderful scope with exceptionally good optics. I’m having a great deal of fun with mine especially for planetary and doubles observing. It’s built incredibly well, I even quite like the rotating focuser now. It sits very nicely on an AZ4 but I have recently upgraded to the AZ75 which is a match made in heaven. 

 

[John]

9 hours ago, Mr Spock said:

Ordered an FTF2025BCR focuser .....

I have one of those on my 130 TMB/LZOS F/9.2. Lovely focuser 👍

Having looked at the new listing I can't believe the price they have reached though 😬